AWS Lambda - Developer Guide

AWS Lambda - Developer Guide
AWS Lambda
Developer Guide
AWS Lambda Developer Guide
AWS Lambda: Developer Guide
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AWS Lambda Developer Guide
Table of Contents
What Is AWS Lambda? ....................................................................................................................... 1
When should I Use Lambda? ....................................................................................................... 1
Are You a First-time User of AWS Lambda? ................................................................................... 2
Lambda Functions .............................................................................................................................. 3
Compute Requirements – Lambda Function Configuration ................................................................ 3
Invocation Types ........................................................................................................................ 4
Building Lambda Functions .......................................................................................................... 5
Authoring Code for Your Lambda Function ............................................................................. 5
Deploying Code and Creating a Lambda Function ................................................................... 6
Monitoring and Troubleshooting ............................................................................................ 7
AWS Lambda-Based Application Examples ............................................................................ 7
Related Topics ................................................................................................................... 8
Programming Model ............................................................................................................ 8
Creating a Deployment Package ......................................................................................... 58
Versioning and Aliases ...................................................................................................... 73
Environment Variables ....................................................................................................... 85
VPC Support ............................................................................................................................ 92
Configuring a Lambda Function for Amazon VPC Access ........................................................ 92
Internet Access for Lambda Functions ................................................................................. 93
Guidelines for Setting Up VPC-Enabled Lambda Functions ..................................................... 93
Tutorials: Accessing Resources in an Amazon VPC ............................................................... 94
Troubleshooting and Monitoring ................................................................................................. 103
Troubleshooting Scenarios ................................................................................................ 104
Accessing CloudWatch Metrics .......................................................................................... 105
Accessing CloudWatch Logs ............................................................................................. 106
Metrics ........................................................................................................................... 107
Dead Letter Queues ........................................................................................................ 109
Building Applications with AWS Lambda ............................................................................................. 111
Example 1 .............................................................................................................................. 112
Example 2 .............................................................................................................................. 113
Example 3: Custom Application Publishes Events and Invokes a Lambda Function ............................ 114
Event Source Mapping ............................................................................................................. 116
Event Source Mapping for AWS Services ........................................................................... 116
Event Source Mapping for AWS Stream-based Services ....................................................... 117
Event Source Mapping for Custom Applications ................................................................... 119
Supported Event Sources ......................................................................................................... 120
Amazon S3 .................................................................................................................... 121
Amazon DynamoDB ........................................................................................................ 121
Amazon Kinesis Streams ................................................................................................. 121
Amazon Simple Notification Service ................................................................................... 121
Amazon Simple Email Service .......................................................................................... 122
Amazon Cognito ............................................................................................................. 122
AWS CloudFormation ...................................................................................................... 123
Amazon CloudWatch Logs ............................................................................................... 123
Amazon CloudWatch Events ............................................................................................. 123
AWS CodeCommit .......................................................................................................... 123
Scheduled Events (powered by Amazon CloudWatch Events) ................................................ 124
AWS Config ................................................................................................................... 124
Amazon Echo ................................................................................................................. 124
Amazon Lex ................................................................................................................... 125
Amazon API Gateway ...................................................................................................... 125
Other Event Sources: Invoking a Lambda Function On Demand ............................................. 125
Sample Event Data ......................................................................................................... 125
Deploying Lambda-based Applications ........................................................................................ 133
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Deploying Serverless Applications Using AWS CloudFormation ..............................................
Using the AWS Serverless Application Model (AWS SAM) .....................................................
Create Your Own Serverless Application .............................................................................
Automating Deployment of Lambda-based Applications .........................................................
How It Works .................................................................................................................................
How Does AWS Lambda Run My Code? The Container Model ......................................................
Concurrent Executions .............................................................................................................
Concurrent Execution Request Rate ..................................................................................
Concurrent Executions Limit .............................................................................................
Retries on Errors ....................................................................................................................
Permissions Model ..................................................................................................................
Manage Permissions: Using an IAM Role (Execution Role) ....................................................
Manage Permissions: Using a Lambda Function Policy .........................................................
Execution Environment .............................................................................................................
Environment Variables Available to Lambda Functions ..........................................................
Getting Started ...............................................................................................................................
Step 1: Set Up an AWS Account and the AWS CLI ......................................................................
Step 1.1: Set Up an Account ............................................................................................
Step 1.2: Set Up the AWS CLI ..........................................................................................
Step 2: Create a HelloWorld Lambda Function and Explore the Console ..........................................
Preparing for the Getting Started .......................................................................................
Step 2.1: Create a Hello World Lambda Function .................................................................
Step 2.2: Invoke the Lambda Function ...............................................................................
Step 2.3: (Optional) Create a Lambda Function Authored in Java ............................................
Step 2.4: (Optional) Create a Lambda Function Authored in C# ..............................................
Step 3: Create a Simple Microservice using Lambda and API Gateway ............................................
Next Step .......................................................................................................................
Step 3.1: Create an API Using Amazon API Gateway ...........................................................
Step 3.2: Test Sending an HTTPS Request ........................................................................
Step 3.3: (Optional) Try Other Blueprints ............................................................................
What's Next? ..................................................................................................................
Use Cases .....................................................................................................................................
Amazon S3 ............................................................................................................................
Tutorial ..........................................................................................................................
Amazon Kinesis ......................................................................................................................
Tutorial ..........................................................................................................................
Amazon DynamoDB ................................................................................................................
Tutorial ..........................................................................................................................
AWS CloudTrail ......................................................................................................................
Tutorial ..........................................................................................................................
Amazon SNS ..........................................................................................................................
Tutorial ..........................................................................................................................
Amazon API Gateway ..............................................................................................................
Using AWS Lambda with Amazon API Gateway (On-Demand Over HTTPS) .............................
Mobile Backend (Android) ........................................................................................................
Tutorial ..........................................................................................................................
Scheduled Events ...................................................................................................................
Tutorial ..........................................................................................................................
Custom User Applications ........................................................................................................
Tutorial ..........................................................................................................................
AWS [email protected] (Preview) .........................................................................................................
How It Works .........................................................................................................................
Authoring Functions for [email protected] ......................................................................................
Permissions ............................................................................................................................
Testing and Debugging ............................................................................................................
Simple Setup ..........................................................................................................................
[email protected] Limits ..............................................................................................................
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API Logging with AWS CloudTrail ......................................................................................................
AWS Lambda Information in CloudTrail ......................................................................................
Understanding AWS Lambda Log File Entries .............................................................................
Best Practices ................................................................................................................................
Limits ............................................................................................................................................
List of AWS Lambda Limits ......................................................................................................
AWS Lambda Limit Errors ........................................................................................................
Authentication and Access Control .....................................................................................................
Authentication .........................................................................................................................
Access Control .......................................................................................................................
Overview of Managing Access ..................................................................................................
AWS Lambda Resources and Operations ...........................................................................
Understanding Resource Ownership ..................................................................................
Managing Access to Resources ........................................................................................
Specifying Policy Elements: Actions, Effects, Resources, and Principals ...................................
Specifying Conditions in a Policy .......................................................................................
Using Identity-Based Policies (IAM Policies) ................................................................................
Permissions Required to Use the AWS Lambda Console ......................................................
AWS Managed (Predefined) Policies for AWS Lambda .........................................................
Customer Managed Policy Examples .................................................................................
Console Permissions .......................................................................................................
Using Resource-Based Policies (Lambda Function Policies) ...........................................................
Allow Amazon S3 to Invoke a Lambda Function ..................................................................
Allow Amazon API Gateway to Invoke a Lambda Function ....................................................
Cross-Account Scenario ...................................................................................................
Retrieve a Lambda Function Policy ....................................................................................
Remove Permissions .......................................................................................................
Working with Lambda Function Versioning, Aliases, and Permissions ......................................
Lambda API Permissions Reference ..........................................................................................
Policy Templates .....................................................................................................................
Basic: 'Basic Lambda Permissions' ....................................................................................
VPCAccess: 'Lambda VPC Access Permissions' ..................................................................
Kinesis: 'Lambda Kinesis stream poller permissions' .............................................................
DynamoDB: 'Lambda DynamoDB stream poller permissions' ..................................................
Edge: 'Basic Edge Lambda permissions' .............................................................................
RedrivePolicySNS: ‘Dead letter queue SNS permissions’ .......................................................
RedrivePolicySQS: 'Dead letter queue SQS permissions' ......................................................
CloudFormation: 'CloudFormation stack read-only permissions' ..............................................
AMI: 'AMI read-only permissions' .......................................................................................
KMS: 'KMS decryption permissions' ...................................................................................
S3: 'S3 object read-only permissions' .................................................................................
Elasticsearch: 'Elasticsearch permissions' ...........................................................................
SES: 'SES bounce permissions' ........................................................................................
TestHarness: 'Test Harness permissions' ............................................................................
Microservice: 'Simple Microservice permissions' ...................................................................
VPN: 'VPN Connection Monitor permissions' .......................................................................
SQS: 'SQS Poller permissions' ..........................................................................................
IoTButton: 'AWS IoT Button permissions' ............................................................................
RekognitionNoDataAccess:'Amazon Rekognition no data permissions' .....................................
RekognitionReadOnlyAccess: 'Amazon Rekognition read-only permissions' ..............................
RekognitionWriteOnlyAccess: 'Amazon Rekognition write-only permissions' ..............................
API Reference ................................................................................................................................
Actions ..................................................................................................................................
AddPermission ................................................................................................................
CreateAlias .....................................................................................................................
CreateEventSourceMapping ..............................................................................................
CreateFunction ...............................................................................................................
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DeleteAlias .....................................................................................................................
DeleteEventSourceMapping ..............................................................................................
DeleteFunction ................................................................................................................
GetAccountSettings .........................................................................................................
GetAlias .........................................................................................................................
GetEventSourceMapping ..................................................................................................
GetFunction ....................................................................................................................
GetFunctionConfiguration .................................................................................................
GetPolicy .......................................................................................................................
Invoke ...........................................................................................................................
InvokeAsync ...................................................................................................................
ListAliases ......................................................................................................................
ListEventSourceMappings .................................................................................................
ListFunctions ..................................................................................................................
ListVersionsByFunction ....................................................................................................
PublishVersion ................................................................................................................
RemovePermission ..........................................................................................................
UpdateAlias ....................................................................................................................
UpdateEventSourceMapping .............................................................................................
UpdateFunctionCode .......................................................................................................
UpdateFunctionConfiguration .............................................................................................
Data Types ............................................................................................................................
AccountLimit ...................................................................................................................
AccountUsage ................................................................................................................
AliasConfiguration ............................................................................................................
DeadLetterConfig ............................................................................................................
Environment ...................................................................................................................
EnvironmentError ............................................................................................................
EnvironmentResponse .....................................................................................................
EventSourceMappingConfiguration .....................................................................................
FunctionCode .................................................................................................................
FunctionCodeLocation ......................................................................................................
FunctionConfiguration ......................................................................................................
VpcConfig ......................................................................................................................
VpcConfigResponse ........................................................................................................
Document History ............................................................................................................................
AWS Glossary ................................................................................................................................
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AWS Lambda Developer Guide
When should I Use Lambda?
What Is AWS Lambda?
AWS Lambda is a compute service that lets you run code without provisioning or managing servers. AWS
Lambda executes your code only when needed and scales automatically, from a few requests per day
to thousands per second. You pay only for the compute time you consume - there is no charge when
your code is not running. With AWS Lambda, you can run code for virtually any type of application or
backend service - all with zero administration. AWS Lambda runs your code on a high-availability compute
infrastructure and performs all of the administration of the compute resources, including server and
operating system maintenance, capacity provisioning and automatic scaling, code monitoring and logging.
All you need to do is supply your code in one of the languages that AWS Lambda supports (currently
Node.js, Java, C# and Python).
You can use AWS Lambda to run your code in response to events, such as changes to data in an Amazon
S3 bucket or an Amazon DynamoDB table; to run your code in response to HTTP requests using Amazon
API Gateway; or invoke your code using API calls made using AWS SDKs. With these capabilities, you
can use Lambda to easily build data processing triggers for AWS services like Amazon S3 and Amazon
DynamoDB process streaming data stored in Amazon Kinesis, or create your own back end that operates
at AWS scale, performance, and security.
You can also build serverless applications composed of functions that are triggered by events and
automatically deploy them using AWS CodePipeline and AWS CodeBuild. For more information, see
Deploying Lambda-based Applications (p. 133).
For more information about the AWS Lambda execution environment, see Lambda Execution Environment
and Available Libraries (p. 152). For information about how AWS Lambda determines compute resources
required to execute your code, see Compute Requirements – Lambda Function Configuration (p. 3).
When Should I Use AWS Lambda?
AWS Lambda is an ideal compute platform for many application scenarios, provided that you can write your
application code in languages supported by AWS Lambda (that is, Node.js, Java, C# and Python), and run
within the AWS Lambda standard runtime environment and resources provided by Lambda.
When using AWS Lambda, you are responsible only for your code. AWS Lambda manages the compute
fleet that offers a balance of memory, CPU, network, and other resources. This is in exchange for flexibility,
which means you cannot log in to compute instances, or customize the operating system or language
runtime. These constraints enable AWS Lambda to perform operational and administrative activities on
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Are You a First-time User of AWS Lambda?
your behalf, including provisioning capacity, monitoring fleet health, applying security patches, deploying
your code, and monitoring and logging your Lambda functions.
If you need to manage your own compute resources, Amazon Web Services also offers other compute
services to meet your needs.
• Amazon Elastic Compute Cloud (Amazon EC2) service offers flexibility and a wide range of EC2 instance
types to choose from. It gives you the option to customize operating systems, network and security
settings, and the entire software stack, but you are responsible for provisioning capacity, monitoring fleet
health and performance, and using Availability Zones for fault tolerance.
• Elastic Beanstalk offers an easy-to-use service for deploying and scaling applications onto Amazon EC2
in which you retain ownership and full control over the underlying EC2 instances.
Are You a First-time User of AWS Lambda?
If you are a first-time user of AWS Lambda, we recommend that you read the following sections in order:
1. Read the product overview and watch the introductory video to understand sample use cases.
These resources are available on the AWS Lambda webpage.
Read the "How It Works" section of this guide. This section introduces various AWS Lambda
components you work with to create an end-to-end experience. For more information, see How It
Works (p. 146).
2. Review the “Lambda Functions” section of this guide. To understand the programming model and
deployment options for a Lambda function there are core concepts you should be familiar with. This
section explains these concepts and provides details of how they work in different languages that you
can use to author your Lambda function code. For more information, see Lambda Functions (p. 3).
3. Try the console-based Getting Started exercise. The exercise provides instructions for you to create
and test your first Lambda function using the console. You also learn about the console provided
blueprints to quickly create your Lambda functions. For more information, see Getting Started (p. 155).
4. Read the "Building Applications with AWS Lambda" section of this guide. This section introduces
various AWS Lambda components you work with to create an end-to-end experience. For more
information, see Building applications with AWS Lambda (p. 111).
Beyond the Getting Started exercise, you can explore the various use cases, each of which is provided with
a tutorial that walks you through an example scenario. Depending on your application needs (for example,
whether you want event driven Lambda function invocation or on-demand invocation), you can follow
specific tutorials that meet your specific needs. For more information, see Use Cases (p. 169).
The following topics provide additional information about AWS Lambda:
•
•
•
•
AWS Lambda Function Versioning and Aliases (p. 73)
Troubleshooting and Monitoring AWS Lambda Functions with Amazon CloudWatch (p. 103)
Best Practices for Working with AWS Lambda Functions (p. 274)
AWS Lambda Limits (p. 275)
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Compute Requirements – Lambda Function Configuration
Lambda Functions
After you package up your custom code, including any dependencies, and upload it to AWS Lambda, you
have created a Lambda function.
If you are new to AWS Lambda, you might ask: what type of code can I run as a Lambda function? How
does AWS Lambda execute my code? How does AWS Lambda know the amount of memory and CPU
requirements needed to run my Lambda code? The following sections provide an overview of how a
Lambda function works.
Depending on your scenario, you can build applications where you use the AWS Lambda service to run all
or parts of your application code. For more information, see Building Lambda Functions (p. 5). How It
Works (p. 146) provides examples that illustrate how to create a Lambda function for specific scenarios.
The sections in this topic provide the following introductory information about Lambda functions:
Topics
• Compute Requirements – Lambda Function Configuration (p. 3)
• Invocation Types (p. 4)
• Introduction: Building Lambda Functions (p. 5)
• Configuring a Lambda Function to Access Resources in an Amazon VPC (p. 92)
• Troubleshooting and Monitoring AWS Lambda Functions with Amazon CloudWatch (p. 103)
Compute Requirements – Lambda Function
Configuration
A Lambda function consists of code and any associated dependencies. In addition, a Lambda function also
has configuration information associated with it. Initially, you specify the configuration information when
you create a Lambda function. Lambda provides an API for you to update some of the configuration data.
Lambda function configuration information includes the following key elements:
• Compute resources that you need – You only specify the amount of memory you want to allocate for
your Lambda function. AWS Lambda allocates CPU power proportional to the memory by using the same
ratio as a general purpose Amazon EC2 instance type, such as an M3 type. For example, if you allocate
256 MB memory, your Lambda function will receive twice the CPU share than if you allocated only 128
MB.
You can update the configuration and request additional memory in 64 MB increments. For information
about relevant limits, see AWS Lambda Limits (p. 275).
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Invocation Types
To change the amount of memory your Lambda function requires, do the following:
1. Sign in to the AWS Management Console and navigate to the AWS Lambda console.
2. Choose the function whose memory size you wish to change.
3. Click the Configuration tab and then expand Advanced settings.
4. In the Memory (MB) list, choose your desired amount.
Optionally, you can update the memory size of your functions using the following AWS CLI command
(using valid 64 MB increments):
$ aws lambda update-function-configuration \
--function-name your function name \
--region region where your function resides \
--memory-size memory amount \
--profile adminuser
For information on setting up and using the AWS CLI, see Step 1: Set Up an AWS Account and the AWS
CLI (p. 155).
• Maximum execution time (timeout) – You pay for the AWS resources that are used to run your
Lambda function. To prevent your Lambda function from running indefinitely, you specify a timeout.
When the specified timeout is reached, AWS Lambda terminates your Lambda function.
• IAM role (execution role) – This is the role that AWS Lambda assumes when it executes the Lambda
function on your behalf.
• Handler name – The handler refers to the method in your code where AWS Lambda begins execution.
AWS Lambda passes any event information, which triggered the invocation, as a parameter to the
handler method.
Invocation Types
AWS Lambda supports synchronous and asynchronous invocation of a Lambda function. You can control
the invocation type only when you invoke a Lambda function (referred to as on-demand invocation). The
following examples illustrate on-demand invocations:
• Your custom application invokes a Lambda function.
• You manually invoke a Lambda function (for example, using the AWS CLI) for testing purposes.
In both cases, you invoke your Lambda function using the Invoke (p. 351) operation, and you can specify
the invocation type as synchronous or asynchronous.
However, when you are using AWS services as event sources, the invocation type is predetermined for
each of these services. You don't have any control over the invocation type that these event sources use
when they invoke your Lambda function. For example, Amazon S3 always invokes a Lambda function
asynchronously and Amazon Cognito always invokes a Lambda function synchronously. For stream4
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Building Lambda Functions
based AWS services (Amazon Kinesis Streams and Amazon DynamoDB Streams), AWS Lambda polls the
stream and invokes your Lambda function synchronously.
Introduction: Building Lambda Functions
You upload your application code in the form of one or more Lambda functions to AWS Lambda, a compute
service, and the service can run the code on your behalf. AWS Lambda takes care of provisioning and
managing the servers to run the code upon invocation.
Typically, the lifecycle for an AWS Lambda-based application includes authoring code, deploying code to
AWS Lambda, and then monitoring and troubleshooting. The following are general questions that come up
in each of these lifecycle phases:
• Authoring code for your Lambda function – What languages are supported? Is there a programming
model that I need to follow? How do I package my code and dependencies for uploading to AWS
Lambda? What tools are available?
• Uploading code and creating Lambda functions – How do I upload my code package to AWS
Lambda? How do I tell AWS Lambda where to begin executing my code? How do I specify compute
requirements like memory and timeout?
• Monitoring and troubleshooting – For my Lambda function that is in production, what metrics are
available? If there are any failures, how do I get logs or troubleshoot issues?
The following sections provide introductory information and the Example section at the end provides
working examples for you to explore.
Note
This topic provides an introductory overview of how you develop AWS Lambda-based applications.
The How It Works (p. 146) section describes the specifics about Lambda functions, event
sources, and how AWS Lambda executes your Lambda functions.
Authoring Code for Your Lambda Function
You can author your Lambda function code in the languages that are supported by AWS Lambda. For a list
of supported languages, see Lambda Execution Environment and Available Libraries (p. 152). There are
tools for authoring code, such as the AWS Lambda console, Eclipse IDE, and Visual Studio IDE. But the
available tools and options depend on the following:
• Language you choose to write your Lambda function code.
• Libraries that you use in your code. AWS Lambda runtime provides some of the libraries and you must
upload any additional libraries that you use.
The following table lists languages, and the available tools and options that you can use.
Language
Tools and Options for Authoring
Code
More Info
Node.js
• AWS Lambda console
You can use the console if the
languages you choose do not require
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Deploying Code and Creating a Lambda Function
Language
Tools and Options for Authoring
Code
More Info
• Visual Studio, with IDE plug-in (see
AWS Lambda Support in Visual
Studio)
• Your own authoring environment
compilation, the code is saved in a
single file, and it does not depend on
any libraries.
Java
• Eclipse, with AWS Toolkit for Eclipse
(see Using AWS Lambda with the
AWS Toolkit for Eclipse)
• Your own authoring environment
The AWS Toolkit also creates the
deployment package, which is explained
in Deploying Code and Creating a
Lambda Function (p. 6).
C#
• Visual Studio, with IDE plug-in (see
AWS Lambda Support in Visual
Studio)
• .NET Core (see .NET Core installation
guide)
• Your own authoring environment
The AWS Toolkit also creates the
deployment package, which is explained
in Deploying Code and Creating a
Lambda Function (p. 6).
Python
• AWS Lambda console
You can use the console if the
languages you choose do not require
compilation, the code is saved in a
single file, and it does not depend on
any libraries.
• Your own authoring environment
In addition, regardless of the language you choose, there is a pattern to writing Lambda function code.
For example, how you write the handler method of your Lambda function (that is, the method that AWS
Lambda first calls when it begins executing the code), how you pass events to the handler, what statements
you can use in your code to generate logs in CloudWatch Logs, how to interact with AWS Lambda runtime
and obtain information such as the time remaining before timeout, and how to handle exceptions. The
Programming Model (p. 8) section provides information for each of the supported languages.
Note
After you familiarize yourself with AWS Lambda, see the Use Cases (p. 169), which provide
step-by-step instructions to help you explore the end-to-end experience.
Deploying Code and Creating a Lambda Function
To create a Lambda function, you first package your code and dependencies in a deployment package.
Then, you upload the deployment package to AWS Lambda to create your Lambda function.
Topics
• Creating a Deployment Package – Organizing Code and Dependencies (p. 6)
• Uploading a Deployment Package – Creating a Lambda Function (p. 7)
• Testing a Lambda Function (p. 7)
Creating a Deployment Package – Organizing Code and
Dependencies
You must first organize your code and dependencies in certain ways and create a deployment package.
Instructions to create a deployment package vary depending on the language you choose to author the
code. For example, you can use build plugins such as Jenkins (for Node.js and Python), and Maven
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Monitoring and Troubleshooting
(for Java) to create the deployment packages. For more information, see Creating a Deployment
Package (p. 58).
When you create Lambda functions using the console, the console creates the deployment package for
you, and then uploads it to create your Lambda function.
Uploading a Deployment Package – Creating a Lambda Function
AWS Lambda provides the CreateFunction (p. 322) operation, which is what you use to create a Lambda
function. You can use the AWS Lambda console, AWS CLI, and AWS SDKs to create a Lambda function.
Internally, all of these interfaces call the CreateFunction operation.
In addition to providing your deployment package, you can provide configuration information when you
create your Lambda function including the compute requirements of your Lambda function, the name of the
handler method in your Lambda function, and the runtime, which depends on the language you chose to
author your code. For more information, see Lambda Functions (p. 3).
Note
This section provides an introductory overview of developing AWS Lambda-based applications.
How It Works (p. 146) describes specifics about Lambda functions, event sources, and how
AWS Lambda executes your Lambda functions.
Testing a Lambda Function
If your Lambda function is designed to process events of a specific type, you can use sample event data to
test your Lambda function using one of the following methods:
• Test your Lambda function in the console.
• Test your Lambda function using the AWS CLI. You can use the Invoke method to invoke your Lambda
function and pass in sample event data.
The console provides sample event data. The same data is also provided in the Sample Events Published
by Event Sources (p. 125) topic, which you can use in the AWS CLI to invoke your Lambda function.
Monitoring and Troubleshooting
After your Lambda function is in production, AWS Lambda automatically monitors functions on your behalf,
reporting metrics through Amazon CloudWatch. For more information, see Accessing Amazon CloudWatch
Metrics for AWS Lambda (p. 105).
To help you troubleshoot failures in a function, Lambda logs all requests handled by your function and also
automatically stores logs that your code generates in Amazon CloudWatch Logs. For more information, see
Accessing Amazon CloudWatch Logs for AWS Lambda (p. 106).
AWS Lambda-Based Application Examples
This guide provides several examples with step-by-step instructions. If you are new to AWS Lambda, we
recommend you try the following exercises:
• Getting Started (p. 155) – The Getting Started exercise provides a console-based experience. The
sample code is authored in Python. You can edit the code in the console, upload it to AWS Lambda, and
test it using sample event data provided in the console.
• Use Cases (p. 169) – If you cannot author your code using the console, you must create your own
deployment packages and use the AWS CLI (or SDKs) to create your Lambda function. For more
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Related Topics
information, see Authoring Code for Your Lambda Function (p. 5). Most examples in the Uses Cases
section use the AWS CLI. If you are new to AWS Lambda, we recommend that you try one of these
exercises.
Related Topics
The following topics provide additional information.
Programming Model (p. 8)
Creating a Deployment Package (p. 58)
AWS Lambda Function Versioning and Aliases (p. 73)
Troubleshooting and Monitoring AWS Lambda Functions with Amazon CloudWatch (p. 103)
Programming Model
You write code for your Lambda function in one of the languages AWS Lambda supports. Regardless of the
language you choose, there is a common pattern to writing code for a Lambda function that includes the
following core concepts:
• Handler – Handler is the function AWS Lambda calls to start execution of your Lambda function. You
identify the handler when you create your Lambda function. When a Lambda function is invoked, AWS
Lambda starts executing your code by calling the handler function. AWS Lambda passes any event data
to this handler as the first parameter. Your handler should process the incoming event data and may
invoke any other functions/methods in your code.
• The context object and how it interacts with Lambda at runtime – AWS Lambda also passes a
context object to the handler function, as the second parameter. Via this context object your code can
interact with AWS Lambda. For example, your code can find the execution time remaining before AWS
Lambda terminates your Lambda function.
In addition, for languages such as Node.js, there is an asynchronous platform that uses callbacks. AWS
Lambda provides additional methods on this context object. You use these context object methods to tell
AWS Lambda to terminate your Lambda function and optionally return values to the caller.
• Logging – Your Lambda function can contain logging statements. AWS Lambda writes these logs to
CloudWatch Logs. Specific language statements generate log entries, depending on the language you
use to author your Lambda function code.
• Exceptions – Your Lambda function needs to communicate the result of the function execution to AWS
Lambda. Depending on the language you author your Lambda function code, there are different ways to
end a request successfully or to notify AWS Lambda an error occurred during execution. If you invoke the
function synchronously, then AWS Lambda forwards the result back to the client.
Note
Your Lambda function code must be written in a stateless style, and have no affinity with the
underlying compute infrastructure. Your code should expect local file system access, child
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processes, and similar artifacts to be limited to the lifetime of the request. Persistent state should
be stored in Amazon S3, Amazon DynamoDB, or another cloud storage service. Requiring
functions to be stateless enables AWS Lambda to launch as many copies of a function as needed
to scale to the incoming rate of events and requests. These functions may not always run on the
same compute instance from request to request, and a given instance of your Lambda function
may be used more than once by AWS Lambda.
The following language specific topics provide detail information:
• Programming Model (Node.js) (p. 9)
• Programming Model for Authoring Lambda Functions in Java (p. 23)
• Programming Model for Authoring Lambda Functions in C# (p. 48)
• Programming Model for Authoring Lambda Functions in Python (p. 41)
Programming Model (Node.js)
AWS Lambda currently supports the following Node.js runtimes:
• Node.js runtime v6.10 (runtime = nodejs6.10)
• Node.js runtime v4.3 (runtime = nodejs4.3)
• Node.js runtime v0.10.42 (runtime = nodejs)
Important
The v0.10.42 runtime will be unavailable to create new functions beginning on December 2016,
given the end-of-life announcement for this version. Use the newer runtimes (nodejs6.10 or
nodejs4.3) while creating new functions and we recommend you migrate existing functions to
the nodejs4.3 or nodejs6.10 runtime as soon as possible. All examples in this documentation will
work with either the nodejs4.3 or nodejs.6.10 runtime. For information about programming model
differences in the v0.10.42 runtime, see Using the Earlier Node.js Runtime v0.10.42 (p. 19).
When you create a Lambda function, you specify the runtime that you want to use. For more information,
see runtime parameter of the CreateFunction (p. 322).
The following sections explain how common programming patterns and core concepts apply when
authoring Lambda function code in Node.js. The programming model described in the following sections
apply to both versions, except where indicated.
Topics
• Lambda Function Handler (Node.js) (p. 9)
• The Context Object (Node.js) (p. 12)
• Logging (Node.js) (p. 15)
• Function Errors (Node.js) (p. 16)
• Using the Earlier Node.js Runtime v0.10.42 (p. 19)
Lambda Function Handler (Node.js)
At the time you create a Lambda function you specify a handler, a function in your code, that AWS Lambda
can invoke when the service executes your code. Use the following general syntax when creating a handler
function in Node.js.
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exports.myHandler = function(event, context,) {
...
}
The callback parameter is optional, depending on whether you want to return information to the caller.
exports.myHandler = function(event, context, callback) {
...
// Use callback() and return information to the caller.
}
In the syntax, note the following:
• event – AWS Lambda uses this parameter to pass in event data to the handler.
• context – AWS Lambda uses this parameter to provide your handler the runtime information of the
Lambda function that is executing. For more information, see The Context Object (Node.js) (p. 12).
• callback – You can use the optional callback to return information to the caller, otherwise return value is
null. For more information, see Using the Callback Parameter (p. 11).
Note
The callback is supported only in the Node.js runtimes v6.10 and v4.3. If you are using
runtime v0.10.42, you need to use the context methods (done, succeed, and fail) to properly
terminate the Lambda function. For information, see Using the Earlier Node.js Runtime
v0.10.42 (p. 19).
• myHandler – This is the name of the function AWS Lambda invokes. You export this so it is visible to
AWS Lambda. Suppose you save this code as helloworld.js. Then, helloworld.myHandler is the
handler. For more information, see handler in CreateFunction (p. 322).
• If you used the RequestResponse invocation type (synchronous execution), AWS Lambda returns
the result of the Node.js function call to the client invoking the Lambda function (in the HTTP
response to the invocation request, serialized into JSON). For example, AWS Lambda console uses
the RequestResponse invocation type, so when you test invoke the function using the console, the
console will display the return value.
If the handler does not return anything, AWS Lambda returns null.
• If you used the Event invocation type (asynchronous execution), the value is discarded.
Example
Consider the following Node.js example code.
exports.myHandler = function(event, context, callback) {
console.log("value1 = " + event.key1);
console.log("value2 = " + event.key2);
callback(null, "some success message");
// or
// callback("some error type");
}
This example has one function, which is also the handler. In the function, the console.log() statements
log some of the incoming event data to CloudWatch Logs. When the callback is called, the Lambda function
exits only after the Node.js event loop is empty (the Node.js event loop is not the same as the event that
was passed as a parameter).
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Note
If you are using runtime v0.10.42, you need to use the context methods (done, succeed, and fail)
to properly terminate the Lambda function. For more information, see Using the Earlier Node.js
Runtime v0.10.42 (p. 19).
To upload and test this code as a Lambda function (console)
1.
In the console, create a Lambda function using the following information:
• Use the hello-world blueprint.
• We recommend specifying nodejs6.10 as the runtime but you can also select nodejs4.3. The code
samples provided will work for either version.
• In Handler, replace index.handler with exports.myHandler.
For instructions to create a Lambda function using the console, see Step 2.1: Create a Hello World
Lambda Function (p. 159).
2.
Replace the template code with the code provided in this section and create the function.
3.
Test the Lambda function using the Sample event template called Hello World provided in the
Lambda console. For instructions on how to do this, see Step 2.2: Invoke the Lambda Function
Manually and Verify Results, Logs, and Metrics (p. 162).
Using the Callback Parameter
The Node.js runtimes v4.3 and v6.10 support the optional callback parameter. You can use it to explicitly
return information back to the caller. The general syntax is:
callback(Error error, Object result);
Where:
• error – is an optional parameter that you can use to provide results of the failed Lambda function
execution. When a Lambda function succeeds, you can pass null as the first parameter.
• result – is an optional parameter that you can use to provide the result of a successful function
execution. The result provided must be JSON.stringify compatible. If an error is provided, this
parameter is ignored.
Note
Using the callback parameter is optional. If you don't use the optional callback parameter, the
behavior is same as if you called the callback() without any parameters. You can specify the
callback in your code to return information to the caller.
If you don't use callback in your code, AWS Lambda will call it implicitly and the return value is null.
When the callback is called (explicitly or implicitly), AWS Lambda continues the Lambda function invocation
until the Node.js event loop is empty.
The following are example callbacks:
callback();
// Indicates success but no information returned to the caller.
callback(null); // Indicates success but no information returned to the caller.
callback(null, "success"); // Indicates success with information returned to the caller.
callback(error);
// Indicates error with error information returned to the caller.
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AWS Lambda treats any non-null value for the error parameter as a handled exception.
Note the following:
• Regardless of the invocation type specified at the time of the Lambda function invocation (see
Invoke (p. 351)), the callback method automatically logs the string representation of non-null values of
error to the Amazon CloudWatch Logs stream associated with the Lambda function.
• If the Lambda function was invoked synchronously (using the RequestResponse invocation type), the
callback returns a response body as follows:
• If error is null, the response body is set to the string representation of result.
• If the error is not null, the error value will be populated in the response body.
Note
When the callback(error, null) (and callback(error)) is called, Lambda will log the first 256
KB of the error object. For a larger error object, AWS Lambda truncates the log and displays the
text Truncated by Lambda next to the error object.
The Context Object (Node.js)
While a Lambda function is executing, it can interact with AWS Lambda to get useful runtime information
such as:
• How much time is remaining before AWS Lambda terminates your Lambda function (timeout is one of the
Lambda function configuration properties).
• The CloudWatch log group and log stream associated with the Lambda function that is executing.
• The AWS request ID returned to the client that invoked the Lambda function. You can use the request ID
for any follow up inquiry with AWS support.
• If the Lambda function is invoked through AWS Mobile SDK, you can learn more about the mobile
application calling the Lambda function.
AWS Lambda provides this information via the context object that the service passes as the second
parameter to your Lambda function handler. For more information, see Lambda Function Handler
(Node.js) (p. 9).
The following sections provide an example Lambda function that uses the context object, and then lists all
of the available methods and attributes.
Example
Consider the following Node.js example. The handler receives runtime information via a context
parameter.
console.log('Loading function');
exports.handler = function(event, context, callback) {
//console.log('Received event:', JSON.stringify(event, null, 2));
console.log('value1 =', event.key1);
console.log('value2 =', event.key2);
console.log('value3 =', event.key3);
console.log('remaining time =', context.getRemainingTimeInMillis());
console.log('functionName =', context.functionName);
console.log('AWSrequestID =', context.awsRequestId);
console.log('logGroupName =', context.logGroupName);
console.log('logStreamName =', context.logStreamName);
console.log('clientContext =', context.clientContext);
if (typeof context.identity !== 'undefined') {
console.log('Cognito
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identity ID =', context.identity.cognitoIdentityId);
}
callback(null, event.key1); // Echo back the first key value
// or
// callback("some error type");
};
The handler code in this example logs some of the runtime information of the Lambda function to
CloudWatch. If you invoke the function using the Lambda console, the console displays the logs in the Log
output section. You can create a Lambda function using this code and test it using the console.
To test this code in the AWS Lambda console
1.
In the console, create a Lambda function using the hello-world blueprint. In runtime, choose
nodejs6.10. For instructions on how to do this, see Step 2.1: Create a Hello World Lambda
Function (p. 159).
2.
Test the function, and then you can also update the code to get more context information.
The Context Object Methods (Node.js)
The context object provides the following methods.
context.getRemainingTimeInMillis()
Returns the approximate remaining execution time (before timeout occurs) of the Lambda function that is
currently executing. The timeout is one of the Lambda function configuration. When the timeout reaches,
AWS Lambda terminates your Lambda function.
You can use this method to check the remaining time during your function execution and take appropriate
corrective action at run time.
The general syntax is:
context.getRemainingTimeInMillis();
The Context Object Properties (Node.js)
The context object provides the following property that you can update:
callbackWaitsForEmptyEventLoop
The default value is true. This property is useful only to modify the default behavior of the callback. By
default, the callback will wait until the Node.js runtime event loop is empty before freezing the process
and returning the results to the caller. You can set this property to false to request AWS Lambda to
freeze the process soon after the callback is called, even if there are events in the event loop. AWS
Lambda will freeze the process, any state data and the events in the Node.js event loop (any remaining
events in the event loop processed when the Lambda function is called next and if AWS Lambda
chooses to use the frozen process). For more information about callback, see Using the Callback
Parameter (p. 11).
In addition, the context object provides the following properties that you can use obtain runtime
information:
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functionName
Name of the Lambda function that is executing.
functionVersion
The Lambda function version that is executing. If an alias is used to invoke the function, then
function_version will be the version the alias points to.
invokedFunctionArn
The ARN used to invoke this function. It can be a function ARN or an alias ARN. An unqualified ARN
executes the $LATEST version and aliases execute the function version it is pointing to.
memoryLimitInMB
Memory limit, in MB, you configured for the Lambda function. You set the memory limit at the time you
create a Lambda function and you can change it later.
awsRequestId
AWS request ID associated with the request. This is the ID returned to the client that called the invoke
method.
Note
If AWS Lambda retries the invocation (for example, in a situation where the Lambda function
that is processing Amazon Kinesis records throws an exception), the request ID remains the
same.
logGroupName
The name of the CloudWatch log group where you can find logs written by your Lambda function.
logStreamName
The name of the CloudWatch log group where you can find logs written by your Lambda function. The
log stream may or may not change for each invocation of the Lambda function.
The value is null if your Lambda function is unable to create a log stream, which can happen if the
execution role that grants necessary permissions to the Lambda function does not include permissions
for the CloudWatch actions.
identity
Information about the Amazon Cognito identity provider when invoked through the AWS Mobile SDK. It
can be null.
• identity.cognitoIdentityId
• identity.cognitoIdentityPoolId
For more information about the exact values for a specific mobile platform, see Identity Context in the
AWS Mobile SDK for iOS Developer Guide, and Identity Context in the AWS Mobile SDK for Android
Developer Guide.
clientContext
Information about the client application and device when invoked through the AWS Mobile SDK. It can
be null. Using clientContext, you can get the following information:
• clientContext.client.installation_id
• clientContext.client.app_title
• clientContext.client.app_version_name
• clientContext.client.app_version_code
• clientContext.client.app_package_name
• clientContext.Custom
Custom values set by the mobile client application.
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• clientContext.env.platform_version
• clientContext.env.platform
• clientContext.env.make
• clientContext.env.model
• clientContext.env.locale
For more information about the exact values for a specific mobile platform, see Client Context in the AWS
Mobile SDK for iOS Developer Guide, and Client Context in the AWS Mobile SDK for Android Developer
Guide.
Logging (Node.js)
Your Lambda function can contain logging statements. AWS Lambda writes these logs to CloudWatch. If
you use the Lambda console to invoke your Lambda function, the console displays the same logs.
The following Node.js statements generate log entries:
• console.log()
• console.error()
• console.warn()
• console.info()
For example, consider the following Node.js code example.
console.log('Loading function');
exports.handler = function(event, context, callback) {
//console.log('Received event:', JSON.stringify(event, null, 2));
console.log('value1 =', event.key1);
console.log('value2 =', event.key2);
console.log('value3 =', event.key3);
callback(null, event.key1); // Echo back the first key value
};
The screenshot shows an example Log output section in Lambda console, you can also find these logs in
CloudWatch. For more information, see Accessing Amazon CloudWatch Logs for AWS Lambda (p. 106).
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The console uses the RequestResponse invocation type (synchronous invocation) when invoking the
function, therefore it gets the return value (value1) back from AWS Lambda which the console displays.
To test the preceding Node.js code in AWS Lambda console
1.
In the console, create a Lambda function using the hello-world blueprint. Make sure to select the
Node.js as the runtime. For instructions on how to do this, see Step 2.1: Create a Hello World Lambda
Function (p. 159).
2.
Test the Lambda function using the Sample event template called Hello World provided in the
Lambda console. For instructions on how to do this, see Step 2.2: Invoke the Lambda Function
Manually and Verify Results, Logs, and Metrics (p. 162). You can also update the code and try other
logging methods and properties discussed in this section.
For step-by-step instructions, see Getting Started (p. 155).
Finding Logs
You can find the logs that your Lambda function writes, as follows:
• In the AWS Lambda console – The Log output section in the AWS Lambda console shows the logs.
• In the response header, when you invoke a Lambda function programmatically – If you invoke a
Lambda function programmatically, you can add the LogType parameter to retrieve the last 4 KB of log
data that is written to CloudWatch Logs. AWS Lambda returns this log information in the x-amz-logresults header in the response. For more information, see Invoke.
If you use AWS CLI to invoke the function, you can specify the --log-type parameter with
value Tail to retrieve the same information.
• In CloudWatch Logs – To find your logs in CloudWatch you need to know the log group name
and log stream name. You can get that information by adding the context.logGroupName, and
context.logStreamName methods in your code. When you run your Lambda function, the resulting logs
in the console or CLI will show you the log group name and log stream name.
Function Errors (Node.js)
If your Lambda function notifies AWS Lambda that it failed to execute properly, Lambda will attempt to
convert the error object to a String. Consider the following example:
console.log('Loading function');
exports.handler = function(event, context, callback) {
// This example code only throws error.
var error = new Error("something is wrong");
callback(error);
};
When you invoke this Lambda function, it will notify AWS Lambda that function execution completed with
an error and passes error information to AWS Lambda. AWS Lambda returns the error information back to
the client:
{
"errorMessage": "something is wrong",
"errorType": "Error",
"stackTrace": [
"exports.handler (/var/task/index.js:10:17)"
]
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}
Note that the stack trace is returned as the stackTrace JSON array of stack trace elements.
How you get the error information back depends on the invocation type that the client specifies at the time
of function invocation:
• If a client specifies the RequestResponse invocation type (that is, synchronous execution), it returns the
result to the client that made the invoke call.
For example, the console always use the RequestResponse invocation type, so the console will display
the error in the Execution result section as shown:
The same information is also sent to CloudWatch and the Log output section shows the same logs.
• If a client specifies the Event invocation type (that is, asynchronous execution), AWS Lambda will not
return anything. Instead, it logs the error information to CloudWatch Logs. You can also see the error
metrics in CloudWatch Metrics.
Depending on the event source, AWS Lambda may retry the failed Lambda function. For example,
if Amazon Kinesis is the event source, AWS Lambda will retry the failed invocation until the Lambda
function succeeds or the records in the stream expire. For more information on retries, see Retries on
Errors (p. 149).
To test the preceding Node.js code (console)
1.
In the console, create a Lambda function using the hello-world blueprint. In runtime, choose Node.js
and, in Role, choose Basic execution role. For instructions on how to do this, see Step 2.1: Create a
Hello World Lambda Function (p. 159).
2.
Replace the template code with the code provided in this section.
3.
Test the Lambda function using the Sample event template called Hello World provided in the
Lambda console. For instructions on how to do this, see Step 2.2: Invoke the Lambda Function
Manually and Verify Results, Logs, and Metrics (p. 162).
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Function Error Handling
You can create custom error handling to raise an exception directly from your Lambda function and
handle it directly (Retry or Catch) within an AWS Step Functions State Machine. For more information, see
Handling Error Conditions Using a State Machine.
Consider a CreateAccount state is a task that writes a customer's details to a database using a Lambda
function.
• If the task succeeds, an account is created and a welcome email is sent.
• If a user tries to create an account for a username that already exists, the Lambda function raises an
error, causing the state machine to suggest a different username and to retry the account-creation
process.
The following code samples demonstrate how to do this. Note that custom errors in Node.js must extend
the error prototype.
exports.handler = function(event, context, callback) {
function AccountAlreadyExistsError(message) {
this.name = "AccountAlreadyExistsError";
this.message = message;
}
AccountAlreadyExistsError.prototype = new Error();
const error = new AccountAlreadyExistsError("Account is in use!");
callback(error);
};
You can configure Step Functions to catch the error using a Catch rule:
{
"StartAt": "CreateAccount",
"States": {
"CreateAccount": {
"Type": "Task",
"Resource": "arn:aws:lambda:us-east-1:123456789012:function:CreateAccount",
"Next": "SendWelcomeEmail",
"Catch": [
{
"ErrorEquals": ["AccountAlreadyExistsError"],
"Next": "SuggestAccountName"
}
]
},
…
}
}
At runtime, AWS Step Functions catches the error, transitioning to the SuggestAccountName state as
specified in the Next transition.
Note
The name property of the Error object must match the ErrorEquals value.
Custom error handling makes it easier to create serverless applications. This feature integrates with all
the languages supported by the Lambda Programming Model (p. 8), allowing you to design your
application in the programming languages of your choice, mixing and matching as you go.
To learn more about creating your own serverless applications using AWS Step Functions and AWS
Lambda, see AWS Step Functions.
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Using the Earlier Node.js Runtime v0.10.42
As of April 2017, AWS Lambda supports Node.js 6.10 and Node.js 4.3. For information about
specifying this runtime when you create your Lambda function, see the --runtime parameter of
CreateFunction (p. 322).
Node v0.10.42 is currently marked as deprecated. As of Jan 2017, you can no longer create new functions
using the Node v0.10.42 runtime. Existing functions will be supported until early 2017. We recommend you
migrate existing functions to the newer Node runtime versions available on AWS Lambda (nodejs4.3 or
nodejs6.10) as soon as possible. The section highlights AWS Lambda's runtime support policy, along with
behavior unique to runtime v0.10.42 and how to migrate your existing functions to newer versions.
Topics
• Runtime Support Policy (p. 19)
• Transitioning Lambda Function Code to Newer Runtimes (p. 19)
• The Context Methods in Node.js Runtime v0.10.42 (p. 20)
Runtime Support Policy
AWS Lambda will only deprecate runtimes that are marked as EOL (End of Life) at the end of their
maintenance window as specified in the Node LTS working group page. Versions that are marked for EOL
(like Node 0.10) will stop supporting new function-creation first. Existing functions will continue to work until
customers have sufficient time to migrate to newer versions, and we will work with individual customers as
needed. AWS Lambda will add support for additional LTS (Long Term Support) versions of Node within a
few months of the version being marked as LTS.
Transitioning Lambda Function Code to Newer Runtimes
The following sections explain how to migrate your existing Lambda function code to newer runtimes:
1. Review all your existing Lambda functions and plan your migration. You can obtain your list of functions
in the following ways:
• Listing Lambda Functions and Updating the Runtime Using the CLI (p. 19)
• Listing Lambda Functions and Updating to Newer Runtime Using the Lambda Console (p. 20)
2. For each function:
a. Update the runtime first. We strongly recommend updating any use of the context method and
replacing it with the callback approach. For more details, see The Context Methods in Node.js
Runtime v0.10.42 (p. 20).
b. Test and verify the Lambda function passes your internal validation for its behavior. If it fails, you may
need to update your Lambda code to work in the new runtime:
• For a list of changes in Node.js v6.10, see Breaking changes between v5 and v6 on GitHub.
• For a list of changes in Node.js v4.3, see API changes between v0.10 and v4 on GitHub.
3. Once your function is invoked successfully, the transition is complete.
Listing Lambda Functions and Updating the Runtime Using the CLI
You can use the ListFunctions (p. 362) command to return a list of all Lambda functions and from that list
those created in the v0.10 runtime. The following code sample demonstrates how to do that:
#!/bin/bash
for REGION in $(aws ec2 describe-regions --output text --query 'Regions[].[RegionName]' |
egrep -v 'ca-central-1|sa-east-1' | sort); do
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echo "...checking $REGION"
echo " nodejs0.10 functions: "
for i in $(aws lambda list-functions --output json --query 'Functions[*].[FunctionName,
Runtime]' --region $REGION | grep -v nodejs4.3 | grep -v nodejs6.10 | grep -B1 nodejs |
grep , | sort); do
echo " -> $i"
done
done
echo "This script only accounts for the \$LATEST versions of functions. You may need to
take a closer look if you are using versioning."
For each Lambda function returned that was created using the v0.10 runtime, use the
UpdateFunctionConfiguration (p. 384) command and set the --runtime value to nodejs4.3 or
nodejs6.10.
Listing Lambda Functions and Updating to Newer Runtime Using the Lambda Console
To migrate Lambda functions to newer runtimes using the console:
• Sign in to the AWS Management Console and open the Lambda console.
• Choose the Runtime tab. This will sort all the Lambda functions for that region by their runtime value.
• Open each Lambda function with a runtime value of node.js and then choose the Configuration tab.
• Set the Runtime value to Node.js 4.3 or Node.js 6.10.
• Repeat this process for each region, as necessary.
The Context Methods in Node.js Runtime v0.10.42
Node.js runtime v0.10.42 does not support the callback parameter for your Lambda function that runtimes
v4.3 and v6.10 support. When using runtime v0.10.42, you use the following context object methods to
properly terminate your Lambda function. The context object supports the done(), succeed(), and fail()
methods that you can use to terminate your Lambda function. These methods are also present in runtimes
v4.3 and v6.10 for backward compatibility. For information about transitioning your code to use runtime v4.3
or v6.10, see Transitioning Lambda Function Code to Newer Runtimes (p. 19).
context.succeed()
Indicates the Lambda function execution and all callbacks completed successfully. Here's the general
syntax:
context.succeed(Object result);
Where:
result – is an optional parameter and it can be used to provide the result of the function execution.
The result provided must be JSON.stringify compatible. If AWS Lambda fails to stringify or encounters
another error, an unhandled exception is thrown, with the X-Amz-Function-Error response header set to
Unhandled.
You can call this method without any parameters (succeed()) or pass a null value (succeed(null)).
The behavior of this method depends on the invocation type specified in the Lambda function invocation.
For more information about invocation types, see Invoke (p. 351).
• If the Lambda function is invoked using the Event invocation type (asynchronous invocation), the method
will return HTTP status 202, request accepted response.
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• If the Lambda function is invoked using the RequestResponse invocation type (synchronous invocation),
the method will return HTTP status 200 (OK) and set the response body to the string representation of
the result.
context.fail()
Indicates the Lambda function execution and all callbacks completed unsuccessfully, resulting in a handled
exception. The general syntax is shown following:
context.fail(Error error);
Where:
error – is an optional parameter that you can use to provide the result of the Lambda function execution.
If the error value is non-null, the method will set the response body to the string representation of error
and also write corresponding logs to CloudWatch. If AWS Lambda fails to stringify or encounters another
error, an unhandled error occurs with the X-Amz-Function-Error header set to Unhandled.
Note
For the error from context.fail(error) and context.done(error, null), Lambda logs the first
256 KB of the error object. For larger error objects, AWS Lambda truncates the error and displays
the text: Truncated by Lambda next to the error object.
You can call this method without any parameters (fail()) or pass a null value (fail(null)).
context.done()
Causes the Lambda function execution to terminate.
Note
This method complements the succeed() and fail() methods by allowing the use of the "error
first" callback design pattern. It provides no additional functionality.
The general syntax is:
context.done(Error error, Object result);
Where:
• error – is an optional parameter that you can use to provide results of the failed Lambda function
execution.
• result – is an optional parameter that you can use to provide the result of a successful function
execution. The result provided must be JSON.stringify compatible. If an error is provided, this
parameter is ignored.
You can call this method without any parameters (done()), or pass null (done(null)).
AWS Lambda treats any non-null value for the error parameter as a handled exception.
The function behavior depends on the invocation type specified at the time of the Lambda invocation. For
more information about invocation types, see Invoke (p. 351).
• Regardless of the invocation type, the method automatically logs the string representation of non-null
values of error to the Amazon CloudWatch Logs stream associated with the Lambda function.
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• If the Lambda function was invoked using the RequestResponse (synchronous) invocation type, the
method returns response body as follows:
• If error is null, set the response body to the JSON representation of result. This is similar to
context.succeed().
• If the error is not null or the function is called with a single argument of type error, the error value
will be populated in the response body.
Note
For the error from both the done(error, null) and fail(error), Lambda logs the first 256 KB of
the error object, and for larger error object, AWS Lambda truncates the log and displays the text
Truncated by Lambda" next to the error object.
Comparing the Context and Callback Methods
If you previously created Lambda functions using Node.js runtime v0.10.42, you used one of the context
object methods (done(), succeed(), and fail()) to terminate your Lambda function. In Node.js runtimes
v4.3 and v6.10, these methods are supported primarily for backward compatibility. We recommend you
use the callback (see Using the Callback Parameter (p. 11)). The following are callback examples
equivalent to the context object methods:
• The following example shows the context.done() method and corresponding equivalent callback
supported in the newer runtime.
// Old way (Node.js runtime v0.10.42).
context.done(null, 'Success message');
// New way (Node.js runtime v4.3 or v6.10).
context.callbackWaitsForEmptyEventLoop = false;
callback(null, 'Success message');
Important
For performance reasons, AWS Lambda may reuse the same Node.js process for multiple
executions of the Lambda function. If this happens, AWS Lambda freezes the Node process
between execution,retaining the state information it needs to continue execution.
When the context methods are called, AWS Lambda freezes the Node process immediately,
without waiting for the event loop associated with the process to empty. The process state and
any events in the event loop are frozen. When the function is invoked again, if AWS Lambda
re-uses the frozen process, the function execution continues with its same global state (for
example, events that remained in the event loop will begin to get processed). However, when
you use callback, AWS Lambda continues the Lambda function execution until the event
loop is empty. After all events in the event loop are processed, AWS Lambda then freezes
the Node process, including any state variables in the Lambda function. Therefore, if you
want the same behavior as the context methods, you must set the context object property,
callbackWaitsForEmptyEventLoop, to false.
• The following example shows the context.succeed() method and corresponding equivalent callback
supported in the newer runtime.
// Old way (Node.js runtime v0.10.42).
context.succeed('Success message');
// New way (Node.js runtime v4.3 or v6.10).
context.callbackWaitsForEmptyEventLoop = false;
callback(null, 'Success message');
• The following example shows the context.fail() method and corresponding equivalent callback
supported in the newer runtime.
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// Old way (Node.js runtime v0.10.42).
context.fail('Fail object');
// New way (Node.js runtime v4.3 or v6.10).
context.callbackWaitsForEmptyEventLoop = false;
callback('Fail object', 'Failed result');
Programming Model for Authoring Lambda Functions in Java
The following sections explain how common programming patterns and core concepts apply when
authoring Lambda function code in Java.
Topics
• Lambda Function Handler (Java) (p. 23)
• The Context Object (Java) (p. 33)
• Logging (Java) (p. 35)
• Function Errors (Java) (p. 39)
Additionally, note that AWS Lambda provides the following libraries:
• aws-lambda-java-core – This library provides the Context object, RequestStreamHandler, and the
RequestHandler interfaces. The Context object (The Context Object (Java) (p. 33)) provides runtime
information about your Lambda function. The predefined interfaces provide one way of defining your
Lambda function handler. For more information, see Leveraging Predefined Interfaces for Creating
Handler (Java) (p. 29).
• aws-lambda-java-events – This library provides predefined types that you can use when writing Lambda
functions to process events published by Amazon S3, Amazon Kinesis, Amazon SNS, and Amazon
Cognito. These classes help you process the event without having to write your own custom serialization
logic.
• Custom Appender for Log4j 1.2 – You can use the custom Log4j (see Apache log4j) appender
provided by AWS Lambda for logging from your lambda functions. For more information, see Logging
(Java) (p. 35).
These libraries are available through the Maven Central Repository and can also be found on GitHub.
Lambda Function Handler (Java)
At the time you create a Lambda function you specify a handler that AWS Lambda can invoke when the
service executes the Lambda function on your behalf.
Lambda supports two approaches for creating a handler:
• Loading the handler method directly without having to implement an interface. This section describes this
approach.
• Implementing standard interfaces provided as part of aws-lambda-java-core library (interface approach).
For more information, see Leveraging Predefined Interfaces for Creating Handler (Java) (p. 29).
The general syntax for the handler is as follows:
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outputType handler-name(inputType input, Context context) {
...
}
In order for AWS Lambda to successfully invoke a handler it must be invoked with input data that can be
serialized into the data type of the input parameter.
In the syntax, note the following:
• inputType – The first handler parameter is the input to the handler, which can be event data (published
by an event source) or custom input that you provide such as a string or any custom data object. In order
for AWS Lambda to successfully invoke this handler, the function must be invoked with input data that
can be serialized into the data type of the input parameter.
• outputType – If you plan to invoke the Lambda function synchronously (using the RequestResponse
invocation type), you can return the output of your function using any of the supported data types.
For example, if you use a Lambda function as a mobile application backend, you are invoking it
synchronously. Your output data type will be serialized into JSON.
If you plan to invoke the Lambda function asynchronously (using the Event invocation type), the
outputType should be void. For example, if you use AWS Lambda with event sources such as Amazon
S3, Amazon Kinesis, and Amazon SNS, these event sources invoke the Lambda function using the
Event invocation type.
• The inputType and outputType can be one of the following:
• Primitive Java types (such as String or int).
• Predefined AWS event types defined in the aws-lambda-java-events library.
For example S3Event is one of the POJOs predefined in the library that provides methods for you to
easily read information from the incoming Amazon S3 event.
• You can also write your own POJO class. AWS Lambda will automatically serialize and deserialize
input and output JSON based on the POJO type.
For more information, see Handler Input/Output Types (Java) (p. 25).
• You can omit the Context object from the handler method signature if it isn't needed. For more
information, see The Context Object (Java) (p. 33).
For example, consider the following Java example code.
package example;
import com.amazonaws.services.lambda.runtime.Context;
public class Hello {
public String myHandler(int myCount, Context context) {
return String.valueOf(myCount);
}
}
In this example input is of type int and output is of type String. If you package this code and dependencies,
and create your Lambda function, you specify example.Hello::myHandler (package.class::methodreference) as the handler.
In the example Java code, the first handler parameter is the input to the handler (myHandler), which can be
event data (published by an event source such as Amazon S3) or custom input you provide such as an int
(as in this example) or any custom data object.
For instructions to create a Lambda function using this Java code, see Step 2.3: (Optional) Create a
Lambda Function Authored in Java (p. 164).
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Handler Overload Resolution
If your Java code contains multiple methods with same name as the handler name, then AWS Lambda
uses the following rules to pick a method to invoke:
1. Select the method with the largest number of parameters.
2. If two or more methods have the same number of parameters, AWS Lambda selects the method that has
the Context as the last parameter.
If none or all of these methods have the Context parameter, then the behavior is undefined.
Additional Information
The following topics provide more information about the handler.
• For more information about the handler input and output types, see Handler Input/Output Types
(Java) (p. 25).
• For information about using predefined interfaces to create a handler, see Leveraging Predefined
Interfaces for Creating Handler (Java) (p. 29).
If you implement these interfaces, you can validate your handler method signature at compile time.
• If your Lambda function throws an exception, AWS Lambda records metrics in CloudWatch indicating
that an error occurred. For more information, see Function Errors (Java) (p. 39).
Handler Input/Output Types (Java)
When AWS Lambda executes the Lambda function, it invokes the handler. The first parameter is the input
to the handler which can be event data (published by an event source) or custom input you provide such as
a string or any custom data object.
AWS Lambda supports the following input/output types for a handler:
• Simple Java types (AWS Lambda supports the String, Integer, Boolean, Map, and List types)
• POJO (Plain Old Java Object) type
• Stream type (If you do not want to use POJOs or if Lambda's serialization approach does not meet your
needs, you can use the byte stream implementation. For more information, see Example: Using Stream
for Handler Input/Output (Java) (p. 28).)
Handler Input/Output: String Type
The following Java class shows a handler called myHandler that uses String type for input and output.
package example;
import com.amazonaws.services.lambda.runtime.Context;
public class Hello {
public String myHandler(String name, Context context) {
return String.format("Hello %s.", name);
}
}
You can have similar handler functions for other simple Java types.
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Note
When you invoke a Lambda function asynchronously, any return value by your Lambda function
will be ignored. Therefore you might want to set the return type to void to make this clear in your
code. For more information, see Invoke (p. 351).
To test an end-to-end example, see Step 2.3: (Optional) Create a Lambda Function Authored in
Java (p. 164).
Handler Input/Output: POJO Type
The following Java class shows a handler called myHandler that uses POJOs for input and output.
package example;
import com.amazonaws.services.lambda.runtime.Context;
public class HelloPojo {
// Define two classes/POJOs for use with Lambda function.
public static class RequestClass {
...
}
public static class ResponseClass {
...
}
public static ResponseClass myHandler(RequestClass request, Context context) {
String greetingString = String.format("Hello %s, %s.", request.getFirstName(),
request.getLastName());
return new ResponseClass(greetingString);
}
}
AWS Lambda serializes based on standard bean naming conventions (see The Java EE 6 Tutorial). You
should use mutable POJOs with public getters and setters.
Note
You shouldn't rely on any other features of serialization frameworks such as annotations. If you
need to customize the serialization behavior, you can use the raw byte stream to use your own
serialization.
If you use POJOs for input and output, you need to provide implementation of the RequestClass
and ResponseClass types. For an example, see Example: Using POJOs for Handler Input/Output
(Java) (p. 26).
Example: Using POJOs for Handler Input/Output (Java)
Suppose your application events generate data that includes first name and last name as shown:
{ "firstName": "John", "lastName": "Doe" }
For this example, the handler receives this JSON and returns the string "Hello John Doe".
public static ResponseClass handleRequest(RequestClass request, Context context){
String greetingString = String.format("Hello %s, %s.", request.firstName,
request.lastName);
return new ResponseClass(greetingString);
}
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To create a Lambda function with this handler, you must provide implementation of the input and output
types as shown in the following Java example. The HelloPojo class defines the handler method.
package example;
import com.amazonaws.services.lambda.runtime.Context;
import com.amazonaws.services.lambda.runtime.RequestHandler;
public class HelloPojo implements RequestHandler<RequestClass, ResponseClass>{
public ResponseClass handleRequest(RequestClass request, Context context){
String greetingString = String.format("Hello %s, %s.", request.firstName,
request.lastName);
return new ResponseClass(greetingString);
}
}
In order to implement the input type, add the following code to a separate file and name it
RequestClass.java. Place it next to the HelloPojo.java class in your directory structure:
package example;
public class RequestClass {
String firstName;
String lastName;
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public RequestClass(String firstName, String lastName) {
this.firstName = firstName;
this.lastName = lastName;
}
public RequestClass() {
}
}
In order to implement the output type, add the following code to a separate file and name it
ResponseClass.java. Place it next to the HelloPojo.java class in your directory structure:
package example;
public class ResponseClass {
String greetings;
public String getGreetings() {
return greetings;
}
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public void setGreetings(String greetings) {
this.greetings = greetings;
}
public ResponseClass(String greetings) {
this.greetings = greetings;
}
public ResponseClass() {
}
}
Note
The get and set methods are required in order for the POJOs to work with AWS Lambda's built
in JSON serializer. The constructors that take no arguments are usually not required, however in
this example we provided other constructors and therefore we need to explicitly provide the zero
argument constructors.
You can upload this code as your Lambda function and test as follows:
• Using the preceding code files, create a deployment package.
• Upload the deployment package to AWS Lambda and create your Lambda function. You can do this
using the console or AWS CLI.
• Invoke the Lambda function manually using the console or the CLI. You can use provide sample JSON
event data when you manually invoke your Lambda function. For example:
{ "firstName":"John", "lastName":"Doe" }
Follow instructions provided in the Getting Started. For more information, see Step 2.3: (Optional) Create a
Lambda Function Authored in Java (p. 164). Note the following differences:
• When you create a deployment package, don't forget the aws-lambda-java-core library dependency.
• When you create the Lambda function, specify example.HelloPojo::myHandler
(package.class::method) as the handler value.
Example: Using Stream for Handler Input/Output (Java)
If you do not want to use POJOs or if Lambda's serialization approach does not meet your needs, you can
use the byte stream implementation. In this case, you can use the InputStream and OutputStream as the
input and output types for the handler. An example handler function is shown:
public void handler(InputStream inputStream, OutputStream outputStream, Context context) {
...
}
Note that in this case the handler function uses parameters for both the request and response streams.
The following is a Lambda function example that implements the handler that uses InputStream and
OutputStream types for the input and output parameters.
Note
The input payload must be valid JSON but the output stream does not carry such a restriction. Any
bytes are supported.
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package example;
import
import
import
import
java.io.InputStream;
java.io.OutputStream;
com.amazonaws.services.lambda.runtime.RequestStreamHandler;
com.amazonaws.services.lambda.runtime.Context;
public class Hello implements RequestStreamHandler{
public static void handler(InputStream inputStream, OutputStream outputStream, Context
context) throws IOException {
int letter;
while((letter = inputStream.read()) != -1)
{
outputStream.write(Character.toUpperCase(letter));
}
}
}
You can do the following to test the code:
• Using the preceding code, create a deployment package.
• Upload the deployment package to AWS Lambda and create your Lambda function. You can do this
using the console or AWS CLI.
• You can manually invoke the code by providing sample input. For example:
test
Follow instructions provided in the Getting Started. For more information, see Step 2.3: (Optional) Create a
Lambda Function Authored in Java (p. 164). Note the following differences:
• When you create a deployment package, don't forget the aws-lambda-java-core library dependency.
• When you create the Lambda function, specify example.Hello::handler (package.class::method) as the
handler value.
Leveraging Predefined Interfaces for Creating Handler (Java)
You can use one of the predefined interfaces provided by the AWS Lambda Java core library (aws-lambdajava-core) to create your Lambda function handler, as an alternative to writing your own handler method
with an arbitrary name and parameters. For more information about handlers, see (see Lambda Function
Handler (Java) (p. 23)).
You can implement one of the predefined interfaces, RequestStreamHandler or RequestHandler and
provide implementation for the handleRequest method that the interfaces provide. You implement one of
these interfaces depending on whether you want to use standard Java types or custom POJO types for
your handler input/output (where AWS Lambda automatically serializes and deserializes the input and
output to Match your data type), or customize the serialization using the Stream type.
Note
These interfaces are available in the aws-lambda-java-core library.
When you implement standard interfaces, they help you validate your method signature at compile time.
If you implement one of the interfaces, you specify package.class in your Java code as the handler when
you create the Lambda function. For example, the following is the modified create-function CLI command
from the getting started. Note that the --handler parameter specifies "example.Hello" value:
aws lambda create-function \
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--region us-west-2 \
--function-name getting-started-lambda-function-in-java \
--zip-file fileb://deployment-package (zip or jar)
path \
--role arn:aws:iam::account-id:role/lambda_basic_execution
--handler example.Hello \
--runtime java8 \
--timeout 15 \
--memory-size 512
\
The following sections provide examples of implementing these interfaces.
Example 1: Creating Handler with Custom POJO Input/Output (Leverage the RequestHandler
Interface)
The example Hello class in this section implements the RequestHandler interface. The interface defines
handleRequest() method that takes in event data as input parameter of the Request type and returns an
POJO object of the Response type:
public Response handleRequest(Request request, Context context) {
...
}
The Hello class with sample implementation of the handleRequest() method is shown. For this example,
we assume event data consists of first name and last name.
package example;
import com.amazonaws.services.lambda.runtime.RequestHandler;
import com.amazonaws.services.lambda.runtime.Context;
public class Hello implements RequestHandler<Request, Response> {
public Response handleRequest(Request request, Context context) {
String greetingString = String.format("Hello %s %s.", request.firstName,
request.lastName);
return new Response(greetingString);
}
}
For example, if the event data in the Request object is:
{
"firstName":"value1",
"lastName" : "value2"
}
The method returns a Response object as follows:
{
"greetings": "Hello value1 value2."
}
Next, you need to implement the Request and Response classes. You can use the following implementation
for testing:
The Request class:
package example;
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public class Request {
String firstName;
String lastName;
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public Request(String firstName, String lastName) {
this.firstName = firstName;
this.lastName = lastName;
}
public Request() {
}
}
The Response class:
package example;
public class Response {
String greetings;
public String getGreetings() {
return greetings;
}
public void setGreetings(String greetings) {
this.greetings = greetings;
}
public Response(String greetings) {
this.greetings = greetings;
}
public Response() {
}
}
You can create a Lambda function from this code and test the end-to-end experience as follows:
• Using the preceding code, create a deployment package.
• Upload the deployment package to AWS Lambda and create your Lambda function.
• Test the Lambda function using either the console or CLI. You can specify any sample JSON data that
conform to the getter and setter in your Request class, for example:
{
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"firstName":"John",
"lastName" : "Doe"
}
The Lambda function will return the following JSON in response.
{
"greetings": "Hello John, Doe."
}
Follow instructions provided in the getting started (see Step 2.3: (Optional) Create a Lambda Function
Authored in Java (p. 164)). Note the following differences:
• When you create a deployment package, don't forget the aws-lambda-java-core library dependency.
• When you create the Lambda function specify example.Hello (package.class) as the handler value.
Example 2: Creating Handler with Stream Input/Output (Leverage the RequestStreamHandler
Interface)
The Hello class in this example implements the RequestStreamHandler interface. The interface defines
handleRequest method as follows:
public void handleRequest(InputStream inputStream, OutputStream outputStream, Context
context)
throws IOException {
...
}
The Hello class with sample implementation of the handleRequest() handler is shown. The handler
processes incoming event data (for example, a string "hello") by simply converting it to uppercase and
return it.
package example;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import com.amazonaws.services.lambda.runtime.RequestStreamHandler;
import com.amazonaws.services.lambda.runtime.Context;
public class Hello implements RequestStreamHandler {
public void handleRequest(InputStream inputStream, OutputStream outputStream, Context
context)
throws IOException {
int letter;
while((letter = inputStream.read()) != -1)
{
outputStream.write(Character.toUpperCase(letter));
}
}
}
You can create a Lambda function from this code and test the end-to-end experience as follows:
• Use the preceding code to create deployment package.
• Upload the deployment package to AWS Lambda and create your Lambda function.
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• Test the Lambda function using either the console or CLI. You can specify any sample string data, for
example:
"test"
The Lambda function will return TEST in response.
Follow instructions provided in the getting started (see Step 2.3: (Optional) Create a Lambda Function
Authored in Java (p. 164)). Note the following differences:
• When you create a deployment package, don't forget the aws-lambda-java-core library dependency.
• When you create the Lambda function specify example.Hello (package.class) as the handler value.
The Context Object (Java)
You interact with AWS Lambda execution environment via the context parameter. The context object allows
you to access useful information available within the Lambda execution environment. For example, you can
use the context parameter to determine the CloudWatch log stream associated with the function, or use the
clientContext property of the context object to learn more about the application calling the Lambda function
(when invoked through the AWS Mobile SDK).
The context object properties are:
• getMemoryLimitInMB(): Memory limit, in MB, you configured for the Lambda function.
• getFunctionName(): Name of the Lambda function that is running.
• getFunctionVersion(): The Lambda function version that is executing. If an alias is used to invoke the
function, then getFunctionVersion will be the version the alias points to.
• getInvokedFunctionArn(): The ARN used to invoke this function. It can be function ARN or alias ARN.
An unqualified ARN executes the $LATEST version and aliases execute the function version it is pointing
to.
• getAwsRequestId(): AWS request ID associated with the request. This is the ID returned to the client
called the invoke(). You can use the request ID for any follow up enquiry with AWS support. Note that
if AWS Lambda retries the function (for example, in a situation where the Lambda function processing
Amazon Kinesis records throw an exception), the request ID remains the same.
• getLogStreamName(): The CloudWatch log stream name for the particular Lambda function execution. It
can be null if the IAM user provided does not have permission for CloudWatch actions.
• getLogGroupName(): The CloudWatch log group name associated with the Lambda function invoked. It
can be null if the IAM user provided does not have permission for CloudWatch actions.
• getClientContext(): Information about the client application and device when invoked through the AWS
Mobile SDK. It can be null. Client context provides client information such as client ID, application title,
version name, version code, and the application package name.
• getIdentity(): Information about the Amazon Cognito identity provider when invoked through the AWS
Mobile SDK. It can be null.
• getRemainingTimeInMillis(): Remaining execution time till the function will be terminated, in
milliseconds. At the time you create the Lambda function you set maximum time limit, at which time AWS
Lambda will terminate the function execution. Information about the remaining time of function execution
can be used to specify function behavior when nearing the timeout.
• getLogger(): Returns the Lambda logger associated with the Context object. For more information, see
Logging (Java) (p. 35).
The following Java code snippet shows a handler function that prints some of the context information.
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public static void handler(InputStream inputStream, OutputStream outputStream, Context
context) {
...
System.out.println("Function name: " + context.getFunctionName());
System.out.println("Max mem allocated: " + context.getMemoryLimitInMB());
System.out.println("Time remaining in milliseconds: " +
context.getRemainingTimeInMillis());
System.out.println("CloudWatch log stream name: " + context.getLogStreamName());
System.out.println("CloudWatch log group name: " + context.getLogGroupName());
}
Example: Using Context Object (Java)
The following Java code example shows how to use the Context object to retrieve runtime information of
your Lambda function, while it is running.
package example;
import java.io.InputStream;
import java.io.OutputStream;
import com.amazonaws.services.lambda.runtime.Context;
public class Hello {
public static void myHandler(InputStream inputStream, OutputStream outputStream,
Context context) {
int letter;
try {
while((letter = inputStream.read()) != -1)
{
outputStream.write(Character.toUpperCase(letter));
}
Thread.sleep(3000); // Intentional delay for testing the
getRemainingTimeInMillis() result.
}
catch (Exception e)
{
e.printStackTrace();
}
// For fun, let us get function info using the context object.
System.out.println("Function name: " + context.getFunctionName());
System.out.println("Max mem allocated: " + context.getMemoryLimitInMB());
System.out.println("Time remaining in milliseconds: " +
context.getRemainingTimeInMillis());
System.out.println("CloudWatch log stream name: " + context.getLogStreamName());
System.out.println("CloudWatch log group name: " + context.getLogGroupName());
}
}
You can do the following to test the code:
• Using the preceding code, create a deployment package.
• Upload the deployment package to AWS Lambda to create your Lambda function. You can do this using
the console or AWS CLI.
• To test your Lambda function use the "Hello World" Sample event that the Lambda console provides.
You can type any string and the function will return the same string in uppercase. In addition, you will
also get the useful function information provided by the context object.
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Follow the instructions provided in the Getting Started. For more information, see Step 2.3: (Optional)
Create a Lambda Function Authored in Java (p. 164). Note the following differences:
• When you create a deployment package, don't forget the aws-lambda-java-core library dependency.
• When you create the Lambda function, specify example.Hello::myHandler (package.class::method)
as the handler value.
Logging (Java)
Your Lambda function can contain logging statements. AWS Lambda writes these logs to CloudWatch. We
recommend you use one of the following to write logs.
• Custom Appender for Log4j™ 1.2
AWS Lambda supports Log4j 1.2 by providing a custom appender. You can use the custom Log4j (see
Apache log4j) appender provided by Lambda for logging from your lambda functions. Every call to Log4j
methods, such as log.debug() or log.error(), will result in a CloudWatch Logs event. The custom
appender is called LambdaAppender and must be used in the log4j.properties file. You must include
the aws-lambda-java-log4j artifact (artifactId:aws-lambda-java-log4j) in the deployment package
(.jar file). For an example, see Example 1: Writing Logs Using Log4J (Java) (p. 36).
Note
Currently, AWS Lambda supports Log4j 1.2 version.
• LambdaLogger.log()
Each call to LambdaLogger.log() results in a CloudWatch Logs event, provided the event size is within
the allowed limits. For information about CloudWatch logs limits, see CloudWatch Logs Limits in the
Amazon CloudWatch User Guide. For an example, see Example 2: Writing Logs Using LambdaLogger
(Java) (p. 37).
In addition, you can also use the following statements in your Lambda function code to generate log entries:
• System.out()
• System.err()
However, note that AWS Lambda treats each line returned by System.out and System.err as a separate
event. This works well when each output line corresponds to a single log entry. When a log entry has
multiple lines of output, AWS Lambda attempts to parse them using line breaks to identify separate events.
For example, the following logs the two words ("Hello" and "world") as two separate events:
System.out.println("Hello \n world");
How to Find Logs
You can find the logs that your Lambda function writes, as follows:
• Find logs in CloudWatch Logs. The context object (in the aws-lambda-java-core library) provides the
getLogStreamName() and the getLogGroupName() methods. Using these methods, you can find the
specific log stream where logs are written.
• If you invoke a Lambda function via the console, the invocation type is always RequestResponse (that
is, synchronous execution) and the console displays the logs that the Lambda function writes using the
LambdaLogger object. AWS Lambda also returns logs from System.out and System.err methods.
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• If you invoke a Lambda function programmatically, you can add the LogType parameter to retrieve the
last 4 KB of log data that is written to CloudWatch Logs. For more information, see Invoke (p. 351).
AWS Lambda returns this log information in the x-amz-log-results header in the response. If you use
the AWS Command Line Interface to invoke the function, you can specify the --log-type parameter with
value Tail.
Logging Examples (Java)
This section provides examples of using Custom Appender for Log4j and the LambdaLogger objects for
logging information.
Example 1: Writing Logs Using Log4J (Java)
The following Java code example writes logs using both the System methods and Log4j to illustrate how
they differ when AWS Lambda logs information to CloudWatch.
package example;
import com.amazonaws.services.lambda.runtime.Context;
import org.apache.logging.log4j.Logger;
public class Hello {
// Initialize the Log4j logger.
static final Logger log = Logger.getLogger(Hello.class);
public String myHandler(String name, Context context) {
// System.out: One log statement but with a line break (AWS Lambda writes two
events to CloudWatch).
System.out.println("log data from stdout \n this is continuation of system.out");
// System.err: One log statement but with a line break (AWS Lambda writes two events
to CloudWatch).
System.err.println("log data from stderr. \n this is a continuation of
system.err");
// Use log4j to log the same thing as above and AWS Lambda will log only one event
in CloudWatch.
log.debug("log data from log4j debug \n this is continuation of log4j debug");
log.error("log data from log4j err. \n this is a continuation of log4j.err");
// Return will include the log stream name so you can look
// up the log later.
return String.format("Hello %s. log stream = %s", name,
context.getLogStreamName());
}
}
The example uses the following log4j.properties file (project-dir/src/main/resources/ directory).
log = .
log4j.rootLogger = DEBUG, LAMBDA
#Define the LAMBDA appender
log4j.appender.LAMBDA=com.amazonaws.services.lambda.runtime.log4j.LambdaAppender
log4j.appender.LAMBDA.layout=org.apache.log4j.PatternLayout
log4j.appender.LAMBDA.layout.conversionPattern=%d{yyyy-MM-dd HH:mm:ss} <%X{AWSRequestId}>
%-5p %c{1}:%L - %m%n
The following is sample of log entries in CloudWatch Logs.
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Note:
• AWS Lambda parses the log string in each of the System.out.println() and System.err.println()
statements logs as two separate events (note the two down arrows in the screenshot) because of the line
break.
• The Log4j methods (log.debug() and log.error()) produce one CloudWatch event.
• AWS Lambda runtime adds the AWSRequestId in the MDC (see Class MDC). To get this value in the log
as shown, we added %X{AWSRequestId} in the conversion pattern in the log4.properties file.
You can do the following to test the code:
• Using the code, create a deployment package. In your project, don't forget to add the log4j.properties
files in the project-dir/src/main/resources/ directory.
• Upload the deployment package to AWS Lambda to create your Lambda function.
• To test your Lambda function use a string ("this is a test") as sample event. The handler code receives
the sample event but does nothing with it. It only shows how to write logs.
Follow the instructions provided in the Getting Started. For more information, see Step 2.3: (Optional)
Create a Lambda Function Authored in Java (p. 164). Note the following differences:
• When you create a deployment package, don't forget the aws-lambda-java-log4j library dependency.
• When you create the Lambda function, specify example.Hello::myHandler (package.class::method)
as the handler value.
Example 2: Writing Logs Using LambdaLogger (Java)
The following Java code example writes logs using both the System methods and the LambdaLogger object
to illustrate how they differ when AWS Lambda logs information to CloudWatch.
package example;
import com.amazonaws.services.lambda.runtime.Context;
import com.amazonaws.services.lambda.runtime.LambdaLogger;
public class Hello {
public String myHandler(String name, Context context) {
// System.out: One log statement but with a line break (AWS Lambda writes two
events to CloudWatch).
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System.out.println("log data from stdout \n this is continuation of system.out");
// System.err: One log statement but with a line break (AWS Lambda writes two
events to CloudWatch).
System.err.println("log data from stderr \n this is continuation of system.err");
LambdaLogger logger = context.getLogger();
// Write log to CloudWatch using LambdaLogger.
logger.log("log data from LambdaLogger \n this is continuation of logger.log");
// Return will include the log stream name so you can look
// up the log later.
return String.format("Hello %s. log stream = %s", name,
context.getLogStreamName());
}
}
The following is sample of log entries in CloudWatch Logs.
Note:
• AWS Lambda parses the log string in each of the System.out.println() and System.err.println()
statements logs as two separate events (note the two down arrows in the screenshot) because of the line
break.
• The LambdaLogger.log() produce one CloudWatch event.
You can do the following to test the code:
• Using the code, create a deployment package.
• Upload the deployment package to AWS Lambda to create your Lambda function.
• To test your Lambda function use a string ("this is a test") as sample event. The handler code receives
the sample event but does nothing with it. It only shows how to write logs.
Follow the instructions provided in the Getting Started. For more information, see Step 2.3: (Optional)
Create a Lambda Function Authored in Java (p. 164). Note the following differences:
• When you create a deployment package, don't forget the aws-lambda-java-core library dependency.
• When you create the Lambda function, specify example.Hello::myHandler (package.class::method)
as the handler value.
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Function Errors (Java)
If your Lambda function throws an exception, AWS Lambda recognizes the failure and serializes the
exception information into JSON and returns it. Following is an example error message:
{
"errorMessage": "Name John Doe is invalid. Exception occurred...",
"errorType": "java.lang.Exception",
"stackTrace": [
"example.Hello.handler(Hello.java:9)",
"sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)",
"sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)",
"sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)",
"java.lang.reflect.Method.invoke(Method.java:497)"
]
}
Note that the stack trace is returned as the stackTrace JSON array of stack trace elements.
The method in which you get the error information back depends on the invocation type that you specified
at the time you invoked the function:
• RequestResponse invocation type (that is, synchronous execution): In this case, you get the error
message back.
For example, if you invoke a Lambda function using the Lambda console, the RequestResponse is always
the invocation type and the console displays the error information returned by AWS Lambda in the
Execution result section as shown in the following image.
• Event invocation type (that is, asynchronous execution): In this case AWS Lambda does not return
anything. Instead, it logs the error information in CloudWatch Logs and CloudWatch metrics.
Depending on the event source, AWS Lambda may retry the failed Lambda function. For example, if
Amazon Kinesis is the event source for the Lambda function, AWS Lambda retries the failed function until
the Lambda function succeeds or the records in the stream expire.
Function Error Handling
You can create custom error handling to raise an exception directly from your Lambda function and
handle it directly (Retry or Catch) within an AWS Step Functions State Machine. For more information, see
Handling Error Conditions Using a State Machine.
Consider a CreateAccount state is a task that writes a customer's details to a database using a Lambda
function.
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• If the task succeeds, an account is created and a welcome email is sent.
• If a user tries to create an account for a username that already exists, the Lambda function raises an
error, causing the state machine to suggest a different username and to retry the account-creation
process.
The following code samples demonstrate how to do this. Note that custom errors in Java must extend the
Exception class.
package com.example;
public static class AccountAlreadyExistsException extends Exception {
public AccountAlreadyExistsException(String message) {
super(message);
}
}
package com.example;
import com.amazonaws.services.lambda.runtime.Context;
public class Handler {
public static void CreateAccount(String name, Context context) throws
AccountAlreadyExistsException {
throw new AccountAlreadyExistsException ("Account is in use!");
}
}
You can configure Step Functions to catch the error using a Catch rule. Lambda automatically sets the
error name to the fully-qualified class name of the exception at runtime:
{
"StartAt": "CreateAccount",
"States": {
"CreateAccount": {
"Type": "Task",
"Resource": "arn:aws:lambda:us-east-1:123456789012:function:CreateAccount",
"Next": "SendWelcomeEmail",
"Catch": [
{
"ErrorEquals": ["com.example.AccountAlreadyExistsException"],
"Next": "SuggestAccountName"
}
]
},
…
}
}
At runtime, AWS Step Functions catches the error, transitioning to the SuggestAccountName state as
specified in the Next transition.
Custom error handling makes it easier to create serverless applications. This feature integrates with all
the languages supported by the Lambda Programming Model (p. 8), allowing you to design your
application in the programming languages of your choice, mixing and matching as you go.
To learn more about creating your own serverless applications using AWS Step Functions and AWS
Lambda, see AWS Step Functions.
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Programming Model for Authoring Lambda Functions in Python
The following sections explain how common programming patterns and core concepts apply when
authoring Lambda function code in Python.
Topics
• Lambda Function Handler (Python) (p. 41)
• The Context Object (Python) (p. 42)
• Logging (Python) (p. 44)
• Function Errors (Python) (p. 46)
Lambda Function Handler (Python)
At the time you create a Lambda function, you specify a handler, which is a function in your code, that AWS
Lambda can invoke when the service executes your code. Use the following general syntax structure when
creating a handler function in Python.
def handler_name(event, context):
...
return some_value
In the syntax, note the following:
• event – AWS Lambda uses this parameter to pass in event data to the handler. This parameter is usually
of the Python dict type. It can also be list, str, int, float, or NoneType type.
• context – AWS Lambda uses this parameter to provide runtime information to your handler. This
parameter is of the LambdaContext type.
• Optionally, the handler can return a value. What happens to the returned value depends on the
invocation type you use when invoking the Lambda function:
• If you use the RequestResponse invocation type (synchronous execution), AWS Lambda returns the
result of the Python function call to the client invoking the Lambda function (in the HTTP response
to the invocation request, serialized into JSON). For example, AWS Lambda console uses the
RequestResponse invocation type, so when you invoke the function using the console, the console will
display the returned value.
If the handler does not return anything, AWS Lambda returns null.
• If you use the Event invocation type (asynchronous execution), the value is discarded.
For example, consider the following Python example code.
def my_handler(event, context):
message = 'Hello {} {}!'.format(event['first_name'],
event['last_name'])
return {
'message' : message
}
This example has one function called my_handler. The function returns a message containing data from the
event it received as input.
To upload and test this code as a Lambda function
1.
Save this file (for example, as hello_python.py).
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2.
Package the file and any dependencies into a .zip file. When creating the zip, include only the code
and its dependencies, not the containing folder.
For instructions, see Creating a Deployment Package (Python) (p. 71).
3.
Upload the .zip file using either the console or AWS CLI to create a Lambda function. You specify
the function name in the Python code to be used as the handler when you create a Lambda function.
For instructions to create a Lambda function using the console, see Step 2.1: Create a Hello World
Lambda Function (p. 159). In this example, the handler is hello_python.my_handler (filename.function-name). Note that the Getting Started (p. 155) uses a blueprint that provides sample
code for a Lambda function. In this case you already have a deployment package. Therefore, in the
configure function step you choose to upload a zip.
The following create-function AWS CLI command creates a Lambda function. Among other
parameters, it specifies the --handler parameter to specify the handler name.
aws lambda create-function \
--region us-west-2 \
--function-name HelloPython \
--zip-file fileb://deployment-package.zip \
--role arn:aws:iam::account-id:role/lambda_basic_execution
--handler hello_python.my_handler \
--runtime python2.7 \
--timeout 15 \
--memory-size 512
\
The Context Object (Python)
Topics
• Example (p. 42)
• The Context Object Methods (Python) (p. 43)
• The Context Object Attributes (Python) (p. 43)
While a Lambda function is executing, it can interact with the AWS Lambda service to get useful runtime
information such as:
• How much time is remaining before AWS Lambda terminates your Lambda function (timeout is one of the
Lambda function configuration properties).
• The CloudWatch log group and log stream associated with the Lambda function that is executing.
• The AWS request ID returned to the client that invoked the Lambda function. You can use the request ID
for any follow up inquiry with AWS support.
• If the Lambda function is invoked through AWS Mobile SDK, you can learn more about the mobile
application calling the Lambda function.
AWS Lambda provides this information via the context object that the service passes as the second
parameter to your Lambda function handler. For more information, see Lambda Function Handler
(Python) (p. 41).
The following sections provide an example Lambda function that uses the context object, and then lists all
of the available methods and attributes.
Example
Consider the following Python example. It has one function that is also the handler. The handler receives
runtime information via the context object passed as parameter.
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from __future__ import print_function
import time
def get_my_log_stream(event, context):
print("Log stream name:", context.log_stream_name)
print("Log group name:", context.log_group_name)
print("Request ID:",context.aws_request_id)
print("Mem. limits(MB):", context.memory_limit_in_mb)
# Code will execute quickly, so we add a 1 second intentional delay so you can see that
in time remaining value.
time.sleep(1)
print("Time remaining (MS):", context.get_remaining_time_in_millis())
The handler code in this example simply prints some of the runtime information. Each print statement
creates a log entry in CloudWatch. If you invoke the function using the Lambda console, the console
displays the logs. The from __future__ statement enables you to write code that is compatible with Python
2 or 3.
To test this code in the AWS Lambda console
1.
In the console, create a Lambda function using the hello-world blueprint. In runtime,
choose Python 2.7. In Handler, replace lambda_function.lambda_handler with
lambda_function.get_my_log_stream. For instructions on how to do this, see Step 2.1: Create a Hello
World Lambda Function (p. 159).
2.
Test the function, and then you can also update the code to get more context information.
The following sections provide a list of available context object methods and attributes that you can use to
get runtime information of your Lambda function.
The Context Object Methods (Python)
The context object provides the following methods:
get_remaining_time_in_millis()
Returns the remaining execution time, in milliseconds, until AWS Lambda terminates the function.
The Context Object Attributes (Python)
The context object provides the following attributes:
function_name
Name of the Lambda function that is executing.
function_version
The Lambda function version that is executing. If an alias is used to invoke the function, then
function_version will be the version the alias points to.
invoked_function_arn
The ARN used to invoke this function. It can be function ARN or alias ARN. An unqualified ARN
executes the $LATEST version and aliases execute the function version it is pointing to.
memory_limit_in_mb
Memory limit, in MB, you configured for the Lambda function. You set the memory limit at the time you
create a Lambda function and you can change it later.
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aws_request_id
AWS request ID associated with the request. This is the ID returned to the client that called the invoke
method.
Note
If AWS Lambda retries the invocation (for example, in a situation where the Lambda function
that is processing Amazon Kinesis records throws an exception), the request ID remains the
same.
log_group_name
The name of the CloudWatch log group where you can find logs written by your Lambda function.
log_stream_name
The name of the CloudWatch log stream where you can find logs written by your Lambda function. The
log stream may or may not change for each invocation of the Lambda function.
The value is null if your Lambda function is unable to create a log stream, which can happen if the
execution role that grants necessary permissions to the Lambda function does not include permissions
for the CloudWatch Logs actions.
identity
Information about the Amazon Cognito identity provider when invoked through the AWS Mobile SDK. It
can be null.
• identity.cognito_identity_id
• identity.cognito_identity_pool_id
client_context
Information about the client application and device when invoked through the AWS Mobile SDK. It can
be null.
• client_context.client.installation_id
• client_context.client.app_title
• client_context.client.app_version_name
• client_context.client.app_version_code
• client_context.client.app_package_name
• client_context.custom
A dict of custom values set by the mobile client application.
• client_context.env
A dict of environment information provided by the AWS Mobile SDK.
Logging (Python)
Your Lambda function can contain logging statements. AWS Lambda writes these logs to CloudWatch. If
you use the Lambda console to invoke your Lambda function, the console displays the same logs.
The following Python statements generate log entries:
• print statements.
• Logger functions in the logging module (for example, logging.Logger.info and
logging.Logger.error).
Both print and logging.* functions write logs to CloudWatch Logs but the logging.* functions write
additional information to each log entry, such as time stamp and log level.
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For example, consider the following Python code example.
import logging
logger = logging.getLogger()
logger.setLevel(logging.INFO)
def my_logging_handler(event, context):
logger.info('got event{}'.format(event))
logger.error('something went wrong')
return 'Hello World!'
Because the code example uses the logging module to write message to the logs, you also get some
additional information in the log such as the time stamp and the log levels. The log level identifies the type
of log, such as [INFO], [ERROR], and [DEBUG], as shown:
The screen shot shows an example Log output section in the Lambda console; you can also find
these logs in CloudWatch. For more information, see Accessing Amazon CloudWatch Logs for AWS
Lambda (p. 106).
Instead of using the logging module, you can use the print statements in your code as shown in the
following Python example:
from __future__ import print_function
def my_other_logging_handler(event, context):
print('this will also show up in cloud watch')
return 'Hello World!'
In this case only the text passed to the print method is sent to CloudWatch. The log entries will not have
additional information that the logging.* function returns. The from __future__ statement enables you to
write code that is compatible with Python 2 or 3.
The console uses the RequestResponse invocation type (synchronous invocation) when invoking the
function. And therefore it gets the return value ("Hello world!") back from AWS Lambda which the console
displays.
To test the preceding Python code (console)
1.
2.
3.
In the console, create a Lambda function using the hello-world-python blueprint. In
runtime, choose Python 2.7. In Handler, replace lambda_function.lambda_handler with
lambda_function.my_other_logging_handler and in Role, choose Basic execution role. You also
replace the code provided by the blueprint by the code in this section. For step-by-step instructions
to create a Lambda function using the console, see Step 2.1: Create a Hello World Lambda
Function (p. 159).
Replace the template code with the code provided in this section.
Test the Lambda function using the Sample event template called Hello World provided in the
Lambda console.
Finding Logs
You can find the logs that your Lambda function writes, as follows:
• In the AWS Lambda console – The Log output section in AWS Lambda console shows the logs.
• In the response header, when you invoke a Lambda function programmatically – If you invoke a
Lambda function programmatically, you can add the LogType parameter to retrieve the last 4 KB of log
data that is written to CloudWatch Logs. AWS Lambda returns this log information in the x-amz-logresults header in the response. For more information, see Invoke (p. 351).
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If you use AWS CLI to invoke the function, you can specify the --log-type parameter with
value Tail to retrieve the same information.
• In CloudWatch Logs – To find your logs in CloudWatch you need to know the log group name and log
stream name. You can use the context.logGroupName, and context.logStreamName properties in your
code to get this information. When you run your Lambda function, the resulting logs in the console or CLI
will show you the log group name and log stream name.
Function Errors (Python)
If your Lambda function raises an exception, AWS Lambda recognizes the failure and serializes the
exception information into JSON and returns it. Consider the following example:
def always_failed_handler(event, context):
raise Exception('I failed!')
When you invoke this Lambda function, it will raise an exception and AWS Lambda returns the following
error message:
{
"errorMessage": "I failed!",
"stackTrace": [
[
"/var/task/lambda_function.py",
3,
"my_always_fails_handler",
"raise Exception('I failed!')"
]
],
"errorType": "Exception"
}
Note that the stack trace is returned as the stackTrace JSON array of stack trace elements.
How you get the error information back depends on the invocation type that the client specifies at the time
of function invocation:
• If a client specifies the RequestResponse invocation type (that is, synchronous execution), it returns the
result to the client that made the invoke call.
For example, the console always use the RequestResponse invocation type, so the console will display
the error in the Execution result section as shown:
The same information is also sent to CloudWatch and the Log output section shows the same logs.
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• If a client specifies the Event invocation type (that is, asynchronous execution), AWS Lambda will not
return anything. Instead, it logs the error information to CloudWatch Logs. You can also see the error
metrics in CloudWatch Metrics.
Depending on the event source, AWS Lambda may retry the failed Lambda function. For example, if
Amazon Kinesis is the event source, AWS Lambda will retry the failed invocation until the Lambda function
succeeds or the records in the stream expire.
To test the preceding Python code (console)
1.
In the console, create a Lambda function using the hello-world blueprint. In runtime,
choose Python 2.7. In Handler, replace lambda_function.lambda_handler with
lambda_function.always_failed_handler. For instructions on how to do this, see Step 2.1: Create a
Hello World Lambda Function (p. 159).
2.
3.
Replace the template code with the code provided in this section.
Test the Lambda function using the Sample event template called Hello World provided in the
Lambda console.
Function Error Handling
You can create custom error handling to raise an exception directly from your Lambda function and
handle it directly (Retry or Catch) within an AWS Step Functions State Machine. For more information, see
Handling Error Conditions Using a State Machine.
Consider a CreateAccount state is a task that writes a customer's details to a database using a Lambda
function.
• If the task succeeds, an account is created and a welcome email is sent.
• If a user tries to create an account for a username that already exists, the Lambda function raises an
error, causing the state machine to suggest a different username and to retry the account-creation
process.
The following code samples demonstrate how to do this. Note that custom errors in Python must extend the
Exception class.
class AccountAlreadyExistsException(Exception): pass
def create_account(event, context):
raise AccountAlreadyExistsException('Account is in use!')
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You can configure Step Functions to catch the error using a Catch rule. Lambda automatically sets the
error name to the simple class name of the exception at runtime:
{
"StartAt": "CreateAccount",
"States": {
"CreateAccount": {
"Type": "Task",
"Resource": "arn:aws:lambda:us-east-1:123456789012:function:CreateAccount",
"Next": "SendWelcomeEmail",
"Catch": [
{
"ErrorEquals": ["AccountAlreadyExistsException"],
"Next": "SuggestAccountName"
}
]
},
…
}
}
At runtime, AWS Step Functions catches the error, transitioning to the SuggestAccountName state as
specified in the Next transition.
Custom error handling makes it easier to create serverless applications. This feature integrates with all
the languages supported by the Lambda Programming Model (p. 8), allowing you to design your
application in the programming languages of your choice, mixing and matching as you go.
To learn more about creating your own serverless applications using AWS Step Functions and AWS
Lambda, see AWS Step Functions.
Programming Model for Authoring Lambda Functions in C#
The following sections explain how common programming patterns and core concepts apply when
authoring Lambda function code in C#.
Topics
• Lambda Function Handler (C#) (p. 49)
• The Context Object (C#) (p. 52)
• Logging (C#) (p. 53)
• Function Errors (C#) (p. 54)
Additionally, note that AWS Lambda provides the following:
• Amazon.Lambda.Core – This library provides a static Lambda logger, serialization interfaces and a
context object. The Context object (The Context Object (C#) (p. 52)) provides runtime information
about your Lambda function.
• Amazon.Lambda.Serialization.Json – This an implementation of the serialization interface in
Amazon.Lambda.Core.
• Amazon.Lambda.Logging.AspNetCore – This provides a library for logging from ASP.NET.
• Event objects (POCOs) for several AWS services, including:
• Amazon.Lambda.APIGatewayEvents
• Amazon.Lambda.CognitoEvents
• Amazon.Lambda.ConfigEvents
• Amazon.Lambda.DynamoDBEvents
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• Amazon.Lambda.KinesisEvents
• Amazon.Lambda.S3Events
• Amazon.Lambda.SNSEvents
These packages are available at Nuget Packages.
Lambda Function Handler (C#)
When you create a Lambda function, you specify a handler that AWS Lambda can invoke when the service
executes the function on your behalf.
You define a Lambda function handler as an instance or static method in a class. If you want access to the
Lambda context object, it is available by defining a method parameter of type ILambdaContext..
returnType handler-name(inputType input, ILambdaContext context) {
...
}
In the syntax, note the following:
• inputType – The first handler parameter is the input to the handler, which can be event data (published
by an event source) or custom input that you provide such as a string or any custom data object.
• returnType – If you plan to invoke the Lambda function synchronously (using the RequestResponse
invocation type), you can return the output of your function using any of the supported data types.
For example, if you use a Lambda function as a mobile application backend, you are invoking it
synchronously. Your output data type will be serialized into JSON.
If you plan to invoke the Lambda function asynchronously (using the Event invocation type), the
returnType should be void. For example, if you use AWS Lambda with event sources such as Amazon
S3, Amazon Kinesis, and Amazon SNS, these event sources invoke the Lambda function using the
Event invocation type.
Handling Streams
Only the System.IO.Stream type is supported as an input parameter by default.
For example, consider the following C# example code.
using System.IO;
{
namespace Example
public class Hello
{
public Stream MyHandler(Stream stream)
{
//function logic
}
}
In the example C# code, the first handler parameter is the input to the handler (MyHandler), which can
be event data (published by an event source such as Amazon S3) or custom input you provide such as a
Stream (as in this example) or any custom data object. The output is of type Stream.
Handling Standard Data Types
All other types, as listed below, require you to specify a serializer.
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• Primitive .NET types (such as string or int).
• Collections and maps - IList, IEnumerable, IList<T>, Array, IDictionary, IDictionary<TKey, TValue>
• POCO types (Plain old CLR objects)
• Predefined AWS event types
• For asynchronous invocations the return-type will be ignored by Lambda. The return type may be set to
void in such cases.
• If you are using .NET asynchronous programming, the return type can be Task and Task<T> types
and use async and await keywords. For more information, see Using Async in C# Functions with AWS
Lambda (p. 51).
Unless your function input and output parameters are of type System.IO.Stream, you will need to serialize
them. AWS Lambda provides a default serializer that can be applied at the assembly or method level
of your application, or you can define your own by implementing the ILambdaSerializer interface
provided by the Amazon.Lambda.Core library. For more information, see Creating a Deployment Package
(C#) (p. 59).
To add the default serializer attribute to a method, first add a dependency on
Amazon.Lambda.Serialization.Json in your project.json file.
{
"version": "1.0.0-*",
"dependencies":{
"Microsoft.NETCore.App": {
"type": "platform",
"version": "1.0.1"
},
"Amazon.Lambda.Serialization.Json": "1.0.0"
},
"frameworks": {
"netcoreapp1.0": {
"imports": "dnxcore50"
}
}
}
The example below illustrates the flexibility you can leverage by specifying the default Json.NET serializer
on one method and another of your choosing on a different method:
public class ProductService{
[LambdaSerializer(typeof(Amazon.Lambda.Serialization.Json.JsonSerializer))]
public Product DescribeProduct(DescribeProductRequest request)
{
return catalogService.DescribeProduct(request.Id);
}
[LambdaSerializer(typeof(MyJsonSerializer))]
public Customer DescribeCustomer(DescribeCustomerRequest request)
{
return customerService.DescribeCustomer(request.Id);
}
}
Handler Signatures
When creating Lambda functions, you have to provide a handler string that tells AWS Lambda where to
look for the code to invoke. In C#, the format is:
ASSEMBLY::TYPE::METHOD where:
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• ASSEMBLY is the name of the .NET assembly file for your application. When using the .NET Core CLI
to build your application, if you haven't set the assembly name using the buildOptions.outputName
setting in project.json, the ASSEMBLY name will be the name of the folder that contains your project.json
file. For more information, see .NET Core CLI (p. 59). In this case, let's assume the folder name is
HelloWorldApp.
• TYPE is the full name of the handler type, which consists of the Namespace and the ClassName. In this case
Example.Hello.
• METHOD is name of the function handler, in this case MyHandler.
Ultimately, the signature will be of this format: Assembly::Namespace.ClassName::MethodName
Again, consider the following example:
using System.IO;
{
namespace Example
public class Hello
{
public Stream MyHandler(Stream stream)
{
//function logic
}
}
The handler string would be: HelloWorldApp::Example.Hello::MyHandler
For instructions to create a Lambda function using this C# code, see Step 2.4: (Optional) Create a Lambda
Function Authored in C# (p. 165).
Important
If the method specified in your handler string is overloaded, you must provide the exact signature
of the method Lambda should invoke. AWS Lambda will reject an otherwise valid signature if the
resolution would require selecting among multiple (overloaded) signatures.
Lambda Function Handler Restrictions
Note that there are some restrictions on the handler signature
• It may not be unsafe and use pointer types in the handler signature, though unsafe context can be used
inside the handler method and its dependencies. For more information, see unsafe (C# Reference).
• It may not pass a variable number of parameters using the params keyword, or use ArgIterator as an
input or return parameter which is used to support variable number of parameters.
• The handler may not be a generic method (e.g. IList<T> Sort<T>(IList<T> input)).
• Async handlers with signature async void are not supported.
Using Async in C# Functions with AWS Lambda
If you know your Lambda function will require a long-running process, such as uploading large files to
Amazon S3 or reading a large stream of records from DynamoDB, you can take advantage of the async/
await pattern. By creating a handler with this signature, Lambda will execute the function synchronously
and wait a maximum of 5 minutes for execution to complete before returning or timing out. For example:
public async Task<Response> ProcessS3ImageResizeAsync(SimpleS3Event input)
{
var response = await client.DoAsyncWork(input);
return response;
}
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If you use this pattern, there are some considerations you must take into account:
• AWS Lambda will not support async void methods.
• If you create an async Lambda function without implementing the await operator, .NET will issue a
compiler warning and you will observe unexpected behavior. For example, some async actions will
execute while others won't. Or some async actions won't complete before the function execution is
complete.
public async Task ProcessS3ImageResizeAsync(SimpleS3Event event) // Compiler warning
{
client.DoAsyncWork(input);
}
• Your Lambda function can include multiple async calls, which can be invoked in parallel. You can use the
Task.WaitAll and Task.WaitAny methods to work with multiple tasks. To use the Task.WaitAll method,
you pass a list of the operations as an array to the method. Note that in the example below, if you neglect
to include any operation to the array, that call may return before its operation completes.
public async Task SaveAsync(Profile profile)
{
var s3Save = s3.SaveImage(profile.image);
var ddbSave = ddb.SaveAttributes(profile.Attributes);
var ddbSave2 = ddb.SaveConnections(profile.connections);
this call completes
// Lambda will return before
// No compiler warnings
return await Task.WaitAll(new Task[]{ s3Save, ddbSave }); // Did not "await" for
ddbSave2
}
To use the Task.WaitAny method, you again pass a list of operations as an array to the method. The call
returns as soon as the first operation completes, even if the others are still running.
public async Task<SearchResult> SearchAsync(Query q)
{
var siteSearch1 = site1.SearchAsync(q);
var siteSearch2 = site2.SearchAsyc(q);
var siteSearch3 = site3.SearchAsync(q);
var tasks[] = new Task[]{siteSearch1, siteSearch2, siteSearch3};
var index = await Task.WaitAny(tasks); // Returns as soon as any of the tasks complete,
other task may run in background
return tasks[index].Result;
}
We do not recommend using Task.WaitAny for the above reasons.
The Context Object (C#)
You can gain useful information on how your Lambda function is interacting with the AWS Lambda runtime
by adding the ILambdaContext parameter to your method. In return, AWS Lambda provides runtime details
such as the CloudWatch log stream associated with the function or the id of the client that called your
functions, which you access via the properties provided by the context object.
To do this, create a method with the following signature:
public void Handler(string Input, ILambdaContext context)
The context object properties are:
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• MemoryLimitInMB: Memory limit, in MB, you configured for the Lambda function.
• FunctionName: Name of the Lambda function that is running.
• FunctionVersion: The Lambda function version that is executing. If an alias is used to invoke the
function, then FunctionVersion will be the version the alias points to.
• InvokedFunctionArn: The ARN used to invoke this function. It can be function ARN or alias ARN. An
unqualified ARN executes the $LATEST version and aliases execute the function version it is pointing to.
• AwsRequestId: AWS request ID associated with the request. This is the ID returned to the client that
invoked this Lambda function. You can use the request ID for any follow up enquiry with AWS support.
Note that if AWS Lambda retries the function (for example, in a situation where the Lambda function
processing Amazon Kinesis records throw an exception), the request ID remains the same.
• LogStreamName: The CloudWatch log stream name for the particular Lambda function execution. It can
be null if the IAM user provided does not have permission for CloudWatch actions.
• LogGroupName: The CloudWatch log group name associated with the Lambda function invoked. It can be
null if the IAM user provided does not have permission for CloudWatch actions.
• ClientContext: Information about the client application and device when invoked through the AWS
Mobile SDK. It can be null. Client context provides client information such as client ID, application title,
version name, version code, and the application package name.
• Identity: Information about the Amazon Cognito identity provider when invoked through the AWS
Mobile SDK. It can be null.
• RemainingTime: Remaining execution time till the function will be terminated. At the time you create the
Lambda function you set maximum time limit, at which time AWS Lambda will terminate the function
execution. Information about the remaining time of function execution can be used to specify function
behavior when nearing the timeout. This is a TimeSpan field.
• Logger: The Lambda logger associated with the ILambdaContext object. For more information, see
Logging (C#) (p. 53).
The following C# code snippet shows a simple handler function that displays the value of the input
parameter and then prints some of the context information.
public async Task Handler(ILambdaContext context)
{
Console.Writeline("Function name: " + context.FunctionName);
Console.Writeline("RemainingTime: " + context.RemainingTime);
await Task.Delay(TimeSpan.FromSeconds(0.42));
Console.Writeline("RemainingTime after sleep: " + context.RemainingTime);
}
Logging (C#)
Your Lambda function can contain logging statements and, in turn, AWS Lambda writes these logs to
CloudWatch Logs.
In the C# programming model, there are three ways to log data in your function:
• Use the static Write or WriteLine methods provided by the C# Console class. Anything written to
standard out or standard error - using Console.Write or a similar method - will be logged in CloudWatch
Logs.
public class ProductService
{
public async Task<Product> DescribeProduct(DescribeProductRequest request)
{
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Console.WriteLine("DescribeProduct invoked with Id " + request.Id);
return await catalogService.DescribeProduct(request.Id);
}
}
• Use the Log method on the Amazon.Lambda.Core.LambdaLogger class. This is a static class that can be
used anywhere in your application. To use this, you must include the Amazon.Lambda.Core library.
using Amazon.Lambda.Core;
public class ProductService
{
public async Task<Product> DescribeProduct(DescribeProductRequest request)
{
LambdaLogger.Log("DescribeProduct invoked with Id " + request.Id);
return await catalogService.DescribeProduct(request.Id);
}
}
Each call to LambdaLogger.Log results in a CloudWatch Logs event, provided the event size is within the
allowed limits. For information about CloudWatch Logs logs limits, see CloudWatch Logs Limits in the
Amazon CloudWatch User Guide.
• Use the logger in ILambdaContext. The ILambdaContext object (if specified) in your method contains a
Logger property that represents a LambdaLogger. The following is an example of using this method:
public class ProductService
{
public async Task<Product> DescribeProduct(DescribeProductRequest request,
ILambdaContext context)
{
context.Logger.Log("DescribeProduct invoked with Id " + request.Id);
return await catalogService.DescribeProduct(request.Id);
}
}
How to Find Logs
You can find the logs that your Lambda function writes, as follows:
• Find logs in CloudWatch Logs. The ILambdaContext object provides the LogStreamName and the
LogGroupName properties. Using these properties, you can find the specific log stream where logs are
written.
• If you invoke a Lambda function via the console, the invocation type is always RequestResponse (that
is, synchronous execution) and the console displays the logs that the Lambda function writes using the
LambdaLogger object. AWS Lambda also returns logs from Console.Write and Console.WriteLine
methods.
• If you invoke a Lambda function programmatically, you can add the LogType parameter to retrieve the
last 4 KB of log data that is written to CloudWatch Logs. For more information, see Invoke (p. 351).
AWS Lambda returns this log information in the x-amz-log-results header in the response. If you use
the AWS Command Line Interface to invoke the function, you can specify the --log-type parameter with
value Tail.
Function Errors (C#)
When an exception occurs in your Lambda function, Lambda will report the exception information back to
you. Exceptions can occur in two different places:
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• Initialization (Lambda loading your code, validating the handler string, and creating an instance of your
class if it is non-static).
• The Lambda function invocation.
The serialized exception information is returned as the payload as a modeled JSON object and outputted to
CloudWatch logs.
In the initialization phase, exceptions can be thrown for invalid handler strings, a rule-breaking type or
method (see Lambda Function Handler Restrictions (p. 51)), or any other validation method (such as
forgetting the serializer attribute and having a POCO as your input or output type). These exceptions are of
type LambdaException. For example:
{
"errorType": "LambdaException",
"errorMessage": "Invalid lambda function handler: 'http://this.is.not.a.valid.handler/'.
The valid format is 'ASSEMBLY::TYPE::METHOD'."
}
If your constructor throws an exception, the error type is also of type LambdaException, but the exception
thrown during construction is provided in the cause property, which is itself a modeled exception object:
{
"errorType": "LambdaException",
"errorMessage": "An exception was thrown when the constructor for type
'LambdaExceptionTestFunction.ThrowExceptionInConstructor'
was invoked. Check inner exception for more details.",
"cause":
{
"errorType": "TargetInvocationException",
"errorMessage": "Exception has been thrown by the target of an invocation.",
"stackTrace": [
"at System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly,
Boolean noCheck, Boolean&canBeCached,
RuntimeMethodHandleInternal&ctor, Boolean& bNeedSecurityCheck)",
"at System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean skipCheckThis,
Boolean fillCache, StackCrawlMark& stackMark)",
"at System.Activator.CreateInstance(Type type, Boolean nonPublic)",
"at System.Activator.CreateInstance(Type type)"
],
"cause":
{
"errorType": "ArithmeticException",
"errorMessage": "Sorry, 2 + 2 = 5",
"stackTrace": [
"at LambdaExceptionTestFunction.ThrowExceptionInConstructor..ctor()"
]
}
}
}
As the example shows, the inner exceptions are always preserved (as the cause property), and can be
deeply nested.
Exceptions can also occur during invocation. In this case, the exception type is preserved and the
exception is returned directly as the payload and in the CloudWatch logs. For example:
{
"errorType": "AggregateException",
"errorMessage": "One or more errors occurred. (An unknown web exception occurred!)",
"stackTrace": [
"at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean
includeTaskCanceledExceptions)",
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"at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification)",
"at lambda_method(Closure , Stream , Stream , ContextInfo )"
],
"cause":
{
"errorType": "UnknownWebException",
"errorMessage": "An unknown web exception occurred!",
"stackTrace": [
"at LambdaDemo107.LambdaEntryPoint.<GetUriResponse>d__1.MoveNext()",
"--- End of stack trace from previous location where exception was thrown ---",
"at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)",
"at
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
task)",
"at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()",
"at LambdaDemo107.LambdaEntryPoint.<CheckWebsiteStatus>d__0.MoveNext()"
],
"cause":
{
"errorType": "WebException",
"errorMessage": "An error occurred while sending the request. SSL peer certificate or
SSH remote key was not OK",
"stackTrace": [
"at System.Net.HttpWebRequest.EndGetResponse(IAsyncResult asyncResult)",
"at System.Threading.Tasks.TaskFactory`1.FromAsyncCoreLogic(IAsyncResult iar,
Func`2 endFunction, Action`1 endAction, Task`1 promise, Boolean requiresSynchronization)",
"--- End of stack trace from previous location where exception was thrown ---",
"at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)",
"at
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
task)",
"at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()",
"at LambdaDemo107.LambdaEntryPoint.<GetUriResponse>d__1.MoveNext()"
],
"cause":
{
"errorType": "HttpRequestException",
"errorMessage": "An error occurred while sending the request.",
"stackTrace": [
"at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)",
"at
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
task)",
"at System.Net.Http.HttpClient.<FinishSendAsync>d__58.MoveNext()",
"--- End of stack trace from previous location where exception was thrown ---",
"at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)",
"at
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
task)",
"at System.Net.HttpWebRequest.<SendRequest>d__63.MoveNext()",
"--- End of stack trace from previous location where exception was thrown ---",
"at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)",
"at
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
task)",
"at System.Net.HttpWebRequest.EndGetResponse(IAsyncResult asyncResult)"
],
"cause":
{
"errorType": "CurlException",
"errorMessage": "SSL peer certificate or SSH remote key was not OK",
"stackTrace": [
"at System.Net.Http.CurlHandler.ThrowIfCURLEError(CURLcode error)",
"at
System.Net.Http.CurlHandler.MultiAgent.FinishRequest(StrongToWeakReference`1 easyWrapper,
CURLcode messageResult)"
]
}
}
}
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}
}
The method in which error information is conveyed depends on the invocation type:
• RequestResponse invocation type (that is, synchronous execution): In this case, you get the error
message back.
For example, if you invoke a Lambda function using the Lambda console, the RequestResponse is always
the invocation type and the console displays the error information returned by AWS Lambda in the
Execution result section of the console.
• Event invocation type (that is, asynchronous execution): In this case AWS Lambda does not return
anything. Instead, it logs the error information in CloudWatch Logs and CloudWatch metrics.
Depending on the event source, AWS Lambda may retry the failed Lambda function. For more information,
see Retries on Errors (p. 149).
Function Error Handling
You can create custom error handling to raise an exception directly from your Lambda function and
handle it directly (Retry or Catch) within an AWS Step Functions State Machine. For more information, see
Handling Error Conditions Using a State Machine.
Consider a CreateAccount state is a task that writes a customer's details to a database using a Lambda
function.
• If the task succeeds, an account is created and a welcome email is sent.
• If a user tries to create an account for a username that already exists, the Lambda function raises an
error, causing the state machine to suggest a different username and to retry the account-creation
process.
The following code samples demonstrate how to do this. Note that custom errors in C# must extend the
Exception class.
namespace Example {
public class AccountAlreadyExistsException : Exception {
public AccountAlreadyExistsException(String message) :
base(message) {
}
}
}
namespace Example {
public class Handler {
public static void CreateAccount() {
throw new AccountAlreadyExistsException("Account is in use!");
}
}
}
You can configure Step Functions to catch the error using a Catch rule. Lambda automatically sets the
error name to the simple class name of the exception at runtime:
{
"StartAt": "CreateAccount",
"States": {
"CreateAccount": {
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"Type": "Task",
"Resource": "arn:aws:lambda:us-east-1:123456789012:function:CreateAccount",
"Next": "SendWelcomeEmail",
"Catch": [
{
"ErrorEquals": ["AccountAlreadyExistsException"],
"Next": "SuggestAccountName"
}
]
},
…
}
}
At runtime, AWS Step Functions catches the error, transitioning to the SuggestAccountName state as
specified in the Next transition.
Custom error handling makes it easier to create serverless applications. This feature integrates with all
the languages supported by the Lambda Programming Model (p. 8), allowing you to design your
application in the programming languages of your choice, mixing and matching as you go.
To learn more about creating your own serverless applications using AWS Step Functions and AWS
Lambda, see AWS Step Functions.
Creating a Deployment Package
To create a Lambda function you first create a Lambda function deployment package, a .zip or .jar file
consisting of your code and any dependencies. When creating the zip, include only the code and its
dependencies, not the containing folder.
• Creating a Deployment Package (Node.js) (p. 58)
• Creating a Deployment Package (Java) (p. 64)
• Creating a Deployment Package (C#) (p. 59)
• Creating a Deployment Package (Python) (p. 71)
Creating a Deployment Package (Node.js)
To create a Lambda function you first create a Lambda function deployment package, a .zip file consisting
of your code and any dependencies.
You can create a deployment package yourself or write your code directly in the Lambda console, in which
case the console creates the deployment package for you and uploads it, creating your Lambda function.
Note the following to determine if you can use the console to create your Lambda function:
• Simple scenario – If your custom code requires only the AWS SDK library, then you can use the inline
editor in the AWS Lambda console. Using the console, you can edit and upload your code to AWS
Lambda. The console will zip up your code with the relevant configuration information into a deployment
package that the Lambda service can run.
You can also test your code in the console by manually invoking it using sample event data.
Note
The Lambda service has preinstalled the AWS SDK for Node.js.
• Advanced scenario – If you are writing code that uses other resources, such as a graphics library for
image processing, or you want to use the AWS CLI instead of the console, you need to first create the
Lambda function deployment package, and then use the console or the CLI to upload the package.
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Note
After you create a deployment package, you may either upload it directly or upload the .zip file first
to an Amazon S3 bucket in the same AWS region where you want to create the Lambda function,
and then specify the bucket name and object key name when you create the Lambda function
using the console or the AWS CLI.
The following is an example procedure to create a deployment package (outside the console). Suppose you
want to create a deployment package that includes a filename.js code file and your code uses the async
library.
1. Open a text editor, and write your code. Save the file (for example, filename.js).
You will use the file name to specify the handler at the time of creating the Lambda function.
2. In the same directory, use npm to install the libraries that your code depends on. For example, if your
code uses the async library, use the following npm command.
npm install async
3. Your directory will then have the following structure:
filename.js
node_modules/async
node_modules/async/lib
node_modules/async/lib/async.js
node_modules/async/package.json
4. Zip the content of the folder, that is your deployment package (for example, sample.zip).
Then, specify the .zip file name as your deployment package at the time you create your Lambda function.
If you want to include your own binaries, including native ones, just package them in the Zip file you
upload and then reference them (including the relative path within the Zip file you created) when you call
them from Node.js or from other processes that you’ve previously started. Ensure that you include the
following at the start of your function code: process.env[‘PATH’] = process.env[‘PATH’] + ‘:’ +
process.env[‘LAMBDA_TASK_ROOT’]
For more information on including native binaries in your Lambda function package, see Running
Executables in AWS Lambda.
Creating a Deployment Package (C#)
You can create .NET-core based AWS Lambda applications and package them for deployment in the
following ways:
• Use the .NET Core CLI, which you can download here to create your Lambda application.
• Use the Lambda plugin to the AWS ToolKit for Microsoft Visual Studio, which can you download here.
Topics
• .NET Core CLI (p. 59)
• AWS Toolkit for Visual Studio (p. 62)
.NET Core CLI
The .NET Core CLI offers a cross-platform way for you to create .NET-based Lambda applications.
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Before You Begin
This section assumes you have done the following:
• Installed the .NET Core CLI. If you haven't, do so here.
Create a .NET Project
To create an application using the .NET Core CLI, open a command prompt and navigate to the folder
where you installed the .NET Core runtime and follow these steps:
1.
Make a directory where your project will be created using the following command: mkdir example
2.
Navigate to that directory using the following command: cd example
3.
Enter the following command: dotnet new
This will create two files in your example directory:
• Program.cs, which is where you write your Lambda function code.
• project.json, which is the file is where you declare Nuget dependencies (or dependencies on
local projects). NuGet is the package manager for the .NET platform. For more information, see
Nuget.org.
Note
Lambda methods don't use the Main() entry point provided by default in .NET, so open the
project.json file and remove the "buildOptions" property. After this, your project.json should
look something like this (exact versions may differ depending on when you installed the
NetCore CLI):
{
"version": "1.0.0-*",
"dependencies": {},
"frameworks": {
"netcoreapp1.0": {
"dependencies": {
"Microsoft.NETCore.App": {
"type": "platform",
"version": "1.1.0"
}
},
"imports": "dnxcore50"
}
}
}
4.
Open the Program.cs file using an editor of you choice, such as Microsoft Visual Studio.
• Replace the default code that is provided with your Lambda function handler code:
At this point, your .cs file structure should resemble this:
using System;
using System.IO;
namespace CSharpLambdaFunction
{
public class LambdaHandler
{
public Stream myHandler(Stream inputStream)
{
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//function logic
}
}
}
Your Lambda function handler signature should be of the format
Assembly::Namespace.ClassName::MethodName. For more information, see Handler Signatures (p. 50).
Using a Serializer
For any Lambda functions that use input or output types other than a Stream object, you will need to add a
serialization library to your application. You can do this in the following ways:
• Use Json.NET. Lambda will provide an implementation for JSON serializer using JSON.NET as a NuGet
package.
• Create your own serialization library by implementing the ILambdaSerializer interface, which is
available as part of the Amazon.Lambda.Core library. The interface defines two methods:
• T Deserialize<T>(Stream requestStream);
You implement this method to deserialize the request payload from the Invoke API into the object that
is passed to the Lambda function handler.
• T Serialize<T>(T response, Stream responseStream);.
You implement this method to serialize the result returned from the Lambda function handler into the
response payload that is returned by the Invoke API.
You use whichever serializer you wish by adding it as a dependency to your project.json file.
{
"version": "1.0.0-*",
"buildOptions": {
},
"dependencies": {
"Microsoft.NETCore.App": {
"type": "platform",
"version": "1.0.1"
},
"Newtonsoft.Json": "9.0.1",
"Amazon.Lambda.Core": "1.0.0*",
"Amazon.Lambda.Serialization.Json": "1.0.0",
"Amazon.Lambda.Tools" : {
"type" :"build",
"version":"0.9.0-preview1"
}
},
"tools": {
"Amazon.Lambda.Tools" : "0.9.0-preview1"
},
"frameworks": {
"netcoreapp1.0": {
"imports": "dnxcore50"
}
}
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}
You then add it to your AssemblyInfo.cs file. For example, if you are using the default Json.NET serializer,
this is what you would add:
[assembly:LambdaSerializer(typeof(Amazon.Lambda.Serialization.Json.JsonSerializer))]
Note
You can define a custom serialization attribute at the method level, which will override the default
serializer specified at the assembly level. For more information, see Handling Standard Data
Types (p. 49).
Create the Deployment Package
To create the deployment package, open a command prompt and navigate to the folder that contains your
project.json file and run the following commands:
• dotnet restore which will restore any references to dependencies of the project that may have changed
during the development process.
• dotnet publish which compiles the application and packages the source code and any dependencies
into a folder. The output of the command window will instruct you where the folder was created. For
example:
publish: Published to C:\Users\yourname\project-folder\bin\debug\netcoreapp1.1\publish
The contents of this folder represent your application and at a minimum would look something like this:
application-name.deps.json
application-name.dll
application-name.pdb
application-name.runtimeconfig.json
Zip the contents of the folder (not the folder itself). This is your deployment package.
AWS Toolkit for Visual Studio
You can build .NET-based Lambda applications using the Lambda plugin to the AWS Toolkit for Visual
Studio. The plugin is available as part of a Nuget package.
Step 1: Create and Build a Project
1.
Launch Microsoft Visual Studio and choose New project.
a.
From the File menu, choose New, and then choose Project.
b.
In the New Project window, choose AWS Lambda Project (.NET Core) and then choose OK.
c.
In the Select Blueprint window, you will be presented with the option of selecting from a list of
sample applications that will provide you with sample code to get started with creating a .NETbased Lambda application.
d.
To create a Lambda application from scratch, choose Blank Function and then choose Finish.
e.
Note that the libraries necessary for you to build a .NET-based Lambda application are provided in
the References node of your project.
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2.
Open the Function.cs file. You will be provided with a template to implement your Lambda function
handler code.
3.
Once you have written the code that represents your Lambda function, you can upload it by rightclicking the Project node in your application and then choosing Publish to AWS Lambda.
4.
In the Upload Lambda Function window, do the following:
• Specify the Region:
• Specify the Function Name:
• Specify the Assembly Name:
• Specify the Type Name:
• Specify the Method Name:
Then choose Next
5.
In the Advanced Function Details window, do the following:
• Specify the Role Name:, which is the IAM role required for your Lambda function's execution. If you
have not yet created an execution role, do the following:
1.
Sign in to the IAM console at https://console.aws.amazon.com/iam/.
2.
Follow the steps in Creating a Role to Delegate Permissions to an AWS Service in the IAM User
Guide to create an IAM role (execution role). As you follow the steps to create a role, note the
following:
• In Role Name, use a name that is unique within your AWS account.
• In Select Role Type, choose AWS Service Roles, and then choose a service role that grants
that service permissions to assume the role.
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• In Attach Policy, choose a permissions policy that is suitable to execute your Lambda
function.
• (Optional) In Environment:: specify any environment variables you wish to use. For more
information, see Environment Variables (p. 85).
• (Optional)Specify the Memory (MB): or Timeout (Secs): configurations.
• (Optional)Specify any VPC: configurations if your Lambda function needs to access resources
running inside a private VPC. For more information, see Configuring a Lambda Function to Access
Resources in an Amazon VPC (p. 92).
• Choose Next and then choose Upload to deploy your application.
Creating a Deployment Package (Java)
Your deployment package can be a .zip file or a standalone jar; it is your choice. You can use any build and
packaging tool you are familiar with to create a deployment package.
We provide examples of using Maven to create standalone jars and using Gradle to create a .zip file. For
more information, see the following topics:
Topics
• Creating a .jar Deployment Package Using Maven without any IDE (Java) (p. 64)
• Creating a .jar Deployment Package Using Maven and Eclipse IDE (Java) (p. 66)
• Creating a .zip Deployment Package (Java) (p. 68)
• Authoring Lambda Functions Using Eclipse IDE and AWS SDK Plugin (Java) (p. 71)
Creating a .jar Deployment Package Using Maven without any IDE (Java)
This section shows how to package your Java code into a deployment package using Maven at the
command line.
Topics
• Before You Begin (p. 64)
• Project Structure Overview (p. 64)
• Step 1: Create Project (p. 65)
• Step 2: Build Project (Create Deployment Package) (p. 66)
Before You Begin
You will need to install the Maven command-line build tool. For more information, go to Maven. If you are
using Linux, check your package manager.
sudo apt-get install mvn
if you are using Homebrew
brew install maven
Project Structure Overview
After you set up the project, you should have the following folder structure:
project-dir/pom.xml
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project-dir/src/main/java/
(your code goes here)
Your code will then be in the /java folder. For example, if your package name is example and you have a
Hello.java class in it, the structure will be:
project-dir/src/main/java/example/Hello.java
After you build the project, the resulting .jar file (that is, your deployment package), will be in the projectdir/target subdirectory.
Step 1: Create Project
Follow the steps in this section to create a Java project.
1.
Create a project directory (project-dir).
2.
In the project-dir directory, create the following:
• Project Object Model file, pom.xml. Add the following project information and configuration details for
Maven to build the project.
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/
XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/mavenv4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>doc-examples</groupId>
<artifactId>lambda-java-example</artifactId>
<packaging>jar</packaging>
<version>1.0-SNAPSHOT</version>
<name>lambda-java-example</name>
<dependencies>
<dependency>
<groupId>com.amazonaws</groupId>
<artifactId>aws-lambda-java-core</artifactId>
<version>1.1.0</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>2.3</version>
<configuration>
<createDependencyReducedPom>false</createDependencyReducedPom>
</configuration>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
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Note
• In the dependencies section, the groupId (that is, com.amazonaws) is the Amazon AWS
group ID for Maven artifacts in the Maven Central Repository. The artifactId (that is,
aws-lambda-java-core) is the AWS Lambda core library that provides definitions of the
RequestHandler, RequestStreamHandler, and the Context AWS Lambda interfaces for
use in your Java application. At the build time Maven resolves these dependencies.
• In the plugins section, the Apache maven-shade-plugin is a plugin that Maven will
download and use during your build process. This plugin is used for packaging jars to
create a standalone .jar (a .zip file), your deployment package.
• If you are following other tutorial topics in this guide, the specific tutorials might require
you to add more dependencies. Make sure to add those dependencies as required.
3.
In the project-dir, create the following structure:
project-dir/src/main/java
4.
Under the /java subdirectory you add your Java files and folder structure, if any. For example, if you
Java package name is example, and source code is Hello.java, your directory structure looks like this:
project-dir/src/main/java/example/Hello.java
Step 2: Build Project (Create Deployment Package)
Now you can build the project using Maven at the command line.
1.
At a command prompt, change directory to the project directory (project-dir).
2.
Run the following mvn command to build the project:
$ mvn package
The resulting .jar is saved as project-dir/target/lambda-java-example-1.0-SNAPSHOT.jar.
The .jar name is created by concatenating the artifactId and version in the pom.xml file.
The build creates this resulting .jar, using information in the pom.xml to do the necessary transforms.
This is a standalone .jar (.zip file) that includes all the dependencies. This is your deployment package
that you can upload to AWS Lambda to create a Lambda function.
Creating a .jar Deployment Package Using Maven and Eclipse IDE (Java)
This section shows how to package your Java code into a deployment package using Eclipse IDE and
Maven plugin for Eclipse.
Topics
• Before You Begin (p. 66)
• Step 1: Create and Build a Project (p. 67)
Before You Begin
Install the Maven Plugin for Eclipse.
1.
Start Eclipse. From the Help menu in Eclipse, choose Install New Software.
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2.
In the Install window, type http://download.eclipse.org/technology/m2e/releases in the Work
with: box, and choose Add.
3.
Follow the steps to complete the setup.
Step 1: Create and Build a Project
In this step, you start Eclipse and create a Maven project. You will add the necessary dependencies, and
build the project. The build will produce a .jar, which is your deployment package.
1.
Create a new Maven project in Eclipse.
a.
From the File menu, choose New, and then choose Project.
b.
In the New Project window, choose Maven Project.
c.
In the New Maven Project window, choose Create a simple project, and leave other default
selections.
d.
In the New Maven Project, Configure project windows, type the following Artifact information:
• Group Id: doc-examples
• Artifact Id: lambda-java-example
• Version: 0.0.1-SNAPSHOT
• Packaging: jar
• Name: lambda-java-example
2.
Add the aws-lambda-java-core dependency to the pom.xml file.
It provides definitions of the RequestHandler, RequestStreamHandler, and Context interfaces. This
allows you to compile code that you can use with AWS Lambda.
a.
Open the context (right-click) menu for the pom.xml file, choose Maven, and then choose Add
Dependency.
b.
In the Add Dependency windows, type the following values:
Group Id: com.amazonaws
Artifact Id: aws-lambda-java-core
Version: 1.1.0
Caution
If you are following other tutorial topics in this guide, the specific tutorials might require
you to add more dependencies. Make sure to add those dependencies as required.
3.
Add Java class to the project.
a.
Open the context (right-click) menu for the src/main/java subdirectory in the project, choose
New, and then choose Class.
b.
In the New Java Class window, type the following values:
• Package: example
• Name: Hello
Caution
If you are following other tutorial topics in this guide, the specific tutorials might
recommend different package name or class name.
c.
4.
Add your Java code. If you are following other tutorial topics in this guide, add the provided code.
Build the project.
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Open the context (right-click) menu for the project in Package Explorer, choose Run As, and then
choose Maven Build .... In the Edit Configuration window, type package in the Goals box.
Note
The resulting .jar, lambda-java-example-0.0.1-SNAPSHOT.jar, is not the final standalone .jar
that you can use as your deployment package. In the next step, you add the Apache mavenshade-plugin to create the standalone .jar. For more information, go to Apache Maven Shade
Plugin.
5.
Add the maven-shade-plugin plugin and rebuild.
The maven-shade-plugin will take artifacts (jars) produced by the package goal (produces customer
code .jar), and created a standalone .jar that contains the compiled customer code, and the resolved
dependencies from the pom.xml.
a.
Open the context (right-click) menu for the pom.xml file, choose Maven, and then choose Add
Plugin.
b.
In the Add Plugin window, type the following values:
• Group Id: org.apache.maven.plugins
• Artifact Id: maven-shade-plugin
• Version: 2.3
c.
Now build again.
This time we will create the jar as before, and then use the maven-shade-plugin to pull in
dependencies to make the standalone .jar.
i.
Open the context (right-click) menu for the project, choose Run As, and then choose Maven
build ....
ii.
In the Edit Configuration windows, type package shade:shade in the Goals box.
iii.
Choose Run.
You can find the resulting standalone .jar (that is, your deployment package), in the /target
subdirectory.
Open the context (right-click) menu for the /target subdirectory, choose Show In, choose
System Explorer, and you will find the lambda-java-example-0.0.1-SNAPSHOT.jar.
Creating a .zip Deployment Package (Java)
This section provides examples of creating .zip file as your deployment package. You can use any build
and packaging tool you like to create this zip. Regardless of the tools you use, the resulting .zip file must
have the following structure:
• All compiled class files and resource files at the root level.
• All required jars to run the code in the /lib directory.
Note
You can also build a standalone .jar (also a zipped file) as your deployment package. For
examples of creating standalone .jar using Maven, see Creating a Deployment Package
(Java) (p. 64).
The following examples use Gradle build and deployment tool to create the .zip.
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Important
Gradle version 2.0 or later is required.
Before You Begin
You will need to download Gradle. For instructions, go to the gradle website, https://gradle.org/ .
Example 1: Creating .zip Using Gradle and the Maven Central Repository
At the end of this walkthrough, you will have a project directory (project-dir) with content having the
following structure:
project-dir/build.gradle
project-dir/src/main/java/
The /java folder will contain your code. For example, if your package name is example, and you have a
Hello.java class in it, the structure will be:
project-dir/src/main/java/example/Hello.java
After you build the project, the resulting .zip file (that is, your deployment package), will be in the projectdir/build/distributions subdirectory.
1.
Create a project directory (project-dir).
2.
In the project-dir, create build.gradle file and add the following content:
apply plugin: 'java'
repositories {
mavenCentral()
}
dependencies {
compile (
'com.amazonaws:aws-lambda-java-core:1.1.0',
'com.amazonaws:aws-lambda-java-events:1.1.0'
)
}
task buildZip(type: Zip) {
from compileJava
from processResources
into('lib') {
from configurations.runtime
}
}
build.dependsOn buildZip
Note
• The repositories section refers to Maven Central Repository. At the build time, it fetches the
dependencies (that is, the two AWS Lambda libraries) from Maven Central.
• The buildZip task describes how to create the deployment package .zip file.
For example, if you unzip the resulting .zip file you should find any of the compiled class
files and resource files at the root level. You should also find a /lib directory with the
required jars for running the code.
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3.
• If you are following other tutorial topics in this guide, the specific tutorials might require you
to add more dependencies. Make sure to add those dependencies as required.
In the project-dir, create the following structure:
project-dir/src/main/java/
4.
Under the /java subdirectory you add your Java files and folder structure, if any. For example, if you
Java package name is example, and source code is Hello.java, then your directory structure looks
like this:
project-dir/src/main/java/example/Hello.java
5.
Run the following gradle command to build and package the project in a .zip file.
project-dir> gradle build
6.
Verify the resulting project-dir.zip file in the project-dir/build/distributions subdirectory.
7.
Now you can upload the .zip file, your deployment package to AWS Lambda to create a Lambda
function and test it by manually invoking it using sample event data. For instruction, see Step 2.3:
(Optional) Create a Lambda Function Authored in Java (p. 164).
Example 2: Creating .zip Using Gradle Using Local Jars
You may choose not to use the Maven Central repository. Instead have all the dependencies in the project
folder. In this case your project folder (project-dir) will have the following structure:
project-dir/jars/
project-dir/build.gradle
project-dir/src/main/java/
(all jars go here)
(your code goes here)
So if your Java code has example package and Hello.java class, the code will be in the following
subdirectory:
project-dir/src/main/java/example/Hello.java
You build.gradle file should be as follows:
apply plugin: 'java'
dependencies {
compile fileTree(dir: 'jars', include: '*.jar')
}
task buildZip(type: Zip) {
from compileJava
from processResources
into('lib') {
from configurations.runtime
}
}
build.dependsOn buildZip
Note that the dependencies specify fileTree which identifies project-dir/jars as the subdirectory that
will include all the required jars.
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Now you build the package. Run the following gradle command to build and package the project in a .zip
file.
project-dir> gradle build
Authoring Lambda Functions Using Eclipse IDE and AWS SDK Plugin (Java)
AWS SDK Eclipse Toolkit provides an Eclipse plugin for you to both create a deployment package and
also upload it to create a Lambda function. If you can use Eclipse IDE as your development environment,
this plugin enables you to author Java code, create and upload a deployment package, and create your
Lambda function. For more information, see the AWS Toolkit for Eclipse Getting Started Guide. For an
example of using the toolkit for authoring Lambda functions, see Using AWS Lambda with the AWS Toolkit
for Eclipse.
Creating a Deployment Package (Python)
To create a Lambda function you first create a Lambda function deployment package, a .zip file consisting
of your code and any dependencies.
You can create a deployment package yourself or write your code directly in the Lambda console, in which
case the console creates the deployment package for you and uploads it, creating your Lambda function.
Note the following to determine if you can use the console to create your Lambda function:
• Simple scenario – If your custom code requires only the AWS SDK library, then you can use the inline
editor in the AWS Lambda console. Using the console, you can edit and upload your code to AWS
Lambda. The console will zip up your code with the relevant configuration information into a deployment
package that the Lambda service can run.
You can also test your code in the console by manually invoking it using sample event data.
Note
The Lambda service has preinstalled the AWS SDK for Python.
• Advanced scenario – If you are writing code that uses other resources, such as a graphics library for
image processing, or you want to use the AWS CLI instead of the console, you need to first create the
Lambda function deployment package, and then use the console or the CLI to upload the package.
Note
After you create a deployment package, you may either upload it directly or upload the .zip file first
to an Amazon S3 bucket in the same AWS region where you want to create the Lambda function,
and then specify the bucket name and object key name when you create the Lambda function
using the console or the AWS CLI.
The following is an example procedure to create a deployment package (outside the console).
Note
This should work for most standard installations of Python and pip when using pure Python
modules in your Lambda function. If you are including modules that have native dependencies or
have Python installed with Homebrew on OS X, you should see the next section which provides
instructions to create a deployment package when using Virtualenv. For more information, see
Create Deployment Package Using a Python Environment Created with Virtualenv (p. 72) and
the Virtualenv website.
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You will use pip to install dependencies/libraries. For information to install pip, go to Installation.
1.
You create a directory, for example project-dir.
2.
Save all of your Python source files (the .py files) at the root level of this directory.
3.
Install any libraries using pip. Again, you install these libraries at the root level of the directory.
pip install module-name -t /path/to/project-dir
For example, the following command installs the requests HTTP library in the project-dir directory.
pip install requests -t /path/to/project-dir
If using Mac OS X and you have Python installed using Homebrew (see Homebrew), the preceding
command will not work. A simple workaround is to add a setup.cfg file in your /path/to/project-dir
with the following content.
[install]
prefix=
4.
Zip the content of the project-dir directory, which is your deployment package.
Important
Zip the directory content, not the directory. The contents of the Zip file are available as the
current working directory of the Lambda function. For example: /project-dir/codefile.py/lib/
yourlibraries
Note
AWS Lambda includes the AWS SDK for Python (Boto 3), so you don't need to include it in your
deployment package. However, if you want to use a version of Boto3 other than the one included
by default, you can include it in your deployment package.
Create Deployment Package Using a Python Environment Created with Virtualenv
This section explains how to create a deployment package if you are using a Python environment that you
created with the Virtualenv tool. Consider the following example:
• Created the following isolated Python environment using the Virtualenv tool and activated the
environment:
virtualenv path/to/my/virtual-env
You can activate the environment on Windows, OS X, and Linux as follows:
• On Windows, you activate using the activate.bat:
path\to\my\virtual-env\Scripts\activate.bat
• On OS X and Linux, you source the activate script:
source
path/to/my/virtual-env/bin/activate
• Also, suppose you have installed the requests package in the activated environment (assume that you
will you use these in your code). You can install these packages as follows :
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pip install requests
Now, to create a deployment package you do the following:
1.
First, create .zip file with your Python code you want to upload to AWS Lambda.
2.
Add the libraries from preceding activated virtual environment to the .zip file. That is, you add the
content of the following directory to the .zip file (note again that you add the content of the directory
and not the directory itself).
For Windows the directory is:
%VIRTUAL_ENV%\Lib\site-packages
For OS X, Linux, the directory is:
$VIRTUAL_ENV/lib/python2.7/site-packages
Note
If you don't find the packages in the site-packages directory in your virtual environment, you
might find it in the dist-packages directory.
For an example of creating a Python deployment package, see Python (p. 179).
AWS Lambda Function Versioning and Aliases
Versioning allows you to better manage your in-production Lambda function code by enabling you to
publish one or more versions of your Lambda function. As a result, you can work with different variations
of your Lambda function in your development workflow, such as development, beta, and production. Each
Lambda function version has a unique Amazon Resource Name (ARN). After you publish a version, it is
immutable (that is, it can't be changed).
AWS Lambda supports creating aliases for each of your Lambda function versions. Conceptually, an
AWS Lambda alias is a pointer to a specific Lambda function version, but it is also a resource similar to a
Lambda function, and each alias has a unique ARN. Each alias maintains an ARN for a function version to
which it points (note that an alias can only point to a function version, not to another alias). Unlike versions,
which are immutable, aliases are mutable (that is, they can be changed) and can be updated to point to
different versions
The following example shows two versions of a helloworld Lambda function (version $LATEST, and version
1). Each of these function versions has an alias (DEV and PROD) pointing to it.
Aliases enable you to abstract the process of promoting new Lambda function versions into production
from the mapping of the Lambda function version and its event source. For more information, see How It
Works (p. 146).
For example, suppose Amazon S3 is the event source that invokes your Lambda function when new
objects are created in a bucket. When Amazon S3 is your event source, you store the event source
mapping information in the bucket notification configuration. In the configuration you can identify the
Lambda function ARN that Amazon S3 can invoke, but, in this case, each time you publish a new version
of your Lambda function you need to update the notification configuration so that Amazon S3 invokes the
correct version. Instead of specifying the function ARN, you can specify an alias ARN in the notification
configuration (for example, PROD alias ARN). As you promote new versions of your Lambda function into
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production, you only need to update the PROD alias to point to the latest stable version, and you don't need
to update the notification configuration in Amazon S3.
The same applies when you need to roll back to a previous version of your Lambda function. In this
scenario, you just update the PROD alias to point to a different function version, and there is no need to
update event source mappings.
We recommend you use versioning and aliases to deploy your Lambda functions when building
applications with multiple dependencies and developers involved.
For detailed information, see the following topics:
Topics
• Introduction to AWS Lambda Versioning (p. 74)
• Introduction to AWS Lambda Aliases (p. 77)
• Versioning, Aliases, and Resource Policies (p. 82)
• Managing Versioning Using the AWS Management Console, the AWS CLI, or Lambda APIs (p. 83)
Introduction to AWS Lambda Versioning
This section explains how to create a Lambda function and publish a version from it. It also explains how
to update function code and configuration information when you have one or more published versions. In
addition, this section includes information on how to delete function versions, either specific versions or the
entire Lambda function (with all of its versions and associated aliases).
Creating a Lambda Function (the $LATEST version)
When you create a Lambda function, there is only one version. It is the $LATEST version.
You can refer to this function using its Amazon Resource Name (ARN). There are two ARNs associated
with this initial version:
• Qualified ARN – The function ARN with the version suffix.
arn:aws:lambda:aws-region:acct-id:function:helloworld:$LATEST
• Unqualified ARN – The function ARN without the version suffix.
You can use this ARN in all relevant operations however you cannot use it to create an alias. For more
information, see Introduction to AWS Lambda Aliases (p. 77).
The unqualified ARN has its own resource policies.
arn:aws:lambda:aws-region:acct-id:function:helloworld
Note
Unless you choose to publish versions, the $LATEST version is the only Lambda function version
you have. You can use either the qualified or unqualified ARN in your event source mapping to
invoke this $LATEST version.
The following is an example response of a CreateFunction API call:
{
"CodeSize": 287,
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"Description": "test function."
"FunctionArn": "arn:aws:lambda:aws-region:acct-id:function:helloworld",
"FunctionName": "helloworld",
"Handler": "helloworld.handler",
"LastModified": "2015-07-16T00:34:31.322+0000",
"MemorySize": 128,
"Role": "arn:aws:iam::acct-id:role/lambda_basic_execution",
"Runtime": "nodejs6.10",
"Timeout": 3,
"CodeSHA256": "OjRFuuHKizEE8tHFIMsI+iHR6BPAfJ5S0rW31Mh6jKg=",
"Version": "$LATEST"
}
For more information, see CreateFunction (p. 322).
In this response, AWS Lambda returns the unqualified ARN of the newly created function as well as its
version, $LATEST. The response also shows that the Version is $LATEST. The CodeSha256 is the checksum
of the deployment package that you uploaded.
Publishing a Lambda Function Version
When you publish a version, AWS Lambda makes a snapshot copy of the Lambda function code (and
configuration) in the $LATEST version. A published version is immutable. That is, you can't change the code
or configuration information. The new version has a unique ARN that includes a version number suffix as
shown:
You can publish a version using any of the following methods:
• Publish a version explicitly – Use the PublishVersion API to explicitly publish a version. For more
information, see PublishVersion (p. 367). This action creates a new version using the code and
configuration in the $LATEST version.
• Publish a version at the time you create or update a Lambda function – Use the CreateFunction or
UpdateFunctionCode requests to also publish a version by adding the optional publish parameter in the
request:
• Specify the publish parameter in your CreateFunction request to create a new Lambda function (the
$LATEST version), and then immediately publish it by creating a snapshot and assigning it to be version
1. For more information about CreateFunction, see CreateFunction (p. 322).
• Specify the publish parameter in your UpdateFunctionCode request to update the code in
the $LATEST version, and then publish a version from the $LATEST. For more information about
UpdateFunctionCode, see UpdateFunctionCode (p. 379).
If you specify the publish parameter at the time you create a Lambda function, the function configuration
information that AWS Lambda returns in response shows the version number of the newly published
version, as shown following (in the example, the version is 1):
{
"CodeSize": 287,
"Description": "test function."
"FunctionArn": "arn:aws:lambda:aws-region:acct-id:function:helloworld",
"FunctionName": "helloworld",
"Handler": "helloworld.handler",
"LastModified": "2015-07-16T00:34:31.322+0000",
"MemorySize": 128,
"Role": "arn:aws:iam::acct-id:role/lambda_basic_execution",
"Runtime": "nodejs6.10",
"Timeout": 3,
"CodeSHA256": "OjRFuuHKizEE8tHFIMsI+iHR6BPAfJ5S0rW31Mh6jKg=",
"Version": "1"
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}
Note
Lambda will only publish a new version if the code has not yet been published or if the code has
changed when compared against the $LATEST version. If there is no change, the $LATEST
published version will be returned.
We recommend that you publish a version at the same time that you create your Lambda function or
update your Lambda function code, especially when multiple developers contribute to the same Lambda
function development. You can use the publish parameter in your request to do this. When you have
multiple developers working on a project, it is possible for developer A to create a Lambda function
($LATEST version) and before developer A publishes a version, developer B updates the code (deployment
package) associated with the $LATEST version. In this case, you lose the original code that developer A
uploaded. When both developers add the publish parameter it prevents the race condition described.
Note
The published versions are immutable. That is, you cannot change code or configuration
information associated with a version.
Each version of a Lambda function is a unique resource with a Amazon Resource Name (ARN). The
following example shows the ARN of version number 1 of the helloworld Lambda function:
arn:aws:lambda:aws-region:acct-id:function:helloworld:1
Note
This is a qualified ARN, where the version number is a suffix. Published versions can have only
qualified ARN.
You can publish multiple versions. Each time you publish a version, AWS Lambda copies $LATEST version
(code and configuration information) to create a new version. When you publish additional versions, AWS
Lambda assigns a monotonically increasing sequence number for versioning, even if the function was
deleted and re-created. Version numbers are never reused, even for a function that has been deleted and
re-created, so that the consumer of that version can depend on the executable of that version to never
change (except if it's deleted). If you want to re-use a qualifier, use aliases with your versions. Aliases can
be deleted and re-created with the same name.
Updating Lambda Function Code and Configuration
AWS Lambda maintains your latest function code in the $LATEST version. When you update your
function code, AWS Lambda replaces the code in the $LATEST version of the Lambda function. For more
information, see UpdateFunctionCode (p. 379).
Published versions are immutable. You cannot update code or configuration information associated with a
published version.
You have the following options of publishing a new version as you update your Lambda function code:
• Publish a version in the same update code request – Use the UpdateFunctionCode API
(recommended).
• First update the code, and then explicitly publish a version – Use the PublishVersion API.
You can update code and configuration information (such as description, memory size, and execution
timeout) of the $LATEST version of the Lambda function. However, published versions are immutable. That
is, you cannot change code or configuration information.
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Deleting a Lambda Function and a Specific Version
With versioning, you have the following choices:
• Delete a specific version – You can delete a Lambda function version by specifying the version you
want to delete in your DeleteFunction request. If there are aliases dependent on this version, the
request will fail. AWS Lambda deletes the version only if there are no aliases dependent on this version.
For more information about aliases, see Introduction to AWS Lambda Aliases (p. 77).
• Delete the entire Lambda function (all of its versions and aliases) – To delete the Lambda function
and all of its versions, do not specify any version in your DeleteFunction request. This deletes the entire
function including all of its versions and aliases.
Important
You can delete a specific function version, but you cannot delete the $LATEST.
Related Topics
Introduction to AWS Lambda Aliases (p. 77)
Managing Versioning Using the AWS Management Console, the AWS CLI, or Lambda APIs (p. 83)
Introduction to AWS Lambda Aliases
You can create aliases for your Lambda function. An AWS Lambda alias is like a pointer to a specific
Lambda function version. For more information about versioning, see Introduction to AWS Lambda
Versioning (p. 74). By using aliases, you can access the Lambda function it is pointing to (for example,
to invoke the function) without the caller having to know the specific version the alias is pointing to.
AWS Lambda aliases enable the following use cases:
• Easier support for promotion of new versions of Lambda functions and roll back when needed
– After initially creating a Lambda function (the $LATEST version) you can first publish a version 1 of it.
By creating an alias named PROD that points to version 1, you can now use the PROD alias to invoke
version 1 of the Lambda function.
Now, you can update the code (the $LATEST version) with all of your improvements, and then publish
another stable and improved version (version 2). You can promote version 2 to production by remapping
the PROD alias so that it points to version 2. If you find something wrong, you can easily roll back the
production version to version 1 by remapping the PROD alias so that it points to version 1.
Note
In this context, the terms promotion and roll back refer to the remapping of aliases to different
function versions.
• Simplify management of event source mappings – Instead of using Lambda function ARNs in event
source mappings, by using an alias ARN you ensure that you don't need to update your event source
mappings when you promote a new version or roll back to a previous version.
An AWS Lambda alias is a resource similar to a Lambda function. However, you can't create an alias
independently. You create an alias for an existing Lambda function. If a Lambda function is a resource, you
can think of an AWS Lambda alias as a subresource that is associated with a Lambda function.
Both the Lambda function and alias are AWS Lambda resources, and like all other AWS resources they
both have unique Amazon Resource Names (ARNs). The following example shows a Lambda function (the
$LATEST version), with one published version. Each version has an alias pointing to it.
You can access the function using either the function ARN or the alias ARN.
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• Because the function version is $LATEST, you can access it using the qualified or unqualified function
ARN.
• Qualified function ARN (with the $LATEST version suffix):
arn:aws:lambda:aws-region:acct-id:function:helloworld:$LATEST
• When using any of the alias ARNs, you are using a qualified ARN. Each alias ARN has an alias name
suffix.
arn:aws:lambda:aws-region:acct-id:function:helloworld:PROD
arn:aws:lambda:aws-region:acct-id:function:helloworld:BETA
arn:aws:lambda:aws-region:acct-id:function:helloworld:DEV
AWS Lambda provides the following APIs for you to create and manages aliases:
• CreateAlias (p. 315)
• UpdateAlias (p. 373)
• GetAlias (p. 337)
• ListAliases (p. 357)
• DeleteAlias (p. 328)
Example: Using Aliases to Manage Lambda Function Versions
The following is an example scenario of how to use versioning and aliases to promote new versions of
Lambda functions into production.
Initially, you create a Lambda function.
It is the $LATEST version. You also create an alias (DEV, for development) that points to the newly
created function. Developers can use this alias to test the function with the event sources in a
development environment.
Test the function version using event sources in a beta environment, in a stable way while
continuing to develop newer versions.
You publish a version from the $LATEST and have another alias (BETA) point to it. This allows you to
associate your beta event sources to this specific alias. In the event source mappings, use the BETA
alias to associate your Lambda function with the event source.
Promote the Lambda function version in production to work with event sources in production
environment.
After testing the BETA version you can define the production version by creating an alias that maps
to version 1. This means you want to point your production event sources to this specific version. You
do this by creating a PROD alias and using the PROD alias ARN in all of your production event source
mappings.
Continue development, publish more versions, and test.
As you develop your code you can update the $LATEST version by uploading updated code and then
publish to beta testing by having the BETA alias point to it. This simple remapping of the beta alias
enables you put version 2 of your Lambda function into beta without changing any of your event
sources. This is how aliases enable you to control which versions of your function are used with
specific event sources in your development environment.
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If you want to try creating this setup using AWS CLI, see Tutorial: Using AWS Lambda Aliases (p. 79).
Related Topics
Introduction to AWS Lambda Versioning (p. 74)
Tutorial: Using AWS Lambda Aliases (p. 79)
Managing Versioning Using the AWS Management Console, the AWS CLI, or Lambda APIs (p. 83)
Tutorial: Using AWS Lambda Aliases
This AWS CLI-based tutorial creates Lambda function versions and aliases that point to it as described in
the Example: Using Aliases to Manage Lambda Function Versions (p. 78).
This example uses the us-west-2 (US West, Oregon) region to create the Lambda function and aliases.
1.
First, you need to create a deployment package that you can upload to create your Lambda function.
a.
Open a text editor, and then copy the following code.
console.log('Loading function');
exports.handler = function(event, context, callback) {
console.log('value1 =', event.key1);
console.log('value2 =', event.key2);
console.log('value3 =', event.key3);
callback(null, "message");
};
2.
b.
Save the file as helloworld.js.
c.
Zip the helloworld.js file as helloworld.zip.
Create an IAM role (execution role) that you can specify at the time you create your Lambda function.
a.
Sign in to the IAM console at https://console.aws.amazon.com/iam/.
b.
Follow the steps in IAM Roles in the IAM User Guide to create an IAM role (execution role). As
you follow the steps to create a role, note the following:
• In Select Role Type, choose AWS Service Roles, and then choose AWS Lambda.
• In Attach Policy, choose the policy named AWSLambdaBasicExecutionRole.
c.
3.
Write down the Amazon Resource Name (ARN) of the IAM role. You need this value when you
create your Lambda function in the next step.
Create a Lambda function (helloworld).
aws lambda create-function \
--region us-west-2 \
--function-name helloworld \
--zip-file fileb://file-path/helloworld.zip \
--role arn:aws:iam::account-id:role/lambda_basic_execution \
--handler helloworld.handler \
--runtime nodejs6.10 \
--profile adminuser
The response returns the configuration information showing $LATEST as the function version as shown
in the following example response:
{
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"CodeSha256": "OjRFuuHKizEE8tHFIMsI+iHR6BPAfJ5S0rW31Mh6jKg=",
"FunctionName": "helloworld",
"CodeSize": 287,
"MemorySize": 128,
"FunctionArn": "arn:aws:lambda:us-west-2:account-id:function:helloworld",
"Version": "$LATEST",
"Role": "arn:aws:iam::account-id:role/lambda_basic_execution",
"Timeout": 3,
"LastModified": "2015-09-30T18:39:53.873+0000",
"Handler": "helloworld.handler",
"Runtime": "nodejs6.10",
"Description": ""
}
4.
Create an alias (DEV) that points to the $LATEST version of the helloworld Lambda function:
aws lambda create-alias \
--region us-west-2 \
--function-name helloworld \
--description "sample alias" \
--function-version "\$LATEST" \
--name DEV \
--profile adminuser
The response returns the alias information, including the function version it is pointing to and the alias
ARN. The ARN is the same as the function ARN with an alias name suffix. The following is an example
response:
{
"AliasArn": "arn:aws:lambda:us-west-2:account-id:function:helloworld:DEV",
"FunctionVersion": "$LATEST",
"Name": "DEV",
"Description": "sample alias"
}
5.
Publish a version of the helloworld Lambda function.
aws lambda publish-version \
--region us-west-2 \
--function-name helloworld \
--profile adminuser
The response returns configuration information of the function version, including the version number,
and the function ARN with the version suffix. The following is an example response:
{
"CodeSha256": "OjRFuuHKizEE8tHFIMsI+iHR6BPAfJ5S0rW31Mh6jKg=",
"FunctionName": "helloworld",
"CodeSize": 287,
"MemorySize": 128,
"FunctionArn": "arn:aws:lambda:us-west-2:account-id:function:helloworld:1",
"Version": "1",
"Role": "arn:aws:iam::account-id:role/lambda_basic_execution",
"Timeout": 3,
"LastModified": "2015-10-03T00:48:00.435+0000",
"Handler": "helloworld.handler",
"Runtime": "nodejs6.10
",
"Description": ""
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}
6.
Create an alias (BETA) for the for the helloworld Lambda function version 1.
aws lambda create-alias \
--region us-west-2 \
--function-name helloworld \
--description "sample alias" \
--function-version 1 \
--name BETA \
--profile adminuser
Now you have two aliases for the helloworld function. The DEV alias points to the $LATEST function
version, and the BETA alias points to version 1 of the Lambda function.
7.
Now suppose you want to put the version 1 of the helloworld function in production. Create another
alias (PROD) that points to version 1.
aws lambda create-alias \
--region us-west-2 \
--function-name helloworld \
--description "sample alias" \
--function-version 1 \
--name PROD \
--profile adminuser
At this time you have both the BETA and PROD aliases pointing to version 1 of the Lambda function.
8.
You can now publish a newer version (for example, version 2), but first you need to update your
code and upload a modified deployment package. If the $LATEST version is not changed, you cannot
publish more than one version of it. Assuming you updated the deployment package, uploaded it, and
published version 2, you can now change the BETA alias to point to version 2 of the Lambda function.
aws lambda update-alias \
--region us-west-2 \
--function-name helloworld \
--function-version 2 \
--name BETA \
--profile adminuser
Now you have three aliases pointing to a different version of the Lambda function (DEV alias points
to the $LATEST version, BETA alias points to version 2, and the PROD alias points to version 1 of the
Lambda function.
For information about using the AWS Lambda console to manage versioning, see Managing Versioning
Using the AWS Management Console, the AWS CLI, or Lambda APIs (p. 83).
Granting Permissions in a Push Model
In a push model (see Event Source Mapping (p. 116)), event sources such as Amazon S3 invoke your
Lambda function. These event sources maintain a mapping that identifies a function version or alias they
will invoke when events occur. Note the following:
• We recommend that you specify an existing Lambda function alias in the mapping configuration (see
Introduction to AWS Lambda Aliases (p. 77)). For example, if the event source is Amazon S3, you
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specify the alias ARN in the bucket notification configuration so that Amazon S3 can invoke the alias
when it detects specific events.
• In the push model, you grant event sources permissions using a resource policy that you attach to your
Lambda function. In versioning, the permissions you add are specific to the qualifier that you specify in
the AddPermission request (see Versioning, Aliases, and Resource Policies (p. 82)).
For example, the following AWS CLI command grants Amazon S3 permissions to invoke the PROD alias
of the helloworld Lambda function (note that the --qualifier parameter specifies the alias name).
aws lambda add-permission \
--region us-west-2 \
--function-name helloworld \
--qualifier PROD \
--statement-id 1 \
--principal s3.amazonaws.com \
--action lambda:InvokeFunction \
--source-arn arn:aws:s3:::examplebucket \
--source-account 111111111111 \
--profile adminuser
In this case, Amazon S3 is now able to invoke the PROD alias and AWS Lambda can then execute the
helloworld Lambda function version that the PROD alias points to. For this to work, you must use the
PROD alias ARN in the S3 bucket's notification configuration.
For information about how to handle Amazon S3 events, see Tutorial: Using AWS Lambda with Amazon
S3 (p. 171).
Note
If you use the AWS Lambda console to add an event source for your Lambda function, the
console adds the necessary permissions for you.
Versioning, Aliases, and Resource Policies
With versioning and aliases you can access a Lambda function using various ARNs. For example, consider
the following scenario:
You can invoke for example the helloworld function version 1 using any of the following two ARNs:
• Using the qualified function ARN:
arn:aws:lambda:aws-region:acct-id:function:helloworld:1
Note
An unqualified function ARN (function ARN without a version or alias suffix), maps to the
$LATEST version.
• Using the BETA alias ARN:
arn:aws:lambda:aws-region:acct-id:function:helloworld:BETA
In a push model, event sources (such as Amazon S3 and custom applications) can invoke any of the
Lambda function versions as long you grant the necessary permissions to these event sources by using an
access policy associated with the Lambda function. For more information about the push model, see Event
Source Mapping (p. 116).
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Assuming that you grant permission, the next question is, "can an event source invoke a function version
using any of the associated ARNs?" The answer is, it depends on how you identified function in your add
permissions request (see AddPermission (p. 311)). The key to understanding this is that the permission
you grant apply only to the ARN used in the add permission request:
• If you use a qualified function name (such as helloworld:1), the permission is valid for invoking
the helloworld function version 1 only using its qualified ARN (using any other ARNs will result in a
permission error).
• If you use an alias name (such as helloworld:BETA), the permission is valid only for invoking the
helloworld function using the BETA alias ARN (using any other ARNs will result in a permission error,
including the function version ARN to which the alias points).
• If you use an unqualified function name (such as helloworld), the permission is valid only for invoking
the helloworld function using the unqualified function ARN (using any other ARNs will result in a
permission error).
Note
Note that even though the access policy is only on the unqualified ARN, the code and
configuration of the invoked Lambda function is still from function version $LATEST. The
unqualified function ARN maps to the $LATEST version but the permissions you add are ARNspecific.
• If you use a qualified function name using the $LATEST version (helloworld:$LATEST), the permission is
valid for invoking the helloworld function version $LATEST only using its qualified ARN (using unqualified
ARN will result in a permission error).
Managing Versioning Using the AWS Management Console, the
AWS CLI, or Lambda APIs
You can manage Lambda function versioning programmatically using AWS SDKs (or make the AWS
Lambda API calls directly, if you need to), using AWS Command Line Interface (AWS CLI), or the AWS
Lambda console.
AWS Lambda provides the following APIs to manage versioning and aliases:
PublishVersion (p. 367)
ListVersionsByFunction (p. 364)
CreateAlias (p. 315)
UpdateAlias (p. 373)
DeleteAlias (p. 328)
GetAlias (p. 337)
ListAliases (p. 357)
In addition to these APIs, existing relevant APIs also support versioning related operations.
For an example of how you can use the AWS CLI, see Tutorial: Using AWS Lambda Aliases (p. 79).
This section explains how you can use the AWS Lambda console to manage versioning. In the AWS
Lambda console, choose a function and then choose Qualifiers.
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The expanded Qualifiers menu displays a Versions and Aliases tab, as shown in the following screen
shot. In the Versions pane, you can see a list of versions for the selected function. If you have not
previously published a version for the selected function, the Versions pane lists only the $LATEST version,
as shown:
Choose the Aliases tab to see a list of aliases for the function. Initially, you won't have any aliases, as
shown following:
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Now, you can publish a version or create aliases for the selected Lambda function using the Actions menu.
To learn about versioning and aliases, see AWS Lambda Function Versioning and Aliases (p. 73).
Environment Variables
Environment variables for Lambda functions enable you to dynamically pass settings to your function
code and libraries, without making changes to your code. Environment variables are key-value pairs that
you create and modify as part of your function configuration, using either the AWS Lambda Console, the
AWS Lambda CLI or the AWS Lambda SDK. AWS Lambda then makes these key value pairs available to
your Lambda function code using standard APIs supported by the language, like process.env for Node.js
functions.
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You can use environment variables to help libraries know what directory to install files in, where to store
outputs, store connection and logging settings, and more. By separating these settings from the application
logic, you don't need to update your function code when you need to change the function behavior based
on different settings.
Setting Up
Suppose you want a Lambda function to behave differently as it moves through lifecycle stages from
development to deployment. For example, the dev, test, and production stages can contain databases
that the function needs to connect to that require different connection information and use different table
names. You can create environment variables to reference the database names, connection information
or table names and set the value for the function based on the stage in which it’s executing (for example,
development, test, production) while your function code remains unchanged.
The following screenshots show how modify your function's configuration using the AWS console. The
first screenshot configures the settings for the function corresponding to a test stage. The second one
configures settings for a production stage.
Note the Enable encryption helpers checkbox. You will learn more about using this in the Create a
Lambda Function Using Environment Variables To Store Sensitive Information (p. 91) tutorial.
You can also use the AWS CLI to create Lambda functions that contain environment variables. For more
details, see the CreateFunction (p. 322) and UpdateFunctionConfiguration (p. 384) APIs. Environment
variables are also supported when creating and updating functions using AWS CloudFormation.
Environment variables can also be used to configure settings specific to the language runtime or a library
included in your function. For example, you can modify PATH to specify a directory where executables
are stored. You can also set runtime-specific environment variables, such as PYTHONPATH for Python or
NODE_PATH for Node.js.
The following example creates a new Lambda function that sets the LD_LIBRARY_PATH environment
variable, which is used to specify a directory where shared libraries are dynamically loaded at runtime. In
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this example, the Lambda function code uses the shared library in the /usr/bin/test/lib64 directory.
Note that the Runtime parameter uses nodejs6.10 but you can also specify nodejs4.3.
aws lambda create-function \
--region us-east-1
--function-name myTestFunction
--zip-file fileb://path/package.zip
--role role-arn
--environment Variables={LD_LIBRARY_PATH=/usr/bin/test/lib64}
--handler index.handler
--runtime nodejs6.10
--profile default
Rules for Naming Environment Variables
There is no limit to the number of environment variables you can create as long as the total size of the set
does not exceed 4 KB.
Other requirements include:
• Must start with letters [a-zA-Z].
• Can only contain alphanumeric characters and underscores ([a-zA-Z0-9_].
In addition, there are a specific set of keys that AWS Lambda reserves. If you try to set values for any of
these reserved keys, you will receive an error message indicating that the action is not allowed. For more
information on these keys, see Environment Variables Available to Lambda Functions (p. 153).
Environment Variables and Function Versioning
Function versioning provides a way to manage your Lambda function code by enabling you to publish one
or more versions of your Lambda function as it proceeds from development to test to production. For each
version of a Lambda function that you publish, the environment variables (as well as other function-specific
configurations such as MemorySize and Timeout limit) are saved as a snapshot of that version and those
settings are immutable (cannot be changed).
As application and configuration requirements evolve, you can create new versions of your Lambda
function and update the environment variables to meet those requirements prior to the newest version
being published. The current version of your function is $LATEST.
In addition, you can create aliases, which are pointers to a particular version of your function. The
advantage of aliases is that if you need to roll back to a previous function version, you point the alias to that
version, which contains the environment variables required for that version. For more information, see AWS
Lambda Function Versioning and Aliases (p. 73).
Environment Variable Encryption
When you create or update Lambda functions that use environment variables, AWS Lambda encrypts
them using the AWS Key Management Service. When your Lambda function is invoked, those values are
decrypted and made available to the Lambda code.
The first time you create or update Lambda functions that use environment variables in a region, a default
service key is created for you automatically within AWS KMS. This key is used to encrypt environment
variables. You can alternatively select a key that you created separately using AWS Key Management
Service, via the IAM console or AWS KMS Keys APIs. Creating your own key gives you more flexibility,
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including the ability to create, rotate, disable, and define access controls, and to audit the encryption keys
used to protect your data. For more information, see the AWS Key Management Service Developer Guide.
If you use your own key, you will be billed per AWS Key Management Service Pricing guidelines. You will
not be billed if you use the default service key provided by AWS Lambda.
If you’re using the default KMS service key for Lambda, then no additional IAM permissions are required
in your function execution role – your role will just work automatically without changes. If you’re supplying
your own (custom) KMS key, then you’ll need to add kms:Decrypt to your execution role. In addition, the
user that will be creating and updating the Lambda function must have permissions to use the KMS key.
For more information on KMS keys, see the Using Key Policies in AWS KMS.
Storing Sensitive Information
As mentioned in the previous section, when you deploy your Lambda function, all the environment variables
you've specified are encrypted by default. They are then decrypted automatically by AWS Lambda when
the function is invoked. However, if you need to store sensitive information in an environment variable, we
strongly suggest you encrypt that information before deploying your Lambda function.
Fortunately, the Lambda console makes that easier for you by providing encryption helpers that leverage
AWS Key Management Service to store that sensitive information as Ciphertext. The Lambda console
also provides decryption helper code to decrypt that information for use in your in Lambda function code.
For more information, see Create a Lambda Function Using Environment Variables To Store Sensitive
Information (p. 91).
Error scenarios
If your function configuration exceeds 4KB, or you use environment variable keys reserved by AWS
Lambda, then your update or create operation will fail with a configuration error. During execution time,
it's possible that the encryption/decryption of environment variables can fail. If AWS Lambda is unable
to decrypt the environment variables due to an AWS KMS service exception, AWS KMS will return an
exception message explaining what the error conditions are and what, if any, remedies you can apply
to address the issue. These will be logged to your function log stream in Amazon CloudWatch logs. For
example, if the KMS key you are using to access the environment variables is disabled, you will see the
following error:
Lambda was unable to configure access to your environment variables because the KMS key
used is disabled.
Please check your KMS key settings.
Next Step
Create a Lambda Function Using Environment Variables (p. 88)
Create a Lambda Function Using Environment Variables
This section will illustrate how you can modify a Lambda function's behavior through configuration changes
that require no changes to the Lambda function code.
In this tutorial, you will do the following:
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• Create a deployment package with sample code that returns the value of an environment variable that
specifies the name of an Amazon S3 bucket.
• Invoke a Lambda function and verify that the Amazon S3 bucket name that is returned matches the value
set by the environment variable.
• Update the Lambda function by changing the Amazon S3 bucket name specified by the environment
variable.
• Invoke the Lambda function again and verify that the Amazon S3 bucket name that is returned matches
the updated value.
Step 1: Prepare
Make sure you have completed the following steps:
• Signed up for an AWS account and created an administrator user in the account.
• Installed and set up the AWS CLI.
For instructions, see Step 1: Set Up an AWS Account and the AWS CLI (p. 155).
Step 2: Set Up the Lambda Environment
In this section, you do the following:
• Create the Lambda function deployment package using the sample code provided.
• Create a Lambda execution role.
• Create the Lambda function by uploading the deployment package, and then test it by invoking it
manually.
Step 2.1: Create the Deployment Package
The code sample below reads the environment variable of a Lambda function that returns the name of an
Amazon S3 bucket.
1. Open a text editor and copy the following code:
var AWS = require('aws-sdk');
exports.handler = function(event, context, callback) {
var bucketName = process.env.S3_BUCKET;
callback(null, bucketName);
}
2. Save the file as index.js.
3. Zip the index.js. file as Test_Environment_Variables.zip.
Step 2.2: Create an Execution Role
Create an IAM role (execution role) that you can specify at the time you create your Lambda function.
1.
Sign in to the IAM console at https://console.aws.amazon.com/iam/.
2.
Follow the steps in IAM Roles in the IAM User Guide to create an IAM role (execution role). As you
follow the steps to create a role, note the following:
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• In Select Role Type, choose AWS Service Roles, and then choose AWS Lambda.
• In Attach Policy, choose the policy named AWSLambdaBasicExecutionRole.
3.
Write down the Amazon Resource Name (ARN) of the IAM role. You need this value when you create
your Lambda function in the next step.
Step 2.3 Create the Lambda function and Test It
In this section, you create a Lambda function containing an environment variable that specifies an Amazon
S3 bucket named Test. When invoked, the function simply returns the name of the Amazon S3 bucket.
Then you update the configuration by changing the Amazon S3 bucket name to Prod and when invoked
again, the function returns the updated name of the Amazon S3 bucket.
To create the Lambda function, open a command prompt and run the following Lambda AWS CLI createfunction command. You need to provide the .zip file path and the execution role ARN. Note that the
Runtime parameter uses nodejs6.10 but you can also specify nodejs4.3.
aws lambda create-function \
--region us-east-1 \
--function-name ReturnBucketName \
--zip-file fileb://file-path/Test_Environment_Variables.zip \
--role role-arn \
--environment Variables={S3_BUCKET=Test} \
--handler index.handler \
--runtime nodejs6.10 \
--version version \
--profile default
Note
Optionally, you can upload the .zip file to an Amazon S3 bucket in the same AWS region, and then
specify the bucket and object name in the preceding command. You need to replace the --zipfile parameter with the --code parameter. For example:
--code S3Bucket=bucket-name,S3Key=zip-file-object-key
Next, run the following Lambda CLI invoke command to invoke the function. Note that the command
requests asynchronous execution. You can optionally invoke it synchronously by specifying
RequestResponse as the invocation-type parameter value.
aws lambda invoke \
--invocation-type Event \
--function-name ReturnBucketName \
--region us-east-1 \
--profile default \
outputfile.txt
The Lambda function will return the name of the Amazon S3 bucket as "Test".
Next, run the following Lambda CLI update-function-configuration command to update the Amazon S3
environment variable by pointing it to the Prod bucket.
aws lambda update-function-configuration
--function-name ReturnBucketName \
--region us-east-1 \
--environment Variables={S3_BUCKET=Prod} \
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Run the aws lambda invoke command again using the same parameters. This time, the Lambda function
will return the Amazon S3 bucket name as Prod.
Create a Lambda Function Using Environment Variables To Store
Sensitive Information
Along with specifying configuration settings for your Lambda function, you can also use environment
variables to store sensitive information, such as a database password, using AWS Key Management
Service and the Lambda console's encryption helpers. For more information, see Environment Variable
Encryption (p. 87). The following example shows you how to do this and also how to use KMS to decrypt
that information.
This tutorial will demonstrate how you can use the Lambda console to encrypt an environment variable
containing sensitive information and provides sample code for decrypting that information to use in your
Lambda function.
Step 1: Create the Lambda Function
1.
Sign in to the AWS Management Console and open the AWS Lambda console at https://
console.aws.amazon.com/lambda/.
2.
Choose Create a Lambda function.
3.
In Select blueprint, choose the Blank Function blueprint.
4.
On the Configure triggers page, you can optionally choose a service that automatically triggers your
Lambda function by choosing the gray box with ellipses (...) to display a list of available services. For
this example, do not configure a trigger and choose Next.
5.
In Configure function, do the following:
• In Name*, specify your Lambda function name.
• In Runtime, specify nodejs6.10 or nodejs4.3.
Note that in Lambda function code section you can take advantage of the Edit code inline option
to do the following:
• Replace the Lambda function handler code with your custom code.
• Implement the decryption helper code that Lambda provides, which you will learn about later in
this exercise.
• Check the Enable encryption helpers checkbox.
• If you already have a KMS key associated with your user account, the Encryption key field will be
auto-populated with that key. If you haven't created a KMS key for your account, you will be provided
a link to the AWS IAM console to create one. The account must have have encrypt and decrypt
permissions for that key.
Note
You cannot use the default Lambda service key for encrypting sensitive information on the
client side.
• In Environment variables, enter your key-value pair. If the value you provided is sensitive, choose
the Encrypt button. This masks the value you entered and results in a call to AWS KMS to encrypt
the value and return it as Ciphertext. Note that the Encrypt button toggles to Decrypt after you
choose it. This affords you the option to update the information. Once you have done that, choose
the Encrypt button.
The Code button provides sample decrypt code specific to the runtime of your Lambda function that
you can use with your application.
• In Role*, choose Choose an existing role.
• In Existing role*, choose lambda_basic_execution.
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Note
6.
If the policy of the execution role does not have the decrypt permission, you will need add
it.
In Review, review the configuration and then choose Create Function.
Configuring a Lambda Function to Access
Resources in an Amazon VPC
Typically, you create resources inside Amazon Virtual Private Cloud (Amazon VPC) so that they cannot
be accessed over the public Internet. These resources could be AWS service resources, such as Amazon
Redshift data warehouses, Amazon ElastiCache clusters, or Amazon RDS instances. They could also
be your own services running on your own EC2 instances. By default, resources within a VPC are not
accessible from within a Lambda function.
AWS Lambda runs your function code securely within a VPC by default. However, to enable your
Lambda function to access resources inside your private VPC, you must provide additional VPC-specific
configuration information that includes VPC subnet IDs and security group IDs. AWS Lambda uses this
information to set up elastic network interfaces (ENIs) that enable your function to connect securely to other
resources within your private VPC.
Important
AWS Lambda does not support connecting to resources within Dedicated Tenancy VPCs. For
more information, see Dedicated VPCs.
Configuring a Lambda Function for Amazon VPC
Access
You add VPC information to your Lambda function configuration using the VpcConfig parameter, either at
the time you create a Lambda function (see CreateFunction (p. 322)), or you can add it to the existing
Lambda function configuration (see UpdateFunctionConfiguration (p. 384)). Following are AWS CLI
examples:
• The create-function CLI command specifies the --vpc-config parameter to provide VPC information
at the time you create a Lambda function.
$ aws lambda create-function \
--function-name ExampleFunction \
--runtime python2.7 \
--role execution-role-arn \
--zip-file fileb://path/app.zip \
--handler app.handler \
--vpc-config SubnetIds=comma-separated-vpc-subnet-ids,SecurityGroupIds=comma-separatedsecurity-group-ids \
--memory-size 1024
Note
The Lambda function execution role must have permissions to create, describe and delete
ENIs. AWS Lambda provides a permissions policy, AWSLambdaVPCAccessExecutionRole,
with permissions for the necessary EC2 actions (ec2:CreateNetworkInterface,
ec2:DescribeNetworkInterfaces, and ec2:DeleteNetworkInterface) that you can use when
creating a role. You can review the policy in the IAM console. Do not delete this role immediately
after your Lambda function execution. There is a delay between the time your Lambda function
executes and ENI deletion. If you do delete the role immediately after function execution, you
are responsible for deleting the ENIs.
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• The update-function-configuration CLI command specifies the --vpc-config parameter to add VPC
information to an existing Lambda function configuration.
$ aws lambda update-function-configuration \
--function-name ExampleFunction \
--vpc-config SubnetIds=comma-separated-vpc-subnet-ids,SecurityGroupIds=security-group-ids
To remove VPC-related information from your Lambda function configuration, use the
UpdateFunctionConfiguration API by providing an empty list of subnet IDs and security group IDs as
shown in the following example CLI command.
$ aws lambda update-function-configuration \
--function-name ExampleFunction \
--vpc-config SubnetIds=[],SecurityGroupIds=[]
Note the following additional considerations:
• We recommend that you avoid DNS resolution of public host names for your VPC. This can take several
seconds to resolve, which adds several seconds of billable time on your request. For example, if your
Lambda function accesses an Amazon RDS instance in your VPC, launch the instance with the nopublicly-accessible option.
• When you add VPC configuration to a Lambda function, it can only access resources in that VPC. If a
Lambda function needs to access both VPC resources and the public Internet, the VPC needs to have a
Network Address Translation (NAT) instance inside the VPC.
• When a Lambda function is configured to run within a VPC, it incurs an additional ENI start-up penalty.
This means address resolution may be delayed when trying to connect to network resources.
Internet Access for Lambda Functions
AWS Lambda uses the VPC information you provide to set up ENIs that allow your Lambda function to
access VPC resources. Each ENI is assigned a private IP address from the IP address range within the
Subnets you specify, but is not assigned any public IP addresses. Therefore, if your Lambda function
requires Internet access (for example, to access AWS services that don't have VPC endpoints, such as
Amazon Kinesis), you can configure a NAT instance inside your VPC or you can use the Amazon VPC NAT
gateway. For more information, see NAT Gateways in the Amazon VPC User Guide. You cannot use an
Internet gateway attached to your VPC, since that requires the ENI to have public IP addresses.
Important
If your Lambda function needs Internet access, do not attach it to a public subnet or to a private
subnet without Internet access. Instead, attach it only to private subnets with Internet access
through a NAT instance or an Amazon VPC NAT gateway.
Guidelines for Setting Up VPC-Enabled Lambda
Functions
Your Lambda function automatically scales based on the number of events it processes. The following are
general guidelines for setting up VPC-enabled Lambda functions to support the scaling behavior.
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• If your Lambda function accesses a VPC, you must make sure that your VPC has sufficient ENI capacity
to support the scale requirements of your Lambda function. You can use the following formula to
approximately determine the ENI capacity.
Projected peak concurrent executions * (Memory in GB / 1.5GB)
Where:
• Projected peak concurrent execution – Use the information in Lambda Function Concurrent
Executions (p. 147) to determine this value.
• Memory – The amount of memory you configured for your Lambda function.
• The subnets you specify should have sufficient available IP addresses to match the number of ENIs.
We also recommend that you specify at least one subnet in each Availability Zone in your Lambda
function configuration. By specifying subnets in each of the Availability Zones, your Lambda function can
run in another Availability Zone if one goes down or runs out of IP addresses.
Caution
If your VPC does not have sufficient ENIs or subnet IPs, your Lambda function will not scale as
requests increase, and you will see an increase in function failures. AWS Lambda currently does
not log errors to CloudWatch Logs that are caused by insufficient ENIs or IP addresses. If you
see an increase in errors without corresponding CloudWatch Logs, you can invoke the Lambda
function synchronously to get the error responses (for example, test your Lambda function in the
AWS Lambda console because the console invokes your Lambda function synchronously and
displays errors).
Topics
• Tutorials: Configuring a Lambda Function to Access Resources in an Amazon VPC (p. 94)
Tutorials: Configuring a Lambda Function to Access
Resources in an Amazon VPC
This section provides end-to-end example tutorials where you create and configure a Lambda function
to access resources in an Amazon VPC, such as an Amazon ElastiCache cluster or an Amazon RDS
database instance.
Topics
• Tutorial: Configuring a Lambda Function to Access Amazon ElastiCache in an Amazon VPC (p. 94)
• Tutorial: Configuring a Lambda Function to Access Amazon RDS in an Amazon VPC (p. 98)
Tutorial: Configuring a Lambda Function to Access Amazon
ElastiCache in an Amazon VPC
In this tutorial, you do the following:
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• Create an Amazon ElastiCache cluster in your default Amazon Virtual Private Cloud (Amazon VPC) in
the us-east-1 region. For more information about Amazon ElastiCache, see Amazon ElastiCache.
• Create a Lambda function to access the ElastiCache cluster. When you create the Lambda function,
you provide subnet IDs in your Amazon VPC and a VPC security group to allow the Lambda function to
access resources in your VPC. For illustration in this tutorial, the Lambda function generates a UUID,
writes it to the cache, and retrieves it from the cache.
• Invoke the Lambda function manually and verify that it accessed the ElastiCache cluster in your VPC.
Important
This tutorial uses the default Amazon VPC in the us-east-1 region in your account. For more
information about Amazon VPC, see How to Get Started with Amazon VPC in the Amazon VPC
User Guide.
Next Step
Step 1: Create an ElastiCache Cluster (p. 95)
Step 1: Create an ElastiCache Cluster
In this step, you create an ElastiCache cluster in the default Amazon VPC in us-east-1 region in your
account.
1.
Run the following AWS CLI command to create a Memcached cluster in the default VPC in the useast-1 region in your account.
aws elasticache create-cache-cluster \
--cache-cluster-id ClusterForLambdaTest \
--cache-node-type cache.m3.medium \
--engine memcached \
--security-group-ids your-default-vpc-security-group \
--num-cache-nodes 1
You can look up the default VPC security group in the VPC console under Security Groups. Your
example Lambda function will add and retrieve an item from this cluster.
You can also launch a cache cluster using the Amazon ElastiCache console. For instructions, see
Getting Started with Amazon ElastiCache in the Amazon ElastiCache User Guide.
2.
Write down the configuration endpoint for the cache cluster that you launched. You can get this from
the Amazon ElastiCache console. You will specify this value in your Lambda function code in the next
section.
Next Step
Step 2: Create a Lambda Function (p. 95)
Step 2: Create a Lambda Function
In this step, you do the following:
• Create a Lambda function deployment package using the sample code provided.
• Create an IAM role (execution role). At the time you upload the deployment package, you need to specify
this role so that Lambda can assume the role and then execute the function on your behalf.
The permissions policy grants AWS Lambda permissions to set up elastic network interfaces (ENIs) to
enable your Lambda function to access resources in the VPC. In this example, your Lambda function
accesses an ElastiCache cluster in the VPC.
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• Create the Lambda function by uploading the deployment package.
Topics
• Step 2.1: Create a Deployment Package (p. 96)
• Step 2.2: Create the Execution Role (IAM Role) (p. 97)
• Step 2.3: Create the Lambda Function (Upload the Deployment Package) (p. 97)
Step 2.1: Create a Deployment Package
Note
At this time, example code for the Lambda function is provided only in Python.
Python
The following example Python code reads and writes an item to your ElastiCache cluster.
1.
Open a text editor, and then copy the following code.
from __future__ import print_function
import time
import uuid
import sys
import socket
import elasticache_auto_discovery
from pymemcache.client.hash import HashClient
#elasticache settings
elasticache_config_endpoint = "your-elasticache-cluster-endpoint:port"
nodes = elasticache_auto_discovery.discover(elasticache_config_endpoint)
nodes = map(lambda x: (x[1], int(x[2])), nodes)
memcache_client = HashClient(nodes)
def handler(event, context):
"""
This function puts into memcache and get from it.
Memcache is hosted using elasticache
"""
#Create a random UUID... this will the sample element we add to the cache.
uuid_inserted = uuid.uuid4().hex
#Put the UUID to the cache.
memcache_client.set('uuid', uuid_inserted)
#Get item (UUID) from the cache.
uuid_obtained = memcache_client.get('uuid')
if uuid_obtained == uuid_inserted:
# this print should go to the CloudWatch Logs and Lambda console.
print ("Success: Fetched value %s from memcache" %(uuid_inserted))
else:
raise Exception("Value is not the same as we put :(. Expected %s got %s"
%(uuid_inserted, uuid_obtained))
return "Fetched value from memcache: " + uuid_obtained
2.
3.
Save the file as app.py.
Install the following library dependencies using pip:
• pymemcache – The Lambda function code uses this library to create a HashClient object to set and
get items from memcache (see pymemcache).
• elasticache-auto-discovery – The Lambda function uses this library to get the nodes in your
Amazon ElastiCache cluster (see elasticache-auto-discovery).
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4.
Zip all of these files into a file named app.zip to create your deployment package. For step-by-step
instructions, see Creating a Deployment Package (Python) (p. 71).
Next Step
Step 2.2: Create the Execution Role (IAM Role) (p. 97)
Step 2.2: Create the Execution Role (IAM Role)
In this step, you create an AWS Identity and Access Management (IAM) role using the following predefined
role type and access permissions policy:
• AWS Lambda (AWS service role) – This role grants AWS Lambda permissions to assume the role.
• AWSLambdaVPCAccessExecutionRole (access permissions policy) – This is the policy that you attach
to the role. The policy grants permissions for the EC2 actions that AWS Lambda needs to manage ENIs.
You can view this AWS managed policy in IAM console.
For more information about IAM roles, see IAM Roles in the IAM User Guide. Use the following procedure
to create the IAM role.
To create an IAM role (execution role)
1.
Sign in to the IAM console at https://console.aws.amazon.com/iam/.
2.
Follow the steps in Creating a Role to Delegate Permissions to an AWS Service in the IAM User Guide
to create an IAM role (execution role). As you follow the steps to create a role, note the following:
• In Role Name, use a name that is unique within your AWS account (for example, lambda-vpcexecution-role).
3.
• In Select Role Type, choose AWS Service Roles, and then choose AWS Lambda. This grants the
AWS Lambda service permissions to assume the role.
• In Attach Policy, choose AWSLambdaVPCAccessExecutionRole. The permissions in this policy
are sufficient for the Lambda function in this tutorial.
Write down the role ARN. You will need it in the next step when you create your Lambda function.
Next Step
Step 2.3: Create the Lambda Function (Upload the Deployment Package) (p. 97)
Step 2.3: Create the Lambda Function (Upload the Deployment Package)
In this step, you create the Lambda function (AccessMemCache) using the create-function AWS CLI
command.
At the command prompt, run the following Lambda CLI create-function command using the adminuser
profile.
You need to update the following create-function command by providing the .zip file path and the
execution role ARN. The --runtime parameter value can be python2.7, nodejs and java8, depending on
the language you used to author your code.
Note
At this time, example code for the Lambda function is provided only in Python.
$ aws lambda create-function \
--function-name AccessMemCache \
--region us-east-1 \
--zip-file fileb://path-to/app.zip \
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--role execution-role-arn \
--handler app.handler \
--runtime python2.7 \
--timeout 30 \
--vpc-config SubnetIds=comma-separated-vpc-subnet-ids,SecurityGroupIds=default-securitygroup-id \
--memory-size 1024
You can find the subnet IDs and the default security group ID of your VPC from the VPC console.
Optionally, you can upload the .zip file to an Amazon S3 bucket in the same AWS region, and then specify
the bucket and object name in the preceding command. You need to replace the --zip-file parameter by
the --code parameter, as shown following:
--code S3Bucket=bucket-name,S3Key=zip-file-object-key
Note
You can also create the Lambda function using the AWS Lambda console. When creating the
function, choose a VPC for the Lambda and then select the subnets and security groups from the
provided fields.
Next Step
Step 3: Test the Lambda Function (Invoke Manually) (p. 98)
Step 3: Test the Lambda Function (Invoke Manually)
In this step, you invoke the Lambda function manually using the invoke command. When the Lambda
function executes, it generates a UUID and writes it to the ElastiCache cluster that you specified in your
Lambda code. The Lambda function then retrieves the item from the cache.
1.
Invoke the Lambda function (AccessMemCache) using the AWS Lambda invoke command.
$ aws lambda invoke \
--function-name AccessMemCache
--region us-east-1 \
--profile adminuser \
output.txt
2.
\
Verify that the Lambda function executed successfully as follows:
• Review the output.txt file.
• Review the results in the AWS Lambda console.
• Verify the results in CloudWatch Logs.
What Next?
Now that you have created a Lambda function that accesses an ElastiCache cluster in your VPC, you can
have the function invoked in response to events. For information about configuring event sources and
examples, see Use Cases (p. 169).
Tutorial: Configuring a Lambda Function to Access Amazon RDS
in an Amazon VPC
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In this tutorial, you do the following:
• Launch an Amazon RDS MySQL database engine instance in your default Amazon VPC. In the MySQL
instance, you create a database (ExampleDB) with a sample table (Employee) in it. For more information
about Amazon RDS, see Amazon RDS.
• Create a Lambda function to access the ExampleDB database, create a table (Employee), add a few
records, and retrieve the records from the table.
• Invoke the Lambda function manually and verify the query results. This is how you verify that your
Lambda function was able to access the RDS MySQL instance in the VPC.
Important
This tutorial uses the default Amazon VPC in the us-east-1 region in your account. For more
information about Amazon VPC, see How to Get Started with Amazon VPC in the Amazon VPC
User Guide.
Next Step
Step 1: Create an Amazon RDS MySQL Instance and ExampleDB Database (p. 99)
Step 1: Create an Amazon RDS MySQL Instance and ExampleDB Database
In this tutorial, the example Lambda function creates a table (Employee), inserts a few records, and then
retrieves the records. The table that the Lambda function creates has the following schema:
Employee(EmpID, Name)
Where EmpID is the primary key. Now, you need to add a few records to this table.
First, you launch an RDS MySQL instance in your default VPC with ExampleDB database. If you already
have an RDS MySQL instance running in your default VPC, skip this step.
Important
This tutorial uses the RDS MySQL DB engine launched in the default VPC in the us-east-1 region.
You can launch an RDS MySQL instance using one of the following methods:
• Follow the instructions at Creating a MySQL DB Instance and Connecting to a Database on a MySQL DB
Instance in the Amazon Relational Database Service User Guide.
• Use the following AWS CLI command:
$ aws rds create-db-instance \
--db-instance-identifier MySQLForLambdaTest \
--db-instance-class db.t2.micro \
--engine MySQL \
--allocated-storage 5 \
--no-publicly-accessible \
--db-name ExampleDB \
--master-username username \
--master-user-password password \
--backup-retention-period 3
Write down the database name, user name, and password. You also need the host address (endpoint) of
the DB instance, which you can get from the RDS console (you might need to wait until the instance status
is available and the Endpoint value appears in the console).
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Next Step
Step 2: Create a Lambda Function (p. 100)
Step 2: Create a Lambda Function
In this step, you do the following:
• Create a Lambda function deployment package using the sample code provided.
• Create an IAM role (execution role) that you specify at the time of creating your Lambda function. This is
the role AWS Lambda assumes when executing the Lambda function.
The permissions policy associated with this role grants AWS Lambda permissions to set up elastic
network interfaces (ENIs) to enable your Lambda function to access resources in the VPC.
• Create the Lambda function by uploading the deployment package.
Topics
• Step 2.1: Create a Deployment Package (p. 100)
• Step 2.2: Create the Execution Role (IAM Role) (p. 101)
• Step 2.3: Create the Lambda Function (Upload the Deployment Package) (p. 102)
Step 2.1: Create a Deployment Package
Note
At this time, example code for the Lambda function is provided only in Python.
Python
The following example Python code runs a SELECT query against the Employee table in the MySQL RDS
instance that you created in the VPC. The code creates a table in the ExampleDB database, adds sample
records, and retrieves those records.
1.
Open a text editor, and then copy the following code.
import sys
import logging
import rds_config
import pymysql
#rds settings
rds_host = "rds-instance-endpoint"
name = rds_config.db_username
password = rds_config.db_password
db_name = rds_config.db_name
logger = logging.getLogger()
logger.setLevel(logging.INFO)
try:
conn = pymysql.connect(rds_host, user=name, passwd=password, db=db_name,
connect_timeout=5)
except:
logger.error("ERROR: Unexpected error: Could not connect to MySql instance.")
sys.exit()
logger.info("SUCCESS: Connection to RDS mysql instance succeeded")
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def handler(event, context):
"""
This function fetches content from mysql RDS instance
"""
item_count = 0
with conn.cursor() as cur:
cur.execute("create table Employee3 ( EmpID int
NOT NULL, PRIMARY KEY (EmpID))")
cur.execute('insert into Employee3 (EmpID, Name)
cur.execute('insert into Employee3 (EmpID, Name)
cur.execute('insert into Employee3 (EmpID, Name)
conn.commit()
cur.execute("select * from Employee3")
for row in cur:
item_count += 1
logger.info(row)
#print(row)
NOT NULL, Name varchar(255)
values(1, "Joe")')
values(2, "Bob")')
values(3, "Mary")')
return "Added %d items from RDS MySQL table" %(item_count)
Note
We recommend that pymysql.connect() is executed outside the handler, as shown, for better
performance.
2.
Save the file as app.py.
3.
Install the following library dependencies using pip:
• pymysql – The Lambda function code uses this library to access your MySQL instance (see
PyMySQL) .
4.
Create a config file that contains the following information and save it as rds_config.py:
#config file containing credentials for rds mysql instance
db_username = "username"
db_password = "password"
db_name = "databasename"
5.
Zip all of these files into a file named app.zip to create your deployment package. For step-by-step
instructions, see Creating a Deployment Package (Python) (p. 71).
Next Step
Step 2.2: Create the Execution Role (IAM Role) (p. 101)
Step 2.2: Create the Execution Role (IAM Role)
In this step, you create an execution role (IAM role) for your Lambda function using the following predefined
role type and access permissions policy:
• AWS Lambda (AWS service role) – This role grants AWS Lambda permissions to assume the role.
• AWSLambdaVPCAccessExecutionRole (access permissions policy) – This role grants AWS Lambda
permissions for EC2 actions to create ENIs and your Lambda function can access VPC resources and
CloudWatch Logs actions to write logs.
For more information about IAM roles, see IAM Roles in the IAM User Guide. Use the following procedure
to create the IAM role.
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Tutorials: Accessing Resources in an Amazon VPC
To create an IAM role (execution role)
1.
Sign in to the IAM console at https://console.aws.amazon.com/iam/.
2.
Follow the steps in Creating a Role to Delegate Permissions to an AWS Service in the IAM User Guide
to create an IAM role (execution role). As you follow the steps to create a role, note the following:
• In Role Name, use a name that is unique within your AWS account (for example, lambda-vpcexecution-role).
• In Select Role Type, choose AWS Service Roles, and then choose AWS Lambda. This grants the
AWS Lambda service permissions to assume the role.
• In Attach Policy, choose AWSLambdaVPCAccessExecutionRole. The permissions in this policy
are sufficient for the Lambda function in this tutorial.
3.
Write down the role ARN. You will need it in the next step when you create your Lambda function.
Next Step
Step 2.3: Create the Lambda Function (Upload the Deployment Package) (p. 102)
Step 2.3: Create the Lambda Function (Upload the Deployment Package)
In this step, you create the Lambda function (ReadMySqlTable) using the create-function AWS CLI
command.
At the command prompt, run the following Lambda CLI create-function command using the adminuser
profile.
You need to update the following create-function command by providing the .zip file path and the
execution role ARN. The --runtime parameter value can be python2.7, nodejs, or java8, depending on
the language you used to author your code.
Note
At this time, example code for the Lambda function is provided only in Python.
$ aws lambda create-function \
--region us-east-1 \
--function-name
CreateTableAddRecordsAndRead \
--zip-file fileb://file-path/app.zip \
--role execution-role-arn \
--handler app.handler \
--runtime python2.7 \
--vpc-config SubnetIds=comma-separated-subnet-ids,SecurityGroupIds=default-vpc-securitygroup-id \
--profile adminuser
Optionally, you can upload the .zip file to an Amazon S3 bucket in the same AWS region, and then specify
the bucket and object name in the preceding command. You need to replace the --zip-file parameter by
the --code parameter, as shown following:
--code S3Bucket=bucket-name,S3Key=zip-file-object-key
Note
You can also create the Lambda function using the AWS Lambda console (use the parameter
values shown in the preceding CLI command).
Next Step
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Troubleshooting and Monitoring
Step 3: Test the Lambda Function (Invoke Manually) (p. 103)
Step 3: Test the Lambda Function (Invoke Manually)
In this step, you invoke the Lambda function manually using the invoke command. When the Lambda
function executes, it runs the SELECT query against the Employee table in the RDS MySQL instance and
prints the results (these results also go to the CloudWatch Logs).
1.
Invoke the Lambda function (ReadMySqlTable) using the AWS Lambda invoke command.
$ aws lambda invoke \
--function-name CreateTableAddRecordsAndRead
--region us-east-1 \
--profile adminuser \
output.txt
2.
\
Verify that the Lambda function executed successfully as follows:
• Review the output.txt file.
• Review the results in the AWS Lambda console.
• Verify the results in CloudWatch Logs.
Troubleshooting and Monitoring AWS Lambda
Functions with Amazon CloudWatch
AWS Lambda automatically monitors Lambda functions on your behalf, reporting metrics through Amazon
CloudWatch. To help you monitor your code as it executes, Lambda automatically tracks the number
of requests, the latency per request, and the number of requests resulting in an error and publishes the
associated CloudWatch metrics. You can leverage these metrics to set CloudWatch custom alarms. For
more information about CloudWatch, see the Amazon CloudWatch User Guide.
You can view request rates and error rates for each of your Lambda functions by using the AWS Lambda
console, the CloudWatch console, and other Amazon Web Services (AWS) resources. The following topics
describe Lambda CloudWatch metrics and how to access them.
• Accessing Amazon CloudWatch Metrics for AWS Lambda (p. 105)
• AWS Lambda Metrics (p. 107)
You can insert logging statements into your code to help you validate that your code is working as
expected. Lambda automatically integrates with Amazon CloudWatch Logs and pushes all logs from
your code to a CloudWatch Logs group associated with a Lambda function (/aws/lambda/<function
name>). To learn more about log groups and accessing them through the CloudWatch console, see the
Monitoring System, Application, and Custom Log Files in the Amazon CloudWatch User Guide. For
information about how to access CloudWatch log entries, see Accessing Amazon CloudWatch Logs for
AWS Lambda (p. 106).
Note
If your Lambda function code is executing, but you don't see any log data being generated after
several minutes, this could mean your execution role for the Lambda function did not grant
permissions to write log data to CloudWatch Logs. For information about how to make sure that
you have set up the execution role correctly to grant these permissions, see Manage Permissions:
Using an IAM Role (Execution Role) (p. 150).
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Troubleshooting Scenarios
AWS Lambda Troubleshooting Scenarios
This sections describes examples of how to monitor and troubleshoot your Lambda functions using the
logging and monitoring capabilities of CloudWatch.
Troubleshooting Scenario 1: Lambda Function Not Working as
Expected
In this scenario, you have just finished Tutorial: Using AWS Lambda with Amazon S3 (p. 171). However,
the Lambda function you created to upload a thumbnail image to Amazon S3 when you create an S3 object
is not working as expected. When you upload objects to Amazon S3, you see that the thumbnail images
are not being uploaded. You can troubleshoot this issue in the following ways.
To determine why your Lambda function is not working as expected
1.
Check your code and verify that it is working correctly. An increased error rate would indicate that it is
not.
You can test your code locally as you would any other Node.js function, or you can test it within the
Lambda console using the console's test invoke functionality, or you can use the AWS CLI Invoke
command. Each time the code is executed in response to an event, it writes a log entry into the log
group associated with a Lambda function, which is /aws/lambda/<function name>.
Following are some examples of errors that might show up in the logs:
• If you see a stack trace in your log, there is probably an error in your code. Review your code and
debug the error that the stack trace refers to.
• If you see a permissions denied error in the log, the IAM role you have provided as an execution
role may not have the necessary permissions. Check the IAM role and verify that it has all of the
necessary permissions to access any AWS resources that your code references. To ensure that you
have correctly set up the execution role, see Manage Permissions: Using an IAM Role (Execution
Role) (p. 150).
• If you see a timeout exceeded error in the log, your timeout setting exceeds the run time of your
function code. This may be because the timeout is too low, or the code is taking too long to execute.
• If you see a memory exceeded error in the log, your memory setting is too low. Set it to a higher
value. For information about memory size limits, see CreateFunction (p. 322). When you change
the memory setting, it can also change how you are charged for duration. For information about
pricing, see the AWS Lambda product website.
2.
Check your Lambda function and verify that it is receiving requests.
Even if your function code is working as expected and responding correctly to test invokes, the function
may not be receiving requests from Amazon S3. If Amazon S3 is able to invoke the function, you
should see an increase in your CloudWatch requests metrics. If you do not see an increase in your
CloudWatch requests, check the access permissions policy associated with the function.
Troubleshooting Scenario 2: Increased Latency in Lambda
Function Execution
In this scenario, you have just finished Tutorial: Using AWS Lambda with Amazon S3 (p. 171). However,
the Lambda function you created to upload a thumbnail image to Amazon S3 when you create an
S3 object is not working as expected. When you upload objects to Amazon S3, you can see that the
thumbnail images are being uploaded, but your code is taking much longer to execute than expected.
You can troubleshoot this issue in a couple of different ways. For example, you could monitor the latency
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Accessing CloudWatch Metrics
CloudWatch metric for the Lambda function to see if the latency is increasing. Or you could see an increase
in the CloudWatch errors metric for the Lambda function, which might be due to timeout errors.
To determine why there is increased latency in the execution of a Lambda function
1.
Test your code with different memory settings.
2.
If your code is taking too long to execute, it could be that it does not have enough compute resources
to execute its logic. Try increasing the memory allocated to your function and testing the code again,
using the Lambda console's test invoke functionality. You can see the memory used, code execution
time, and memory allocated in the function log entries. Changing the memory setting can change how
you are charged for duration. For information about pricing, see AWS Lambda.
Investigate the source of the execution bottleneck that is using logs.
You can test your code locally, as you would with any other Node.js function, or you can test it within
Lambda using the test invoke capability on the Lambda console, or using the asyncInvoke command
by using AWS CLI. Each time the code is executed in response to an event, it writes a log entry into
the log group associated with a Lambda function, which is named aws/lambda/<function name>. Add
logging statements around various parts of your code, such as callouts to other services, to see how
much time it takes to execute different parts of your code.
Accessing Amazon CloudWatch Metrics for AWS
Lambda
AWS Lambda automatically monitors functions on your behalf, reporting metrics through Amazon
CloudWatch. These metrics include total requests, latency, and error rates. For more information about
Lambda metrics, see AWS Lambda Metrics (p. 107). For more information about CloudWatch, see the
Amazon CloudWatch User Guide.
You can monitor metrics for Lambda and view logs by using the Lambda console, the CloudWatch console,
the AWS CLI, or the CloudWatch API. The following procedures show you how to access metrics using
these different methods.
To access metrics using the Lambda console
1.
2.
3.
Sign in to the AWS Management Console and open the AWS Lambda console at https://
console.aws.amazon.com/lambda/.
If you have not created a Lambda function before, see Getting Started (p. 155).
On the Functions page, choose the function name and then choose the Monitoring tab.
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A graphical representation of the metrics for the Lambda function are shown.
4.
Choose View logs in CloudWatch to view the logs.
To access metrics using the CloudWatch console
1.
Open the CloudWatch console at https://console.aws.amazon.com/cloudwatch/.
2.
From the navigation bar, choose a region.
3.
In the navigation pane, choose Metrics.
4.
In the CloudWatch Metrics by Category pane, choose Lambda Metrics.
5.
(Optional) In the graph pane, choose a statistic and a time period, and then create a CloudWatch alarm
using these settings.
To access metrics using the AWS CLI
Use the list-metrics and get-metric-statistics commands.
To access metrics using the CloudWatch CLI
Use the mon-list-metrics and mon-get-stats commands.
To access metrics using the CloudWatch API
Use the ListMetrics and GetMetricStatistics operations.
Accessing Amazon CloudWatch Logs for AWS
Lambda
AWS Lambda automatically monitors Lambda functions on your behalf, reporting metrics through Amazon
CloudWatch. To help you troubleshoot failures in a function, Lambda logs all requests handled by your
function and also automatically stores logs generated by your code through Amazon CloudWatch Logs.
You can insert logging statements into your code to help you validate that your code is working as
expected. Lambda automatically integrates with CloudWatch Logs and pushes all logs from your code to
a CloudWatch Logs group associated with a Lambda function, which is named /aws/lambda/<function
name>. To learn more about log groups and accessing them through the CloudWatch console, see the
Monitoring System, Application, and Custom Log Files in the Amazon CloudWatch User Guide.
You can view logs for Lambda by using the Lambda console, the CloudWatch console, the AWS CLI, or the
CloudWatch API. The following procedure show you how to view the logs by using the Lambda console.
Note
There is no additional charge for using Lambda logs; however, standard CloudWatch Logs
charges apply. For more information, see CloudWatch Pricing.
To view logs using the Lambda console
1.
Sign in to the AWS Management Console and open the AWS Lambda console at https://
console.aws.amazon.com/lambda/.
2.
If you have not created a Lambda function before, see Getting Started (p. 155).
3.
On the Functions page, choose the function name and then choose the Monitoring tab.
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Metrics
A graphical representation of the metrics for the Lambda function are shown.
4.
Choose View logs in CloudWatch to view the logs.
For more information on accessing CloudWatch Logs, see the following guides:
• Amazon CloudWatch User Guide
• Amazon CloudWatch Logs API Reference
• Monitoring Log Files in the Amazon CloudWatch User Guide
AWS Lambda Metrics
This topic describes the AWS Lambda namespace, metrics, and dimensions. AWS Lambda automatically
monitors functions on your behalf, reporting metrics through Amazon CloudWatch. These metrics include
total invocations, errors, duration, throttles, DLQ errors and Iterator age for stream-based invocations.
CloudWatch is basically a metrics repository. A metric is the fundamental concept in CloudWatch and
represents a time-ordered set of data points. You (or AWS services) publish metrics data points into
CloudWatch and you retrieve statistics about those data points as an ordered set of time-series data.
Metrics are uniquely defined by a name, a namespace, and one or more dimensions. Each data point has
a time stamp, and, optionally, a unit of measure. When you request statistics, the returned data stream is
identified by namespace, metric name, and dimension. For more information about CloudWatch, see the
Amazon CloudWatch User Guide.
AWS Lambda CloudWatch Metrics
The AWS Lambda namespace for CloudWatch is AWS/Lambda.
The following metrics are available from the AWS Lambda service.
Metric
Description
Invocations
Measures the number of times a function is invoked in response to an event
or invocation API call. This replaces the deprecated RequestCount metric.
This includes successful and failed invocations, but does not include throttled
attempts. This equals the billed requests for the function. Note that AWS
Lambda only sends these metrics to CloudWatch if they have a nonzero
value.
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Metrics
Metric
Description
Units: Count
Errors
Measures the number of invocations that failed due to errors in the function
(response code 4XX). This replaces the deprecated ErrorCount metric. Failed
invocations may trigger a retry attempt that succeeds. This includes:
• Handled exceptions (e.g., context.fail(error))
• Unhandled exceptions causing the code to exit
• Out of memory exceptions
• Timeouts
• Permissions errors
This does not include invocations that fail due to invocation rates exceeding
default concurrent limits (error code 429) or failures due to internal service
errors (error code 500).
Units: Count
Dead Letter Error
The Dead Letter Error metric will be incremented when Lambda is
unable to write the failed event payload to your configured Dead Letter
Queues (p. 109). This could be due to the following:
• Permissions errors
• Throttles from downstream services
• Misconfigured resources
• Timeouts
Units: Count
Duration
Measures the elapsed wall clock time from when the function code starts
executing as a result of an invocation to when it stops executing. This replaces
the deprecated Latency metric. The maximum data point value possible is the
function timeout configuration. The billed duration will be rounded up to the
nearest 100 millisecond. Note that AWS Lambda only sends these metrics to
CloudWatch if they have a nonzero value.
Units: Milliseconds
Throttles
Measures the number of Lambda function invocation attempts that were
throttled due to invocation rates exceeding the customer’s concurrent limits
(error code 429). Failed invocations may trigger a retry attempt that succeeds.
Units: Count
Iterator Age
Emitted for stream-based invocations only (functions triggered by a
DynamoDB stream or Amazon Kinesis stream). Measures the age of the last
record for each batch of records processed. Age is the difference between the
time Lambda received the batch and the time the last record in the batch was
written to the stream.
Units: Milliseconds
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Dead Letter Queues
Errors/Invocations Ratio
When calculating the error rate on Lambda function invocations, it’s important to distinguish
between an invocation request and an actual invocation. It is possible for the error rate to exceed
the number of billed Lambda function invocations. Lambda reports an invocation metric only if the
Lambda function code is executed. If the invocation request yields a throttling or other initialization
error that prevents the Lambda function code from being invoked, Lambda will report an error, but
it does not log an invocation metric.
• Lambda emits Invocations=1 when the function is executed. If the Lambda function is not
executed, nothing is emitted.
• Lambda emits a data point for Errors for each invoke request. Errors=0 means that there is no
function execution error. Errors=1 means that there is a function execution error.
• Lambda emits a data point for Throttles for each invoke request. Throttles=0 means there is
no invocation throttle. Throttles=1 means there is an invocation throttle.
AWS Lambda CloudWatch Dimensions
You can use the dimensions in the following table to refine the metrics returned for your Lambda functions.
Dimension
Description
FunctionName
Filters the metric data by Lambda function.
Resource
Filters the metric data by Lambda function resource.
Version
Filters the metric data by Lambda version.
Alias
Filters the metric data by Lambda alias.
Dead Letter Queues
By default, a failed Lambda function invoked asynchronously is retried twice, and then the event is
discarded. Using Dead Letter Queues (DLQ), you can indicate to Lambda that unprocessed events should
be sent to an Amazon SQS queue or Amazon SNS topic instead, where you can take further action.
You configure a DLQ by specifying a target Amazon Resource Name (ARN) on a Lambda function's
DeadLetterConfig parameter of an Amazon SNS topic or an Amazon SQS queue where you want the
event payload delivered, as shown in the following code. For more information about creating an Amazon
SNS topic, see Create an SNS Topic. For more information about creating an Amazon SQS queue, see
Tutorial: Creating an Amazon SQS Queue.
{
"Code": {
"ZipFile": blob,
"S3Bucket": “string”,
"S3Key": “string”,
"S3ObjectVersion": “string”
},
"Description": "string",
"FunctionName": "string",
"Handler": "string",
"MemorySize": number,
"Role": "string",
"Runtime": "string",
"Timeout": number
"Publish": bool,
"DeadLetterConfig": {
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"TargetArn": "string"
}
}
Lambda directs events that cannot be processed to the Amazon SNS topic or Amazon SQS queue that
you’ve configured for the Lambda function. Functions without an associated DLQ discard events after they
have exhausted their retries. For more information about retry policies, see Retries on Errors (p. 149).
You need to explicitly provide read/publish/sendMessage access to your DLQ resource as part of the
execution role for your Lambda function. The payload written to the DLQ target ARN is the original event
payload with no modifications to the message body. The attributes of the message, described below,
contain information to help you understand why the event wasn’t processed:
Name
Type
Value
RequestID
String
Unique request identifier
ErrorCode
Number
3-digit HTTP error code
ErrorMessage
String
Error message (truncated to
1 KB)
If for some reason, the event payload consistently fails to reach the target ARN, Lambda increments a
CloudWatch metric called DeadLetterErrors and then deletes the event payload.
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Building applications with AWS
Lambda
When building applications on AWS Lambda, including serverless applications, the core components
are Lambda functions and event sources. An event source is the AWS service or custom application that
publishes events, and a Lambda function is the custom code that processes the events. To illustrate,
consider the following scenarios:
• File processing – Suppose you have a photo sharing application. People use your application to upload
photos, and the application stores these user photos in an Amazon S3 bucket. Then, your application
creates a thumbnail version of each user's photos and displays them on the user's profile page. In this
scenario, you may choose to create a Lambda function that creates a thumbnail automatically. Amazon
S3 is one of the supported AWS event sources that can publish object-created events and invoke your
Lambda function. Your Lambda function code can read the photo object from the S3 bucket, create a
thumbnail version, and then save it in another S3 bucket.
• Data and analytics – Suppose you are building an analytics application and storing raw data in a
DynamoDB table. When you write, update, or delete items in a table, DynamoDB streams can publish
item update events to a stream associated with the table. In this case, the event data provides the item
key, event name (such as insert, update, and delete), and other relevant details. You can write a Lambda
function to generate custom metrics by aggregating raw data.
• Websites – Suppose you are creating a website and you want to host the backend logic on Lambda. You
can invoke your Lambda function over HTTP using Amazon API Gateway as the HTTP endpoint. Now,
your web client can invoke the API, and then API Gateway can route the request to Lambda.
• Mobile applications – Suppose you have a custom mobile application that produces events. You
can create a Lambda function to process events published by your custom application. For example,
in this scenario you can configure a Lambda function to process the clicks within your custom mobile
application.
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Example 1
Each of these event sources uses a specific format for the event data. For more information, see Sample
Events Published by Event Sources (p. 125). When a Lambda function is invoked, it receives the event as
a parameter for the Lambda function.
AWS Lambda supports many AWS services as event sources. For more information, see Supported Event
Sources (p. 120). When you configure these event sources to trigger a Lambda function, the Lambda
function is invoked automatically when events occur. You define event source mapping, which is how you
identify what events to track and which Lambda function to invoke.
In addition to the supported AWS services, user applications can also generate events—you can build
your own custom event sources. Custom event sources invoke a Lambda function using the AWS Lambda
Invoke (p. 351) operation. User applications, such as client, mobile, or web applications, can publish
events and invoke Lambda functions on demand using the AWS SDKs or AWS Mobile SDKs, such as the
AWS Mobile SDK for Android.
The following are introductory examples of event sources and how the end-to-end experience works.
Example 1: Amazon S3 Pushes Events and Invokes
a Lambda Function
Amazon S3 can publish events of different types, such as PUT, POST, COPY, and DELETE object events
on a bucket. Using the bucket notification feature, you can configure an event source mapping that directs
Amazon S3 to invoke a Lambda function when a specific type of event occurs, as shown in the following
illustration.
The diagram illustrates the following sequence:
1. The user creates an object in a bucket.
2. Amazon S3 detects the object created event.
3. Amazon S3 invokes your Lambda function using the permissions provided by the execution role. For
more information on execution roles, see Authentication and Access Control for AWS Lambda (p. 277).
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Example 2
Amazon S3 knows which Lambda function to invoke based on the event source mapping that is stored in
the bucket notification configuration.
4. AWS Lambda executes the Lambda function, specifying the event as a parameter.
Note the following:
• The event source mapping is maintained within the event source service, Amazon S3 in this scenario.
This is true for all supported AWS event sources except the stream-based sources (Amazon Kinesis and
DynamoDB streams). The next example explains stream-based event sources.
• The event source (Amazon S3) invokes the Lambda function (referred to as the push model). Again, this
is true for all supported AWS services except the stream-based event sources.
• In order for the event source (Amazon S3) to invoke your Lambda function, you must grant permissions
using the permissions policy attached to the Lambda function.
Example 2: AWS Lambda Pulls Events from an
Amazon Kinesis Stream and Invokes a Lambda
Function
For stream-based event sources, AWS Lambda polls the stream and invokes the Lambda function when
records are detected on the stream. These stream sources are special in that event source mapping
information is stored in Lambda. AWS Lambda provides an API for you to create and manage these event
source mappings.
The following diagram shows how a custom application writes records to an Amazon Kinesis stream.
The diagram illustrates the following sequence:
1. The custom application writes records to an Amazon Kinesis stream.
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Example 3: Custom Application Publishes
Events and Invokes a Lambda Function
2. AWS Lambda continuously polls the stream, and invokes the Lambda function when the service detects
new records on the stream. AWS Lambda knows which stream to poll and which Lambda function to
invoke based on the event source mapping you create in Lambda.
3. The Lambda function is invoked with the incoming event.
Note the following:
• When working with stream-based event sources:
• You create event source mappings in AWS Lambda.
• AWS Lambda invokes the Lambda function (referred to as the pull model).
• AWS Lambda does not need permission to invoke your Lambda function, therefore you don't need to add
any permissions to the permissions policy attached to your Lambda function.
• Your Lambda role needs permission to read from the stream.
Example 3: Custom Application Publishes Events
and Invokes a Lambda Function
The following diagram shows how a custom application in your account invokes your Lambda function.
The diagram illustrates the following sequence:
1. The custom application invokes your Lambda function using the AWS SDK.
2. The Lambda function is invoked with the incoming event.
The following diagram shows how a custom mobile application invokes a Lambda function.
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Example 3: Custom Application Publishes
Events and Invokes a Lambda Function
1. The mobile application sends a request to Amazon Cognito with an identity pool ID in the request (you
create the identity pool as part of the setup).
2. Amazon Cognito returns temporary security credentials to the application.
Amazon Cognito assumes the role associated with the identity pool to generate temporary credentials.
3. The mobile application invokes the Lambda function using the temporary credentials (Cognito Identity).
4. AWS Lambda assumes the execution role to execute your Lambda function on your behalf.
5. The Lambda function executes.
6. AWS Lambda returns results to the mobile application, assuming the app invoked the Lambda function
using the RequestResponse invocation type (referred to as synchronous invocation).
Note the following:
• This is an example of an on-demand invocation of a Lambda function. For on-demand invocations, you
don't need to preconfigure an event source mapping like you do for AWS services.
• In this example, because the custom application is using the same account credentials as the account
that owns the Lambda function, it does not require additional permissions to invoke the function.
Suggested Reading
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Event Source Mapping
If you are new to AWS Lambda, at this time you can continue and read all of the topics in this How It Works
chapter for details. You might also consider exploring the Getting Started (p. 155) exercise first to get
hands-on experience creating and testing a Lambda function, and then read the topics in this chapter.
Additionally, the Building Lambda Functions (p. 5) also provides introductory information that you might find
useful, before you dive deep into the technology.
Event Source Mapping
In AWS Lambda, Lambda functions and event sources are the core components in AWS Lambda. An
event source is the entity that publishes events, and a Lambda function is the custom code that processes
the events. Supported event sources refer to those AWS services that can be preconfigured to work with
AWS Lambda. The configuration is referred to as event source mapping, which maps an event source to a
Lambda function. It enables automatic invocation of your Lambda function when events occur.
Each event source mapping identifies the type of events to publish and the Lambda function to invoke
when events occur. The specific Lambda function then receives the event information as a parameter, your
Lambda function code can then process the event.
Note the following about the event sources. These event sources can be any of the following:
• AWS services – These are the supported AWS services that can be preconfigured to work with AWS
Lambda. You can group these services as regular AWS services or stream-based services. Amazon
Kinesis Streams and Amazon DynamoDB Streams are stream-based event sources, all others AWS
services do not use stream-based event sources. Where you maintain the event source mapping and
how the Lambda function is invoked depends on whether or not you're using a stream-based event
source.
• Custom applications – You can have your custom applications publish events and invoke a Lambda
function.
You may be wondering—where do I keep the event mapping information? Do I keep it within the event
source or within AWS Lambda? The following sections explain event source mapping for each of these
event source categories. These sections also explain how the Lambda function is invoked and how you
manage permissions to allow invocation of your Lambda function.
Topics
• Event Source Mapping for AWS Services (p. 116)
• Event Source Mapping for AWS Stream-based Services (p. 117)
• Event Source Mapping for Custom Applications (p. 119)
Event Source Mapping for AWS Services
Except for the stream-based AWS services (Amazon Kinesis Streams and DynamoDB streams), other
supported AWS services publish events and can also invoke your Lambda function (referred to as the push
model). In the push model, note the following:
• Event source mappings are maintained within the event source. Relevant API support in the event
sources enables you to create and manage event source mappings. For example, Amazon S3 provides
the bucket notification configuration API. Using this API, you can configure an event source mapping that
identifies the bucket events to publish and the Lambda function to invoke.
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• Because the event sources invoke your Lambda function, you need to grant the event source the
necessary permissions using a resource-based policy (referred to as the Lambda function policy). For
more information, see AWS Lambda Permissions Model (p. 150).
The following example illustrates how this model works.
Example – Amazon S3 Pushes Events and Invokes a Lambda Function
Suppose that you want your AWS Lambda function invoked for each object created bucket event. You add
the necessary event source mapping in the bucket notification configuration.
The diagram illustrates the flow:
1. The user creates an object in a bucket.
2. Amazon S3 detects the object created event.
3. Amazon S3 invokes your Lambda function according to the event source mapping described in the
bucket notification configuration.
4. AWS Lambda verifies the permissions policy attached to the Lambda function to ensure that Amazon S3
has the necessary permissions. For more information on permissions policies, see Authentication and
Access Control for AWS Lambda (p. 277)
5. Once AWS Lambda verifies the attached permissions policy, it executes the Lambda function.
Remember that your Lambda function receives the event as a parameter.
Event Source Mapping for AWS Stream-based
Services
The Amazon Kinesis Streams and DynamoDB streams are the stream-based services that you can
preconfigure to use with AWS Lambda. After you do the necessary event source mapping, AWS Lambda
polls the streams and invokes your Lambda function (referred to as the pull model). In the pull model, note
the following:
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• The event source mappings are maintained within the AWS Lambda. AWS Lambda provides
the relevant APIs to create and manage event source mappings. For more information, see
CreateEventSourceMapping (p. 318).
• AWS Lambda needs your permission to poll the stream and read records. You grant these permissions
via the execution role, using the permissions policy associated with role that you specify when you create
your Lambda function. AWS Lambda does not need any permissions to invoke your Lambda function.
The following example illustrates how this model works.
Example – AWS Lambda Pulls Events from an Amazon Kinesis Stream and Invokes a
Lambda Function
The following diagram shows a custom application that writes records to an Amazon Kinesis stream and
how AWS Lambda polls the stream. When AWS Lambda detects a new record on the stream, it invokes
your Lambda function.
Suppose you have a custom application that writes records to an Amazon Kinesis stream. You want to
invoke a Lambda function when new records are detected on the stream. You create a Lambda function
and the necessary event source mapping in AWS Lambda.
The diagram illustrates the following sequence:
1. The custom application writes records to an Amazon Kinesis stream.
2. AWS Lambda continuously polls the stream, and invokes the Lambda function when the service detects
new records on the stream. AWS Lambda knows which stream to poll and which Lambda function to
invoke based on the event source mapping you create in AWS Lambda.
3. Assuming the attached permission policy, which allows AWS Lambda to poll the stream, is verified,
AWS Lambda then executes the Lambda function. For more information on permissions policies, see
Authentication and Access Control for AWS Lambda (p. 277)
The example uses an Amazon Kinesis stream but the same applies when working with a DynamoDB
stream.
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Event Source Mapping for Custom Applications
If you have custom applications that publish and process events, you can create a Lambda function to
process these events. In this case, there is no preconfiguration required—you don't have to set up an
event source mapping. Instead, the event source uses the AWS Lambda Invoke API. If the application and
Lambda function are owned by different AWS accounts, the AWS account that owns the Lambda function
must allow cross-account permissions in the permissions policy associated with the Lambda function.
The following example illustrates how this works.
Example – Custom Application Publishes Events and Invokes a Lambda Function
The following diagram shows how a custom application in your account can invoke a Lambda function. In
this example, the custom application is using the same account credentials as the account that owns the
Lambda function, and, therefore, does not require additional permissions to invoke the function.
In the following example, the user application and Lambda function are owned by different AWS accounts.
In this case, the AWS account that owns the Lambda function must have cross-account permissions in
the permissions policy associated with the Lambda function. For more information, see AWS Lambda
Permissions Model (p. 150).
Suggested Reading
If you are new to AWS Lambda, we suggest you read through all of the topics in the How It Works section
to familiarize yourself with Lambda. The next topic is Supported Event Sources (p. 120).
After you read all of the topics in the How it Works section, we recommend that you review Building
Lambda Functions (p. 5), try the Getting Started (p. 155) exercise, and then explore the Use
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Cases (p. 169). Each use case provides step-by-step instructions for you to set up the end-to-end
experience.
Supported Event Sources
This topic lists the supported AWS services that you can configure as event sources for AWS Lambda
functions. After you preconfigure the event source mapping, your Lambda function gets invoked
automatically when these event sources detect events. For more information about invocation modes, see
Event Source Mapping (p. 116).
For all of the event sources listed in this topic, note the following:
• Event sources maintain the event source mapping, except for the stream-based services (Amazon
Kinesis Streams and Amazon DynamoDB Streams). For the stream-based services, AWS Lambda
maintains the event source mapping. AWS Lambda provides the CreateEventSourceMapping (p. 318)
operation for you to create and manage the event source mapping. For more information, see Event
Source Mapping (p. 116).
• The invocation type that these event sources use when invoking a Lambda function is also
preconfigured. For example, Amazon S3 always invokes a Lambda function asynchronously and Amazon
Cognito invokes a Lambda function synchronously. The only time you can control the invocation type is
when you are invoking the Lambda function yourself using the Invoke (p. 351) operation (for example,
invoking a Lambda function on demand from your custom application).
You can also invoke a Lambda function on demand. For details, see Other Event Sources: Invoking a
Lambda Function On Demand (p. 125).
For examples of events that are published by these event sources, see Sample Events Published by Event
Sources (p. 125).
Topics
• Amazon S3 (p. 121)
• Amazon DynamoDB (p. 121)
• Amazon Kinesis Streams (p. 121)
• Amazon Simple Notification Service (p. 121)
• Amazon Simple Email Service (p. 122)
• Amazon Cognito (p. 122)
• AWS CloudFormation (p. 123)
• Amazon CloudWatch Logs (p. 123)
• Amazon CloudWatch Events (p. 123)
• AWS CodeCommit (p. 123)
• Scheduled Events (powered by Amazon CloudWatch Events) (p. 124)
• AWS Config (p. 124)
• Amazon Echo (p. 124)
• Amazon Lex (p. 125)
• Amazon API Gateway (p. 125)
• Other Event Sources: Invoking a Lambda Function On Demand (p. 125)
• Sample Events Published by Event Sources (p. 125)
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Amazon S3
Amazon S3
You can write Lambda functions to process S3 bucket events, such as the object-created or object-deleted
events. For example, when a user uploads a photo to a bucket, you might want Amazon S3 to invoke your
Amazon S3 function so that it reads the image and creates a thumbnail for the photo.
You can use the bucket notification configuration feature in Amazon S3 to configure the event source
mapping, identifying the bucket events that you want Amazon S3 to publish and which Lambda function to
invoke.
For an example Amazon S3 event, see Event Message Structure, Amazon S3 Put Sample
Event (p. 131), and Amazon S3 Delete Sample Event (p. 132). For an example use case, see Using
AWS Lambda with Amazon S3 (p. 169).
Error handling for a given event source depends on how Lambda is invoked. Amazon S3 invokes
your Lambda function asynchronously. For more information on how errors are retried, see Retries on
Errors (p. 149).
Amazon DynamoDB
You can use Lambda functions as triggers for your Amazon DynamoDB table. Triggers are custom actions
you take in response to updates made to the DynamoDB table. To create a trigger, first you enable Amazon
DynamoDB Streams for your table. AWS Lambda polls the stream and your Lambda function processes
any updates published to the stream.
This is a stream-based event source. For stream-based service, you create event source mapping in AWS
Lambda, identifying the stream to poll and which Lambda function to invoke.
For an example DynamoDB event, see Step 2.3.2: Test the Lambda Function (Invoke Manually) (p. 203)
and Amazon DynamoDB Update Sample Event (p. 129). For general format, see GetRecord in the
Amazon DynamoDB API Reference. For an example use case, see Using AWS Lambda with Amazon
DynamoDB (p. 196).
Error handling for a given event source depends on how Lambda is invoked. DynamoDB is a stream-based
event source. For more information on how errors are retried, see Retries on Errors (p. 149).
Amazon Kinesis Streams
You can configure AWS Lambda to automatically poll your stream and process any new records such as
website click streams, financial transactions, social media feeds, IT logs, and location-tracking events.
Then, AWS Lambda polls the stream periodically (multiple times per second) for new records.
For stream-based service, you create event source mapping in AWS Lambda, identifying the stream to poll
and which Lambda function to invoke.
For an example event, see Step 2.3: Create the Lambda Function and Test It Manually (p. 191) and
Amazon Kinesis Streams Sample Event (p. 131). For an example use case, see Using AWS Lambda with
Amazon Kinesis (p. 186).
Error handling for a given event source depends on how Lambda is invoked. Amazon Kinesis Streams
is a stream-based event source. For more information on how errors are retried, see Retries on
Errors (p. 149).
Amazon Simple Notification Service
You can write Lambda functions to process Amazon Simple Notification Service notifications. When a
message is published to an Amazon SNS topic, the service can invoke your Lambda function by passing
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the message payload as parameter. Your Lambda function code can then process the event, for example
publish the message to other Amazon SNS topics, or send the message to other AWS services.
This also enables you to trigger a Lambda function in response to Amazon CloudWatch alarms and other
AWS services that use Amazon SNS.
You configure the event source mapping in Amazon SNS via topic subscription configuration. For more
information, see Invoking Lambda functions using Amazon SNS notifications in the Amazon Simple
Notification Service Developer Guide.
For an example event, see Appendix: Message and JSON Formats and Amazon SNS Sample
Event (p. 128). For an example use case, see Using AWS Lambda with Amazon SNS from Different
Accounts (p. 222).
When a user calls the SNS Publish API on a topic that your Lambda function is subscribed to, Amazon
SNS will call Lambda to invoke your function asynchronously. Lambda will then return a delivery status. If
there was an error calling Lambda, Amazon SNS will retry invoking the Lambda function up to three times.
After three tries, if Amazon SNS still could not successfully invoke the Lambda function, then Amazon SNS
will send a delivery status failure message to CloudWatch.
Error handling for a given event source depends on how Lambda is invoked. Amazon SNS invokes
your Lambda function asynchronously. For more information on how errors are retried, see Retries on
Errors (p. 149).
Amazon Simple Email Service
Amazon Simple Email Service (Amazon SES) is a cost-effective email service. With Amazon SES, in
addition to sending emails, you can also use the service to receive messages. For more information about
Amazon SES, see Amazon Simple Email Service. When you use Amazon SES to receive messages, you
can configure Amazon SES to call your Lambda function when messages arrive. The service can then
invoke your Lambda function by passing in the incoming email event as parameter. For example scenarios,
see Considering Your Use Case for Amazon SES Email Receiving.
You configure event source mapping using the rule configuration in Amazon SES. The following topics
provide additional information in the Amazon Simple Email Service Developer Guide:
• For sample events, see Lambda Action and Amazon SES Email Receiving Sample Event (p. 126).
• For Lambda function examples, see Lambda Function Examples.
Error handling for a given event source depends on how Lambda is invoked. Amazon SES invokes
your Lambda function asynchronously. For more information on how errors are retried, see Retries on
Errors (p. 149).
Amazon Cognito
The Amazon Cognito Events feature enables you to run Lambda function in response to events in Amazon
Cognito. For example, you can invoke a Lambda function for the Sync Trigger events, that is published
each time a dataset is synchronized. To learn more and walk through an example, see Introducing Amazon
Cognito Events: Sync Triggers in the Mobile Development blog.
You configure event source mapping using Amazon Cognito event subscription configuration. For
information about event source mapping and a sample event, see Amazon Cognito Events in the Amazon
Cognito Developer Guide. For another example event, see Amazon Cognito Sync Trigger Sample
Event (p. 130)
Error handling for a given event source depends on how Lambda is invoked. Amazon Cognito is configured
to invoke a Lambda function synchronously. For more information on how errors are retried, see Retries on
Errors (p. 149).
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AWS CloudFormation
As part of deploying AWS CloudFormation stacks, you can specify a Lambda function as a custom
resource to execute any custom commands. Associating a Lambda function with a custom resource
enables you to invoke your Lambda function whenever you create, update, or delete AWS CloudFormation
stacks.
You configure event source mapping in AWS CloudFormation using stack definition. For more information,
see AWS Lambda-backed Custom Resources in the AWS CloudFormation User Guide.
For an example event, see AWS CloudFormation Create Request Sample Event (p. 126).
Error handling for a given event source depends on how Lambda is invoked. AWS CloudFormation invokes
your Lambda function asynchronously. For more information on how errors are retried, see Retries on
Errors (p. 149).
Amazon CloudWatch Logs
You can use AWS Lambda functions to perform custom analysis on Amazon CloudWatch Logs using
CloudWatch Logs subscriptions. CloudWatch Logs subscriptions provide access to a real-time feed of log
events from CloudWatch Logs and deliver it to your AWS Lambda function for custom processing, analysis,
or loading to other systems. For more information about CloudWatch Logs, see Monitoring Log Files.
You maintain event source mapping in Amazon CloudWatch Logs using the log subscription configuration.
For more information, see Real-time Processing of Log Data with Subscriptions (Example 2: AWS Lambda)
in the Amazon CloudWatch User Guide.
For an example event, see Amazon CloudWatch Logs Sample Event (p. 128).
Error handling for a given event source depends on how Lambda is invoked. Amazon CloudWatch Logs
invokes your Lambda function asynchronously (invoking a Lambda function does not block write operation
into the logs). For more information on how errors are retried, see Retries on Errors (p. 149).
Amazon CloudWatch Events
Amazon CloudWatch Events help you to respond to state changes in your AWS resources. When your
resources change state, they automatically send events into an event stream. You can create rules that
match selected events in the stream and route them to your AWS Lambda function to take action. For
example, you can automatically invoke an AWS Lambda function to log the state of an EC2 instance or
AutoScaling Group.
You maintain event source mapping in Amazon CloudWatch Events by using a rule target definition. For
more information, see the PutTargets operation in the Amazon CloudWatch Events API Reference.
For sample events, see Supported Event Types in the Amazon CloudWatch User Guide.
Error handling for a given event source depends on how Lambda is invoked. Amazon CloudWatch Events
invokes your Lambda function asynchronously. For more information on how errors are retried, see Retries
on Errors (p. 149).
AWS CodeCommit
You can create a trigger for an AWS CodeCommit repository so that events in the repository will invoke
a Lambda function. For example, you can invoke a Lambda function when a branch or tag is created
or when a push is made to an existing branch. For more information, see Manage Triggers for an AWS
CodeCommit Repository.
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Amazon CloudWatch Events)
You maintain the event source mapping in AWS CodeCommit by using a repository trigger. For more
information, see the PutRepositoryTriggers operation.
Error handling for a given event source depends on how Lambda is invoked. AWS CodeCommit invokes
your Lambda function asynchronously. For more information on how errors are retried, see Retries on
Errors (p. 149).
Scheduled Events (powered by Amazon CloudWatch
Events)
You can also set up AWS Lambda to invoke your code on a regular, scheduled basis using the schedule
event capability in Amazon CloudWatch Events. To set a schedule you can specify a fixed rate (number
of hours, days, or weeks) or specify a cron expression (see Schedule Expression Syntax for Rules in the
Amazon CloudWatch User Guide).
You maintain event source mapping in Amazon CloudWatch Events by using a rule target definition. For
more information, see the PutTargets operation in the Amazon CloudWatch Events API Reference.
For an example use case, see Using AWS Lambda with Scheduled Events (p. 253).
For an example event, see Scheduled Event Sample Event (p. 128).
Error handling for a given event source depends on how Lambda is invoked. Amazon CloudWatch Events
is configured to invoke a Lambda function asynchronously. For more information on how errors are retried,
see Retries on Errors (p. 149).
AWS Config
You can use AWS Lambda functions to evaluate whether your AWS resource configurations comply with
your custom Config rules. As resources are created, deleted, or changed, AWS Config records these
changes and sends the information to your Lambda functions. Your Lambda functions then evaluate the
changes and report results to AWS Config. You can then use AWS Config to assess overall resource
compliance: you can learn which resources are noncompliant and which configuration attributes are the
cause of noncompliance.
You maintain event source mapping in AWS Config by using a rule target definition. For more information,
see the PutConfigRule operation in the AWS Config API reference.
For more information, see Evaluating Resources With AWS Config Rules. For an example of setting a
custom rule, see Developing a Custom Rule for AWS Config. For example Lambda functions, see Example
AWS Lambda Functions for AWS Config Rules (Node.js).
Error handling for a given event source depends on how Lambda is invoked. AWS Config is configured to
invoke a Lambda function asynchronously. For more information on how errors are retried, see Retries on
Errors (p. 149).
Amazon Echo
You can use Lambda functions to build services that give new skills to Alexa, the Voice assistant on
Amazon Echo. The Alexa Skills Kit provides the APIs, tools, and documentation to create these new skills,
powered by your own services running as Lambda functions. Amazon Echo users can access these new
skills by asking Alexa questions or making requests. For more information, see Getting Started with Alexa
Skills Kit.
Error handling for a given event source depends on how Lambda is invoked. Amazon Echo is configured
to invoke a Lambda function synchronously. For more information on how errors are retried, see Retries on
Errors (p. 149).
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Amazon Lex
Amazon Lex is an AWS service for building conversational interfaces into applications using voice and text.
Amazon Lex provides pre-build integration with AWS Lambda, allowing you to create Lambda functions
for use as code hook with your Amazon Lex bot. In your intent configuration, you can identify your Lambda
function to perform initialization/validation, fulfillment, or both.
For more information, see Using Lambda Functions. For an example use case, see Exercise 1: Create
Amazon Lex Bot Using a Blueprint.
Error handling for a given event source depends on how Lambda is invoked. Amazon Lex is configured to
invoke a Lambda function synchronously. For more information on how errors are retried, see Retries on
Errors (p. 149).
Amazon API Gateway
You can invoke a Lambda function over HTTPS. You can do this by defining a custom REST API and
endpoint using Amazon API Gateway. You map individual API operations, such as GET and PUT, to specific
Lambda functions. When you send an HTTPS request to the API endpoint, the Amazon API Gateway
service invokes the corresponding Lambda function.
For more information, see Make Synchronous Calls to Lambda Functions. For an example use case, see
Using AWS Lambda with Amazon API Gateway (On-Demand Over HTTPS) (p. 227).
Error handling for a given event source depends on how Lambda is invoked. Amazon API Gateway is
configured to invoke a Lambda function synchronously. For more information on how errors are retried, see
Retries on Errors (p. 149).
In addition, you can also use Lambda functions with other AWS services that publish data to one of the
supported AWS event sources listed in this topic. For example, you can:
• Trigger Lambda functions in response to CloudTrail updates because it records all API access events to
an Amazon S3 bucket.
• Trigger Lambda functions in response to CloudWatch alarms because it publishes alarm events to an
Amazon SNS topic.
Other Event Sources: Invoking a Lambda Function On
Demand
In addition to invoking Lambda functions using event sources, you can also invoke your Lambda function
on demand. You don't need to preconfigure any event source mapping in this case. However, make sure
that the custom application has the necessary permissions to invoke your Lambda function.
For example, user applications can also generate events (build your own custom event sources). User
applications such as client, mobile, or web applications can publish events and invoke Lambda functions
using the AWS SDKs or AWS Mobile SDKs such as the AWS Mobile SDK for Android.
For more information, see Tools for Amazon Web Services. For an example tutorial, see Using AWS
Lambda with Amazon API Gateway (On-Demand Over HTTPS) (p. 227).
Sample Events Published by Event Sources
The following is a list of example events published by the supported AWS services. For more information
about the supported AWS event sources, see Supported Event Sources (p. 120).
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Sample Events
• AWS CloudFormation Create Request Sample Event (p. 126)
• Amazon SES Email Receiving Sample Event (p. 126)
• Scheduled Event Sample Event (p. 128)
• Amazon CloudWatch Logs Sample Event (p. 128)
• Amazon SNS Sample Event (p. 128)
• Amazon DynamoDB Update Sample Event (p. 129)
• Amazon Cognito Sync Trigger Sample Event (p. 130)
• Amazon Kinesis Streams Sample Event (p. 131)
• Amazon S3 Put Sample Event (p. 131)
• Amazon S3 Delete Sample Event (p. 132)
• Mobile Backend Sample Event (p. 132)
• Amazon Lex Sample Event (p. 133)
AWS CloudFormation Create Request Sample Event
{
"StackId": stackidarn,
"ResponseURL": "http://pre-signed-S3-url-for-response",
"ResourceProperties": {
"StackName": "stack-name",
"List": [
"1",
"2",
"3"
]
},
"RequestType": "Create",
"ResourceType": "Custom::TestResource",
"RequestId": "unique id for this create request",
"LogicalResourceId": "MyTestResource"
}
Amazon SES Email Receiving Sample Event
"Records": [
{
"eventVersion": "1.0",
"ses": {
"mail": {
"commonHeaders": {
"from": [
"Jane Doe <[email protected]>"
],
"to": [
"[email protected]"
],
"returnPath": "[email protected]",
"messageId": "<0123456789example.com>",
"date": "Wed, 7 Oct 2015 12:34:56 -0700",
"subject": "Test Subject"
},
"source": "[email protected]",
"timestamp": "1970-01-01T00:00:00.000Z",
"destination": [
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"[email protected]"
],
"headers": [
{
"name": "Return-Path",
"value": "<[email protected]>"
},
{
"name": "Received",
"value": "from mailer.example.com (mailer.example.com
[203.0.113.1]) by inbound-smtp.us-west-2.amazonaws.com with SMTP id
o3vrnil0e2ic28trm7dfhrc2v0cnbeccl4nbp0g1x for [email protected]; Wed, 07 Oct 2015
12:34:56 +0000 (UTC)"
},
{
"name": "DKIM-Signature",
"value": "v=1; a=rsa-sha256; c=relaxed/relaxed; d=example.com;
s=example; h=mime-version:from:date:message-id:subject:to:content-type;
bh=jX3F0bCAI7sIbkHyy3mLYO28ieDQz2R0P8HwQkklFj4x=; b=sQwJ+LMe9RjkesGu
+vqU56asvMhrLRRYrWCbVt6WJulueecwfEwRf9JVWgkBTKiL6m2hr70xDbPWDhtLdLO
+jB3hzjVnXwK3pYIOHw3vxG6NtJ6o61XSUwjEsp9tdyxQjZf2HNYee873832l3K1EeSXKzxYk9Pwqcpi3dMC74ct9GukjIevf1H
+k6khpurTQQ4sp4PZPRlgHtnj3Zzv7nmpTo7dtPG5z5S9J+L+Ba7dixT0jn3HuhaJ9b
+VThboo4YfsX9PMNhWWxGjVksSFOcGluPO7QutCPyoY4gbxtwkN9W69HA=="
},
{
"name": "MIME-Version",
"value": "1.0"
},
{
"name": "From",
"value": "Jane Doe <[email protected]>"
},
{
"name": "Date",
"value": "Wed, 7 Oct 2015 12:34:56 -0700"
},
{
"name": "Message-ID",
"value": "<0123456789example.com>"
},
{
"name": "Subject",
"value": "Test Subject"
},
{
"name": "To",
value": "[email protected]"
},
{
"name": "Content-Type",
"value": "text/plain; charset=UTF-8"
}
],
"headersTruncated": false,
"messageId": "o3vrnil0e2ic28trm7dfhrc2v0clambda4nbp0g1x"
},
"receipt": {
"recipients": [
"[email protected]"
],
"timestamp": "1970-01-01T00:00:00.000Z",
"spamVerdict": {
"status": "PASS"
},
"dkimVerdict": {
"status": "PASS"
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},
"processingTimeMillis": 574,
"action": {
"type": "Lambda",
"invocationType": "Event",
"functionArn": functionarn
},
"spfVerdict": {
"status": "PASS"
},
"virusVerdict": {
"status": "PASS"
}
}
},
"eventSource": "aws:ses"
}
]
}]}
Scheduled Event Sample Event
{
"account": "123456789012",
"region": "us-east-1",
"detail": {},
"detail-type": "Scheduled Event",
"source": "aws.events",
"time": "1970-01-01T00:00:00Z",
"id": "cdc73f9d-aea9-11e3-9d5a-835b769c0d9c",
"resources": [
"arn:aws:events:us-east-1:123456789012:rule/my-schedule"
]
}
Amazon CloudWatch Logs Sample Event
{
"awslogs": {
"data": "H4sIAAAAAAAAAHWPwQqCQBCGX0Xm7EFtK
+smZBEUgXoLCdMhFtKV3akI8d0bLYmibvPPN3wz00CJxmQnTO41whwWQRIctmEcB6sQbFC3CjW3XW8kxpOpP
+OC22d1Wml1qZkQGtoMsScxaczKN3plG8zlaHIta5KqWsozoTYw3/djzwhpLwivWFGHGpAFe7DL68JlBUk
+l7KSN7tCOEJ4M3/qOI49vMHj+zCKdlFqLaU2ZHV2a4Ct/an0/ivdX8oYc1UVX860fQDQiMdxRQEAAA=="
}
}
Amazon SNS Sample Event
{
"Records": [
{
"EventVersion": "1.0",
"EventSubscriptionArn": eventsubscriptionarn,
"EventSource": "aws:sns",
"Sns": {
"SignatureVersion": "1",
"Timestamp": "1970-01-01T00:00:00.000Z",
"Signature": "EXAMPLE",
"SigningCertUrl": "EXAMPLE",
"MessageId": "95df01b4-ee98-5cb9-9903-4c221d41eb5e",
"Message": "Hello from SNS!",
"MessageAttributes": {
"Test": {
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"Type": "String",
"Value": "TestString"
},
"TestBinary": {
"Type": "Binary",
"Value": "TestBinary"
}
},
"Type": "Notification",
"UnsubscribeUrl": "EXAMPLE",
"TopicArn": topicarn,
"Subject": "TestInvoke"
}
}
]
}
Amazon DynamoDB Update Sample Event
{
"Records": [
{
"eventID": "1",
"eventVersion": "1.0",
"dynamodb": {
"Keys": {
"Id": {
"N": "101"
}
},
"NewImage": {
"Message": {
"S": "New item!"
},
"Id": {
"N": "101"
}
},
"StreamViewType": "NEW_AND_OLD_IMAGES",
"SequenceNumber": "111",
"SizeBytes": 26
},
"awsRegion": "us-west-2",
"eventName": "INSERT",
"eventSourceARN": eventsourcearn,
"eventSource": "aws:dynamodb"
},
{
"eventID": "2",
"eventVersion": "1.0",
"dynamodb": {
"OldImage": {
"Message": {
"S": "New item!"
},
"Id": {
"N": "101"
}
},
"SequenceNumber": "222",
"Keys": {
"Id": {
"N": "101"
}
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},
"SizeBytes": 59,
"NewImage": {
"Message": {
"S": "This item has changed"
},
"Id": {
"N": "101"
}
},
"StreamViewType": "NEW_AND_OLD_IMAGES"
},
"awsRegion": "us-west-2",
"eventName": "MODIFY",
"eventSourceARN": sourcearn,
"eventSource": "aws:dynamodb"
},
{
"eventID": "3",
"eventVersion": "1.0",
"dynamodb": {
"Keys": {
"Id": {
"N": "101"
}
},
"SizeBytes": 38,
"SequenceNumber": "333",
"OldImage": {
"Message": {
"S": "This item has changed"
},
"Id": {
"N": "101"
}
},
"StreamViewType": "NEW_AND_OLD_IMAGES"
},
"awsRegion": "us-west-2",
"eventName": "REMOVE",
"eventSourceARN": sourcearn,
"eventSource": "aws:dynamodb"
}
]
}
Amazon Cognito Sync Trigger Sample Event
{
"datasetName": "datasetName",
"eventType": "SyncTrigger",
"region": "us-east-1",
"identityId": "identityId",
"datasetRecords": {
"SampleKey2": {
"newValue": "newValue2",
"oldValue": "oldValue2",
"op": "replace"
},
"SampleKey1": {
"newValue": "newValue1",
"oldValue": "oldValue1",
"op": "replace"
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}
},
"identityPoolId": "identityPoolId",
"version": 2
}
Amazon Kinesis Streams Sample Event
"Records": [
{
"eventID":
"shardId-000000000000:49545115243490985018280067714973144582180062593244200961",
"eventVersion": "1.0",
"kinesis": {
"partitionKey": "partitionKey-3",
"data": "SGVsbG8sIHRoaXMgaXMgYSB0ZXN0IDEyMy4=",
"kinesisSchemaVersion": "1.0",
"sequenceNumber": "49545115243490985018280067714973144582180062593244200961"
},
"invokeIdentityArn": identityarn,
"eventName": "aws:kinesis:record",
"eventSourceARN": eventsourcearn,
"eventSource": "aws:kinesis",
"awsRegion": "us-east-1"
}
]
}
Amazon S3 Put Sample Event
{
"Records": [
{
"eventVersion": "2.0",
"eventTime": "1970-01-01T00:00:00.000Z",
"requestParameters": {
"sourceIPAddress": "127.0.0.1"
},
"s3": {
"configurationId": "testConfigRule",
"object": {
"eTag": "0123456789abcdef0123456789abcdef",
"sequencer": "0A1B2C3D4E5F678901",
"key": "HappyFace.jpg",
"size": 1024
},
"bucket": {
"arn": bucketarn,
"name": "sourcebucket",
"ownerIdentity": {
"principalId": "EXAMPLE"
}
},
"s3SchemaVersion": "1.0"
},
"responseElements": {
"x-amz-id-2": "EXAMPLE123/5678abcdefghijklambdaisawesome/
mnopqrstuvwxyzABCDEFGH",
"x-amz-request-id": "EXAMPLE123456789"
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},
"awsRegion": "us-east-1",
"eventName": "ObjectCreated:Put",
"userIdentity": {
"principalId": "EXAMPLE"
},
"eventSource": "aws:s3"
}
]
}
Amazon S3 Delete Sample Event
{
"Records": [
{
"eventVersion": "2.0",
"eventTime": "1970-01-01T00:00:00.000Z",
"requestParameters": {
"sourceIPAddress": "127.0.0.1"
},
"s3": {
"configurationId": "testConfigRule",
"object": {
"sequencer": "0A1B2C3D4E5F678901",
"key": "HappyFace.jpg"
},
"bucket": {
"arn": bucketarn,
"name": "sourcebucket",
"ownerIdentity": {
"principalId": "EXAMPLE"
}
},
"s3SchemaVersion": "1.0"
},
"responseElements": {
"x-amz-id-2": "EXAMPLE123/5678abcdefghijklambdaisawesome/
mnopqrstuvwxyzABCDEFGH",
"x-amz-request-id": "EXAMPLE123456789"
},
"awsRegion": "us-east-1",
"eventName": "ObjectRemoved:Delete",
"userIdentity": {
"principalId": "EXAMPLE"
},
"eventSource": "aws:s3"
}
]
}
Mobile Backend Sample Event
{
"operation": "echo",
"message": "Hello world!"
}
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Amazon Lex Sample Event
{
"messageVersion": "1.0",
"invocationSource": "FulfillmentCodeHook or DialogCodeHook",
"userId": "user-id specified in the POST request to Amazon Lex.",
"sessionAttributes": {
"key1": "value1",
"key2": "value2",
},
"bot": {
"name": "bot-name",
"alias": "bot-alias",
"version": "bot-version"
},
"outputDialogMode": "Text or Voice, based on ContentType request header in runtime
API request",
"currentIntent": {
"name": "intent-name",
"slots": {
"slot-name": "value",
"slot-name": "value",
"slot-name": "value"
},
"confirmationStatus": "None, Confirmed, or Denied
(intent confirmation, if configured)"
}
}
Deploying Lambda-based Applications
Lambda-based applications (also referred to as serverless applications) are composed of functions
triggered by events. A typical serverless application consists of one or more functions triggered by events
such as object uploads to Amazon S3, Amazon SNS notifications, and API actions. Those functions can
stand alone or leverage other resources such as DynamoDB tables or Amazon S3 buckets. The most basic
serverless application is simply a function.
AWS Lambda provides API operations that you can use to create and update Lambda functions by
providing a deployment package as a ZIP file. However, this mechanism might not be convenient for
automating deployment steps for functions, or coordinating deployments and updates to other elements of
a serverless application (like event sources and downstream resources). For example, in order to deploy
an Amazon SNS trigger, you need to update the function, the Amazon SNS topic, the mapping between
the function and the topic, and any other downstream resources required by your function such as a
DynamoDB table.
Deploying Serverless Applications Using AWS
CloudFormation
You can use AWS CloudFormation to specify, deploy, and configure serverless applications. AWS
CloudFormation is a service that helps you model and set up your AWS resources so that you can spend
less time managing those resources and more time focusing on your applications that run in AWS.
You create a template that describes all of the AWS resources that you want (like Lambda functions
and DynamoDB tables), and AWS CloudFormation takes care of provisioning and configuring those
resources for you. You don't need to individually create and configure AWS resources and figure out
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what's dependent on what—AWS CloudFormation handles all of that. For more information, see AWS
CloudFormation Concepts in the AWS CloudFormation User Guide.
Using the AWS Serverless Application Model (AWS
SAM)
The AWS Serverless Application Model (AWS SAM) is a model to define serverless applications. AWS
SAM is natively supported by AWS CloudFormation and defines simplified syntax for expressing serverless
resources. The specification currently covers APIs, Lambda functions and Amazon DynamoDB tables. The
specification is available under Apache 2.0 for AWS partners and customers to adopt and extend within
their own toolsets. For details on the specification, see the AWS Serverless Application Model.
Serverless Resources Within AWS CloudFormation
AWS SAM supports special resource types that simplify how to express functions, APIs, mappings, and
DynamoDB tables for serverless applications, as well as some features for these services like environment
variables. The AWS CloudFormation description of these resources conforms to the AWS Serverless
Application Model. In order to deploy your application, simply specify the resources you need as part of
your application, along with their associated permissions policies in an AWS CloudFormation template file
(written in either JSON or YAML), package your deployment artifacts, and deploy the template.
An AWS CloudFormation template with serverless resources conforming to the AWS SAM model is
referred to as a SAM file or template.
The examples below illustrate how to leverage AWS SAM to declare common components of a serverless
application. Note that the Handler and Runtime parameter values should match the ones you used when
you created the function in the previous section.
Lambda function
The following shows the notation you use to describe a Lambda function:
AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Resources:
FunctionName:
Type: AWS::Serverless::Function
Properties:
Handler: handler
Runtime: runtime
CodeUri: s3://bucketName/codepackage.zip
The handler value of the Handler property points to the module containing the code your Lambda
function will execute when invoked. The index value of the Handler property indicates the name of the file
containing the code. You can declare as many functions as your serverless application requires.
You can also declare environment variables, which are configuration settings you can set for your
application. The following shows an example of a serverless app with two Lambda functions and an
environment variable that points to a DynamoDB table. You can update environment variables without
needing to modify, repackage, or redeploy your Lambda function code. For more information, see
Environment Variables (p. 85).
AWSTemplateFormatVersion: '2010-09-09'
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Transform: AWS::Serverless-2016-10-31
Resources:
PutFunction:
Type: AWS::Serverless::Function
Properties:
Handler: index.handler
Runtime: nodejs6.10
Policies: AWSLambdaDynamoDBExecutionRole
CodeUri: s3://bucketName/codepackage.zip
Environment:
Variables:
TABLE_NAME: !Ref Table
DeleteFunction:
Type: AWS::Serverless::Function
Properties:
Handler: index.handler
Runtime: nodejs6.10
Policies: AWSLambdaDynamoDBExecutionRole
CodeUri: s3://bucketName/codepackage.zip
Environment:
Variables:
TABLE_NAME: !Ref Table
Events:
Stream:
Type: DynamoDB
Properties:
Stream: !GetAtt DynamoDBTable.StreamArn
BatchSize: 100
StartingPosition: TRIM_HORIZON
DynamoDBTable:
Type: AWS::DynamoDB::Table
Properties:
AttributeDefinitions:
- AttributeName: id
AttributeType: S
KeySchema:
- AttributeName: id
KeyType: HASH
ProvisionedThroughput:
ReadCapacityUnits: 5
WriteCapacityUnits: 5
StreamSpecification:
StreamViewType: streamview type
Note the notation at the top:
AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
This is required in order to include objects defined by the AWS Serverless Application Model within an AWS
CloudFormation template.
SimpleTable
SimpleTable is a resource that creates a DynamoDB table with a single-attribute primary key. You can use
this simplified version if the data your serverless application is interacting with only needs to be accessed
by a single-valued key. You could update the previous example to use a SimpleTable, as shown following:
AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
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Resources:
TableName:
Type: AWS::Serverless::SimpleTable
Properties:
PrimaryKey:
Name: id
Type: String
ProvisionedThroughput:
ReadCapacityUnits: 5
WriteCapacityUnits: 5
Events
Events are AWS resources that trigger the Lambda function, such as an Amazon API Gateway endpoint or
an Amazon SNS notification. The Events property is an array, which allows you to set multiple events per
function. The following shows the notation you use to describe a Lambda function with a DynamoDB table
as an event source:
AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Resources:
FunctionName:
Type: AWS::Serverless::Function
Properties:
Handler: index.handler
Runtime: nodejs6.10
Events:
Stream:
Type: DynamoDB
Properties:
Stream: !GetAtt DynamoDBTable.StreamArn
BatchSize: 100
StartingPosition: TRIM_HORIZON
TableName:
Type: AWS::DynamoDB::Table
Properties:
AttributeDefinitions:
- AttributeName: id
AttributeType: S
KeySchema:
- AttributeName: id
KeyType: HASH
ProvisionedThroughput:
ReadCapacityUnits: 5
WriteCapacityUnits: 5
As mentioned above, you can set multiple event sources that will trigger the Lambda function. The example
below shows a Lambda function that can be triggered by either an HTTP PUT or POST event.
API
There are two ways to define an API using AWS SAM. The following uses Swagger to configure the
underlying Amazon API Gateway resources:
AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Resources:
Api:
Type: AWS::Serverless::Api
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Properties:
StageName: prod
DefinitionUri: swagger.yml
In the next example, the AWS::Serverless::Api resource type is implicity added from the union of API
events defined on AWS::Serverless::Function resources.
AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Resources:
GetFunction:
Type: AWS::Serverless::Function
Properties:
Handler: index.get
Runtime: nodejs6.10
CodeUri: s3://bucket/api_backend.zip
Policies: AmazonDynamoDBReadOnlyAccess
Environment:
Variables:
TABLE_NAME: !Ref Table
Events:
GetResource:
Type: Api
Properties:
Path: /resource/{resourceId}
Method: get
PutFunction:
Type: AWS::Serverless::Function
Properties:
Handler: index.put
Runtime: nodejs6.10
CodeUri: s3://bucket/api_backend.zip
Policies: AmazonDynamoDBFullAccess
Environment:
Variables:
TABLE_NAME: !Ref Table
Events:
PutResource:
Type: Api
Properties:
Path: /resource/{resourceId}
Method: put
DeleteFunction:
Type: AWS::Serverless::Function
Properties:
Handler: index.delete
Runtime: nodejs6.10
CodeUri: s3://bucket/api_backend.zip
Policies: AmazonDynamoDBFullAccess
Environment:
Variables:
TABLE_NAME: !Ref Table
Events:
DeleteResource:
Type: Api
Properties:
Path: /resource/{resourceId}
Method: delete
Table:
Type: AWS::Serverless::SimpleTable
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In the example above, AWS CloudFormation will automatically generate an Amazon API Gateway API with
the path "/resource/{resourceId}" and with the methods GET, PUT and DELETE.
Permissions
You can supply an IAM role ARN to be used as this function's execution role, as shown below:
AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Resources:
FunctionName:
Type: AWS::Serverless::Function
Properties:
Role:role arn
Alternatively, you could supply one or more managed policies to the Lambda function resource. AWS
CloudFormation will then create a new role with the managed policies plus the default Lambda basic
execution policy.
AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Resources:
FunctionName:
Type: AWS::Serverless::Function
Properties:
Policies: AmazonDynamoDBFullAccess
If none of these are supplied, a default execution role is created with Lambda basic execution permissions.
Note
In addition to using the serverless resources, you can also use conventional CloudFormation
syntax for expressing resources in the same template. Any resources not included in the current
SAM model can still be created in the AWS CloudFormation template using AWS CloudFormation
syntax. In addition, you can use AWS CloudFormation syntax to express serverless resources as
an alternative to using the SAM model. For information about specifying a Lambda function using
conventional CloudFormation syntax as part of your SAM template, see AWS::Lambda::Function
in the AWS CloudFormation User Guide.
For a list of complete serverless application examples, see Examples of How to Use AWS
Lambda (p. 169).
Next Step
Create Your Own Serverless Application (p. 138)
Create Your Own Serverless Application
In the following tutorial, you create a simple serverless application that consists of a single function that
returns the name of an Amazon S3 bucket you specify as an environment variable. Follow these steps:
1. Copy and paste the following into a text file and save it as index.js
var AWS = require('aws-sdk');
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exports.handler = function(event, context, callback) {
var bucketName = process.env.S3_BUCKET;
callback(null, bucketName);
}
2. Paste the following into a text file and save it as example.yaml. Note that the Runtime parameter uses
nodejs6.10 but you can specify nodejs4.3.
AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Resources:
TestFunction:
Type: AWS::Serverless::Function
Properties:
Handler: index.handler
Runtime: nodejs6.10
Environment:
Variables:
S3_BUCKET: bucket-name
3. Create a folder called examplefolder and place the example.yaml file and the index.js file inside the
folder.
Your example folder now contains the following two files that you can then use to package the serverless
application:
• example.yaml
• index.js
Packaging and Deployment
After you create your Lambda function handler and your example.yaml file, you can use the AWS CLI to
package and deploy your serverless application.
Packaging
To package your application, create an Amazon S3 bucket that the package command will use to upload
your ZIP deployment package (if you haven't specified one in your example.yaml file). You can use the
following command to create the Amazon S3 bucket:
aws s3 mb s3://bucket-name --region region
Next, open a command prompt and type the following:
aws cloudformation package \
--template-file example.yaml \
--output-template-file serverless-output.yaml \
--s3-bucket s3-bucket-name
The package command returns an AWS SAM template, in this case serverless-output.yaml that contains
the CodeUri that points to the deployment zip in the Amazon S3 bucket that you specified. This template
represents your serverless application. You are now ready to deploy it.
Deployment
To deploy the application, run the following command:
aws cloudformation deploy \
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--template-file serverless-output.yaml \
--stack-name new-stack-name \
--capabilities CAPABILITY_IAM
Note that the value you specify for the --template-file parameter is the name of the SAM template
that was returned by the package command. In addition, the --capabilities parameter is optional. The
AWS::Serverless::Function resource will implicitly create a role to execute the Lambda function if one is
not specified in the template. You use the --capabilities parameter to explicitly acknowledge that AWS
CloudFormation is allowed to create roles on your behalf.
When you run the aws cloudformation deploy command, it creates an AWS CloudFormation ChangeSet,
which is a list of changes to the AWS CloudFormation stack, and then deploys it. Some stack templates
might include resources that can affect permissions in your AWS account, for example, by creating new
AWS Identity and Access Management (IAM) users. For those stacks, you must explicitly acknowledge
their capabilities by specifying the --capabilities parameter. For more information, see CreateChangeSet
in the AWS CloudFormation API Reference.
To verify your results, open the AWS CloudFormation console to view the newly created AWS
CloudFormation stack and the Lambda console to view your function.
For a list of complete serverless application examples, see Examples of How to Use AWS
Lambda (p. 169).
Exporting a Serverless Application
You can export a serverless application and re-deploy it to, for example, a different AWS region or
development stage, using the Lambda console. When you export a Lambda function, you will be provided
with a ZIP deployment package and a SAM template that represents your serverless application. You can
then use the package and deploy commands described in the previous section for re-deployment.
You can also select one of Lambda blueprints to create a ZIP package for you to package and deploy.
Follow the steps below to do this:
To export a serverless application using the Lambda console
1.
Sign in to the AWS Management Console and open the AWS Lambda console at https://
console.aws.amazon.com/lambda/.
2.
Do any of the following:
• Create a function using a Lambda blueprint – Choose a blueprint and follow the steps to create a
Lambda function. For an example, see Step 2.1: Create a Hello World Lambda Function (p. 159).
When you reach the Review page, choose Export function.
• Create a function – Choose Create function, and then create your function. After your Lambda
function is created, you can export it by selecting the function. Choose Actions, then choose Export
function.
• Open an existing Lambda function – Open the function by choosing the Function name, choose
Actions, choose Export function.
3.
In the Export your function window, you have the following options:
• Choose Download AWS SAM file, which defines the Lambda function and other resources that
comprise your serverless application.
• Choose Download deployment package, which contains your Lambda function code and any
dependent libraries.
Use the AWS SAM file and the ZIP deployment package and follow the steps in Packaging and
Deployment (p. 139) to re-deploy the serverless application.
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Automating Deployment of Lambda-based
Applications
In the previous section, you learned how to create a SAM template, generate your deployment package,
and use the AWS CLI to manually deploy your serverless application. In this section, you will leverage the
following AWS services to fully automate the deployment process.
• CodePipeline: You use CodePipeline to model, visualize, and automate the steps required to release
your serverless application. For more information, see What is AWS CodePipeline?
• CodeBuild: You use CodeBuild to build, locally test, and package your serverless application. For more
information, see What is AWS CodeBuild?
• AWS CloudFormation: You use AWS CloudFormation to deploy your application. For more information,
see What is AWS CloudFormation?
Building a Pipeline for Your Serverless Application
In the following tutorial, you will create an AWS CodePipeline that automates the deployment of your
serverless application. First, you will need to set up a source stage to trigger your pipeline. For the
purposes of this tutorial:
• We will use GitHub. For instructions on how to create a GitHub repository, see Create a Repository in
GitHub.
• You will need to create an AWS CloudFormation role and add the AWSLambdaBasicExecutionRole
policy to that role, as outlined below:
1.
Sign in to the IAM console at https://console.aws.amazon.com/iam/.
2.
Follow the steps in Creating a Role to Delegate Permissions to an AWS Service in the IAM User
Guide to create an IAM role (execution role). As you follow the steps to create a role, note the
following:
• In Role Name, use a name that is unique within your AWS account (for example,
cloudformation-lambda-execution-role).
• In Select Role Type, choose AWS Service Roles, and then choose AWS CloudFormation. This
grants the AWS CloudFormation service permissions to assume the role.
• In Attach Policy, choose AWSLambdaExecute.
• Open the role you just created and under the Permissions tab, expand Inline Policies and then
choose Create Role Policy.
• Choose Custom Policy and then choose Select.
• In Policy Name enter a name for your custom policy and then paste the following into the Policy
Document field:
{
"Statement": [
{
"Action": [
"s3:GetObject",
"s3:GetObjectVersion",
"s3:GetBucketVersioning"
],
"Resource": "*",
"Effect": "Allow"
},
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{
"Action": [
"s3:PutObject"
],
"Resource": [
"arn:aws:s3:::codepipeline*"
],
"Effect": "Allow"
},
{
"Action": [
"lambda:*"
],
"Resource": [
"arn:aws:lambda:region:account-id:function:*"
],
"Effect": "Allow"
},
{
"Action": [
"apigateway:*"
],
"Resource": [
"arn:aws:apigateway:region::*"
],
"Effect": "Allow"
},
{
"Action": [
"iam:GetRole",
"iam:CreateRole",
"iam:DeleteRole"
],
"Resource": [
"arn:aws:iam::account-id:role/*"
],
"Effect": "Allow"
},
{
"Action": [
"iam:AttachRolePolicy",
"iam:DetachRolePolicy"
],
"Resource": [
"arn:aws:iam::account-id:role/*"
],
"Effect": "Allow"
},
{
"Action": [
"iam:PassRole"
],
"Resource": [
"*"
],
"Effect": "Allow"
},
{
"Action": [
"cloudformation:CreateChangeSet"
],
"Resource": [
"arn:aws:cloudformation:region:aws:transform/Serverless-2016-10-31"
],
"Effect": "Allow"
}
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],
"Version": "2012-10-17"
}
• Choose Validate Policy and then choose Apply Policy.
Step 1: Set Up Your Repository
To set up your repository, do the following:
• Add an index.js file containing the code below:
var time = require('time');
exports.handler = (event, context, callback) => {
var currentTime = new time.Date();
currentTime.setTimezone("America/Los_Angeles");
callback(null, {
statusCode: '200',
body: 'The time in Los Angeles is: ' + currentTime.toString(),
});
};
• Add a samTemplate.yaml file, containing the content below. This is the SAM template that defines the
resources in your application. This SAM template defines a Lambda function that is triggered by API
Gateway. Note that the runtime parameter uses nodejs6.10 but you can also specify nodejs4.3. For
more information about AWS SAM see AWS Serverless Application Model.
AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: Outputs the time
Resources:
TimeFunction:
Type: AWS::Serverless::Function
Properties:
Handler: index.handler
Runtime: nodejs6.10
CodeUri: ./
Events:
MyTimeApi:
Type: Api
Properties:
Path: /TimeResource
Method: GET
• Add a buildspec.yml file. A build spec is a collection of build commands and related settings, in YAML
format, that AWS CodeBuild uses to run a build. For more information, see Build Specification Reference
for AWS CodeBuild. In this example, the build action will be:
• Use npm to install the time package.
• Running the Package command to prepare your deployment package for subsequent deployment steps
in your pipeline. For more information on the package command, see Uploading Local Artifacts to an
S3 Bucket
version: 0.1
phases:
install:
commands:
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- npm install time
- aws cloudformation package --template-file samTemplate.yaml --s3-bucket bucketname
--output-template-file NewSamTemplate.yaml
artifacts:
type: zip
files:
- NewSamTemplate.yaml
Note that you need to supply the --s3-bucket parameter value with the name of the your Amazon
S3 bucket, similar to the step you would take if you were manually going to package the deployment
package with SAM, as discussed in the Packaging (p. 139) step of the previous tutorial.
Step 2: Create Your Pipeline
Follow the steps below to create your AWS CodePipeline.
1.
Sign in to the AWS Management Console and open the AWS CodePipeline console.
2.
Choose Get Started Now.
3.
In Pipeline name: enter a name for your pipeline and then choose Next step.
4.
In Source provider: choose GitHub.
5.
Choose Connect to GitHub: and then choose the Repository and Branch you want to connect to.
Every git push to the branch you select will trigger your pipeline. Choose Next step.
6.
Choose AWS CodeBuild as your Build provider.
7.
Choose Create a new build project and enter a project name.
8.
Choose Ubuntu as the operating system.
9.
Choose Node.js as the runtime.
10. In Version choose aws/codebuild/nodejs:4.3.2
11. Choose Save build project.
Note
A service role for AWS CodeBuild will automatically be created on your behalf.
Choose Next step.
12. In Deployment provider: choose AWS CloudFormation.
By selecting this option, AWS CloudFormation commands will be used to deploy the SAM template.
For more information see Serverless Resources Within AWS CloudFormation (p. 134).
13. In Action mode: choose create or replace a change set.
14. In Stack name: enter MyBetaStack.
15. In Change set name: enter MyChangeSet.
16. In Template file: enter NewSamTemplate.yaml.
17. In Capabilities: choose CAPABILITY_IAM.
18. In Role select the AWS CloudFormation role you created at the beginning of this tutorial and then
choose Next step.
19. Choose Create role. Choose Next and then choose Allow. Choose Next step.
20. Review your pipeline and then choose Create pipeline.
Step 3: Update the Generated Service Policy
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Follow the steps below to allow CodeBuild to upload build artifacts to your Amazon S3 bucket.
1.
2.
Go to the IAM Management console.
Choose Roles.
3.
Open the service role that was generated for your project, typically code-build-project-name-servicerole.
4.
Under the Permissions tab, choose Attach Policy.
5.
6.
7.
Under the Permissions tab, choose Create Role Policy.
Choose Policy Generator and then choose Select.
In the AWS Service list, choose Amazon S3.
8.
In Actions, choose PutObject.
9.
In Amazon Resource Name (ARN), enter arn:aws:s3:::bucket-name*.
10. Choose Add Statement and then choose Next Step.
11. In Review Policy choose Validate Policy and then choose Apply Policy.
Step 4: Complete Your Beta Deployment Stage
Follow the steps below to complete your Beta stage.
1.
Choose Edit.
2.
Choose the
3.
4.
icon for your beta stage.
In the beta stage, choose the + Action icon that is located below your existing action.
In Category: choose Deploy.
5.
6.
In Action: enter execute_cs.
In Deployment provider: choose AWS CloudFormation.
7.
In Action mode: choose execute a changeset. This is similar to the step you would take if you were
manually going to deploy the package, as discussed in the Deployment (p. 139) step of the previous
tutorial. CreateChangeSet transforms the SAM template to the full AWS CloudFormation format and
deployChangeSet deploys the AWS CloudFormation template.
In Stack name: enter MyBetaStack.
8.
9. In Change set name: enter MyChangeSet.
10. Choose Add action.
11. Choose Save pipeline changes.
12. Choose Save and continue.
Your pipeline is ready. Any git push to the branch you connected to this pipeline is going to trigger a
deployment. To test your pipeline and deploy your application for the first time, do one of the following:
• Perform a git push to the branch connected to your pipeline.
• Go the AWS CodePipeline console, choose the name of the pipeline you created and then choose
Release change.
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How Does AWS Lambda Run
My Code? The Container Model
AWS Lambda: How It Works
How Does AWS Lambda Run My Code? The
Container Model
When AWS Lambda executes your Lambda function on your behalf, it takes care of provisioning and
managing resources needed to run your Lambda function. When you create a Lambda function, you specify
configuration information, such as the amount of memory and maximum execution time that you want to
allow for your Lambda function. When a Lambda function is invoked, AWS Lambda launches a container
(that is, an execution environment) based on the configuration settings you provided.
Note
The content of this section is for information only. AWS Lambda manages container creations and
deletion, there is no AWS Lambda API for you to manage containers.
It takes time to set up a container and do the necessary bootstrapping, which adds some latency each time
the Lambda function is invoked. You typically see this latency when a Lambda function is invoked for the
first time or after it has been updated because AWS Lambda tries to reuse the container for subsequent
invocations of the Lambda function.
After a Lambda function is executed, AWS Lambda maintains the container for some time in anticipation
of another Lambda function invocation. In effect, the service freezes the container after a Lambda function
completes, and thaws the container for reuse, if AWS Lambda chooses to reuse the container when the
Lambda function is invoked again. This container reuse approach has the following implications:
• Any declarations in your Lambda function code (outside the handler code, see Programming
Model (p. 8)) remains initialized, providing additional optimization when the function is invoked again.
For example, if your Lambda function establishes a database connection, instead of reestablishing the
connection, the original connection is used in subsequent invocations. You can add logic in your code to
check if a connection already exists before creating one.
• Each container provides some disk space in the /tmp directory. The directory content remains when the
container is frozen, providing transient cache that can be used for multiple invocations. You can add
extra code to check if the cache has the data that you stored. For disk space size, see AWS Lambda
Limits (p. 275).
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Concurrent Executions
• Background processes or callbacks initiated by your Lambda function that did not complete when the
function ended resume if AWS Lambda chooses to reuse the container. You should make sure any
background processes or callbacks (in case of Node.js) in your code are complete before the code exits.
Note
When you write your Lambda function code, do not assume that AWS Lambda always reuses the
container because AWS Lambda may choose not to reuse the container. Depending on various
other factors, AWS Lambda may simply create a new container instead of reusing an existing
container.
Lambda Function Concurrent Executions
Concurrent executions refers to the number of executions of your function code that are happening at
any given time. You can estimate the concurrent execution count, but the concurrent execution count will
differ depending on whether or not your Lambda function is processing events from a stream-based event
source.
• Stream-based event sources – If you create a Lambda function that processes events from streambased services (Amazon Kinesis Streams or DynamoDB streams), the number of shards per stream is
the unit of concurrency. If your stream has 100 active shards, there will be 100 Lambda functions running
concurrently. Then, each Lambda function processes events on a shard in the order that they arrive.
• Event sources that aren't stream-based – If you create a Lambda function to process events from
event sources that aren't stream-based (for example, Amazon S3 or API Gateway), each published event
is a unit of work. Therefore, the number of events (or requests) these event sources publish influences
the concurrency.
You can use the following formula to estimate your concurrent Lambda function invocations:
events (or requests) per second * function duration
For example, consider a Lambda function that processes Amazon S3 events. Suppose that the Lambda
function takes on average three seconds and Amazon S3 publishes 10 events per second. Then, you will
have 30 concurrent executions of your Lambda function.
Request Rate
Request rate refers to the rate at which your Lambda function is invoked. For all services except the
stream-based services, the request rate is the rate at which the event sources generate the events. For
stream-based services, AWS Lambda calculates the request rate as follow:
request rate = number of concurrent executions / function duration
For example, if there are five active shards on a stream (that is, you have five Lambda functions running in
parallel) and your Lambda function takes about two seconds, the request rate is 2.5 requests/second.
Concurrent Execution Limit
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Concurrent Executions Limit
By default, AWS Lambda limits the total concurrent executions across all functions within a given region to
400. To increase this limit above the default, follow the steps in To request a limit increase for concurrent
executions (p. 148).
Any invocation that causes your function's concurrent execution to exceed the safety limit is throttled, and
does not execute your function. Each throttled invocation increases the CloudWatch Throttles metric for
the function.
The throttled invocation is handled differently based on how the function is invoked:
• Event sources that aren't stream-based – Some of these event sources invoke a Lambda function
synchronously and others invoke it asynchronously.
• Synchronous invocation – If the function is invoked synchronously and is throttled, the invoking
application receives a 429 error and the invoking application is responsible for retries. These event
sources may have additional retries built into the integration. For example, CloudWatch Logs retries
the failed batch up to five times with delays between retries. For a list of supported event sources and
the invocation types that they use, see Supported Event Sources (p. 120).
If you invoke Lambda through API Gateway, you need to make sure you map Lambda response errors
to API Gateway error codes. If you invoke the function directly, such as through the AWS SDKs using
the RequestResponse invocation mode or through API Gateway, your client receives the 429 error and
you can choose to retry the invocation.
• Asynchronous invocation – If your Lambda function is invoked asynchronously and is throttled,
AWS Lambda automatically retries the throttled event for up to six hours, with delays between retries.
Asynchronous events are queued before they are used to invoke the Lambda function.
• Stream-based event sources – For stream-based event sources (Amazon Kinesis Streams and
DynamoDB streams), AWS Lambda polls your stream and invokes your Lambda function. Therefore,
when your Lambda function is throttled, AWS Lambda attempts to process the throttled batch of records
until the time the data expires, which can be up to seven days for Amazon Kinesis Streams. The throttled
request is treated as blocking per shard and Lambda will not read any new records from the shard until
the throttled batch of records either expires or succeeds. If there is more than one shard in the stream,
Lambda will continue invokes on the non-throttled shards until one gets through.
To request a limit increase for concurrent executions
1.
Open the AWS Support Center page, sign in, if necessary, and then click Create case.
2.
Under Regarding, select Service Limit Increase.
3.
Under Limit Type, select Lambda, fill in the necessary fields in the form, and then click the button at
the bottom of the page for your preferred method of contact.
Note
AWS may automatically raise the concurrent execution limit on your behalf to enable your function
to match the incoming event rate, as in the case of triggering the function from an Amazon S3
bucket.
Suggested Reading
If you are new to AWS Lambda, we suggest you read through all of the topics in the How It Works section
to familiarize yourself with Lambda. The next topic is Retries on Errors (p. 149).
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Retries on Errors
After you read all of the topics in the How it Works section, we recommend that you review Building
Lambda Functions (p. 5), try the Getting Started (p. 155) exercise, and then explore the Use
Cases (p. 169). Each use case provides step-by-step instructions for you to set up the end-to-end
experience.
Retries on Errors
A Lambda function can fail for any of the following reasons:
• The function times out while trying to reach an endpoint.
• The function fails to successfully parse input data.
• The function experiences resource constraints, such as out-of-memory errors or other timeouts.
If any of these failures occur, your function will throw an exception. How the exception is handled depends
upon how the Lambda function was invoked:
• Event sources that aren't stream-based – Some of these event sources are set up to invoke a Lambda
function synchronously and others invoke it asynchronously. Accordingly, exceptions are handled as
follows:
• Synchronous invocation – The invoking application receives a 429 error, and is responsible for
retries. For a list of supported event sources and the invocation types they use, see Supported Event
Sources. These event sources may have additional retries built into the integration.
If you invoked the Lambda function directly through AWS SDKs, or through API Gateway, your client
receives the error and can choose to retry. If you are invoking Lambda through API Gateway, you need
to make sure you map Lambda response errors to API Gateway error codes.
• Asynchronous invocation – Asynchronous events are queued before being used to invoke the
Lambda function. If AWS Lambda is unable to fully process the event, it will automatically retry the
invocation twice, with delays between retries. If you have specified a Dead Letter Queue for your
function, then the failed event is sent to the specified Amazon SQS queue or Amazon SNS topic. If
you don't specify a Dead Letter Queue (DLQ), which is not required and is the default setting, then the
event will be discarded. For more information, see Dead Letter Queues (p. 109).
• Stream-based event sources – For stream-based event sources (Amazon Kinesis Streams and
DynamoDB streams), AWS Lambda polls your stream and invokes your Lambda function. Therefore,
if a Lambda function fails, AWS Lambda attempts to process the erring batch of records until the time
the data expires, which can be up to seven days for Amazon Kinesis Streams. The exception is treated
as blocking, and AWS Lambda will not read any new records from the stream until the failed batch of
records either expires or processed successfully. This ensures that AWS Lambda processes the stream
events in order.
For more information about invocation modes, see Event Source Mapping (p. 116).
Suggested Reading
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Permissions Model
If you are new to AWS Lambda, we suggest you read through all of the topics in the How It Works section
to familiarize yourself with Lambda. The next topic is AWS Lambda Permissions Model (p. 150).
After you read all of the topics in the How it Works section, we recommend that you review Building
Lambda Functions (p. 5), try the Getting Started (p. 155) exercise, and then explore the Use
Cases (p. 169). Each use case provides step-by-step instructions for you to set up the end-to-end
experience.
AWS Lambda Permissions Model
For the end-to-end AWS Lambda-based applications to work, you have to manage various permissions.
For example:
• For event sources, except for the stream-based services (Amazon Kinesis Streams and DynamoDB
streams), you must grant the event source permissions to invoke your AWS Lambda function.
• For stream-based event sources (Amazon Kinesis Streams and DynamoDB streams), AWS Lambda
polls the streams on your behalf and reads new records on the stream, so you need to grant AWS
Lambda permissions for the relevant stream actions.
• When your Lambda function executes, it can access AWS resources in your account (for example,
read an object from your S3 bucket). AWS Lambda executes your Lambda function on your behalf by
assuming the role you provided at the time of creating the Lambda function. Therefore, you need to grant
the role the necessary permissions that your Lambda function needs, such as permissions for Amazon
S3 actions to read an object.
The following sections describe permissions management.
Topics
• Manage Permissions: Using an IAM Role (Execution Role) (p. 150)
• Manage Permissions: Using a Lambda Function Policy (p. 151)
Manage Permissions: Using an IAM Role (Execution
Role)
Each Lambda function has an IAM role (execution role) associated with it. You specify the IAM role when
you create your Lambda function. Permissions you grant to this role determine what AWS Lambda can do
when it assumes the role. There are two types of permissions that you grant to the IAM role:
• If your Lambda function code accesses other AWS resources, such as to read an object from an S3
bucket or write logs to CloudWatch Logs, you need to grant permissions for relevant Amazon S3 and
CloudWatch actions to the role.
• If the event source is stream-based (Amazon Kinesis Streams and DynamoDB streams), AWS Lambda
polls these streams on your behalf. AWS Lambda needs permissions to poll the stream and read new
records on the stream so you need to grant the relevant permissions to this role.
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Manage Permissions: Using a Lambda Function Policy
For more information about IAM roles, see Roles (Delegation and Federation) in the IAM User Guide.
Important
The user that creates the IAM role is, in effect, passing permissions to AWS Lambda to assume
this role, which requires the user to have permissions for the iam:PassRole action. If an
administrator user is creating this role, you don't need to do anything extra to set up permissions
for the iam:PassRole action because the administrator user has full permissions, including the
iam:PassRole action.
To simplify the process for creating an execution role, AWS Lambda provides the following AWS managed
(predefined) permissions policies that you can use. These policies include common permissions for specific
scenarios:
• AWSLambdaBasicExecutionRole – Grants permissions only for the Amazon CloudWatch Logs actions
to write logs. You can use this policy if your Lambda function does not access any other AWS resources
except writing logs.
• AWSLambdaKinesisExecutionRole – Grants permissions for Amazon Kinesis Streams actions, and
CloudWatch Logs actions. If you are writing a Lambda function to process Amazon Kinesis stream
events you can attach this permissions policy.
• AWSLambdaDynamoDBExecutionRole – Grants permissions for DynamoDB streams actions and
CloudWatch Logs actions. If you are writing a Lambda function to process DynamoDB stream events you
can attach this permissions policy.
• AWSLambdaVPCAccessExecutionRole – Grants permissions for Amazon Elastic Compute Cloud
(Amazon EC2) actions to manage elastic network interfaces (ENIs). If you are writing a Lambda function
to access resources in a VPC in the Amazon Virtual Private Cloud (Amazon VPC) service, you can
attach this permissions policy. The policy also grants permissions for CloudWatch Logs actions to write
logs.
You can find these AWS managed permissions policies in the IAM console. Search for these policies and
you can see the permissions each of these policies grant.
Manage Permissions: Using a Lambda Function Policy
All supported event sources, except the stream-based services (Amazon Kinesis and DynamoDB streams),
invoke your Lambda function (the push model), provided that you grant the necessary permissions. For
example, if you want Amazon S3 to invoke your Lambda function when objects are created in a bucket,
Amazon S3 needs permissions to invoke your Lambda function.
You can grant these permissions via the function policies. AWS Lambda provides APIs for you to manage
permission in a function policy. For example, see AddPermission (p. 311).
You can also grant cross-account permissions using the function policy. For example, if a user-defined
application and the Lambda function it invokes belong to the same AWS account, you don't need to grant
explicit permissions. Otherwise, the AWS account that owns the Lambda function must allow cross-account
permissions in the permissions policy associated with the Lambda function.
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Execution Environment
Note
Instead of using a Lambda function policy, you can create another IAM role that grants the event
sources (for example, Amazon S3 or DynamoDB) permissions to invoke your Lambda function.
However, you might find that resource policies are easier to set up and they make it easier for you
to track which event sources have permissions to invoke your Lambda function.
For more information about Lambda function policies, see Using Resource-Based Policies for AWS
Lambda (Lambda Function Policies) (p. 295). For more information about Lambda permissions, see
Authentication and Access Control for AWS Lambda (p. 277).
Suggested Reading
If you are new to AWS Lambda, we suggest you read through all of the topics in the How It Works section
to familiarize yourself with Lambda. The next topic is Lambda Execution Environment and Available
Libraries (p. 152).
After you read all of the topics in the How it Works section, we recommend that you review Building
Lambda Functions (p. 5), try the Getting Started (p. 155) exercise, and then explore the Use
Cases (p. 169). Each use case provides step-by-step instructions for you to set up the end-to-end
experience.
Lambda Execution Environment and Available
Libraries
The underlying AWS Lambda execution environment is based on the following:
• Public Amazon Linux AMI version (AMI name: amzn-ami-hvm-2016.03.3.x86_64-gp2):
For information about using an AMI, see Amazon Machine Images (AMI) in the Amazon EC2 User Guide
for Linux Instances.
• Linux kernel version – 4.4.35-33.55.amzn1.x86_64
If you are using any native binaries in your code, make sure they are compiled in this environment. Note
that only 64-bit binaries are supported on AWS Lambda.
AWS Lambda supports the following runtime versions:
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Environment Variables Available to Lambda Functions
• Node.js – v4.3.2 and 6.10
• Java – Java 8
• Python – Python 2.7
• .NET Core – .NET Core 1.0.1 (C#)
The following libraries are available in the AWS Lambda execution environment, regardless of the
supported runtime you use, so you don't need to include them:
• AWS SDK – AWS SDK for JavaScript version 2.22.0
• AWS SDK for Python (Boto 3) version 1.4.4, Botocore version 1.5.13
• Amazon Linux build of java-1.8.0-openjdk for Java.
Environment Variables Available to Lambda Functions
The following is a list of environment variables that are part of the AWS Lambda execution environment and
made available to Lambda functions. The table below indicates which ones are reserved by AWS Lambda
and cannot be changed as well as which ones you can set when creating your Lambda function. For more
information on using environment variables with your Lambda function, see Environment Variables (p. 85).
Lambda Environment Variables
Key
Reserved
Value
LAMBDA_TASK_ROOT
Yes
Contains the path to your Lambda
function code.
AWS_EXECUTION_ENV
Yes
The environment variable is set
to one of the following options,
depending on the runtime of the
Lambda function:
• AWS_Lambda_java8
• AWS_Lambda_nodejs
• AWS_Lambda_nodejs4.3
• AWS_Lambda_nodejs6.10
• AWS_Lambda_python2.7
• AWS_Lambda_dotnetcore1.0
LAMBDA_RUNTIME_DIR
Yes
Restricted to Lambda runtime-related
artifacts. For example the aws-sdk for
Node.js and boto3 for Python can be
found under this path.
AWS_REGION
Yes
The AWS region where the Lambda
function is executed.
AWS_DEFAULT_REGION
Yes
The AWS region where the Lambda
function is executed.
AWS_LAMBDA_LOG_GROUP_NAME Yes
The name of Amazon CloudWatch
Logs group where log streams
containing your Lambda function logs
are created.
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Environment Variables Available to Lambda Functions
Key
Reserved
Value
AWS_LAMBDA_LOG_STREAM_NAMEYes
The Amazon CloudWatch Logs
streams containing your Lambda
function logs.
AWS_LAMBDA_FUNCTION_NAME
The name of the Lambda function.
Yes
AWS_LAMBDA_FUNCTION_MEMORY_SIZE
Yes
The size of the Lambda function in
MB.
AWS_LAMBDA_FUNCTION_VERSION Yes
The version of the Lambda function.
AWS_ACCESS_KEY
Yes
The security credentials required
to execute the Lambda function,
depending on which runtime is used.
Different runtimes use a subset of
these keys. They are generated via
an IAM execution role specified for
the function.
PATH
No
Contains /usr/local/bin, /usr/bin or /bin
for running executables.
LANG
No
Set to en_US.UTF-8. This is the
Locale of the runtime.
LD_LIBRARY_PATH
No
Contains /lib64, /usr/lib64,
LAMBDA_TASK_ROOT,
LAMBDA_TASK_ROOT/lib. Used
to store helper libraries and function
code.
NODE_PATH
No
Set for the Node.js runtime. It
contains LAMBDA_RUNTIME_DIR,
LAMBDA_RUNTIME_DIR/
node_modules,
LAMBDA_TASK_ROOT.
PYTHON_PATH
No
Set for the Python runtime. It contains
LAMBDA_RUNTIME_DIR.
AWS_ACCESS_KEY_ID
AWS_SECRET_KEY
AWS_SECRET_ACCESS_KEY
AWS_SESSION_TOKEN
AWS_SECURITY_TOKEN
Suggested Reading
If you are new to AWS Lambda, we suggest you read through all of the topics in the How It Works section
to familiarize yourself with Lambda, starting with How It Works (p. 146).
After you read all of the topics in the How it Works section, we recommend that you review Building
Lambda Functions (p. 5), try the Getting Started (p. 155) exercise, and then explore the Use
Cases (p. 169). Each use case provides step-by-step instructions for you to set up the end-to-end
experience.
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Step 1: Set Up an AWS Account and the AWS CLI
Getting Started
In this Getting Started section, you do the following:
• Set up an AWS account and AWS Command Line Interface (AWS CLI). Most tutorials use the AWS CLI
commands.
• Create and test a simple Hello World Lambda function.
To get started, complete the steps in the following topics:
Topics
• Step 1: Set Up an AWS Account and the AWS CLI (p. 155)
• Step 2: Create a HelloWorld Lambda Function and Explore the Console (p. 158)
• Step 3: Create a Simple Microservice using Lambda and API Gateway (p. 166)
Step 1: Set Up an AWS Account and the AWS CLI
If you have not already done so, you need to sign up for an AWS account and create an administrator user
in the account. You also need to set up the AWS Command Line Interface (AWS CLI). Many of the tutorials
use the AWS CLI.
To complete the setup, follow the instructions in the following topics:
Topics
• Step 1.1: Set Up an AWS Account and Create an Administrator User (p. 155)
• Step 1.2: Set Up the AWS Command Line Interface (AWS CLI) (p. 158)
Step 1.1: Set Up an AWS Account and Create an
Administrator User
Before you use AWS Lambda for the first time, complete the following tasks:
1. Sign up for AWS (p. 156)
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Step 1.1: Set Up an Account
2. Create an IAM User (p. 156)
Sign up for AWS
When you sign up for Amazon Web Services (AWS), your AWS account is automatically signed up for all
services in AWS, including AWS Lambda. You are charged only for the services that you use.
With AWS Lambda, you pay only for the resources you use. For more information about AWS Lambda
usage rates, see the AWS Lambda product page. If you are a new AWS customer, you can get started with
AWS Lambda for free. For more information, see AWS Free Usage Tier.
If you already have an AWS account, skip to the next task. If you don't have an AWS account, use the
following procedure to create one.
To create an AWS account
1.
Open https://aws.amazon.com/, and then choose Create an AWS Account.
2.
Follow the online instructions.
Part of the sign-up procedure involves receiving a phone call and entering a PIN using the phone
keypad.
Note your AWS account ID, because you'll need it for the next task.
Create an IAM User
Services in AWS, such as AWS Lambda, require that you provide credentials when you access them,
so that the service can determine whether you have permissions to access the resources owned by that
service. The console requires your password. You can create access keys for your AWS account to access
the AWS CLI or API. However, we don't recommend that you access AWS using the credentials for your
AWS account. Instead, we recommend that you use AWS Identity and Access Management (IAM). Create
an IAM user, add the user to an IAM group with administrative permissions, and then grant administrative
permissions to the IAM user that you created. You can then access AWS using a special URL and that IAM
user's credentials.
If you signed up for AWS, but you haven't created an IAM user for yourself, you can create one using the
IAM console.
The Getting Started exercises and tutorials in this guide assume you have a user (adminuser) with
administrator privileges. When you follow the procedure, create a user with name adminuser.
To create an IAM user for yourself and add the user to an Administrators group
1.
Sign in to the IAM console at https://console.aws.amazon.com/iam/.
2.
3.
In the navigation pane, choose Users, and then choose Add user.
For User name, type a user name, such as Administrator. The name can consist of letters, digits,
and the following characters: plus (+), equal (=), comma (,), period (.), at (@), underscore (_), and
hyphen (-). The name is not case sensitive and can be a maximum of 64 characters in length.
Select the check box next to AWS Management Console access, select Custom password, and
then type the new user's password in the text box. You can optionally select Require password reset
to force the user to select a new password the next time the user signs in.
Choose Next: Permissions.
On the Set permissions for user page, choose Add user to group.
Choose Create group.
4.
5.
6.
7.
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8.
In the Create group dialog box, type the name for the new group. The name can consist of letters,
digits, and the following characters: plus (+), equal (=), comma (,), period (.), at (@), underscore (_),
and hyphen (-). The name is not case sensitive and can be a maximum of 128 characters in length.
9. For Filter, choose Job function.
10. In the policy list, select the check box for AdministratorAccess. Then choose Create group.
11. Back in the list of groups, select the check box for your new group. Choose Refresh if necessary to
see the group in the list.
12. Choose Next: Review to see the list of group memberships to be added to the new user. When you
are ready to proceed, choose Create user.
You can use this same process to create more groups and users, and to give your users access to your
AWS account resources. To learn about using policies to restrict users' permissions to specific AWS
resources, go to Access Management and Example Policies for Administering AWS Resources.
To sign in as the new IAM user
1.
Sign out of the AWS Management Console.
2.
Use the following URL format to log in to the console:
https://aws_account_number.signin.aws.amazon.com/console/
3.
The aws_account_number is your AWS account ID without hyphen. For example, if your AWS account
ID is 1234-5678-9012, your AWS account number is 123456789012. For information about how to find
your account number, see Your AWS Account ID and Its Alias in the IAM User Guide.
Enter the IAM user name and password that you just created. When you're signed in, the navigation
bar displays your_user_name @ your_aws_account_id.
If you don't want the URL for your sign-in page to contain your AWS account ID, you can create an account
alias.
To create or remove an account alias
1.
2.
Sign in to the IAM console at https://console.aws.amazon.com/iam/.
On the navigation pane, choose Dashboard.
3.
4.
Find the IAM users sign-in link.
To create the alias, click Customize, enter the name you want to use for your alias, and then choose
Yes, Create.
To remove the alias, choose Customize, and then choose Yes, Delete. The sign-in URL reverts to
using your AWS account ID.
5.
To sign in after you create an account alias, use the following URL:
https://your_account_alias.signin.aws.amazon.com/console/
To verify the sign-in link for IAM users for your account, open the IAM console and check under IAM users
sign-in link: on the dashboard.
For more information about IAM, see the following:
• Identity and Access Management (IAM)
• Getting Started
• IAM User Guide
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Next Step
Step 1.2: Set Up the AWS Command Line Interface (AWS CLI) (p. 158)
Step 1.2: Set Up the AWS Command Line Interface
(AWS CLI)
All the exercises in this guide assume that you are using administrator user credentials (adminuser) in your
account to perform the operations. For instructions on creating an administrator user in your AWS account,
see Step 1.1: Set Up an AWS Account and Create an Administrator User (p. 155), and then follow the
steps to download and configure the AWS Command Line Interface (AWS CLI).
To set up the AWS CLI
1.
Download and configure the AWS CLI. For instructions, see the following topics in the AWS Command
Line Interface User Guide.
• Getting Set Up with the AWS Command Line Interface
• Configuring the AWS Command Line Interface
2.
Add a named profile for the administrator user in the AWS CLI config file. You use this profile when
executing the AWS CLI commands.
[profile adminuser]
aws_access_key_id = adminuser access key ID
aws_secret_access_key = adminuser secret access key
region = aws-region
For a list of available AWS regions, see Regions and Endpoints in the Amazon Web Services General
Reference.
3.
Verify the setup by entering the following commands at the command prompt.
• Try the help command to verify that the AWS CLI is installed on your computer:
aws help
• Try a Lambda command to verify the user can reach AWS Lambda. This command lists Lambda
functions in the account, if any. The AWS CLI uses the adminuser credentials to authenticate the
request.
aws lambda list-functions --profile adminuser
Now that you have set up an account and AWS CLI, you can create your first Lambda function. For
instructions, see Step 2: Create a HelloWorld Lambda Function and Explore the Console (p. 158).
Step 2: Create a HelloWorld Lambda Function and
Explore the Console
In this Getting Started exercise you first create a Hello World Lambda function using the AWS Lambda
console. Next, you manually invoke the Lambda function using a sample event data. AWS Lambda
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executes the Lambda function and returns results. You then verify execution results, including the logs that
your Lambda function created and various CloudWatch metrics.
As you follow the steps, you will also familiarize yourself with the AWS Lambda console including:
• Explore the blueprints. Each blueprint provides sample code and sample configurations that enable you
to create Lambda functions with just a few clicks. The Getting Started exercise uses the hello-worldpython blueprint.
• View and update configuration information of your Lambda function.
• Invoke a Lambda function manually and explore results in the Execution results section.
• Monitor CloudWatch metrics in the console.
Although not required, we recommend you review How It Works (p. 146) first.
Preparing for the Getting Started
First, you need to sign up for an AWS account and create an administrator user in your account. For
instructions, see Step 1: Set Up an AWS Account and the AWS CLI (p. 155).
Next Step
Step 2.1: Create a Hello World Lambda Function (p. 159)
Step 2.1: Create a Hello World Lambda Function
Follow the steps in this section to create a Hello World Lambda function. In this step, you will do the
following:
• Select a blueprint – For this exercise, you use the hello-world-python blueprint. It provides sample
code authored in Python. The language used for the Lambda function does not matter for this exercise.
Later you can create your own Lambda functions in any of the supported languages.
Blueprints provide example code to do some minimal processing. Most blueprints process events from
specific event sources, such as Amazon S3, DynamoDB, or custom application. For example, if you
select an s3-get-object blueprint, it provides sample code that processes an object-created event
published by Amazon S3 that Lambda receives as parameter.
• Configure function – Because you select a blueprint for this exercise, the console will have some of the
configuration information prepopulated. For example, it preconfigures Python 2.7 as the runtime, provides
example code, identifies the handler in the code sample, and other configuration information such as
memory and timeout. For more information about configuring functions, see Lambda Functions (p. 3). For
more information about the function configuration parameters, see CreateFunction (p. 322).
You will also create an IAM role (referred as the execution role) with the necessary permissions that
AWS Lambda can assume to invoke your Lambda function on your behalf.
To create a Hello World Lambda function
1.
Sign in to the AWS Management Console and open the AWS Lambda console.
2.
Choose Get Started Now.
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Note
The console shows the Get Started Now page only if you do not have any Lambda functions
created. If you have created functions already, you will see the Lambda > Functions page.
On the list page, choose Create a Lambda function to go to the Lambda > New function
page.
3.
On the Select blueprint page, first explore the available blueprints. Then, select a specific blueprint for
this Getting Started exercise.
a.
Review the blueprints. You can also use the Filter to search for specific blueprints. For example:
• Enter S3 in Filter to get only the list of blueprints available to process Amazon S3 events.
• Enter dynamodb in Filter to get a list of available blueprints to process Amazon DynamoDB
events.
b.
4.
For this Getting Started exercise, enter hello-world-python in Filter, and then choose the helloworld-python blueprint.
On the Configure triggers page, you can optionally choose a service that automatically triggers your
Lambda function by choosing the gray box with ellipses (...) to display a list of available services.
a.
Depending on which service you select, you are prompted to provide relevant information for that
service. For example, if you select DynamoDB, you need to provide the following:
• The name of the DynamoDB table
• Batch size
• Starting position
b.
5.
For this Getting Started exercise, do not configure a trigger and choose Next.
On the Configure function page, do the following:
a.
Review the preconfigured Lambda function configuration information, including:
• Runtime is Python 2.7.
• Code authored in Python is provided. It reads incoming event data and logs some of the
information to CloudWatch.
• Handler shows lambda_function.lambda_handler value. It is the filename.handlerfunction. The console saves the sample code in the lambda_function.py file and in the code
lambda_handler is the function name that receives the event as a parameter when the Lambda
function is invoked. For more information, see Lambda Function Handler (Python) (p. 41).
b.
Enter the function name hello-world-python in Name.
c.
In the Lambda Function Code section, do the following:
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•
Review the sample code. Note that:
• The console saves this code as lambda_handler.py. The console then zips the file, and
uploads it to AWS Lambda creating your Lambda function.
• The sample code processes incoming events of the following form:
{
"key3": "value3",
"key2": "value2",
"key1": "value1"
}
After creating the Lambda function, you invoke it using sample events of this form in the
next section.
d.
In the Lambda function handler and role section, do the following:
i.
Note the Handler* value. It is of the form python-file-name.handler-function.
ii.
In Role*, choose Create new role from template(s).
iii.
In Role name, type a name for the role.
iv. In Role templates, Lambda provides a list of optional templates that, should you select one,
automatically creates the role with the requisite permissions attached to that policy. For a list
of the Policy templates, see Policy Templates (p. 301). For the purpose of this tutorial,
you can leave this field blank because your Lambda function already has the basic execution
permission it needs.
Note
Optionally, you could select Choose an existing role if you already have a role
created with specific permissions beyond basic execution. You can also select Create a
custom role. When you choose this option, a window appears where you can edit the
permissions policy inline.
e.
In the Advanced settings section, leave the default Lambda function configuration values.
The memory and timeout values are sufficient for the Lambda function you are creating. These
configurations influence the performance of your code. For more information, see Lambda
Functions (p. 3).
f.
Choose Next.
g.
Choose Create Function to create a Lambda function.
The console saves the code into a file and then zips the file, which is the deployment package.
The console then uploads the deployment package to AWS Lambda creating your Lambda
function. The console shows the hello-world-python Lambda function, you can now perform
various action including test the function:
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Note the tabs in the console:
• Code – Shows the Lambda function code.
• Configuration – shows current function configuration and you can change the configuration
as needed. After you change any configuration settings, you choose Save to save the updated
configuration.
• Triggers – Shows any triggers you configured for this function (does not apply to this Getting
Started exercise).
• Monitoring – Provides various CloudWatch metrics for your Lambda function. In the next
section, you invoke your hello-world-python Lambda function and review these metrics.
Next Step
Step 2.2: Invoke the Lambda Function Manually and Verify Results, Logs, and Metrics (p. 162)
Step 2.2: Invoke the Lambda Function Manually and
Verify Results, Logs, and Metrics
Follow the steps to invoke your Lambda function using the sample event data provided in the console.
1.
On the Lambda > Functions > HelloWorld page, choose Test.
2.
In the Input test event page, choose Hello World from the Sample event template list. The following
sample event template appears in the window.
{
"key3": "value3",
"key2": "value2",
"key1": "value1"
}
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You can change key and values in the sample JSON, but don't change the event structure. If you do
change any keys and values, you must update the sample code accordingly. Choose Save and test.
3.
AWS Lambda executes your function on your behalf. The handler in your Lambda function receives
and then processes the sample event.
4.
Upon successful execution, view results in the console.
Note the following:
• The Execution result section shows the execution status as succeeded and also shows the
function execution results, returned by the return statement.
Note
The console always uses the RequestResponse invocation type (synchronous invocation)
when invoking a Lambda function which causes AWS Lambda to return a response
immediately. For more information, see Invocation Types (p. 4).
• The Summary section shows the key information reported in the Log output section (the REPORT
line in the execution log).
• The Log output section shows the log AWS Lambda generates for each execution. These are the
logs written to CloudWatch by the Lambda function. The AWS Lambda console shows these logs for
your convenience.
Note that the Click here link shows logs in the CloudWatch console. The function then adds logs to
Amazon CloudWatch in the log group that corresponds to the Lambda function.
5.
Run the Lambda function a few times to gather some metrics that you can view in the next step.
6.
Choose the Monitoring tab to view the CloudWatch metrics for your Lambda function. This page
shows four CloudWatch metrics.
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Lambda Function Authored in Java
Note the following:
• The X-axis shows the past 24 hours from the current time (for example, 2:00 pm as shown in the
screen shot).
• Invocation count shows the number of invocations during this interval.
• Invocation duration shows how long it took for your Lambda function to run. It shows minimum,
maximum, and average time of execution.
• Invocation errors show the number of times your Lambda function failed. You can compare the
number of times your function executed and how many times it failed (if any).
• Throttled invocation metrics show whether AWS Lambda throttled your Lambda function invocation.
For more information, see List of AWS Lambda Limits (p. 275).
• The AWS Lambda console shows these CloudWatch metrics for your convenience. You can see
these metrics in the Amazon CloudWatch console by clicking any of these metrics.
Next Step
Step 2.3: (Optional) Create a Lambda Function Authored in Java (p. 164)
Step 2.3: (Optional) Create a Lambda Function
Authored in Java
The blueprints provide sample code authored either in Python or Node.js. You can easily modify the
example using the inline editor in the console. However, if you want to author code for your Lambda
function in Java, there are no blueprints provided. Also, there is no inline editor for you to write Java code in
the AWS Lambda console.
That means, you must write your Java code and also create your deployment package outside the console.
After you create the deployment package, you can use the console to upload the package to AWS Lambda
to create your Lambda function. You can also use the console to test the function by manually invoking it.
In this section you create a Lambda function using the following Java code example.
package example;
import com.amazonaws.services.lambda.runtime.Context;
import com.amazonaws.services.lambda.runtime.LambdaLogger;
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public class Hello {
public String myHandler(int myCount, Context context) {
LambdaLogger logger = context.getLogger();
logger.log("received : " + myCount);
return String.valueOf(myCount);
}
}
The programming model explains how to write your Java code in detail, for example the input/output types
AWS Lambda supports. For more information about the programming model, see Programming Model for
Authoring Lambda Functions in Java (p. 23). For now, note the following about this code:
• When you package and upload this code to create your Lambda function, you specify the
example.Hello::myHandler method reference as the handler.
• The handler in this example uses the int type for input and the String type for output.
AWS Lambda supports input/output of JSON-serializable types and InputStream/OutputStream types.
When you invoke this function you will pass a sample int (for example, 123).
• In this exercise you use the console to manually invoke this Lambda function. The console always uses
the RequestResponse invocation type (synchronous) and therefore you will see the response in the
console.
• The handler includes the optional Context parameter. In the code we use the LambdaLogger provided
by the Context object to write log entries to CloudWatch logs. For information about using the Context
object, see The Context Object (Java) (p. 33).
First, you need to package this code and any dependencies into a deployment package. Then, you can
use the Getting Started exercise to upload the package to create your Lambda function and test using the
console.
Next Step
Step 2.4: (Optional) Create a Lambda Function Authored in C# (p. 165)
Step 2.4: (Optional) Create a Lambda Function
Authored in C#
The AWS Lambda console blueprints provide sample code authored either in Python or Node.js. You can
easily modify the example using the inline editor in the console. However, if you want to author code for
your Lambda function in C#, there are no blueprints provided. Also, there is no inline editor for you to write
C# code in the AWS Lambda console.
While the Lambda console does not offer editing for compiled languages such as Java and C#, you can
use your choice of IDEs, such as Visual Studio, to create and package your C# code and libraries. Once
packaged as a ZIP file, you can use the AWS Lambda console to upload and test C# Lambda functions and
to view logs and metrics for them.
In this section you create a Lambda function using the following C# code example.
using Amazon.Lambda.Core;
namespace LambdaFunctionExample{
public class Hello {
public string MyHandler(int count, ILambdaContext context) {
var logger = context.Logger;
logger.log("received : " + count);
return count.ToString();
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}
}
}
Your Lambda function handler signature should be of the format
Assembly::Namespace.ClassName::MethodName. The programming model explains how to write your C#
code in detail, for example the input/output types AWS Lambda supports. For more information about the
programming model, see Programming Model for Authoring Lambda Functions in C# (p. 48). For now, note
the following about this code:
• The handler in this example uses the int type for input and the string type for output.
When you invoke this function you will pass a sample int (for example, 123).
• In this exercise you use the console to manually test this Lambda function. The console always uses the
RequestResponse invocation type (synchronous) and therefore you will see the response in the console.
• The handler includes the optional ILambdaContext parameter. In the code we use the LambdaLogger
provided by the Amazon.Lambda.Core.LambdaLogger object to write log entries to CloudWatch logs. For
information about using the ILambdaContext object, see The Context Object (C#) (p. 52).
First, you need to package this code and any dependencies into a deployment package. Then, you can
use the Getting Started exercise to upload the package to create your Lambda function and test using the
console. For more information, see Creating a Deployment Package (C#) (p. 59).
Next Step
Step 3: Create a Simple Microservice using Lambda and API Gateway (p. 166)
Step 3: Create a Simple Microservice using Lambda
and API Gateway
In this exercise you will use the Lambda console to create a Lambda function (MyLambdaMicroservice),
and an Amazon API Gateway endpoint to trigger that function. You will be able to call the endpoint with any
method (GET, POST, PATCH, etc.) to trigger your Lambda function. When the endpoint is called, the entire
request will be passed through to your Lambda function. Your function action will depend on the method
you call your endpoint with:
• DELETE: delete an item from a DynamoDB table
• GET: scan table and return all items
• POST: Create an item
• PUT: Update an item
Next Step
Step 3.1: Create an API Using Amazon API Gateway (p. 166)
Step 3.1: Create an API Using Amazon API Gateway
Follow the steps in this section to create a new Lambda function and an API Gateway endpoint to trigger it:
1. Sign in to the AWS Management Console and open the AWS Lambda console.
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2. Choose Create Lambda function.
3. On the Select blueprint page, choose the microservice-http-endpoint blueprint. You can use the
Filter to find it.
4. The Configure triggers page will be populated with an API Gateway trigger. The default API name that
will be created is LambdaMicroservice (You can change this name via the API Name field if you wish).
Note
When you complete the wizard and create your function, Lambda automatically creates a
proxy resource named MyLambdaMicroservice (your function name) under the API name you
selected. For more information about proxy resources, see Configure Proxy Integration for a
Proxy Resource. A proxy resource has an AWS_PROXY integration type and a catch-all method
ANY. The AWS_PROXY integration type applies a default mapping template to pass through the
entire request to the Lambda function and transforms the output from the Lambda function to
HTTP responses. The ANY method defines the same integration setup for all the supported
methods, including GET, POST, PATCH, DELETE and others.
After reviewing your trigger, choose Next.
5. On the Configure function page, do the following:
a. Review the preconfigured Lambda function configuration information, including:
• Runtime is Node.js 4.3
• Code authored in JavaScript is provided. The code performs DynamoDB operations based on the
method called and payload provided.
• Handler shows index.handler. The format is: filename.handler-function
b. Enter the function name MyLambdaMicroservice in Name.
c. In Role, enter a role name for the new role that will be created.
Note
The microservice-http-endpoint blueprint pre-populates the Simple Microservice
permission policy template in the Policy templates field, to be added to your new role upon
creation. This automatically adds the requisite permissions attached to that policy to your
new role. For more information, see Policy Templates (p. 301).
6. Choose Create function.
Next Step
Step 3.2: Test Sending an HTTPS Request (p. 167)
Step 3.2: Test Sending an HTTPS Request
In this step, you will use the console to test the Lambda function. In addition, you can run a curl command
to test the end-to-end experience. That is, send an HTTPS request to your API method and have Amazon
API Gateway invoke your Lambda function.
1. With your MyLambdaMicroService function still open in the console, choose the Actions tab and then
choose Configure test event.
2. Replace the existing text with the following:
{
"httpMethod": "GET",
"queryStringParameters": {
"TableName": "MyTable"
}
}
3. After entering the text above choose Save and test.
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Next Step
Step 3.3: (Optional) Try Other Blueprints (p. 168)
Step 3.3: (Optional) Try Other Blueprints
You can optionally try the following exercises:
• You used the hello-world-python blueprint in this Getting Started exercise. This blueprint provides
sample code authored in Python. There is also the hello-world blueprint that provides similar Lambda
function code that is authored in Node.js.
• Both the hello-world-python and the hello-world blueprints process custom events. For this Getting
Started exercise, you used hand-crafted sample event data. Your can write Lambda functions to process
events published by event sources such as Amazon S3 and DynamoDB. This requires event source
configuration in the console.
For example, you can write a Lambda function to process Amazon S3 events. Then, you configure
Amazon S3 as the event source to publish object-created events to AWS Lambda. When you upload an
object to your bucket, Amazon S3 detects the event and invokes your Lambda function. Your Lambda
function receives the event data as a parameter. You can verify your Lambda function executed by
reviewing the CloudWatch logs either in the Lambda console or the CloudWatch console.
The Lambda console provide blueprint to set up an example Lambda function to process Amazon S3
events. When creating a Lambda function in the console on the Select blueprint page, enter s3 in the
Filter box to search for a list of available blueprints.
For more information about working with different event sources, see Use Cases (p. 169).
Next Step
What's Next? (p. 168)
What's Next?
This Getting Started exercise provided you with an overview of how to use the AWS Lambda console.
AWS Lambda functions can also be automatically invoked in response to events in other AWS services
such as Amazon S3 and DynamoDB. Lambda functions can also be invoked on-demand over HTTPS.
You can also build your own custom event sources and invoke Lambda functions on demand. For more
information, see How It Works (p. 146).
Depending on your integration scenario, whether your application needs event-driven Lambda function
invocation or on-demand invocation, see the following sections:
•
•
•
•
Using AWS Lambda with Amazon S3 (p. 169)
Using AWS Lambda with Amazon Kinesis (p. 186)
Using AWS Lambda with Amazon DynamoDB (p. 196)
Using AWS Lambda with AWS CloudTrail (p. 207)
• Using AWS Lambda with Amazon API Gateway (On-Demand Over HTTPS) (p. 227)
• Using AWS Lambda as Mobile Application Backend (Custom Event Source: Android) (p. 240)
The console provides several blueprints for you to set up example Lambda functions quickly that can
process events from these event sources. You may want to explore other blueprints in the console to get
started with Lambda functions triggered by these event sources.
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Examples of How to Use AWS
Lambda
The use cases for AWS Lambda can be grouped into the following categories:
• Using AWS Lambda with AWS services as event sources – Event sources publish events that
cause the Lambda function to be invoked. These can be AWS services such as Amazon S3. For more
information and tutorials, see the following topics:
Using AWS Lambda with Amazon S3 (p. 169)
Using AWS Lambda with Amazon Kinesis (p. 186)
Using AWS Lambda with Amazon DynamoDB (p. 196)
Using AWS Lambda with AWS CloudTrail (p. 207)
Using AWS Lambda with Amazon SNS from Different Accounts (p. 222)
• On-demand Lambda function invocation over HTTPS (Amazon API Gateway) – In addition to
invoking Lambda functions using event sources, you can also invoke your Lambda function over HTTPS.
You can do this by defining a custom REST API and endpoint using API Gateway. For more information
and a tutorial, see Using AWS Lambda with Amazon API Gateway (On-Demand Over HTTPS) (p. 227).
• On-demand Lambda function invocation (build your own event sources using custom apps) –
User applications such as client, mobile, or web applications can publish events and invoke Lambda
functions using the AWS SDKs or AWS Mobile SDKs, such as the AWS Mobile SDK for Android.
For more information and a tutorial, see Getting Started (p. 155) and Using AWS Lambda as Mobile
Application Backend (Custom Event Source: Android) (p. 240)
• Scheduled events – You can also set up AWS Lambda to invoke your code on a regular, scheduled
basis using the AWS Lambda console. You can specify a fixed rate (number of hours, days, or weeks)
or you can specify a cron expression. For more information and a tutorial, see Using AWS Lambda with
Scheduled Events (p. 253).
Using AWS Lambda with Amazon S3
Amazon S3 can publish events (for example, when an object is created in a bucket) to AWS Lambda and
invoke your Lambda function by passing the event data as a parameter. This integration enables you
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to write Lambda functions that process Amazon S3 events. In Amazon S3, you add bucket notification
configuration that identifies the type of event that you want Amazon S3 to publish and the Lambda function
that you want to invoke.
Note the following about how the Amazon S3 and AWS Lambda integration works:
• Non-stream based (async) model – This is a model (see Event Source Mapping (p. 116)), where
Amazon S3 monitors a bucket and invokes the Lambda function by passing the event data as a
parameter. In a push model, you maintain event source mapping within Amazon S3 using the bucket
notification configuration. In the configuration, you specify the event types that you want Amazon S3 to
monitor and which AWS Lambda function you want Amazon S3 to invoke. For more information, see
Configuring Amazon S3 Event Notifications in the Amazon Simple Storage Service Developer Guide.
• Asynchronous invocation – AWS Lambda invokes a Lambda function using the Event invocation type
(asynchronous invocation). For more information about invocation types, see Invocation Types (p. 4).
• Event structure – The event your Lambda function receives is for a single object and it provides
information, such as the bucket name and object key name.
Note that there are two types of permissions policies that you work with when you set up the end-to-end
experience:
• Permissions for your Lambda function – Regardless of what invokes a Lambda function, AWS
Lambda executes the function by assuming the IAM role (execution role) that you specify at the time
you create the Lambda function. Using the permissions policy associated with this role, you grant your
Lambda function the permissions that it needs. For example, if your Lambda function needs to read an
object, you grant permissions for the relevant Amazon S3 actions in the permissions policy. For more
information, see Manage Permissions: Using an IAM Role (Execution Role) (p. 150).
• Permissions for Amazon S3 to invoke your Lambda function – Amazon S3 cannot invoke your
Lambda function without your permission. You grant this permission via the permissions policy
associated with the Lambda function.
The following diagram summarizes the flow:
1. User uploads an object to an S3 bucket (object-created event).
2. Amazon S3 detects the object-created event.
3. Amazon S3 invokes a Lambda function that is specified in the bucket notification configuration.
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4. AWS Lambda executes the Lambda function by assuming the execution role that you specified at the
time you created the Lambda function.
5. The Lambda function executes.
For a tutorial that walks you through an example setup, see Tutorial: Using AWS Lambda with Amazon
S3 (p. 171).
Tutorial: Using AWS Lambda with Amazon S3
Suppose you want to create a thumbnail for each image (.jpg and .png objects) that is uploaded to a
bucket. You can create a Lambda function (CreateThumbnail) that Amazon S3 can invoke when objects
are created. Then, the Lambda function can read the image object from the source bucket and create a
thumbnail image target bucket (in this tutorial, it's called the sourceresized bucket).
Important
You must use two buckets. If you use the same bucket as the source and the target, each
thumbnail uploaded to the source bucket triggers another object-created event, which then invokes
the Lambda function again, creating an unwanted recursion.
Implementation Summary
The following diagram illustrates the application flow:
1. A user uploads an object to the source bucket in Amazon S3 (object-created event).
2. Amazon S3 detects the object-created event.
3. Amazon S3 publishes the s3:ObjectCreated:* event to AWS Lambda by invoking the Lambda function
and passing event data as a function parameter.
4. AWS Lambda executes the Lambda function by assuming the execution role that you specified at the
time you created the Lambda function.
5. From the event data it receives, the Lambda function knows the source bucket name and object key
name. The Lambda function reads the object and creates a thumbnail using graphics libraries, and saves
it to the target bucket.
Note that upon completing this tutorial, you will have the following Amazon S3, Lambda, and IAM resources
in your account:
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In Lambda:
• A Lambda function.
• An access permissions policy associated with your Lambda function – You grant Amazon S3 permissions
to invoke the Lambda function using this permissions policy. You will also restrict the permissions so that
Amazon S3 can invoke the Lambda function only for object-created events from a specific bucket that is
owned by a specific AWS account.
Note
It is possible for an AWS account to delete a bucket and some other AWS account to later
create a bucket with the same name. The additional conditions ensure that Amazon S3 can
invoke the Lambda function only if Amazon S3 detects object-created events from a specific
bucket owned by a specific AWS account.
For more information, see How It Works (p. 146).
In IAM:
• Administrator user – Called adminuser. Using root credentials of an AWS account is not recommended.
Instead, use the adminuser credentials to perform the steps in this tutorial.
• An IAM role (execution role) – You grant permissions that your Lambda function needs through the
permissions policy associated with this role.
In Amazon S3:
• Two buckets named source and sourceresized. Note that source is a placeholder name and you need
to replace it with your actual bucket name. For example, if you have a bucket named example as your
source, you will create exampleresized as the target bucket.
• Notification configuration on the source bucket – You add notification configuration on your source bucket
identifying the type of events (object-created events) you want Amazon S3 to publish to AWS Lambda
and the Lambda function to invoke. For more information about the Amazon S3 notification feature, see
Setting Up Notification of Bucket Events in Amazon Simple Storage Service Developer Guide..
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Now you are ready to start the tutorial. Note that after the initial preparation, the tutorial is divided into two
main sections:
• First, you complete the necessary setup steps to create a Lambda function and invoke it manually using
Amazon S3 sample event data. This intermediate testing verifies that the function works.
• Second, you add notification configuration to your source bucket so that Amazon S3 can invoke your
Lambda function when it detects object-created events.
Next Step
Step 1: Prepare (p. 173)
Step 1: Prepare
In this section, you do the following:
• Sign up for an AWS account and set up the AWS CLI.
• Create two buckets (source and sourceresized bucket) with a sample .jpg object (HappyFace.jpg) in the
source bucket. For instructions, see the following procedure.
Step 1.1: Sign Up for AWS and Set Up the AWS CLI
Make sure you have completed the following steps:
• Signed up for an AWS account and created an administrator user in the account (called adminuser).
• Installed and set up the AWS CLI.
For instructions, see Step 1: Set Up an AWS Account and the AWS CLI (p. 155).
Step 1.2: Create Buckets and Upload a Sample Object
Follow the steps to create buckets and upload an object.
Important
Both the source bucket and your Lambda function must be in the same AWS region. In addition,
the example code used for the Lambda function also assumes that both of the buckets are in the
same region. In this tutorial, we use the us-west-2 region.
1. Using the IAM User Sign-In URL, sign in to the Amazon S3 console as adminuser.
2. Create two buckets. The target bucket name must be source followed by resized, where source is the
name of the bucket you want to use for the source. For example, mybucket and mybucketresized.
For instructions, see Create a Bucket in the Amazon Simple Storage Service Getting Started Guide.
3. In the source bucket, upload a .jpg object, HappyFace.jpg.
When you invoke the Lambda function manually before you connect to Amazon S3, you pass sample
event data to the function that specifies the source bucket and HappyFace.jpg as the newly created
object so you need to create this sample object first.
Next Step
Step 2: Create a Lambda Function and Invoke It Manually (Using Sample Event Data) (p. 174)
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Step 2: Create a Lambda Function and Invoke It Manually (Using
Sample Event Data)
In this section, you do the following:
• Create a Lambda function deployment package using the sample code provided.
Note
To see more examples of using other AWS services within your function, including calling other
Lambda functions, see AWS SDK for JavaScript
• Create an IAM role (execution role). At the time you upload the deployment package, you need to specify
an IAM role (execution role) that Lambda can assume to execute the function on your behalf.
• Create the Lambda function by uploading the deployment package, and then test it by invoking it
manually using sample Amazon S3 event data.
Topics
• Step 2.1: Create a Deployment Package (p. 174)
• Step 2.2: Create the Execution Role (IAM Role) (p. 181)
• Step 2.3: Create the Lambda Function and Test It Manually (p. 181)
Step 2.1: Create a Deployment Package
From the Filter View list, choose the language you want to use for your Lambda function. The appropriate
section appears with code and specific instructions for creating a deployment package.
Node.js
The deployment package is a .zip file containing your Lambda function code and dependencies.
1.
Create a folder (examplefolder), and then create a subfolder (node_modules).
2.
3.
Install the Node.js platform. For more information, see the Node.js website.
Install dependencies. The code examples use the following libraries:
• AWS SDK for JavaScript in Node.js
• gm, GraphicsMagick for node.js
• Async utility module
The AWS Lambda runtime already has the AWS SDK for JavaScript in Node.js, so you only need to
install the other libraries. Open a command prompt, navigate to the examplefolder, and install the
libraries using the npm command, which is part of Node.js.
npm install async gm
4.
Open a text editor, and then copy the following code.
// dependencies
var async = require('async');
var AWS = require('aws-sdk');
var gm = require('gm')
.subClass({ imageMagick: true }); // Enable ImageMagick integration.
var util = require('util');
// constants
var MAX_WIDTH
= 100;
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var MAX_HEIGHT = 100;
// get reference to S3 client
var s3 = new AWS.S3();
exports.handler = function(event, context, callback) {
// Read options from the event.
console.log("Reading options from event:\n", util.inspect(event, {depth: 5}));
var srcBucket = event.Records[0].s3.bucket.name;
// Object key may have spaces or unicode non-ASCII characters.
var srcKey
=
decodeURIComponent(event.Records[0].s3.object.key.replace(/\+/g, " "));
var dstBucket = srcBucket + "resized";
var dstKey
= "resized-" + srcKey;
// Sanity check: validate that source and destination are different buckets.
if (srcBucket == dstBucket) {
callback("Source and destination buckets are the same.");
return;
}
// Infer the image type.
var typeMatch = srcKey.match(/\.([^.]*)$/);
if (!typeMatch) {
callback("Could not determine the image type.");
return;
}
var imageType = typeMatch[1];
if (imageType != "jpg" && imageType != "png") {
callback('Unsupported image type: ${imageType}');
return;
}
// Download the image from S3, transform, and upload to a different S3 bucket.
async.waterfall([
function download(next) {
// Download the image from S3 into a buffer.
s3.getObject({
Bucket: srcBucket,
Key: srcKey
},
next);
},
function transform(response, next) {
gm(response.Body).size(function(err, size) {
// Infer the scaling factor to avoid stretching the image unnaturally.
var scalingFactor = Math.min(
MAX_WIDTH / size.width,
MAX_HEIGHT / size.height
);
var width = scalingFactor * size.width;
var height = scalingFactor * size.height;
// Transform the image buffer in memory.
this.resize(width, height)
.toBuffer(imageType, function(err, buffer) {
if (err) {
next(err);
} else {
next(null, response.ContentType, buffer);
}
});
});
},
function upload(contentType, data, next) {
// Stream the transformed image to a different S3 bucket.
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s3.putObject({
Bucket: dstBucket,
Key: dstKey,
Body: data,
ContentType: contentType
},
next);
}
], function (err) {
if (err) {
console.error(
'Unable to resize ' + srcBucket + '/'
' and upload to ' + dstBucket + '/' +
' due to an error: ' + err
);
} else {
console.log(
'Successfully resized ' + srcBucket +
' and uploaded to ' + dstBucket + '/'
);
}
+ srcKey +
dstKey +
'/' + srcKey +
+ dstKey
callback(null, "message");
}
);
};
Note
5.
The code sample is compliant with the Node.js runtimes v6.10 or v4.3. For more information,
see Programming Model (Node.js) (p. 9)
Review the preceding code and note the following:
• The function knows the source bucket name and the key name of the object from the event data it
receives as parameters. If the object is a .jpg, the code creates a thumbnail and saves it to the target
bucket.
6.
• The code assumes that the destination bucket exists and its name is a concatenation of the source
bucket name followed by the string resized. For example, if the source bucket identified in the event
data is examplebucket, the code assumes you have an examplebucketresized destination bucket.
• For the thumbnail it creates, the code derives its key name as the concatenation of the string
resized- followed by the source object key name. For example, if the source object key is
sample.jpg, the code creates a thumbnail object that has the key resized-sample.jpg.
Save the file as CreateThumbnail.js in examplefolder. After you complete this step, you will have the
following folder structure:
CreateThumbnail.js
/node_modules/gm
/node_modules/async
7.
Zip the CreateThumbnail.js file and the node_modules folder as CreateThumbnail.zip.
This is your Lambda function deployment package.
Next Step
Step 2.2: Create the Execution Role (IAM Role) (p. 181)
Java
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The following is example Java code that reads incoming Amazon S3 events and creates a thumbnail.
Note that it implements the RequestHandler interface provided in the aws-lambda-java-core library.
Therefore, at the time you create a Lambda function you specify the class as the handler (that is,
example.S3EventProcessorCreateThumbnail). For more information about using interfaces to provide a
handler, see Leveraging Predefined Interfaces for Creating Handler (Java) (p. 29).
The S3Event type that the handler uses as the input type is one of the predefined classes in the awslambda-java-events library that provides methods for you to easily read information from the incoming
Amazon S3 event. The handler returns a string as output.
package example;
import
import
import
import
import
import
import
import
import
import
import
java.awt.Color;
java.awt.Graphics2D;
java.awt.RenderingHints;
java.awt.image.BufferedImage;
java.io.ByteArrayInputStream;
java.io.ByteArrayOutputStream;
java.io.IOException;
java.io.InputStream;
java.net.URLDecoder;
java.util.regex.Matcher;
java.util.regex.Pattern;
import javax.imageio.ImageIO;
import
import
import
import
import
import
import
import
import
com.amazonaws.services.lambda.runtime.Context;
com.amazonaws.services.lambda.runtime.RequestHandler;
com.amazonaws.services.lambda.runtime.events.S3Event;
com.amazonaws.services.s3.AmazonS3;
com.amazonaws.services.s3.AmazonS3Client;
com.amazonaws.services.s3.event.S3EventNotification.S3EventNotificationRecord;
com.amazonaws.services.s3.model.GetObjectRequest;
com.amazonaws.services.s3.model.ObjectMetadata;
com.amazonaws.services.s3.model.S3Object;
public class S3EventProcessorCreateThumbnail implements
RequestHandler<S3Event, String> {
private static final float MAX_WIDTH = 100;
private static final float MAX_HEIGHT = 100;
private final String JPG_TYPE = (String) "jpg";
private final String JPG_MIME = (String) "image/jpeg";
private final String PNG_TYPE = (String) "png";
private final String PNG_MIME = (String) "image/png";
public String handleRequest(S3Event s3event, Context context) {
try {
S3EventNotificationRecord record = s3event.getRecords().get(0);
String srcBucket = record.getS3().getBucket().getName();
// Object key may have spaces or unicode non-ASCII characters.
String srcKey = record.getS3().getObject().getKey()
.replace('+', ' ');
srcKey = URLDecoder.decode(srcKey, "UTF-8");
String dstBucket = srcBucket + "resized";
String dstKey = "resized-" + srcKey;
// Sanity check: validate that source and destination are different
// buckets.
if (srcBucket.equals(dstBucket)) {
System.out
.println("Destination bucket must not match source bucket.");
return "";
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}
// Infer the image type.
Matcher matcher = Pattern.compile(".*\\.([^\\.]*)").matcher(srcKey);
if (!matcher.matches()) {
System.out.println("Unable to infer image type for key "
+ srcKey);
return "";
}
String imageType = matcher.group(1);
if (!(JPG_TYPE.equals(imageType)) && !(PNG_TYPE.equals(imageType))) {
System.out.println("Skipping non-image " + srcKey);
return "";
}
// Download the image from S3 into a stream
AmazonS3 s3Client = new AmazonS3Client();
S3Object s3Object = s3Client.getObject(new GetObjectRequest(
srcBucket, srcKey));
InputStream objectData = s3Object.getObjectContent();
// Read the source image
BufferedImage srcImage = ImageIO.read(objectData);
int srcHeight = srcImage.getHeight();
int srcWidth = srcImage.getWidth();
// Infer the scaling factor to avoid stretching the image
// unnaturally
float scalingFactor = Math.min(MAX_WIDTH / srcWidth, MAX_HEIGHT
/ srcHeight);
int width = (int) (scalingFactor * srcWidth);
int height = (int) (scalingFactor * srcHeight);
BufferedImage resizedImage = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
Graphics2D g = resizedImage.createGraphics();
// Fill with white before applying semi-transparent (alpha) images
g.setPaint(Color.white);
g.fillRect(0, 0, width, height);
// Simple bilinear resize
// If you want higher quality algorithms, check this link:
// https://today.java.net/pub/a/today/2007/04/03/perils-of-imagegetscaledinstance.html
g.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
RenderingHints.VALUE_INTERPOLATION_BILINEAR);
g.drawImage(srcImage, 0, 0, width, height, null);
g.dispose();
// Re-encode image to target format
ByteArrayOutputStream os = new ByteArrayOutputStream();
ImageIO.write(resizedImage, imageType, os);
InputStream is = new ByteArrayInputStream(os.toByteArray());
// Set Content-Length and Content-Type
ObjectMetadata meta = new ObjectMetadata();
meta.setContentLength(os.size());
if (JPG_TYPE.equals(imageType)) {
meta.setContentType(JPG_MIME);
}
if (PNG_TYPE.equals(imageType)) {
meta.setContentType(PNG_MIME);
}
// Uploading to S3 destination bucket
System.out.println("Writing to: " + dstBucket + "/" + dstKey);
s3Client.putObject(dstBucket, dstKey, is, meta);
System.out.println("Successfully resized " + srcBucket + "/"
+ srcKey + " and uploaded to " + dstBucket + "/" + dstKey);
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return "Ok";
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}
Amazon S3 invokes your Lambda function using the Event invocation type, where AWS Lambda executes
the code asynchronously. What you return does not matter. However, in this case we are implementing an
interface that requires us to specify a return type, so in this example the handler uses String as the return
type.
Using the preceding code (in a file named S3EventProcessorCreateThumbnail.java), create a deployment
package. Make sure that you add the following dependencies:
• aws-lambda-java-core.
• aws-lambda-java-events
These can be found at aws-lambda-java-libs.
For more information, see Programming Model for Authoring Lambda Functions in Java (p. 23).
Your deployment package can be a .zip file or a standalone .jar. You can use any build and packaging
tool you are familiar with to create a deployment package. For examples of how to use the Maven build
tool to create a standalone .jar, see Creating a .jar Deployment Package Using Maven without any IDE
(Java) (p. 64) and Creating a .jar Deployment Package Using Maven and Eclipse IDE (Java) (p. 66). For an
example of how to use the Gradle build tool to create a .zip file, see Creating a .zip Deployment Package
(Java) (p. 68).
After you verify that your deployment package is created, go to the next step to create an IAM role
(execution role). You specify this role at the time you create your Lambda function.
Next Step
Step 2.2: Create the Execution Role (IAM Role) (p. 181)
Python
In this section, you create an example Python function and install dependencies.
1.
Open a text editor, and copy the following code. The code uploads the resized image to a different
bucket with the same image name, as shown following:
source-bucket/image.png -> source-bucketresized/image.png
from __future__ import print_function
import boto3
import os
import sys
import uuid
from PIL import Image
import PIL.Image
s3_client = boto3.client('s3')
def resize_image(image_path, resized_path):
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with Image.open(image_path) as image:
image.thumbnail(tuple(x / 2 for x in image.size))
image.save(resized_path)
def handler(event, context):
for record in event['Records']:
bucket = record['s3']['bucket']['name']
key = record['s3']['object']['key']
download_path = '/tmp/{}{}'.format(uuid.uuid4(), key)
upload_path = '/tmp/resized-{}'.format(key)
s3_client.download_file(bucket, key, download_path)
resize_image(download_path, upload_path)
s3_client.upload_file(upload_path, '{}resized'.format(bucket), key)
2.
Save the file as CreateThumbnail.py.
3.
If your source code is on a local host, copy it over.
scp -i key.pem /path/to/my_code.py [email protected]:~/CreateThumbnail.py
4.
Connect to a 64-bit Amazon Linux instance via SSH.
ssh -i key.pem [email protected]
5.
Ensure basic build requirements are installed.
sudo yum install python27-devel python27-pip gcc
6.
Install native dependencies required by Pillow.
sudo yum install libjpeg-devel zlib-devel
7.
Create and activate a virtual environment.
virtualenv ~/shrink_venv
source ~/shrink_venv/bin/activate
8.
Install libraries in the virtual environment.
pip install Pillow
pip install boto3
Note
AWS Lambda includes the AWS SDK for Python (Boto 3), so you don't need to include it in
your deployment package, but you can optionally include it for local testing.
9.
Create a .zip file
zip -9 ~/CreateThumbnail.zip
10. Add the contents of lib and lib64 site-packages to your .zip file.
cd $VIRTUAL_ENV/lib/python2.7/site-packages
zip -r9 ~/CreateThumbnail.zip *
cd $VIRTUAL_ENV/lib64/python2.7/site-packages
zip -r9 ~/CreateThumbnail.zip *
11. Add your python code to the .zip file
cd ~
zip -g CreateThumbnail.zip CreateThumbnail.py
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Next Step
Step 2.2: Create the Execution Role (IAM Role) (p. 181)
Step 2.2: Create the Execution Role (IAM Role)
In this section, you create an IAM role using the following predefined role type and access permissions
policy:
• AWS service role of the type AWS Lambda – This role grants AWS Lambda permissions to assume the
role.
• AWSLambdaExecute access permissions policy that you attach to the role.
For more information about IAM roles, see IAM Roles in the IAM User Guide. Use the following procedure
to create the IAM role.
To create an IAM role (execution role)
1.
Sign in to the IAM console at https://console.aws.amazon.com/iam/.
2.
Follow the steps in Creating a Role to Delegate Permissions to an AWS Service in the IAM User Guide
to create an IAM role (execution role). As you follow the steps to create a role, note the following:
• In Role Name, use a name that is unique within your AWS account (for example, lambda-s3execution-role).
• In Select Role Type, choose AWS Service Roles, and then choose AWS Lambda. This grants the
AWS Lambda service permissions to assume the role.
• In Attach Policy, choose AWSLambdaExecute.
3.
Write down the role ARN. You will need it in the next step when you create your Lambda function.
Next Step
Step 2.3: Create the Lambda Function and Test It Manually (p. 181)
Step 2.3: Create the Lambda Function and Test It Manually
In this section, you do the following:
• Create a Lambda function by uploading the deployment package.
• Test the Lambda function by invoking it manually and passing sample Amazon S3 event data as a
parameter.
Step 2.3.1: Create the Lambda Function (Upload the Deployment Package)
In this step, you upload the deployment package using the AWS CLI.
1.
At the command prompt, run the following Lambda AWS CLI create-function command using the
adminuser as the --profile. You need to update the command by providing the .zip file path and the
execution role ARN. For the runtime parameter, choose between nodejs6.10, nodejs4.3, python2.7
or java8, depending on the code sample you when you created your deployment package.
$ aws lambda create-function \
--region us-west-2 \
--function-name CreateThumbnail \
--zip-file fileb://file-path/CreateThumbnail.zip \
--role role-arn \
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--handler CreateThumbnail.handler \
--runtime runtime \
--profile adminuser \
--timeout 10 \
--memory-size 1024
Optionally, you can upload the .zip file to an Amazon S3 bucket in the same AWS region, and then
specify the bucket and object name in the preceding command. You need to replace the --zip-file
parameter by the --code parameter, as shown following:
--code S3Bucket=bucket-name,S3Key=zip-file-object-key
2.
Write down the function ARN. You will need this in the next section when you add notification
configuration to your Amazon S3 bucket.
3.
(Optional) The preceding command specifies a 10-second timeout value as the function configuration.
Depending on the size of objects you upload, you might need to increase the timeout value using the
following AWS CLI command.
$ aws lambda update-function-configuration \
--function-name CreateThumbnail \
--region us-west-2 \
--timeout timeout-in-seconds \
--profile adminuser
Note
You can create the Lambda function using the AWS Lambda console, in which case note the value
of the create-function AWS CLI command parameters. You provide the same values in the
console UI.
Step 2.3.2: Test the Lambda Function (Invoke Manually)
In this step, you invoke the Lambda function manually using sample Amazon S3 event data. You can test
the function using the AWS Management Console or the AWS CLI.
To test the Lambda function (console)
1.
Follow the steps in the Getting Started to create and invoke the Lambda function at Step 2.2: Invoke
the Lambda Function Manually and Verify Results, Logs, and Metrics (p. 162). For the sample event
for testing, choose S3 Put in Sample event template.
2.
Verify that the thumbnail was created in the target bucket and monitor the activity of your Lambda
function in the AWS Lambda console as follows:
• The AWS Lambda console shows a graphical representation of some of the CloudWatch metrics in
the Cloudwatch Metrics at a glance section for your function.
• For each graph, you can also click the logs link to view the CloudWatch Logs directly.
To test the Lambda function (AWS CLI)
1.
Save the following Amazon S3 sample event data in a file and save it as input.txt. You need to
update the JSON by providing your sourcebucket name and a .jpg object key.
{
"Records":[
{
"eventVersion":"2.0",
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"eventSource":"aws:s3",
"awsRegion":"us-west-2",
"eventTime":"1970-01-01T00:00:00.000Z",
"eventName":"ObjectCreated:Put",
"userIdentity":{
"principalId":"AIDAJDPLRKLG7UEXAMPLE"
},
"requestParameters":{
"sourceIPAddress":"127.0.0.1"
},
"responseElements":{
"x-amz-request-id":"C3D13FE58DE4C810",
"x-amz-id-2":"FMyUVURIY8/IgAtTv8xRjskZQpcIZ9KG4V5Wp6S7S/
JRWeUWerMUE5JgHvANOjpD"
},
"s3":{
"s3SchemaVersion":"1.0",
"configurationId":"testConfigRule",
"bucket":{
"name":"sourcebucket",
"ownerIdentity":{
"principalId":"A3NL1KOZZKExample"
},
"arn":"arn:aws:s3:::sourcebucket"
},
"object":{
"key":"HappyFace.jpg",
"size":1024,
"eTag":"d41d8cd98f00b204e9800998ecf8427e",
"versionId":"096fKKXTRTtl3on89fVO.nfljtsv6qko"
}
}
}
]
}
2.
Run the following Lambda CLI invoke command to invoke the function. Note that the command
requests asynchronous execution. You can optionally invoke it synchronously by specifying
RequestResponse as the invocation-type parameter value.
$ aws lambda invoke \
--invocation-type Event \
--function-name CreateThumbnail \
--region us-west-2 \
--payload file://file-path/inputfile.txt \
--profile adminuser \
outputfile.txt
Note
You are able to invoke this function because you are using your own credentials to invoke
your own function. In the next section, you configure Amazon S3 to invoke this function on
your behalf, which requires you to add permissions to the access policy associated with your
Lambda function to grant Amazon S3 permissions to invoke your function.
3.
Verify that the thumbnail was created in the target bucket and monitor the activity of your Lambda
function in the AWS Lambda console as follows:
• The AWS Lambda console shows a graphical representation of some of the CloudWatch metrics in
the Cloudwatch Metrics at a glance section for your function.
• For each graph, you can also click the logs link to view the CloudWatch Logs directly.
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Next Step
Step 3: Add an Event Source (Configure Amazon S3 to Publish Events) (p. 184)
Step 3: Add an Event Source (Configure Amazon S3 to Publish
Events)
In this step, you add the remaining configuration so that Amazon S3 can publish object-created events to
AWS Lambda and invoke your Lambda function. You do the following in this step:
• Add permissions to the Lambda function access policy to allow Amazon S3 to invoke the function.
• Add notification configuration to your source bucket. In the notification configuration, you provide the
following:
• Event type for which you want Amazon S3 to publish events. For this tutorial, you specify the
s3:ObjectCreated:* event type so that Amazon S3 publishes events when objects are created.
• Lambda function to invoke.
Step 3.1: Add Permissions to the Lambda Function's Access Permissions Policy
1.
Run the following Lambda CLI add-permission command to grant Amazon S3 service principal
(s3.amazonaws.com) permissions to perform the lambda:InvokeFunction action. Note that permission
is granted to Amazon S3 to invoke the function only if the following conditions are met:
• An object-created event is detected on a specific bucket.
• The bucket is owned by a specific AWS account. If a bucket owner deletes a bucket, some other
AWS account can create a bucket with the same name. This condition ensures that only a specific
AWS account can invoke your Lambda function.
$ aws lambda add-permission \
--function-name CreateThumbnail \
--region us-west-2 \
--statement-id some-unique-id \
--action "lambda:InvokeFunction" \
--principal s3.amazonaws.com \
--source-arn arn:aws:s3:::sourcebucket \
--source-account bucket-owner-account-id \
--profile adminuser
2.
Verify the function's access policy by running the AWS CLI get-policy command.
$ aws lambda get-policy \
--function-name function-name \
--profile adminuser
Step 3.2: Configure Notification on the Bucket
Add notification configuration on the source bucket to request Amazon S3 to publish object-created events
to Lambda. In the configuration, you specify the following:
• Event type – For this tutorial, select the ObjectCreated (All) Amazon S3 event type.
• Lambda function – This is your Lambda function that you want Amazon S3 to invoke.
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For instructions on adding notification configuration to a bucket, see Enabling Event Notifications in the
Amazon Simple Storage Service Console User Guide.
Step 3.3: Test the Setup
You're all done! Now adminuser can test the setup as follows:
1. Upload .jpg or .png objects to the source bucket using the Amazon S3 console.
2. Verify that the thumbnail was created in the target bucket using the CreateThumbnail function.
3. The adminuser can also verify the CloudWatch Logs. You can monitor the activity of your Lambda
function in the AWS Lambda console. For example, choose the logs link in the console to view logs,
including logs your function wrote to CloudWatch Logs.
Step 4: Deploy With AWS SAM and AWS CloudFormation
In the previous section, you used AWS Lambda APIs to create and update a Lambda function by providing
a deployment package as a ZIP file. However, this mechanism may not be convenient for automating
deployment steps for functions, or coordinating deployments and updates to other elements of a serverless
application, like event sources and downstream resources.
You can use AWS CloudFormation to easily specify, deploy, and configure serverless applications. AWS
CloudFormation is a service that helps you model and set up your Amazon Web Services resources so
that you can spend less time managing those resources and more time focusing on your applications
that run in AWS. You create a template that describes all the AWS resources that you want (like Lambda
functions and DynamoDB tables), and AWS CloudFormation takes care of provisioning and configuring
those resources for you.
In addition, you can use the AWS Serverless Application Model to express resources that comprise the
serverless application. These resource types, such as Lambda functions and APIs, are fully supported by
AWS CloudFormation and make it easier for you to define and deploy your serverless application.
For more information, see Deploying Lambda-based Applications (p. 133).
Specification for Amazon S3 Thumbnail Application
The following contains the SAM template for this application. Copy the text below to a .yaml file and save
it next to the ZIP package you created previously. Note that the Handler and Runtime parameter values
should match the ones you used when you created the function in the previous section.
AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Resources:
CreateThumbnail:
Type: AWS::Serverless::Function
Properties:
Handler: handler
Runtime: runtime
Timeout: 60
Policies: AWSLambdaExecute
Events:
Type: S3
Properties:
Bucket: !Ref SrcBucket
Events: s3:ObjectCreated:*
SrcBucket:
Type: AWS::S3::Bucket
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Deploying the Serverless Application
For information on how to package and deploy your serverless application using the package and deploy
commands, see Packaging and Deployment (p. 139).
Using AWS Lambda with Amazon Kinesis
You can create an Amazon Kinesis stream to continuously capture and store terabytes of data per hour
from hundreds of thousands of sources such as website click streams, financial transactions, social media
feeds, IT logs, and location-tracking events. For more information, see Amazon Kinesis.
You can subscribe Lambda functions to automatically read batches of records off your Amazon Kinesis
stream and process them if records are detected on the stream. AWS Lambda then polls the stream
periodically (once per second) for new records.
Note the following about how the Amazon Kinesis and AWS Lambda integration works:
• Stream-based model – This is a model (see Event Source Mapping (p. 116)), where AWS Lambda polls
the stream and, when it detects new records, invokes your Lambda function by passing the new records
as a parameter.
In a stream-based model, you maintain event source mapping in AWS Lambda. The event source
mapping describes which stream maps to which Lambda function. AWS Lambda provides an API
(CreateEventSourceMapping (p. 318)) that you can use to create the mapping. You can also use the
AWS Lambda console to create event source mappings.
• Synchronous invocation – AWS Lambda invokes a Lambda function using the RequestResponse
invocation type (synchronous invocation) by polling the Kinesis Stream. For more information about
invocation types, see Invocation Types (p. 4).
• Event structure – The event your Lambda function receives is a collection of records AWS Lambda
reads from your stream. When you configure event source mapping, the batch size you specify is the
maximum number of records that you want your Lambda function to receive per invocation.
Regardless of what invokes a Lambda function, AWS Lambda always executes a Lambda function on
your behalf. If your Lambda function needs to access any AWS resources, you need to grant the relevant
permissions to access those resources. You also need to grant AWS Lambda permissions to poll your
Amazon Kinesis stream. You grant all of these permissions to an IAM role (execution role) that AWS
Lambda can assume to poll the stream and execute the Lambda function on your behalf. You create this
role first and then enable it at the time you create the Lambda function. For more information, see Manage
Permissions: Using an IAM Role (Execution Role) (p. 150).
The following diagram illustrates the application flow:
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1. Custom app writes records to the stream.
2. AWS Lambda polls the stream and, when it detects new records in the stream, invokes your Lambda
function.
3. AWS Lambda executes the Lambda function by assuming the execution role you specified at the time
you created the Lambda function.
For a tutorial that walks you through an example setup, see Tutorial: Using AWS Lambda with Amazon
Kinesis (p. 187).
Tutorial: Using AWS Lambda with Amazon Kinesis
In this tutorial, you create a Lambda function to consume events from an Amazon Kinesis stream.
The tutorial is divided into two main sections:
• First, you perform the necessary setup to create a Lambda function and then you test it by invoking it
manually using sample event data (you don't need an Amazon Kinesis stream).
• Second, you create an Amazon Kinesis stream (event source). You add an event source mapping
in AWS Lambda to associate the stream with your Lambda function. AWS Lambda starts polling the
stream, you add test records to the stream using the Amazon Kinesis API, and then you verify that AWS
Lambda executed your Lambda function.
Important
Both the Lambda function and the Amazon Kinesis stream must be in the same AWS region. This
tutorial assumes that you create these resources in the us-west-2 region.
In this tutorial, you use the AWS Command Line Interface to perform AWS Lambda operations such
as creating a Lambda function, creating a stream, and adding records to the stream. You use the AWS
Lambda console to manually invoke the function before you create a Amazon Kinesis stream. You verify
return values and logs in the console UI.
Next Step
Step 1: Prepare (p. 187)
Step 1: Prepare
Make sure you have completed the following steps:
• Signed up for an AWS account and created an administrator user in the account.
• Installed and set up the AWS CLI.
For instructions, see Step 1: Set Up an AWS Account and the AWS CLI (p. 155).
Next Step
Step 2: Create a Lambda Function and Invoke It Manually (Using Sample Event Data) (p. 187)
Step 2: Create a Lambda Function and Invoke It Manually (Using
Sample Event Data)
In this section, you do the following:
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• Create a Lambda function deployment package using the sample code provided. The sample Lambda
function code that you'll use to process Amazon Kinesis events is provided in various languages. Select
one of the languages and follow the corresponding instructions to create a deployment package.
Note
To see more examples of using other AWS services within your function, including calling other
Lambda functions, see AWS SDK for JavaScript
• Create an IAM role (execution role). At the time you upload the deployment package, you need to specify
an IAM role (execution role) that Lambda can assume to execute the function on your behalf.
• Create the Lambda function by uploading the deployment package, and then test it by invoking it
manually using sample Amazon Kinesis event data.
Topics
• Step 2.1: Create a Deployment Package (p. 188)
• Step 2.2: Create the Execution Role (IAM Role) (p. 191)
• Step 2.3: Create the Lambda Function and Test It Manually (p. 191)
Step 2.1: Create a Deployment Package
From the Filter View list, choose the language you want to use for your Lambda function. The appropriate
section appears with code and specific instructions for creating a deployment package.
Node.js
The following is example Node.js code that receives Amazon Kinesis event records as input and processes
them. For illustration, the code writes some of the incoming event data to CloudWatch Logs.
Follow the instructions to create a AWS Lambda function deployment package.
1.
Open a text editor, and then copy the following code.
console.log('Loading function');
exports.handler = function(event, context, callback) {
//console.log(JSON.stringify(event, null, 2));
event.Records.forEach(function(record) {
// Kinesis data is base64 encoded so decode here
var payload = new Buffer(record.kinesis.data, 'base64').toString('ascii');
console.log('Decoded payload:', payload);
});
callback(null, "message");
};
Note
The code sample is compliant with the Node.js runtimes v6.10 or v4.3. For more information,
see Programming Model (Node.js) (p. 9)
2.
Save the file as ProcessKinesisRecords.js.
3.
Zip the ProcessKinesisRecords.js file as ProcessKinesisRecords.zip.
Next Step
Step 2.2: Create the Execution Role (IAM Role) (p. 191)
Java
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The following is example Java code that receives Amazon Kinesis event record data as a input and
processes it. For illustration, the code writes some of the incoming event data to CloudWatch Logs.
In the code, recordHandler is the handler. The handler uses the predefined KinesisEvent class that is
defined in the aws-lambda-java-events library.
package example;
import java.io.IOException;
import com.amazonaws.services.lambda.runtime.events.KinesisEvent;
import com.amazonaws.services.lambda.runtime.events.KinesisEvent.KinesisEventRecord;
public class ProcessKinesisEvents {
public void recordHandler(KinesisEvent event) throws IOException {
for(KinesisEventRecord rec : event.getRecords()) {
System.out.println(new String(rec.getKinesis().getData().array()));
}
}
}
If the handler returns normally without exceptions, Lambda considers the input batch of records as
processed successfully and begins reading new records in the stream. If the handler throws an exception,
Lambda considers the input batch of records as not processed and invokes the function with the same
batch of records again.
Using the preceding code (in a file named ProcessKinesisEvents.java), create a deployment package.
Make sure that you add the following dependencies:
• aws-lambda-java-core
• aws-lambda-java-events
For more information, see Programming Model for Authoring Lambda Functions in Java (p. 23).
Your deployment package can be a .zip file or a standalone .jar. You can use any build and packaging
tool you are familiar with to create a deployment package. For examples of how to use the Maven build
tool to create a standalone .jar, see Creating a .jar Deployment Package Using Maven without any IDE
(Java) (p. 64) and Creating a .jar Deployment Package Using Maven and Eclipse IDE (Java) (p. 66). For an
example of how to use the Gradle build tool to create a .zip file, see Creating a .zip Deployment Package
(Java) (p. 68).
After you verify that your deployment package is created, go to the next step to create an IAM role
(execution role). You specify this role at the time you create your Lambda function.
Next Step
Step 2.2: Create the Execution Role (IAM Role) (p. 191)
C#
The following is example C# code that receives Amazon Kinesis event record data as a input and
processes it. For illustration, the code writes some of the incoming event data to CloudWatch Logs.
In the code, HandleKinesisRecord is the handler. The handler uses the predefined KinesisEvent class
that is defined in the Amazon.Lambda.KinesisEvents library.
using System;
using System.IO;
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using System.Text;
using Amazon.Lambda.Core;
using Amazon.Lambda.KinesisEvents;
namespace KinesisStreams
{
public class KinesisSample
{
[LambdaSerializer(typeof(JsonSerializer))]
public void HandleKinesisRecord(KinesisEvent kinesisEvent)
{
Console.WriteLine($"Beginning to process {kinesisEvent.Records.Count}
records...");
foreach (var record in kinesisEvent.Records)
{
Console.WriteLine($"Event ID: {record.EventId}");
Console.WriteLine($"Event Name: {record.EventName}");
string recordData = GetRecordContents(record.Kinesis);
Console.WriteLine($"Record Data:");
Console.WriteLine(recordData);
}
Console.WriteLine("Stream processing complete.");
}
private string GetRecordContents(KinesisEvent.Record streamRecord)
{
using (var reader = new StreamReader(streamRecord.Data, Encoding.ASCII))
{
return reader.ReadToEnd();
}
}
}
}
To create a deployment package, follow the steps outlined in .NET Core CLI (p. 59). In doing so, note the
following after you've created your .NET project:
• Rename the default Program.cs file with a file name of your choice, such as ProcessingKinesisEvents.cs.
• Replace the default contents of the renamed Program.cs file with the code example above.
• In the project.json file, make sure the following references are included in the dependencies node.
• "Amazon.Lambda.Core": "1.0.0-*"
• "Amazon.Lambda.KinesisEvents":"1.0.0-*"
• "Amazon.Lambda.Serialization.Json":"1.0.0-*"
After you verify that your deployment package is created, go to the next step to create an IAM role
(execution role). You specify this role at the time you create your Lambda function.
Next Step
Step 2.2: Create the Execution Role (IAM Role) (p. 191)
Python
The following is example Python code that receives Amazon Kinesis event record data as input and
processes it. For illustration, the code writes to some of the incoming event data to CloudWatch Logs.
Follow the instructions to create a AWS Lambda function deployment package.
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1.
Open a text editor, and then copy the following code.
from __future__ import print_function
#import json
import base64
def lambda_handler(event, context):
for record in event['Records']:
#Kinesis data is base64 encoded so decode here
payload=base64.b64decode(record["kinesis"]["data"])
print("Decoded payload: " + payload)
2.
3.
Save the file as ProcessKinesisRecords.py.
Zip the ProcessKinesisRecords.py file as ProcessKinesisRecords.zip.
Next Step
Step 2.2: Create the Execution Role (IAM Role) (p. 191)
Step 2.2: Create the Execution Role (IAM Role)
In this section, you create an IAM role using the following predefined role type and access policy:
• AWS service role of the type AWS Lambda – This role grants AWS Lambda permissions to assume the
role.
• AWSLambdaKinesisExecutionRole – This is the access permissions policy that you attach to the role.
For more information about IAM roles, see IAM Roles in the IAM User Guide. Use the following procedure
to create the IAM role.
To create an IAM role (execution role)
1.
2.
Sign in to the IAM console at https://console.aws.amazon.com/iam/.
Follow the steps in Creating a Role to Delegate Permissions to an AWS Service in the IAM User Guide
to create an IAM role (execution role). As you follow the steps to create a role, note the following:
• In Role Name, use a name that is unique within your AWS account (for example, lambda-kinesisexecution-role).
• In Select Role Type, choose AWS Service Roles, and then choose AWS Lambda. This grants the
AWS Lambda service permissions to assume the role.
• In Attach Policy, choose AWSLambdaKinesisExecutionRole. The permissions in this policy are
sufficient for the Lambda function in this tutorial.
3.
Write down the role ARN. You will need it in the next step when you create your Lambda function.
Next Step
Step 2.3: Create the Lambda Function and Test It Manually (p. 191)
Step 2.3: Create the Lambda Function and Test It Manually
In this section, you do the following:
• Create a Lambda function by uploading the deployment package.
• Test the Lambda function by invoking it manually. Instead of creating an event source, you use sample
Amazon Kinesis event data.
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In the next section, you create an Amazon Kinesis stream and test the end-to-end experience.
Step 2.3.1: Create a Lambda Function (Upload the Deployment Package)
In this step, you upload the deployment package using the AWS CLI.
At the command prompt, run the following Lambda CLI create-function command using the adminuser
profile.
You need to update the command by providing the .zip file path and the execution role ARN. The -runtime parameter value can be python2.7, nodejs6.10, nodejs4.3, or java8, depending on the language
you used to author your code.
$ aws lambda create-function \
--region us-west-2 \
--function-name ProcessKinesisRecords \
--zip-file fileb://file-path/ProcessKinesisRecords.zip \
--role execution-role-arn \
--handler handler \
--runtime runtime-value \
--profile adminuser
The --handler parameter value for Java should be example.ProcessKinesisRecords::recordHandler.
For Node.js, it should be ProcessKinesisRecords.handler and for Python it should be
ProcessKinesisRecords.lambda_handler.
Optionally, you can upload the .zip file to an Amazon S3 bucket in the same AWS region, and then specify
the bucket and object name in the preceding command. You need to replace the --zip-file parameter by
the --code parameter, as shown following:
--code S3Bucket=bucket-name,S3Key=zip-file-object-key
Note
You can create the Lambda function using the AWS Lambda console, in which case note the value
of the create-function AWS CLI command parameters. You provide the same values in the
console UI.
Step 2.3.2: Test the Lambda Function (Invoke Manually)
Invoke the function manually using sample Amazon Kinesis event data. We recommend that you invoke
the function using the console because the console UI provides a user-friendly interface for reviewing the
execution results, including the execution summary, logs written by your code, and the results returned by
the function (because the console always performs synchronous execution—invokes the Lambda function
using the RequestResponse invocation type).
To test the Lambda function (console)
1.
Follow the steps in the Getting Started to create and invoke the Lambda function at Step 2.2: Invoke
the Lambda Function Manually and Verify Results, Logs, and Metrics (p. 162). For the sample event
for testing, choose Kinesis in Sample event template.
2.
Verify the results in the console.
To test the Lambda function (AWS CLI)
1.
Copy the following JSON into a file and save it as input.txt.
{
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"Records": [
{
"kinesis": {
"partitionKey": "partitionKey-3",
"kinesisSchemaVersion": "1.0",
"data": "SGVsbG8sIHRoaXMgaXMgYSB0ZXN0IDEyMy4=",
"sequenceNumber":
"49545115243490985018280067714973144582180062593244200961"
},
"eventSource": "aws:kinesis",
"eventID":
"shardId-000000000000:49545115243490985018280067714973144582180062593244200961",
"invokeIdentityArn": "arn:aws:iam::account-id:role/testLEBRole",
"eventVersion": "1.0",
"eventName": "aws:kinesis:record",
"eventSourceARN": "arn:aws:kinesis:us-west-2:35667example:stream/
examplestream",
"awsRegion": "us-west-2"
}
]
}
2.
Execute the following invoke command:
$ aws lambda invoke \
--invocation-type Event \
--function-name ProcessKinesisRecords \
--region us-west-2 \
--payload file://file-path/input.txt \
--profile adminuser
outputfile.txt
Note
In this tutorial example, the message is saved in the outputfile.txt file. If you request
synchronous execution (RequestResponse as the invocation type), the function returns the
string message in the response body.
For Node.js, it could be one of the following (whatever one you specify in the code):
context.succeed("message")
context.fail("message")
context.done(null, "message)
For Python or Java, it is the message in the return statement:
return "message"
Next Step
Step 3: Add an Event Source (Create an Amazon Kinesis Stream and Associate It with Your Lambda
Function) (p. 193)
Step 3: Add an Event Source (Create an Amazon Kinesis Stream
and Associate It with Your Lambda Function)
In this section, you create an Amazon Kinesis stream, and then you add an event source in AWS Lambda
to associate the Amazon Kinesis stream with your Lambda function.
After you create an event source, AWS Lambda starts polling the stream. You then test the setup by adding
events to the stream and verify that AWS Lambda executed your Lambda function on your behalf:
Step 3.1: Create an Amazon Kinesis Stream
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Use the following Amazon Kinesis create-stream CLI command to create a stream.
$ aws kinesis create-stream \
--stream-name examplestream \
--shard-count 1 \
--region us-west-2 \
--profile adminuser
Run the following Amazon Kinesis describe-stream AWS CLI command to get the stream ARN.
$ aws kinesis describe-stream \
--stream-name examplestream \
--region us-west-2 \
--profile adminuser
You need the stream ARN in the next step to associate the stream with your Lambda function. The stream
is of the form:
arn:aws:kinesis:aws-region:account-id:stream/stream-name
Step 3.2: Add an Event Source in AWS Lambda
Run the following AWS CLI add-event-source command. After the command executes, note down the
UUID. You'll need this UUID to refer to the event source in any commands (for example, when deleting the
event source).
$ aws lambda create-event-source-mapping \
--region us-west-2 \
--function-name ProcessKinesisRecords \
--event-source kinesis-stream-arn \
--batch-size 100 \
--starting-position TRIM_HORIZON \
--profile adminuser
You can get a list of event source mappings by running the following command.
$ aws lambda list-event-source-mappings \
--region us-west-2 \
--function-name ProcessKinesisRecords \
--event-source kinesis-stream-arn \
--profile adminuser \
--debug
In the response, you can verify the status value is enabled.
Note
If you disable the event source mapping, AWS Lambda stops polling the Amazon Kinesis stream.
If you re-enable event source mapping, it will resume polling from the sequence number where it
stopped, so each record is processed either before you disabled the mapping or after you enabled
it. If the sequence number falls behind TRIM_HORIZON, when you re-enable it polling will start
from TRIM_HORIZON. However, if you create a new event source mapping, polling will always start
from TRIM_HORIZON, LATEST or AT_TIMESTAMP, depending on the starting position you specify.
This applies even if you delete an event source mapping and create a new one with the same
configuration as the deleted one.
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Step 3.3: Test the Setup
You're all done! Now adminuser can test the setup as follows:
1. Using the following AWS CLI command, add event records to your Amazon Kinesis stream. The -data value is a base64-encoded value of the "Hello, this is a test." string. You can run the same
command more than once to add multiple records to the stream.
$ aws kinesis put-record \
--stream-name examplestream \
--data "This is a test. final" \
--partition-key shardId-000000000000 \
--region us-west-2 \
--profile adminuser
2. AWS Lambda polls the stream and, when it detects updates to the stream, it invokes your Lambda
function by passing in the event data from the stream.
AWS Lambda assumes the execution role to poll the stream. You have granted the role permissions for
the necessary Amazon Kinesis actions so that AWS Lambda can poll the stream and read events from
the stream.
3. Your function executes and adds logs to the log group that corresponds to the Lambda function in
Amazon CloudWatch.
The adminuser can also verify the logs reported in the Amazon CloudWatch console. Make sure you
are checking for logs in the same AWS region where you created the Lambda function.
Step 4: Deploy With AWS SAM and AWS CloudFormation
In the previous section, you used AWS Lambda APIs to create and update a Lambda function by providing
a deployment package as a ZIP file. However, this mechanism may not be convenient for automating
deployment steps for functions, or coordinating deployments and updates to other elements of a serverless
application, like event sources and downstream resources.
You can use AWS CloudFormation to easily specify, deploy, and configure serverless applications. AWS
CloudFormation is a service that helps you model and set up your Amazon Web Services resources so
that you can spend less time managing those resources and more time focusing on your applications
that run in AWS. You create a template that describes all the AWS resources that you want (like Lambda
functions and DynamoDB tables), and AWS CloudFormation takes care of provisioning and configuring
those resources for you.
In addition, you can use the AWS Serverless Application Model to express resources that comprise the
serverless application. These resource types, such as Lambda functions and APIs, are fully supported by
AWS CloudFormation and make it easier for you to define and deploy your serverless application.
For more information, see Deploying Lambda-based Applications (p. 133).
Specification for Amazon Kinesis Application
The following contains the SAM template for this application. Copy the text below to a .yaml file and save
it next to the ZIP package you created previously. Note that the Handler and Runtime parameter values
should match the ones you used when you created the function in the previous section.
AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Resources:
ProcessKinesisRecords:
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Type: AWS::Serverless::Function
Properties:
Handler: handler
Runtime: runtime
Policies: AWSLambdaKinesisExecutionRole
Events:
Stream:
Type: Kinesis
Properties:
Stream: !GetAtt ExampleStream.Arn
BatchSize: 100
StartingPosition: TRIM_HORIZON
ExampleStream:
Type: AWS::Kinesis::Stream
Properties:
ShardCount: 1
Deploying the Serverless Application
For information on how to package and deploy your serverless application using the package and deploy
commands, see Packaging and Deployment (p. 139).
Using AWS Lambda with Amazon DynamoDB
You can use Lambda functions as triggers for your Amazon DynamoDB table. Triggers are custom actions
you take in response to updates made to the DynamoDB table. To create a trigger, first you enable Amazon
DynamoDB Streams for your table. Then, you write a Lambda function to process the updates published to
the stream.
Note the following about how the Amazon DynamoDB and AWS Lambda integration works:
• Stream-based model – This is a model (see Event Source Mapping (p. 116)), where AWS Lambda polls
the stream and, when it detects new records, invokes your Lambda function by passing the update event
as parameter.
In a stream-based model, you maintain event source mapping in AWS Lambda. The event source
mapping describes which stream maps to which Lambda function. AWS Lambda provides an API
(CreateEventSourceMapping (p. 318)) for you to create the mapping. You can also use the AWS
Lambda console to create event source mappings.
• Synchronous invocation – AWS Lambda invokes a Lambda function using the RequestResponse
invocation type (synchronous invocation). For more information about invocation types, see Invocation
Types (p. 4).
• Event structure – The event your Lambda function receives is the table update information AWS
Lambda reads from your stream. When you configure event source mapping, the batch size you specify
is the maximum number of records that you want your Lambda function to receive per invocation.
Regardless of what invokes a Lambda function, AWS Lambda always executes a Lambda function on
your behalf. If your Lambda function needs to access any AWS resources, you need to grant the relevant
permissions to access those resources. You also need to grant AWS Lambda permissions to poll your
DynamoDB stream. You grant all of these permissions to an IAM role (execution role) that AWS Lambda
can assume to poll the stream and execute the Lambda function on your behalf. You create this role
first and then enable it at the time you create the Lambda function. For more information, see Manage
Permissions: Using an IAM Role (Execution Role) (p. 150).
The following diagram illustrates the application flow:
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1. Custom app updates the DynamoDB table.
2. Amazon DynamoDB publishes item updates to the stream.
3. AWS Lambda polls the stream and invokes your Lambda function when it detects new records in the
stream.
4. AWS Lambda executes the Lambda function by assuming the execution role you specified at the time
you created the Lambda function.
For a tutorial that walks you through an example setup, see Tutorial: Using AWS Lambda with Amazon
DynamoDB (p. 197).
Tutorial: Using AWS Lambda with Amazon DynamoDB
In this tutorial, you create a Lambda function to consume events from a DynamoDB stream.
The tutorial is divided into two main sections:
• First, you perform the necessary setup to create a Lambda function and then you test it by invoking it
manually using sample event data.
• Second, you create an DynamoDB stream-enabled table and add an event source mapping in AWS
Lambda to associate the stream with your Lambda function. AWS Lambda starts polling the stream.
Then, you test the end-to-end setup. As you create, update, and delete items from the table, Amazon
DynamoDB writes records to the stream. AWS Lambda detects the new records as it polls the stream
and executes your Lambda function on your behalf.
Important
Both the Lambda function and the DynamoDB stream must be in the same AWS region. This
tutorial assumes that you create these resources in the us-east-1 region.
In this tutorial, you use the AWS Command Line Interface to perform AWS Lambda operations such
as creating a Lambda function, creating a stream, and adding records to the stream. You use the AWS
Lambda console to manually invoke the function before you create a DynamoDB stream. You verify return
values and logs in the console UI.
Next Step
Step 1: Prepare (p. 198)
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Step 1: Prepare
Make sure you have completed the following steps:
• Signed up for an AWS account and created an administrator user in the account.
• Installed and set up the AWS CLI.
For instructions, see Step 1: Set Up an AWS Account and the AWS CLI (p. 155).
Next Step
Step 2: Create a Lambda Function and Invoke It Manually (Using Sample Event Data) (p. 198)
Step 2: Create a Lambda Function and Invoke It Manually (Using
Sample Event Data)
In this section, you do the following:
• Create a Lambda function deployment package using the sample code provided. The sample Lambda
function code that you'll use to process DynamoDB events is provided in various languages. Select one
of the languages and follow the corresponding instructions to create a deployment package.
Note
To see more examples of using other AWS services within your function, including calling other
Lambda functions, see AWS SDK for JavaScript
• Create an IAM role (execution role). At the time you upload the deployment package, you need to
specify an IAM role (execution role) that Lambda can assume to execute the function on your behalf. For
example, AWS Lambda needs permissions for DynamoDB actions so it can poll the stream and read
records from the stream. In the pull model you must also grant AWS Lambda permissions to invoke your
Lambda function. The example Lambda function writes some of the event data to CloudWatch, so it
needs permissions for necessary CloudWatch actions.
• Create the Lambda function by uploading the deployment package, and then test it by invoking it
manually using sample DynamoDB event data. You provide both the deployment package and the IAM
role at the time of creating a Lambda function. You can also specify other configuration information, such
as the function name, memory size, runtime environment to use, and the handler. For more information
about these parameters, see CreateFunction (p. 322). After creating the Lambda function, you invoke it
using sample Amazon DynamoDB event data.
Topics
• Step 2.1: Create a Lambda Function Deployment Package (p. 198)
• Step 2.2: Create the Execution Role (IAM Role) (p. 201)
• Step 2.3: Create the Lambda Function and Test It Manually (p. 202)
Step 2.1: Create a Lambda Function Deployment Package
From the Filter View list, choose the language you want to use for your Lambda function. The appropriate
section appears with code and specific instructions for creating a deployment package.
Node.js
1.
Open a text editor, and then copy the following code.
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console.log('Loading function');
exports.lambda_handler = function(event, context, callback) {
console.log(JSON.stringify(event, null, 2));
event.Records.forEach(function(record) {
console.log(record.eventID);
console.log(record.eventName);
console.log('DynamoDB Record: %j', record.dynamodb);
});
callback(null, "message");
};
Note
The code sample is compliant with the Node.js runtimes v6.10 or v4.3. For more information,
see Programming Model (Node.js) (p. 9)
2.
Save the file as ProcessDynamoDBStream.js.
3.
Zip the ProcessDynamoDBStream.js file as ProcessDynamoDBStream.zip.
Next Step
Step 2.2: Create the Execution Role (IAM Role) (p. 201)
Java
In the following code, handleRequest is the handler that AWS Lambda invokes and provides event data.
The handler uses the predefined DynamodbEvent class, which is defined in the aws-lambda-java-events
library.
package example;
import
import
import
import
import
com.amazonaws.services.lambda.runtime.Context;
com.amazonaws.services.lambda.runtime.LambdaLogger;
com.amazonaws.services.lambda.runtime.RequestHandler;
com.amazonaws.services.lambda.runtime.events.DynamodbEvent;
com.amazonaws.services.lambda.runtime.events.DynamodbEvent.DynamodbStreamRecord;
public class DDBEventProcessor implements
RequestHandler<DynamodbEvent, String> {
public String handleRequest(DynamodbEvent ddbEvent, Context context) {
for (DynamodbStreamRecord record : ddbEvent.getRecords()){
System.out.println(record.getEventID());
System.out.println(record.getEventName());
System.out.println(record.getDynamodb().toString());
}
return "Successfully processed " + ddbEvent.getRecords().size() + " records.";
}
}
If the handler returns normally without exceptions, Lambda considers the input batch of records as
processed successfully and begins reading new records in the stream. If the handler throws an exception,
Lambda considers the input batch of records as not processed and invokes the function with the same
batch of records again.
Using the preceding code (in a file named DDBEventProcessor.java), create a deployment package. Make
sure that you add the following dependencies:
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• aws-lambda-java-core
• aws-lambda-java-events
For more information, see Programming Model for Authoring Lambda Functions in Java (p. 23).
Your deployment package can be a .zip file or a standalone .jar. You can use any build and packaging
tool you are familiar with to create a deployment package. For examples of how to use the Maven build
tool to create a standalone .jar, see Creating a .jar Deployment Package Using Maven without any IDE
(Java) (p. 64) and Creating a .jar Deployment Package Using Maven and Eclipse IDE (Java) (p. 66). For an
example of how to use the Gradle build tool to create a .zip file, see Creating a .zip Deployment Package
(Java) (p. 68).
After you verify that your deployment package is created, go to the next step to create an IAM role
(execution role). You specify this role at the time you create your Lambda function.
Next Step
Step 2.2: Create the Execution Role (IAM Role) (p. 201)
C#
In the following code, ProcessDynamoEvent is the handler that AWS Lambda invokes and provides
event data. The handler uses the predefined DynamoDbEvent class, which is defined in the
Amazon.Lambda.DynamoDBEvents library.
using
using
using
using
using
System;
System.IO;
System.Text;
Amazon.Lambda.Core;
Amazon.Lambda.DynamoDBEvents;
using Amazon.Lambda.Serialization.Json;
namespace DynamoDBStreams
{
public class DdbSample
{
private static readonly JsonSerializer _jsonSerializer = new JsonSerializer();
public void ProcessDynamoEvent(DynamoDBEvent dynamoEvent)
{
Console.WriteLine($"Beginning to process {dynamoEvent.Records.Count}
records...");
foreach (var record in dynamoEvent.Records)
{
Console.WriteLine($"Event ID: {record.EventID}");
Console.WriteLine($"Event Name: {record.EventName}");
string streamRecordJson = SerializeObject(record.Dynamodb);
Console.WriteLine($"DynamoDB Record:");
Console.WriteLine(streamRecordJson);
}
Console.WriteLine("Stream processing complete.");
}
private string SerializeObject(object streamRecord)
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{
using (var ms = new MemoryStream())
{
_jsonSerializer.Serialize(streamRecord, ms);
return Encoding.UTF8.GetString(ms.ToArray());
}
}
}
}
To create a deployment package, follow the steps outlined in .NET Core CLI (p. 59). In doing so, note the
following after you've created your .NET project:
• Rename the default Program.cs file with a file name of your choice, such as
ProcessingDynamoDBStreams.cs.
• Replace the default contents of the renamed Program.cs file with the code example above.
• In the project.json file, add the following references to the dependencies node.
• "Amazon.Lambda.Core":"1.0.0-*"
• "Amazon.Lambda.Serialiation.Json":"1.0.0-*"
• "Amazon.Lambda.DynamoDBEvents":"1.0.0-*"
After you verify that your deployment package is created, go to the next step to create an IAM role
(execution role). You specify this role at the time you create your Lambda function.
Next Step
Step 2.2: Create the Execution Role (IAM Role) (p. 201)
Python
1.
Open a text editor, and then copy the following code.
from __future__ import print_function
def lambda_handler(event, context):
for record in event['Records']:
print(record['eventID'])
print(record['eventName'])
print('Successfully processed %s records.' % str(len(event['Records'])))
2.
Save the file as ProcessDynamoDBStream.py.
3.
Zip the ProcessDynamoDBStream.py file as ProcessDynamoDBStream.zip.
Next Step
Step 2.2: Create the Execution Role (IAM Role) (p. 201)
Step 2.2: Create the Execution Role (IAM Role)
In this section, you create an IAM role using the following predefined role type and access policy:
• AWS service role of the type AWS Lambda – This role grants AWS Lambda permissions to assume the
role.
• AWSLambdaDynamoDBExecutionRole – This is the access permissions policy that you attach to the
role.
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For more information about IAM roles, see IAM Roles in the IAM User Guide. Use the following procedure
to create the IAM role.
To create an IAM role (execution role)
1.
Sign in to the IAM console at https://console.aws.amazon.com/iam/.
2.
Follow the steps in Creating a Role to Delegate Permissions to an AWS Service in the IAM User Guide
to create an IAM role (execution role). As you follow the steps to create a role, note the following:
• In Role Name, use a name that is unique within your AWS account (for example, lambdadynamodb-execution-role).
• In Select Role Type, choose AWS Service Roles, and then choose AWS Lambda. This grants the
AWS Lambda service permissions to assume the role.
• In Attach Policy, choose AWSLambdaDynamoDBExecutionRole. The permissions in this policy
are sufficient for the Lambda function in this tutorial.
3.
Write down the role ARN. You will need it in the next step when you create your Lambda function.
Next Step
Step 2.3: Create the Lambda Function and Test It Manually (p. 202)
Step 2.3: Create the Lambda Function and Test It Manually
In this section, you do the following:
• Create a Lambda function by uploading the deployment package.
• Test the Lambda function by invoking it manually. Instead of creating an event source, you use sample
DynamoDB event data.
In the next section, you create an DynamoDB stream and test the end-to-end experience.
Step 2.3.1: Create a Lambda Function (Upload the Deployment Package)
In this step, you upload the deployment package using the AWS CLI.
At the command prompt, run the following Lambda CLI create-function command using the adminuser
profile.
You need to update the command by providing the .zip file path and the execution role ARN. The -runtime parameter value can be python2.7, nodejs6.10 nodejs4.3, or java8, depending on the language
you used to author your code.
$ aws lambda create-function \
--region us-east-1 \
--function-name ProcessDynamoDBStream \
--zip-file fileb://file-path/ProcessDynamoDBStream.zip \
--role role-arn \
--handler ProcessDynamoDBStream.lambda_handler \
--runtime runtime-value \
--profile adminuser
Note
If you choose Java 8 as the runtime, the handler value must be packageName::methodName.
For more information, see CreateFunction (p. 322). AWS Lambda creates the function and returns
function configuration information.
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Optionally, you can upload the .zip file to an Amazon S3 bucket in the same AWS region, and then specify
the bucket and object name in the preceding command. You need to replace the --zip-file parameter by
the --code parameter, as shown following:
--code S3Bucket=bucket-name,S3Key=zip-file-object-key
Step 2.3.2: Test the Lambda Function (Invoke Manually)
In this step, you invoke your Lambda function manually using the invoke AWS Lambda CLI command and
the following sample DynamoDB event.
1.
Copy the following JSON into a file and save it as input.txt.
{
"Records":[
{
"eventID":"1",
"eventName":"INSERT",
"eventVersion":"1.0",
"eventSource":"aws:dynamodb",
"awsRegion":"us-east-1",
"dynamodb":{
"Keys":{
"Id":{
"N":"101"
}
},
"NewImage":{
"Message":{
"S":"New item!"
},
"Id":{
"N":"101"
}
},
"SequenceNumber":"111",
"SizeBytes":26,
"StreamViewType":"NEW_AND_OLD_IMAGES"
},
"eventSourceARN":"stream-ARN"
},
{
"eventID":"2",
"eventName":"MODIFY",
"eventVersion":"1.0",
"eventSource":"aws:dynamodb",
"awsRegion":"us-east-1",
"dynamodb":{
"Keys":{
"Id":{
"N":"101"
}
},
"NewImage":{
"Message":{
"S":"This item has changed"
},
"Id":{
"N":"101"
}
},
"OldImage":{
"Message":{
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"S":"New item!"
},
"Id":{
"N":"101"
}
},
"SequenceNumber":"222",
"SizeBytes":59,
"StreamViewType":"NEW_AND_OLD_IMAGES"
},
"eventSourceARN":"stream-ARN"
},
{
"eventID":"3",
"eventName":"REMOVE",
"eventVersion":"1.0",
"eventSource":"aws:dynamodb",
"awsRegion":"us-east-1",
"dynamodb":{
"Keys":{
"Id":{
"N":"101"
}
},
"OldImage":{
"Message":{
"S":"This item has changed"
},
"Id":{
"N":"101"
}
},
"SequenceNumber":"333",
"SizeBytes":38,
"StreamViewType":"NEW_AND_OLD_IMAGES"
},
"eventSourceARN":"stream-ARN"
}
]
}
2.
Execute the following invoke command.
$ aws lambda invoke \
--invocation-type RequestResponse \
--function-name ProcessDynamoDBStream \
--region us-east-1 \
--payload file://file-path/input.txt \
--profile adminuser \
outputfile.txt
Note that the invoke command specifies the RequestResponse as the invocation type, which requests
synchronous execution. For more information, see Invoke (p. 351). The function returns the string
message (message in the context.succeed() in the code) in the response body.
3.
Verify the output in the outputfile.txt file.
You can monitor the activity of your Lambda function in the AWS Lambda console.
• The AWS Lambda console shows a graphical representation of some of the CloudWatch metrics
in the Cloudwatch Metrics at a glance section for your function. Sign in to the AWS Management
Console at https://console.aws.amazon.com/.
• For each graph you can also click the logs link to view the CloudWatch logs directly.
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Next Step
Step 3: Add an Event Source (Create a DynamoDB Stream and Associate It with Your Lambda
Function) (p. 205)
Step 3: Add an Event Source (Create a DynamoDB Stream and
Associate It with Your Lambda Function)
In this section, you do the following:
• Create an Amazon DynamoDB table with a stream enabled.
• Create an event source mapping in AWS Lambda. This event source mapping associates the
DynamoDB stream with your Lambda function. After you create this event source mapping, AWS
Lambda starts polling the stream.
• Test the end-to-end experience. As you perform table updates, DynamoDB writes event records to
the stream. As AWS Lambda polls the stream, it detects new records in the stream and executes your
Lambda function on your behalf by passing events to the function.
Step 3.1: Create a DynamoDB Table with a Stream Enabled
Follow the procedure to create a table with a stream:
1.
Sign in to the AWS Management Console and open the DynamoDB console at https://
console.aws.amazon.com/dynamodb/.
2.
In the DynamoDB console, create a table with streams enabled. Make sure you have the US East (N.
Virginia) region selected before you create the table.
Important
You must create a DynamoDB table in the same region where you created the Lambda
function. This tutorial assumes the US East (N. Virginia) region. In addition, both the table and
the Lambda functions must belong to the same AWS account.
3.
Write down the stream ARN. You need this in the next step when you associate the stream with your
Lambda function.
Step 3.2: Add an Event Source in AWS Lambda
Run the following AWS CLI create-event-source-mapping command. After the command executes, note
down the UUID. You'll need this UUID to refer to the event source mapping in any commands, for example,
when deleting the event source mapping.
$ aws lambda create-event-source-mapping \
--region us-east-1 \
--function-name ProcessDynamoDBStream \
--event-source DynamoDB-stream-arn \
--batch-size 100 \
--starting-position TRIM_HORIZON \
--profile adminuser
Note
This creates a mapping between the specified DynamoDB stream and the Lambda function.
You can associate a DynamoDB stream with multiple Lambda functions, and associate the
same Lambda function with multiple streams. However, the Lambda functions will share the read
throughput for the stream they share.
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You can get the list of event source mappings by running the following command.
$ aws lambda list-event-source-mappings \
--region us-east-1 \
--function-name ProcessDynamoDBStream \
--event-source DynamoDB-stream-arn \
--profile adminuser
The list returns all of the event source mappings you created, and for each mapping it shows the
LastProcessingResult, among other things. This field is used to provide an informative message if there
are any problems. Values such as No records processed (indicates that AWS Lambda has not started
polling or that there are no records in the stream) and OK (indicates AWS Lambda successfully read records
from the stream and invoked your Lambda function) indicate that there no issues. If there are issues, you
receive an error message.
Step 3.3: Test the Setup
You're all done! Now adminuser can test the setup as follows:
1. In the DynamoDB console, add, update, delete items to the table. DynamoDB writes records of these
actions to the stream.
2. AWS Lambda polls the stream and when it detects updates to the stream, it invokes your Lambda
function by passing in the event data it finds in the stream.
3. Your function executes and creates logs in Amazon CloudWatch. The adminuser can also verify the
logs reported in the Amazon CloudWatch console.
Step 4: Deploy With AWS SAM and AWS CloudFormation
In the previous section, you used AWS Lambda APIs to create and update a Lambda function by providing
a deployment package as a ZIP file. However, this mechanism may not be convenient for automating
deployment steps for functions, or coordinating deployments and updates to other elements of a serverless
application, like event sources and downstream resources.
You can use AWS CloudFormation to easily specify, deploy, and configure serverless applications. AWS
CloudFormation is a service that helps you model and set up your Amazon Web Services resources so
that you can spend less time managing those resources and more time focusing on your applications
that run in AWS. You create a template that describes all the AWS resources that you want (like Lambda
functions and DynamoDB tables), and AWS CloudFormation takes care of provisioning and configuring
those resources for you.
In addition, you can use the AWS Serverless Application Model to express resources that comprise the
serverless application. These resource types, such as Lambda functions and APIs, are fully supported by
AWS CloudFormation and make it easier for you to define and deploy your serverless application.
For more information, see Deploying Lambda-based Applications (p. 133).
Specification for DynamoDB Application
The following contains the SAM template for this application. Copy the text below to a .yaml file and save
it next to the ZIP package you created previously. Note that the Handler and Runtime parameter values
should match the ones you used when you created the function in the previous section.
AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Resources:
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ProcessDynamoDBStream:
Type: AWS::Serverless::Function
Properties:
Handler: handler
Runtime: runtime
Policies: AWSLambdaDynamoDBExecutionRole
Events:
Stream:
Type: DynamoDB
Properties:
Stream: !GetAtt DynamoDBTable.StreamArn
BatchSize: 100
StartingPosition: TRIM_HORIZON
DynamoDBTable:
Type: AWS::DynamoDB::Table
Properties:
AttributeDefinitions:
- AttributeName: id
AttributeType: S
KeySchema:
- AttributeName: id
KeyType: HASH
ProvisionedThroughput:
ReadCapacityUnits: 5
WriteCapacityUnits: 5
StreamSpecification:
StreamViewType: NEW_IMAGE
Deploying the Serverless Application
For information on how to package and deploy your serverless application using the package and deploy
commands, see Packaging and Deployment (p. 139).
Using AWS Lambda with AWS CloudTrail
You can enable CloudTrail in your AWS account to get logs of API calls and related events history in your
account. CloudTrail records all of the API access events as objects in your Amazon S3 bucket that you
specify at the time you enable CloudTrail.
You can take advantage of Amazon S3's bucket notification feature and direct Amazon S3 to publish
object-created events to AWS Lambda. Whenever CloudTrail writes logs to your S3 bucket, Amazon S3
can then invoke your Lambda function by passing the Amazon S3 object-created event as a parameter.
The S3 event provides information, including the bucket name and key name of the log object that
CloudTrail created. Your Lambda function code can read the log object and process the access records
logged by CloudTrail. For example, you might write Lambda function code to notify you if specific API call
was made in your account.
In this scenario, you enable CloudTrail so it can write access logs to your S3 bucket. As for AWS Lambda,
Amazon S3 is the event source so Amazon S3 publishes events to AWS Lambda and invokes your
Lambda function.
Note
Amazon S3 can only support one event destination.
For detailed information about how to configure Amazon S3 as the event source, see Using AWS Lambda
with Amazon S3 (p. 169).
The following diagram summarizes the flow:
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1. AWS CloudTrail saves logs to an S3 bucket (object-created event).
2. Amazon S3 detects the object-created event.
3. Amazon S3 publishes the s3:ObjectCreated:* event to AWS Lambda by invoking the Lambda function,
as specified in the bucket notification configuration. Because the Lambda function's access permissions
policy includes permissions for Amazon S3 to invoke the function, Amazon S3 can invoke the function.
4. AWS Lambda executes the Lambda function by assuming the execution role that you specified at the
time you created the Lambda function.
5. The Lambda function reads the Amazon S3 event it receives as a parameter, determines where the
CloudTrail object is, reads the CloudTrail object, and then it processes the log records in the CloudTrail
object.
6. If the log includes a record with specific eventType and eventSource values, it publishes the event to
your Amazon SNS topic. In Tutorial: Using AWS Lambda with AWS CloudTrail (p. 208), you subscribe
to the SNS topic using the email protocol, so you get email notifications.
For a tutorial that walks you through an example scenario, see Tutorial: Using AWS Lambda with AWS
CloudTrail (p. 208).
Tutorial: Using AWS Lambda with AWS CloudTrail
Suppose you have turned on AWS CloudTrail for your AWS account to maintain records (logs) of AWS API
calls made on your account and you want to be notified anytime an API call is made to create an SNS topic.
As API calls are made in your account, CloudTrail writes logs to an Amazon S3 bucket that you configured.
In this scenario, you want Amazon S3 to publish the object-created events to AWS Lambda and invoke
your Lambda function as CloudTrail creates log objects.
When Amazon S3 invokes your Lambda function, it passes an S3 event identifying, among other things, the
bucket name and key name of the object that CloudTrail created. Your Lambda function can read the log
object, and it knows the API calls that were reported in the log.
Each object CloudTrail creates in your S3 bucket is a JSON object, with one or more event records. Each
record, among other things, provides eventSource and eventName.
{
"Records":[
{
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"eventVersion":"1.02",
"userIdentity":{
...
},
"eventTime":"2014-12-16T19:17:43Z",
"eventSource":"sns.amazonaws.com",
"eventName":"CreateTopic",
"awsRegion":"us-west-2",
"sourceIPAddress":"72.21.198.64",
...
},
{
...
},
...
}
For illustration, the Lambda function notifies you by email if an API call to create an Amazon SNS topic
is reported in the log. That is, when your Lambda function parses the log, it looks for records with the
following:
• eventSource = "sns.amazonaws.com"
• eventName = "CreateTopic"
If found, it publishes the event to your Amazon SNS topic (you configure this topic to notify you by email).
Implementation Summary
Upon completing this tutorial, you will have Amazon S3, AWS Lambda, Amazon SNS, and AWS Identity
and Access Management (IAM) resources in your account:
Note
This tutorial assumes that you create these resources in the us-west-2 region.
In Lambda:
• A Lambda function.
• An access policy associated with your Lambda function – You grant Amazon S3 permissions to invoke
the Lambda function using this permissions policy. You will also restrict the permissions so that Amazon
S3 can invoke the Lambda function only for object-created events from a specific bucket that is owned by
a specific AWS account.
Note
It is possible for an AWS account to delete a bucket and some other AWS account to later
create a bucket with same name. The additional conditions ensure that Amazon S3 can invoke
the Lambda function only if Amazon S3 detects object-created events from a specific bucket
owned by a specific AWS account.
For more information, see How It Works (p. 146).
In IAM:
• An IAM role (execution role) – You grant permissions that your Lambda function needs through the
permissions policy associated with this role.
In Amazon S3:
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• A bucket – In this tutorial, the bucket name is examplebucket. When you turn the trail on in the CloudTrail
console, you specify this bucket for CloudTrail to save the logs.
• Notification configuration on the examplebucket – In the configuration, you direct Amazon S3 to publish
object-created events to Lambda, by invoking your Lambda function. For more information about the
Amazon S3 notification feature, see Setting Up Notification of Bucket Events in Amazon Simple Storage
Service Developer Guide.
• Sample CloudTrail log object (ExampleCloudTrailLog.json) in examplebucket bucket – In the first half
of this exercise, you create and test your Lambda function by manually invoking it using a sample S3
event. This sample event identifies examplebucket as the bucket name and this sample object key name.
Your Lambda function then reads the object and sends you email notifications using an SNS topic.
In Amazon SNS
• An SNS topic – You subscribe to this topic by specifying email as the protocol.
Now you are ready to start the tutorial.
Next Step
Step 1: Prepare (p. 210)
Step 1: Prepare
In this section you do the following:
• Sign up for an AWS account and set up the AWS CLI.
• Turn on CloudTrail in your account.
• Create an SNS topic and subscribe to it.
Follow the steps in the following sections to walk through the setup process.
Note
In this tutorial, we assume that you are setting the resources in the us-west-2 region.
Step 1.1: Sign Up for AWS and Set Up the AWS CLI
Make sure you have completed the following steps:
• Signed up for an AWS account and created an administrator user in the account (called adminuser).
• Installed and set up the AWS CLI.
For instructions, see Step 1: Set Up an AWS Account and the AWS CLI (p. 155).
Step 1.2: Turn on CloudTrail
In the AWS CloudTrail console, turn on the trail in your account by specifying examplebucket in the uswest-2 region for CloudTrail to save logs. When configuring the trail, do not enable SNS notification.
For instructions, see Creating and Updating Your Trail in the AWS CloudTrail User Guide.
Note
Although you turn CloudTrail on now, you do not perform any additional configuration for your
Lambda function to process the real CloudTrail logs in the first half of this exercise. Instead, you
will use sample CloudTrail log objects (that you will upload) and sample S3 events to manually
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invoke and test your Lambda function. In the second half of this tutorial, you perform additional
configuration steps that enable your Lambda function to process the CloudTrail logs.
Step 1.3: Create an SNS Topic and Subscribe to the Topic
Follow the procedure to create an SNS topic in the us-west-2 region and subscribe to it by providing an
email address as the endpoint.
To create and subscribe to a topic
1.
Create an SNS topic.
For instructions, see Create a Topic in the Amazon Simple Notification Service Developer Guide.
2.
Subscribe to the topic by providing an email address as the endpoint.
For instructions, see Subscribe to a Topic in the Amazon Simple Notification Service Developer Guide.
3.
Note down the topic ARN. You will need the value in the following sections.
Next Step
Step 2: Create a Lambda Function and Invoke It Manually (Using Sample Event Data) (p. 211)
Step 2: Create a Lambda Function and Invoke It Manually (Using
Sample Event Data)
In this section, you do the following:
• Create a Lambda function deployment package using the sample code provided. The sample Lambda
function code that you'll use to process Amazon S3 events is provided in various languages. Select one
of the languages and follow the corresponding instructions to create a deployment package.
Note
Your Lambda function uses an S3 event that provides the bucket name and key name of the
object CloudTrail created. Your Lambda function then reads that object to process CloudTrail
records.
• Create an IAM role (execution role). At the time you upload the deployment package, you need to specify
an IAM role (execution role) that Lambda can assume to execute the function on your behalf.
• Create the Lambda function by uploading the deployment package, and then test it by invoking it
manually using sample CloudTrail event data.
Topics
• Step 2.1: Create a Deployment Package (p. 211)
• Step 2.2: Create the Execution Role (IAM Role) (p. 213)
• Step 2.3: Create the Lambda Function and Test It Manually (p. 214)
Step 2.1: Create a Deployment Package
The deployment package is a .zip file containing your Lambda function code. For this tutorial, you will need
to install the async library. To do this, open a command window and navigate to the directory where you
intend to store the code file file you will copy and save below. Use npm to install the async library as shown
below :
npm install async
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Node.js
1.
Open a text editor, and then copy the following code.
var aws = require('aws-sdk');
var zlib = require('zlib');
var async = require('async');
var
var
var
var
EVENT_SOURCE_TO_TRACK
EVENT_NAME_TO_TRACK
DEFAULT_SNS_REGION =
SNS_TOPIC_ARN
=
= /sns.amazonaws.com/;
= /CreateTopic/;
'us-west-2';
'The ARN of your SNS topic';
var s3 = new aws.S3();
var sns = new aws.SNS({
apiVersion: '2010-03-31',
region: DEFAULT_SNS_REGION
});
exports.handler = function(event, context, callback) {
var srcBucket = event.Records[0].s3.bucket.name;
var srcKey = event.Records[0].s3.object.key;
async.waterfall([
function fetchLogFromS3(next){
console.log('Fetching compressed log from S3...');
s3.getObject({
Bucket: srcBucket,
Key: srcKey
},
next);
},
function uncompressLog(response, next){
console.log("Uncompressing log...");
zlib.gunzip(response.Body, next);
},
function publishNotifications(jsonBuffer, next) {
console.log('Filtering log...');
var json = jsonBuffer.toString();
console.log('CloudTrail JSON from S3:', json);
var records;
try {
records = JSON.parse(json);
} catch (err) {
next('Unable to parse CloudTrail JSON: ' + err);
return;
}
var matchingRecords = records
.Records
.filter(function(record) {
return record.eventSource.match(EVENT_SOURCE_TO_TRACK)
&& record.eventName.match(EVENT_NAME_TO_TRACK);
});
console.log('Publishing ' + matchingRecords.length + ' notification(s) in
parallel...');
async.each(
matchingRecords,
function(record, publishComplete) {
console.log('Publishing notification: ', record);
sns.publish({
Message:
'Alert... SNS topic created: \n TopicARN=' +
record.responseElements.topicArn + '\n\n' +
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JSON.stringify(record),
TopicArn: SNS_TOPIC_ARN
}, publishComplete);
},
next
);
}
], function (err) {
if (err) {
console.error('Failed to publish notifications: ', err);
} else {
console.log('Successfully published all notifications.');
}
callback(null,"message");
});
};
Note
The code sample is compliant with the Node.js runtimes v6.10 or v4.3. For more information,
see Programming Model (Node.js) (p. 9)
2.
Save the file as CloudTrailEventProcessing.js.
3.
Zip the CloudTrailEventProcessing.js file as CloudTrailEventProcessing.zip.
Note
We're using Node.js in this tutorial example, but you can author your Lambda functions in Java or
Python too.
Next Step
Step 2.2: Create the Execution Role (IAM Role) (p. 213)
Step 2.2: Create the Execution Role (IAM Role)
Now you create an IAM role (execution role) that you specify when creating your Lambda function. This role
has a permissions policy that grant the necessary permissions that your Lambda function needs, such as
permissions to write CloudWatch logs, permissions to read CloudTrail log objects from an S3 bucket, and
permissions to publish events to your SNS topic when your Lambda function finds specific API calls in the
CloudTrail records.
For more information about the execution role, see Manage Permissions: Using an IAM Role (Execution
Role) (p. 150).
To create an IAM role (execution role)
1.
Sign in to the IAM console at https://console.aws.amazon.com/iam/.
2.
Create a managed policy and attach it to the IAM role. In this step, you modify an existing AWS
Managed Policy, save it using a different name, and then attach the permissions policy to an IAM role
that you create.
a.
b.
In the navigation pane of the IAM console, choose Policies, and then choose Create Policy.
Next to Copy an AWS Managed Policy, choose Select.
c.
d.
Next to AWSLambdaExecute, choose Select.
Copy the following policy into the Policy Document, replacing the existing policy, and then update
the policy with the ARN of the Amazon SNS topic that you created.
{
"Version": "2012-10-17",
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"Statement": [
{
"Effect": "Allow",
"Action": [
"logs:*"
],
"Resource": "arn:aws:logs:*:*:*"
},
{
"Effect": "Allow",
"Action": [
"s3:GetObject"
],
"Resource": "arn:aws:s3:::examplebucket/*"
},
{
"Effect": "Allow",
"Action": [
"sns:Publish"
],
"Resource": "your sns topic ARN"
}
]
}
3.
4.
Note the permissions policy name because you will use it in the next step.
Follow the steps in Creating a Role to Delegate Permissions to an AWS Service in the IAM User Guide
to create an IAM role and then attach the permissions policy you just created to the role. As you follow
the steps to create a role, note the following:
• In Role Name, use a name that is unique within your AWS account (for example, lambdacloudtrail-execution-role).
• In Select Role Type, choose AWS Service Roles, and then choose AWS Lambda.
• In Attach Policy, choose the policy you created in the previous step.
Next Step
Step 2.3: Create the Lambda Function and Test It Manually (p. 214)
Step 2.3: Create the Lambda Function and Test It Manually
In this section, you do the following:
• Create a Lambda function by uploading the deployment package.
• Test the Lambda function by invoking it manually.
In this step, you use a sample S3 event that identifies your bucket name and the sample object (that
is, an example CloudTrail log). In the next section you configure your S3 bucket notification to publish
object-created events and test the end-to-end experience.
Step 2.3.1: Create the Lambda Function (Upload the Deployment Package)
In this step, you upload the deployment package using the AWS CLI and provide configuration information
when you create the Lambda function. At the command prompt, run the following Lambda CLI createfunction command using the adminuser profile.
Note
You need to update the command by providing the .zip file path (//file-path/
CloudTrailEventProcessing.zip \) and the execution role ARN (execution-role-arn). If
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you used the sample code provided earlier in this tutorial, set the --runtime parameter value to
nodejs6.10 or nodejs4.3.
You can author your Lambda functions in Java or Python too. If you use another language, change
the --runtime parameter value to java8 or python2.7 as needed.
$ aws lambda create-function \
--region us-west-2 \
--function-name CloudTrailEventProcessing \
--zip-file fileb://file-path/CloudTrailEventProcessing.zip \
--role execution-role-arn \
--handler CloudTrailEventProcessing.handler \
--runtime nodejs6.10 \
--profile adminuser \
--timeout 10 \
--memory-size 1024
Optionally, you can upload the .zip file to an Amazon S3 bucket in the same AWS region, and then specify
the bucket and object name in the preceding command. You need to replace the --zip-file parameter by
the --code parameter as shown:
--code S3Bucket=bucket-name,S3Key=zip-file-object-key
Note
You can create the Lambda function using the AWS Lambda console, in which case note the value
of the create-function AWS CLI command parameters. You provide the same values in the
console.
Step 2.3.2: Test the Lambda Function (Invoke Manually)
In this section, you invoke the Lambda function manually using sample Amazon S3 event data. When the
Lambda function executes, it reads the S3 object (a sample CloudTrail log) from the bucket identified in the
S3 event data, and then it publishes an event to your SNS topic if the sample CloudTrail log reports use
a specific API. For this tutorial, the API is the SNS API used to create a topic. That is, the CloudTrail log
reports a record identifying sns.amazonaws.com as the eventSource, and CreateTopic as the eventName.
1.
Save the following sample CloudTrail log to a file (ExampleCloudTrailLog.json).
Note
Note that one of events in this log has sns.amazonaws.com as the eventSource and
CreateTopic as the eventName. Your Lambda function reads the logs and if it finds an event
of this type, it publishes the event to the Amazon SNS topic that you created and then you
receive one email when you invoke the Lambda function manually.
{
"Records":[
{
"eventVersion":"1.02",
"userIdentity":{
"type":"Root",
"principalId":"account-id",
"arn":"arn:aws:iam::account-id:root",
"accountId":"account-id",
"accessKeyId":"access-key-id",
"sessionContext":{
"attributes":{
"mfaAuthenticated":"false",
"creationDate":"2015-01-24T22:41:54Z"
}
}
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},
"eventTime":"2015-01-24T23:26:50Z",
"eventSource":"sns.amazonaws.com",
"eventName":"CreateTopic",
"awsRegion":"us-west-2",
"sourceIPAddress":"205.251.233.176",
"userAgent":"console.amazonaws.com",
"requestParameters":{
"name":"dropmeplease"
},
"responseElements":{
"topicArn":"arn:aws:sns:us-west-2:account-id:exampletopic"
},
"requestID":"3fdb7834-9079-557e-8ef2-350abc03536b",
"eventID":"17b46459-dada-4278-b8e2-5a4ca9ff1a9c",
"eventType":"AwsApiCall",
"recipientAccountId":"account-id"
},
{
"eventVersion":"1.02",
"userIdentity":{
"type":"Root",
"principalId":"account-id",
"arn":"arn:aws:iam::account-id:root",
"accountId":"account-id",
"accessKeyId":"access-key-id",
"sessionContext":{
"attributes":{
"mfaAuthenticated":"false",
"creationDate":"2015-01-24T22:41:54Z"
}
}
},
"eventTime":"2015-01-24T23:27:02Z",
"eventSource":"sns.amazonaws.com",
"eventName":"GetTopicAttributes",
"awsRegion":"us-west-2",
"sourceIPAddress":"205.251.233.176",
"userAgent":"console.amazonaws.com",
"requestParameters":{
"topicArn":"arn:aws:sns:us-west-2:account-id:exampletopic"
},
"responseElements":null,
"requestID":"4a0388f7-a0af-5df9-9587-c5c98c29cbec",
"eventID":"ec5bb073-8fa1-4d45-b03c-f07b9fc9ea18",
"eventType":"AwsApiCall",
"recipientAccountId":"account-id"
}
]
}
2.
Run the gzip command to create a .gz file from the preceding source file.
$ gzip ExampleCloudTrailLog.json
This creates ExampleCloudTrailLog.json.gz file.
3.
Upload the ExampleCloudTrailLog.json.gz file to the examplebucket that you specified in the
CloudTrail configuration.
This object is specified in the sample Amazon S3 event data that we use to manually invoke the
Lambda function.
4.
Save the following JSON (an example S3 event) in a file, input.txt. Note the bucket name and the
object key name values.
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You provide this sample event when you invoke your Lambda function. For more information about the
S3 event structure, see Event Message Structure in the Amazon Simple Storage Service Developer
Guide.
{
"Records":[
{
"eventVersion":"2.0",
"eventSource":"aws:s3",
"awsRegion":"us-west-2",
"eventTime":"1970-01-01T00:00:00.000Z",
"eventName":"ObjectCreated:Put",
"userIdentity":{
"principalId":"AIDAJDPLRKLG7UEXAMPLE"
},
"requestParameters":{
"sourceIPAddress":"127.0.0.1"
},
"responseElements":{
"x-amz-request-id":"C3D13FE58DE4C810",
"x-amz-id-2":"FMyUVURIY8/IgAtTv8xRjskZQpcIZ9KG4V5Wp6S7S/
JRWeUWerMUE5JgHvANOjpD"
},
"s3":{
"s3SchemaVersion":"1.0",
"configurationId":"testConfigRule",
"bucket":{
"name":"your bucket name",
"ownerIdentity":{
"principalId":"A3NL1KOZZKExample"
},
"arn":"arn:aws:s3:::mybucket"
},
"object":{
"key":"ExampleCloudTrailLog.json.gz",
"size":1024,
"eTag":"d41d8cd98f00b204e9800998ecf8427e",
"versionId":"096fKKXTRTtl3on89fVO.nfljtsv6qko"
}
}
}
]
}
5.
In the AWS Management Console, invoke the function manually using sample Amazon S3 event data.
For instructions, see the Getting Started exercise Step 2.2: Invoke the Lambda Function Manually and
Verify Results, Logs, and Metrics (p. 162). In the console, use the following sample Amazon S3 event
data.
Note
We recommend that you invoke the function using the console because the console UI
provides a user-friendly interface for reviewing the execution results, including the execution
summary, logs written by your code, and the results returned by the function (because the
console always performs synchronous execution—invokes the Lambda function using the
RequestResponse invocation type).
{
"Records":[
{
"eventVersion":"2.0",
"eventSource":"aws:s3",
"awsRegion":"us-west-2",
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"eventTime":"1970-01-01T00:00:00.000Z",
"eventName":"ObjectCreated:Put",
"userIdentity":{
"principalId":"AIDAJDPLRKLG7UEXAMPLE"
},
"requestParameters":{
"sourceIPAddress":"127.0.0.1"
},
"responseElements":{
"x-amz-request-id":"C3D13FE58DE4C810",
"x-amz-id-2":"FMyUVURIY8/IgAtTv8xRjskZQpcIZ9KG4V5Wp6S7S/
JRWeUWerMUE5JgHvANOjpD"
},
"s3":{
"s3SchemaVersion":"1.0",
"configurationId":"testConfigRule",
"bucket":{
"name":"your bucket name",
"ownerIdentity":{
"principalId":"A3NL1KOZZKExample"
},
"arn":"arn:aws:s3:::mybucket"
},
"object":{
"key":"ExampleCloudTrailLog.json.gz",
"size":1024,
"eTag":"d41d8cd98f00b204e9800998ecf8427e",
"versionId":"096fKKXTRTtl3on89fVO.nfljtsv6qko"
}
}
}
]
}
6.
Execute the following AWS CLI command to invoke the function manually using the adminuser
profile.
$
aws lambda invoke-async \
--function-name CloudTrailEventProcessing \
--region us-west-2 \
--invoke-args /filepath/input.txt \
--debug \
--profile adminuser
Because your example log object has an event record showing the SNS API to call to create a topic,
the Lambda function posts that event to your SNS topic, and you should get an email notification.
You can monitor the activity of your Lambda function by using CloudWatch metrics and logs. For
more information about CloudWatch monitoring, see Troubleshooting and Monitoring AWS Lambda
Functions with Amazon CloudWatch (p. 103).
7.
(Optional) Manually invoke the Lambda function using AWS CLI as follows:
a.
Save the JSON from Step 2 earlier in this procedure to a file called input.txt.
b.
Execute the following invoke command:
$ aws lambda invoke \
--invocation-type Event \
--function-name CloudTrailEventProcessing \
--region us-west-2 \
--payload file://file-path/input.txt \
--profile adminuser
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outputfile.txt
Note
In this tutorial example, the message is saved in the outputfile.txt file. If you request
synchronous execution (RequestResponse as the invocation type), the function returns
the string message in the response body.
For Node.js, it could be one of the following (whatever one you specify in the code):
context.succeed("message")
context.fail("message")
context.done(null, "message)
For Python or Java, it is the message in the return statement:
return "message"
Next Step
Step 3: Add Event Source (Configure Amazon S3 to Publish Events) (p. 219)
Step 3: Add Event Source (Configure Amazon S3 to Publish
Events)
In this section, you add the remaining configuration so Amazon S3 can publish object-created events to
AWS Lambda and invoke your Lambda function. You will do the following:
• Add permissions to the Lambda function's access policy to allow Amazon S3 to invoke the function.
• Add notification configuration to your source bucket. In the notification configuration, you provide the
following:
• Event type for which you want Amazon S3 to publish events. For this tutorial, you specify the
s3:ObjectCreated:* event type.
• Lambda function to invoke.
Step 3.1: Add Permissions to the Lambda Function's Access Permissions Policy
1.
Run the following Lambda CLI add-permission command to grant Amazon S3 service principal
(s3.amazonaws.com) permissions to perform the lambda:InvokeFunction action. Note that permission
is granted to Amazon S3 to invoke the function only if the following conditions are met:
• An object-created event is detected on a specific bucket.
• The bucket is owned by a specific AWS account. If a bucket owner deletes a bucket, some other
AWS account can create a bucket with the same name. This condition ensures that only a specific
AWS account can invoke your Lambda function.
$ aws lambda add-permission \
--function-name CloudTrailEventProcessing \
--region us-west-2 \
--statement-id Id-1 \
--action "lambda:InvokeFunction" \
--principal s3.amazonaws.com \
--source-arn arn:aws:s3:::examplebucket \
--source-account examplebucket-owner-account-id \
--profile adminuser
2.
Verify the function's access policy by running the AWS CLI get-policy command.
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$ aws lambda get-policy \
--function-name function-name \
--profile adminuser
Step 3.2: Configure Notification on the Bucket
Add notification configuration on the examplebucket to request Amazon S3 to publish object-created events
to Lambda. In the configuration, you specify the following:
• Event type – For this tutorial, these can be any event types that create objects.
• Lambda function ARN – This is your Lambda function that you want Amazon S3 to invoke. The ARN is of
the following form:
arn:aws:lambda:aws-region:account-id:function:function-name
For example, the function CloudTrailEventProcessing created in us-west-2 region has the following
ARN:
arn:aws:lambda:us-west-2:account-id:function:CloudTrailEventProcessing
For instructions on adding notification configuration to a bucket, see Enabling Event Notifications in the
Amazon Simple Storage Service Console User Guide.
Step 3.3: Test the Setup
You're all done! Now you can test the setup as follows:
1. Perform some action in your AWS account. For example, add another topic in the Amazon SNS console.
2. You receive an email notification about this event.
3. AWS CloudTrail creates a log object in your bucket.
4. If you open the log object (.gz file), the log shows the CreateTopic SNS event.
5. For each object AWS CloudTrail creates, Amazon S3 invokes your Lambda function by passing in the
log object as event data.
6. Lambda executes your function. The function parses the log, finds a CreateTopic SNS event, and then
you receive an email notification.
You can monitor the activity of your Lambda function by using CloudWatch metrics and logs. For more
information about CloudWatch monitoring, see Troubleshooting and Monitoring AWS Lambda Functions
with Amazon CloudWatch (p. 103).
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Step 4: Deploy With AWS SAM and AWS CloudFormation
In the previous section, you used AWS Lambda APIs to create and update a Lambda function by providing
a deployment package as a ZIP file. However, this mechanism may not be convenient for automating
deployment steps for functions, or coordinating deployments and updates to other elements of a serverless
application, like event sources and downstream resources.
You can use AWS CloudFormation to easily specify, deploy, and configure serverless applications. AWS
CloudFormation is a service that helps you model and set up your Amazon Web Services resources so
that you can spend less time managing those resources and more time focusing on your applications
that run in AWS. You create a template that describes all the AWS resources that you want (like Lambda
functions and DynamoDB tables), and AWS CloudFormation takes care of provisioning and configuring
those resources for you.
In addition, you can use the AWS Serverless Application Model to express resources that comprise the
serverless application. These resource types, such as Lambda functions and APIs, are fully supported by
AWS CloudFormation and make it easier for you to define and deploy your serverless application.
For more information, see Deploying Lambda-based Applications (p. 133).
Specification for Amazon API Gateway Application
The following contains the SAM template for this application. Copy the text below to a .yaml file and save it
next to the ZIP package you created in the previous section. Note that the Handler and Runtime parameter
values should match the ones you used when you created the function in the previous section.
AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Parameters:
NotificationEmail:
Type: String
Resources:
CloudTrailEventProcessing:
Type: AWS::Serverless::Function
Properties:
Handler: handler
Runtime: runtime
Timeout: 10
MemorySize: 1024
Policies:
Statement:
- Effect: Allow
Action: s3:GetObject
Resource: !Sub 'arn:aws:s3:::${Bucket}/*'
- Effect: Allow
Action: sns:Publish
Resource: !Ref Topic
Events:
PhotoUpload:
Type: S3
Properties:
Bucket: !Ref Bucket
Events: s3:ObjectCreated:*
Environment:
Variables:
SNS_TOPIC_ARN: !Ref Topic
Bucket:
Type: AWS::S3::Bucket
Trail:
Type: AWS::CloudTrail::Trail
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Properties:
IsLogging: true
S3BucketName: !Ref Bucket
Topic:
Type: AWS::SNS::Topic
Properties:
Subscription:
- Protocol: email
Endpoint: !Ref NotificationEmail
Deploying the Serverless Application
For information on how to package and deploy your serverless application using the package and deploy
commands, see Packaging and Deployment (p. 139).
Using AWS Lambda with Amazon SNS from
Different Accounts
In order to perform cross account Amazon SNS deliveries to Lambda, you need to authorize your Lambda
function to be invoked from Amazon SNS. In turn, Amazon SNS needs to allow the Lambda account to
subscribe to the Amazon SNS topic. For example, if the Amazon SNS topic is in account A and the Lambda
function is in account B, both accounts must grant permissions to the other to access their respective
resources. Since not all the options for setting up cross-account permissions are available from the AWS
console, you use the AWS CLI to set up the entire process.
For a tutorial that walks you through an example setup, see Tutorial: Using AWS Lambda with Amazon
SNS (p. 222).
Tutorial: Using AWS Lambda with Amazon SNS
In this tutorial, you create a Lambda function in one AWS account to subscribe to an Amazon SNS topic in
a separate AWS account.
The tutorial is divided into three main sections:
• First, you perform the necessary setup to create a Lambda function.
• Second, you create an Amazon SNS topic in a separate AWS account.
• Third, you grant permissions from each account in order for the Lambda function to subscribe to the
Amazon SNS topic. Then, you test the end-to-end setup.
Important
This tutorial assumes that you create these resources in the us-east-1 region.
In this tutorial, you use the AWS Command Line Interface to perform AWS Lambda operations such as
creating a Lambda function, creating an Amazon SNS topic and granting permissions to allow these two
resources to access each other.
Next Step
Step 1: Prepare (p. 222)
Step 1: Prepare
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• Sign up for an AWS account and create an administrator user in the account (called adminuser).
• Install and set up the AWS CLI.
For instructions, see Step 1: Set Up an AWS Account and the AWS CLI (p. 155).
Next Step
Step 2: Create a Lambda Function (p. 223)
Step 2: Create a Lambda Function
In this section, you do the following:
• Create a Lambda function deployment package using the sample code provided. The sample Lambda
function code that you'll use to subscribe to an Amazon SNS topic is provided in various languages.
Select one of the languages and follow the corresponding instructions to create a deployment package.
• Create an IAM role (execution role). At the time you upload the deployment package, you need to specify
an IAM role (execution role) that Lambda can assume to execute the function on your behalf.
Topics
• Step 2.1: Create a Lambda Function Deployment Package (p. 223)
• Step 2.2: Create the Execution Role (IAM Role) (p. 225)
Step 2.1: Create a Lambda Function Deployment Package
From the Filter View list, choose the language you want to use for your Lambda function. The appropriate
section appears with code and specific instructions for creating a deployment package.
Node.js
1.
Open a text editor, and then copy the following code.
console.log('Loading function');
exports.handler = function(event, context, callback) {
// console.log('Received event:', JSON.stringify(event, null, 4));
var message = event.Records[0].Sns.Message;
console.log('Message received from SNS:', message);
callback(null, "Success");
};
Note
2.
3.
The code sample is compliant with the Node.js runtimes v6.10 or v4.3. For more information,
see Programming Model (Node.js) (p. 9)
Save the file as index.js.
Zip the index.js file as LambdaWithSNS.zip.
Next Step
Step 2.2: Create the Execution Role (IAM Role) (p. 225)
Java
Open a text editor, and then copy the following code.
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package example;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import com.amazonaws.services.lambda.runtime.RequestHandler;
import com.amazonaws.services.lambda.runtime.Context;
import com.amazonaws.services.lambda.runtime.events.SNSEvent;
public class LogEvent implements RequestHandler<SNSEvent, Object> {
public Object handleRequest(SNSEvent request, Context context){
String timeStamp = new SimpleDateFormat("yyyy-MMdd_HH:mm:ss").format(Calendar.getInstance().getTime());
context.getLogger().log("Invocation started: " + timeStamp);
context.getLogger().log(request.getRecords().get(0).getSNS().getMessage());
timeStamp = new SimpleDateFormat("yyyy-MMdd_HH:mm:ss").format(Calendar.getInstance().getTime());
context.getLogger().log("Invocation completed: " + timeStamp);
return null;
}
}
Using the preceding code (in a file named LambdaWithSNS.java), create a deployment package. Make sure
that you add the following dependencies:
• aws-lambda-java-core
• aws-lambda-java-events
For more information, see Programming Model for Authoring Lambda Functions in Java (p. 23).
Your deployment package can be a .zip file or a standalone .jar. You can use any build and packaging
tool you are familiar with to create a deployment package. For examples of how to use the Maven build
tool to create a standalone .jar, see Creating a .jar Deployment Package Using Maven without any IDE
(Java) (p. 64) and Creating a .jar Deployment Package Using Maven and Eclipse IDE (Java) (p. 66). For an
example of how to use the Gradle build tool to create a .zip file, see Creating a .zip Deployment Package
(Java) (p. 68).
After you verify that your deployment package is created, go to the next step to create an IAM role
(execution role). You specify this role at the time you create your Lambda function.
Next Step
Step 2.2: Create the Execution Role (IAM Role) (p. 225)
Python
1.
Open a text editor, and then copy the following code.
from __future__ import print_function
import json
print('Loading function')
def lambda_handler(event, context):
#print("Received event: " + json.dumps(event, indent=2))
message = event['Records'][0]['Sns']['Message']
print("From SNS: " + message)
return message
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2.
Save the file as lambda_handler.py.
3.
Zip the lambda_handler.py file as LambdaWithSNS.zip.
Next Step
Step 2.2: Create the Execution Role (IAM Role) (p. 225)
Step 2.2: Create the Execution Role (IAM Role)
In this section, you create an IAM role using the following predefined role type and access policy:
• AWS service role of the type AWS Lambda – This role grants AWS Lambda permissions to assume the
role.
• AWSLambdaBasicExecutionRole – This is the access permissions policy that you attach to the role.
For more information about IAM roles, see IAM Roles in the IAM User Guide. Use the following procedure
to create the IAM role.
To create an IAM role (execution role)
1.
Sign in to the IAM console at https://console.aws.amazon.com/iam/.
2.
Follow the steps in Creating a Role to Delegate Permissions to an AWS Service in the IAM User Guide
to create an IAM role (execution role). As you follow the steps to create a role, note the following:
3.
• In Role Name, use a name that is unique within your AWS account (for example, lambda-snsexecution-role).
• In Select Role Type, choose AWS Service Roles, and then choose AWS Lambda. This grants the
AWS Lambda service permissions to assume the role.
• In Attach Policy, choose AWSLambdaBasicExecutionRole. The permissions in this policy are
sufficient for the Lambda function in this tutorial.
Write down the role ARN. You will need it in the next step when you create your Lambda function.
Step 3: Set Up Cross-Account Permissions
In this section, you use CLI commands to set permissions across the Lambda function account and the
Amazon SNS topic account and then test the subscription.
1. From account A, create the Amazon SNS topic:
aws sns create-topic \
--name lambda-x-account
Note the topic arn that is returned by the command. You will need it when you add permissions to the
Lambda function to subscribe to the topic.
2. From account B, create the Lambda function. For the runtime parameter, select either nodejs6.10,
nodejs4.3, python2.7 or java8, depending on the code sample you selected when you created your
deployment package.
aws lambda create-function \
--function-name SNS-X-Account \
--runtime runtime language \
--role role arn \
--handler handler-name \
--description "SNS X Account Test Function" \
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--timeout 60 \
--memory-size 128 \
--zip-file fileb://path/LambdaWithSNS.zip
Note the function arn that is returned by the command. You will need it when you add permissions to
allow Amazon SNS to invoke your function.
3. From account A add permission to account B to subscribe to the topic:
aws sns add-permission \
--region us-east-1 \
--topic-arn Amazon SNS topic arn \
--label lambda-access \
--aws-account-id B \
--action-name Subscribe ListSubscriptionsByTopic Receive
4. From account B add the Lambda permission to allow invocation from Amazon SNS:
aws lambda add-permission \
--function-name SNS-X-Account \
--statement-id sns-x-account \
--action "lambda:InvokeFunction" \
--principal sns.amazonaws.com \
--source-arn Amazon SNS topic arn
In response, Lambda returns the following JSON code. The Statement value is a JSON string version of
the statement added to the Lambda function policy:
{
"Statement": "{\"Condition\":{\"ArnLike\":{\"AWS:SourceArn\":\"arn:aws:lambda:useast-1:B:function:SNS-X-Account\"}},\"Action\":[\"lambda:InvokeFunction\"],\"Resource\":
\"arn:aws:lambda:us-east-1:A:function:SNS-X-Account\",\"Effect\":\"Allow\",\"Principal
\":{\"Service\":\"sns.amazonaws.com\"},\"Sid\":\"sns-x-account1\"}"
}
Note
Do not use the --source-account parameter to add a source account to the Lambda policy when
adding the policy. Source account is not supported for Amazon SNS event sources and will
result in access being denied. This has no security impact as the source account is included in
the source ARN.
5. From account B subscribe the Lambda function to the topic:
aws sns subscribe \
--topic-arn Amazon SNS topic arn \
--protocol lambda \
--notification-endpoint arn:aws:lambda:us-east-1:B:function:SNS-X-Account
You should see JSON output similar to the following:
{
"SubscriptionArn": "arn:aws:sns:us-east-1:A:lambda-x-account:5d906xxxx-7c8x-45dxa9dx-0484e31c98xx"
}
6. From account A you can now test the subscription. Type "Hello World" into a text file and save it as
message.txt. Then run the following command:
aws sns publish \
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--topic-arn arn:aws:sns:us-east-1:A:lambda-x-account \
--message file://message.txt \
--subject Test
This will return a message id with a unique identifier, indicating the message has been accepted by the
Amazon SNS service. Amazon SNS will then attempt to deliver it to the topic's subscribers.
Note
Alternatively, you could supply a JSON string directly to the message parameter, but using a text
file allows for line breaks in the message.
For more information on Amazon SNS, see What is Amazon Simple Notification Service?
Using AWS Lambda with Amazon API Gateway
(On-Demand Over HTTPS)
You can invoke AWS Lambda functions over HTTPS. You can do this by defining a custom REST API
and endpoint using Amazon API Gateway, and then mapping individual methods, such as GET and PUT, to
specific Lambda functions. Alternatively, you could add a special method named ANY to map all supported
methods (GET, POST, PATCH, DELETE) to your Lambda function. When you send an HTTPS request to the
API endpoint, the Amazon API Gateway service invokes the corresponding Lambda function. For more
information about the ANY method, see Step 3: Create a Simple Microservice using Lambda and API
Gateway (p. 166).
Amazon API Gateway also adds a layer between your application users and your app logic that enables the
following:
• Ability to throttle individual users or requests.
• Protect against Distributed Denial of Service attacks.
• Provide a caching layer to cache response from your Lambda function.
Note the following about how the Amazon API Gateway and AWS Lambda integration works:
• Push-event model – This is a model (see Event Source Mapping (p. 116)), where Amazon API Gateway
invokes the Lambda function by passing data in the request body as parameter to the Lambda function.
• Synchronous invocation – The Amazon API Gateway can invoke the Lambda function and get a
response back in real time by specifying RequestResponse as the invocation type. For information about
invocation types, see Invocation Types (p. 4).
• Event structure – The event your Lambda function receives is the body from the HTTPS request that
Amazon API Gateway receives and your Lambda function is the custom code written to process the
specific event type.
Note that there are two types of permissions policies that you work with when you set up the end-to-end
experience:
• Permissions for your Lambda function – Regardless of what invokes a Lambda function, AWS
Lambda executes the function by assuming the IAM role (execution role) that you specify at the time
you create the Lambda function. Using the permissions policy associated with this role, you grant your
Lambda function the permissions that it needs. For example, if your Lambda function needs to read an
object, you grant permissions for the relevant Amazon S3 actions in the permissions policy. For more
information, see Manage Permissions: Using an IAM Role (Execution Role) (p. 150).
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• Permission for Amazon API Gateway to invoke your Lambda function – Amazon API Gateway
cannot invoke your Lambda function without your permission. You grant this permission via the
permission policy associated with the Lambda function.
For a tutorial that walks you through an example setup, see Using AWS Lambda with Amazon API
Gateway (On-Demand Over HTTPS) (p. 228).
Using AWS Lambda with Amazon API Gateway (OnDemand Over HTTPS)
In this example you create a simple API (DynamoDBOperations) using Amazon API Gateway. An Amazon
API Gateway is a collection of resources and methods. For this tutorial, you create one resource
(DynamoDBManager) and define one method (POST) on it. The method is backed by a Lambda function
(LambdaFunctionForAPIGateway). That is, when you invoke the method through an HTTPS endpoint,
Amazon API Gateway invokes the Lambda function.
The POST method on the DynamoDBManager resource supports the following DynamoDB operations:
• Create, update, and delete an item.
• Read an item.
• Scan an item.
• Other operations (echo, ping), not related to DynamoDB, that you can use for testing.
The request payload you send in the POST request identifies the DynamoDB operation and provides
necessary data. For example:
• The following is a sample request payload for a DynamoDB put item operation:
{
"operation": "create",
"tableName": "LambdaTable",
"payload": {
"Item": {
"Id": "1",
"name": "Bob"
}
}
}
• The following is a sample request payload for a DynamoDB read item operation:
{
"operation": "read",
"tableName": "LambdaTable",
"payload": {
"Key": {
"Id": "1"
}
}
}
• The following is a sample request payload for a the echo operation. You will then send HTTPS PUT
request to the endpoint, using the following data in the request body.
{
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"operation": "echo",
"payload": {
"somekey1": "somevalue1",
"somekey2": "somevalue2"
}
}
You can also create and manage API endpoints from the AWS Lambda console. For example, search
for the microservice in the blueprints. This tutorial does not use the console, instead it uses AWS CLI to
provide you with more details of how the API works.
Note
API Gateway offers advanced capabilities, such as:
• Pass through the entire request – A Lambda function can receive the entire HTTP request
(instead of just the request body) and set the HTTP response (instead of just the response body)
using the AWS_PROXY integration type.
• Catch-all methods – Map all methods of an API resource to a single function with a single
mapping, using the ANY catch-all method.
• Catch-all resources – Map all sub-paths of a resource to a Lambda function without any
additional configuration using the new path parameter ({proxy+}).
To learn more about these API Gateway features, see Configure Proxy Integration for a Proxy
Resource.
Next Step
Step 1: Prepare (p. 229)
Step 1: Prepare
Make sure you have completed the following steps:
• Signed up for an AWS account and created an administrator user in the account.
• Installed and set up the AWS CLI.
For instructions, see Step 1: Set Up an AWS Account and the AWS CLI (p. 155).
Important
This example uses the region region to create an API using Amazon API Gateway and a Lambda
function.
Next Step
Step 2: Create a Lambda Function and Test It Manually (p. 229)
Step 2: Create a Lambda Function and Test It Manually
In this section, you do the following:
• Create a Lambda function deployment package using the sample code provided.
• Create an IAM role (execution role). At the time you upload the deployment package, you need to specify
an IAM role (execution role) that Lambda can assume to execute the function on your behalf.
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• Create the Lambda function and then test it manually.
Topics
• Step 2.1: Create a Deployment Package (p. 230)
• Step 2.2: Create the Execution Role (IAM Role) (p. 232)
• Step 2.3: Create the Lambda Function and Test It Manually (p. 233)
Step 2.1: Create a Deployment Package
From the Filter View list, choose the language you want to use for your Lambda function. The appropriate
section appears with code and specific instructions for creating a deployment package.
Node.js
Follow the instructions to create a AWS Lambda function deployment package.
1.
Open a text editor, and then copy the following code.
console.log('Loading function');
var AWS = require('aws-sdk');
var dynamo = new AWS.DynamoDB.DocumentClient();
/**
* Provide an event that contains the following keys:
*
*
- operation: one of the operations in the switch statement below
*
- tableName: required for operations that interact with DynamoDB
*
- payload: a parameter to pass to the operation being performed
*/
exports.handler = function(event, context, callback) {
//console.log('Received event:', JSON.stringify(event, null, 2));
var operation = event.operation;
if (event.tableName) {
event.payload.TableName = event.tableName;
}
switch (operation) {
case 'create':
dynamo.put(event.payload, callback);
break;
case 'read':
dynamo.get(event.payload, callback);
break;
case 'update':
dynamo.update(event.payload, callback);
break;
case 'delete':
dynamo.delete(event.payload, callback);
break;
case 'list':
dynamo.scan(event.payload, callback);
break;
case 'echo':
callback(null, "Success");
break;
case 'ping':
callback(null, "pong");
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break;
default:
callback('Unknown operation: ${operation}');
}
};
Note
The code sample is compliant with the Node.js runtimes v6.10 or v4.3. For more information,
see Programming Model (Node.js) (p. 9)
2.
Save the file as LambdaFunctionOverHttps.js.
3.
Zip the LambdaFunctionOverHttps.js file as LambdaFunctionOverHttps.zip.
Next Step
Step 2.2: Create the Execution Role (IAM Role) (p. 232)
Python
Follow the instructions to create AWS Lambda function deployment package.
1.
Open a text editor, and then copy the following code.
from __future__ import print_function
import boto3
import json
print('Loading function')
def handler(event, context):
'''Provide an event that contains the following keys:
- operation: one of the operations in the operations dict below
- tableName: required for operations that interact with DynamoDB
- payload: a parameter to pass to the operation being performed
'''
#print("Received event: " + json.dumps(event, indent=2))
operation = event['operation']
if 'tableName' in event:
dynamo = boto3.resource('dynamodb').Table(event['tableName'])
operations = {
'create': lambda x: dynamo.put_item(**x),
'read': lambda x: dynamo.get_item(**x),
'update': lambda x: dynamo.update_item(**x),
'delete': lambda x: dynamo.delete_item(**x),
'list': lambda x: dynamo.scan(**x),
'echo': lambda x: x,
'ping': lambda x: 'pong'
}
if operation in operations:
return operations[operation](event.get('payload'))
else:
raise ValueError('Unrecognized operation "{}"'.format(operation))
2.
Save the file as LambdaFunctionOverHttps.py.
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3.
Zip the LambdaFunctionOverHttps.py file as LambdaFunctionOverHttps.zip.
Next Step
Step 2.2: Create the Execution Role (IAM Role) (p. 232)
Step 2.2: Create the Execution Role (IAM Role)
In this section, you create an IAM role using the following predefined role type:
• AWS service role of the type AWS Lambda – This role grants AWS Lambda permissions to assume the
role.
For more information about IAM roles, see IAM Roles in the IAM User Guide. Use the following procedure
to create the IAM role.
To create an IAM role (execution role)
1.
Sign in to the IAM console at https://console.aws.amazon.com/iam/.
2.
Follow the steps in Creating a Role to Delegate Permissions to an AWS Service in the IAM User Guide
to create an IAM role (execution role). As you follow the steps to create a role, note the following:
• In Role Name, use a name that is unique within your AWS account (for example, lambda-gatewayexecution-role).
• In Select Role Type, choose AWS Service Roles, and then choose AWS Lambda. This grants the
AWS Lambda service permissions to assume the role.
• You create an IAM role without attaching a permissions policy in the console. After you create the
role, you update the role, and then attach the following permissions policy to the role.
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "Stmt1428341300017",
"Action": [
"dynamodb:DeleteItem",
"dynamodb:GetItem",
"dynamodb:PutItem",
"dynamodb:Query",
"dynamodb:Scan",
"dynamodb:UpdateItem"
],
"Effect": "Allow",
"Resource": "*"
},
{
"Sid": "",
"Resource": "*",
"Action": [
"logs:CreateLogGroup",
"logs:CreateLogStream",
"logs:PutLogEvents"
],
"Effect": "Allow"
}
]
}
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3.
Write down the role ARN (Amazon Resource Name). You need it in the next step when you create
your Lambda function.
Next Step
Step 2.3: Create the Lambda Function and Test It Manually (p. 233)
Step 2.3: Create the Lambda Function and Test It Manually
In this section, you do the following:
• Create a Lambda function by uploading the deployment package.
• Test the Lambda function by invoking it manually and passing sample event data.
Step 2.3.1: Create a Lambda Function (Upload the Deployment Package)
In this step, you upload the deployment package using the AWS CLI.
At the command prompt, run the following Lambda CLI create-function command using the adminuser
profile.
You need to update the command by providing the .zip file path and the execution role ARN. The -runtime parameter value can be python2.7, nodejs6.10, nodejs4.3, or java8, depending on the language
you used to author your code.
$ aws lambda create-function \
--region region \
--function-name LambdaFunctionOverHttps \
--zip-file fileb://file-path/LambdaFunctionOverHttps.zip \
--role execution-role-arn \
--handler LambdaFunctionOverHttps.handler \
--runtime runtime-value \
--profile adminuser
Optionally, you can upload the .zip file to an Amazon S3 bucket in the same AWS region, and then specify
the bucket and object name in the preceding command. You need to replace the --zip-file parameter by
the --code parameter, as shown following:
--code S3Bucket=bucket-name,S3Key=zip-file-object-key
Note
You can create the Lambda function using the AWS Lambda console, in which case note the value
of the create-function AWS CLI command parameters. You provide the same values in the
console UI.
Step 2.3.2: Test the Lambda Function (Invoke Manually)
Invoke the function manually using the sample event data. We recommend that you invoke the function
using the console because the console UI provides a user-friendly interface for reviewing the execution
results, including the execution summary, logs written by your code, and the results returned by the function
(because the console always performs synchronous execution—invokes the Lambda function using the
RequestResponse invocation type).
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To test the Lambda function (AWS Management Console)
1.
Follow the steps in the Getting Started exercise to create and invoke the Lambda function at Step 2.2:
Invoke the Lambda Function Manually and Verify Results, Logs, and Metrics (p. 162). For the sample
event for testing, choose Hello World in Sample event template, and then replace the data using the
following:
{
"operation": "echo",
"payload": {
"somekey1": "somevalue1",
"somekey2": "somevalue2"
}
}
2.
To test one of the dynamo operations, such as read, change the input data to the following:
{
"operation": "read",
"tableName": "the name of your stream table",
"payload": {
"Key": {
"the primary key of the table": "the value of the key"
}
}
}
3.
Verify the results in the console.
To test the Lambda function (AWS CLI)
1.
Copy the following JSON into a file and save it as input.txt.
{
"operation": "echo",
"payload": {
"somekey1": "somevalue1",
"somekey2": "somevalue2"
}
}
2.
Execute the following invoke command:
$ aws lambda invoke \
--invocation-type Event \
--function-name LambdaFunctionOverHttps \
--region region \
--payload file://file-path/input.txt \
--profile adminuser
outputfile.txt
Note
In this tutorial example, the message is saved in the outputfile.txt file if you request
synchronous execution (RequestResponse as the invocation type). The function returns the
string message in the response body. If you use the Event invocation type, no message is
returned to the output file. In either case, the outputfile.txt parameter is required.
For Node.js, it could be one of the following (whatever one you specify in the code):
context.succeed("message")
context.fail("message")
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context.done(null, "message)
For Python or Java, it is the message in the return statement:
return "message"
Next Step
Step 3: Create an API Using Amazon API Gateway and Test It (p. 235)
Step 3: Create an API Using Amazon API Gateway and Test It
In this step, you associate your Lambda function with a method in the API that you created using Amazon
API Gateway and test the end-to-end experience. That is, when an HTTPS request is sent to an API
method, Amazon API Gateway invokes your Lambda function.
First, you create an API (DynamoDBOperations) using Amazon API Gateway with one resource
(DynamoDBManager) and one method (POST). You associate the POST method with your Lambda function.
Then, you test the end-to-end experience.
Step 3.1: Create the API
Run the following create-rest-api command to create the DynamoDBOperations API for this tutorial.
$ aws apigateway create-rest-api \
--name DynamoDBOperations
The following is an example response:
{
"name": "DynamoDBOperations",
"id": "api-id",
"createdDate": 1447724091
}
Note the API ID.
You also need the ID of the API root resource. To get the ID, run the get-resources command.
$ aws apigateway get-resources \
--rest-api-id api-id
The following is example response (at this time you only have the root resource, but you add more
resources in the next step):
{
"items": [
{
"path": "/",
"id": "root-id"
}
]
}
Step 3.2: Create a Resource (DynamoDBManager) in the API
Run the following create-resource command to create a resource (DynamoDBManager) in the API that you
created in the preceding section.
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$ aws apigateway create-resource \
--rest-api-id api-id \
--parent-id root-id \
--path-part DynamoDBManager
The following is an example response:
{
"path": "/DynamoDBManager",
"pathPart": "DynamoDBManager",
"id": "resource-id",
"parentId": "root-id"
}
Note the ID in the response. This is the ID of the resource (DynamoDBManager) that you created.
Step 3.3: Create Method (POST) on the Resource
Run the following put-method command to create a method (POST) on the resource (DynamoDBManager) in
your API (DynamoDBOperations).
$ aws apigateway put-method \
--rest-api-id api-id \
--resource-id resource-id \
--http-method POST \
--authorization-type NONE
We specify NONE for the --authorization-type parameter, which means that unauthenticated requests for
this method are supported. This is fine for testing but in production you should use either the key-based or
role-base authentication.
The following is an example response:
{
"apiKeyRequired": false,
"httpMethod": "POST",
"authorizationType": "NONE"
}
Step 3.4: Set the Lambda Function as the Destination for the POST Method
Run the following command to set the Lambda function as the integration point for the POST method (this
is the method Amazon API Gateway invokes when you make an HTTPS request for the POST method
endpoint).
$ aws apigateway put-integration \
--rest-api-id api-id \
--resource-id resource-id \
--http-method POST \
--type AWS \
--integration-http-method POST \
--uri arn:aws:apigateway:aws-region:lambda:path/2015-03-31/functions/arn:aws:lambda:awsregion:aws-acct-id:function:your-lambda-function-name/invocations
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Note
• --rest-api-id is the ID of the API (DynamoDBOperations) that you created in Amazon API
Gateway.
• --resource-id is the resource ID of the resource (DynamoDBManager) you created in the API
• --http-method is the API Gateway method and --integration-http-method is the method that
API Gateway uses to communicate with AWS Lambda.
• --uri is unique identifier for the endpoint to which Amazon API Gateway can send request.
The following is an example response:
{
"httpMethod": "POST",
"type": "AWS",
"uri": "arn:aws:apigateway:region:lambda:path/2015-03-31/functions/
arn:aws:lambda:region:aws-acct-id:function:LambdaFunctionForAPIGateway/invocations",
"cacheNamespace": "resource-id"
}
Set content-type of the POST method response and integration response to JSON as follows:
• Run the following command to set the POST method response to JSON. This is the response type that
your API method returns.
$ aws apigateway put-method-response \
--rest-api-id api-id \
--resource-id resource-id \
--http-method POST \
--status-code 200 \
--response-models "{\"application/json\": \"Empty\"}"
• Run the following command to set the POST method integration response to JSON. This is the response
type that Lambda function returns.
$ aws apigateway put-integration-response \
--rest-api-id api-id \
--resource-id resource-id \
--http-method POST \
--status-code 200 \
--response-templates "{\"application/json\": \"\"}"
Step 3.5: Deploy the API
In this step, you deploy the API that you created to a stage called prod.
$ aws apigateway create-deployment \
--rest-api-id api-id \
--stage-name prod
The following is an example response:
{
"id": "deployment-id",
"createdDate": 1447726017
}
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Step 3.6: Grant Permissions that Allows Amazon API Gateway to Invoke the
Lambda Function
Now that you have an API created using Amazon API Gateway and you've deployed it, you can test. First,
you need to add permissions so that Amazon API Gateway can invoke your Lambda function when you
send HTTPS request to the POST method.
To do this, you need to add a permissions to the permissions policy associated with your Lambda
function. Run the following add-permission AWS Lambda command to grant the Amazon API
Gateway service principal (apigateway.amazonaws.com) permissions to invoke your Lambda function
(LambdaFunctionForAPIGateway).
$ aws lambda add-permission \
--function-name LambdaFunctionOverHttps \
--statement-id apigateway-test-2 \
--action lambda:InvokeFunction \
--principal apigateway.amazonaws.com \
--source-arn "arn:aws:execute-api:region:aws-acct-id:api-id/*/POST/DynamoDBManager"
You must grant this permission to enable testing (if you go to the Amazon API Gateway and choose Test
to test the API method, you need this permission). Note the --source-arn specifies a wildcard character (*)
as the stage value (indicates testing only). This allows you to test without deploying the API.
Now, run the same command again, but this time you grant to your deployed API permissions to invoke the
Lambda function.
$ aws lambda add-permission \
--function-name LambdaFunctionOverHttps \
--statement-id apigateway-prod-2 \
--action lambda:InvokeFunction \
--principal apigateway.amazonaws.com \
--source-arn "arn:aws:execute-api:region:aws-acct-id:api-id/prod/POST/DynamoDBManager"
You grant this permission so that your deployed API has permissions to invoke the Lambda function. Note
that the --source-arn specifies a prod which is the stage name we used when deploying the API.
Step 3.7: Test Sending an HTTPS Request
In this step, you are ready to send an HTTPS request to the POST method endpoint. You can use either Curl
or a method (test-invoke-method) provided by Amazon API Gateway.
If you want to test operations that your Lambda function supports on a DynamoDB table, first you need to
create a table in Amazon DynamoDB LambdaTable (Id), where Id is the hash key of string type.
If you are testing the echo and ping operations that your Lambda function supports, you don't need to
create the DynamoDB table.
You can use Amazon API Gateway CLI commands to send an HTTPS POST request to the resource
(DynamoDBManager) endpoint. Because you deployed your Amazon API Gateway, you can use Curl to
invoke the methods for the same operation.
The Lambda function supports using the create operation to create an item in your DynamoDB table. To
request this operation, use the following JSON:
{
"operation": "create",
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"tableName": "LambdaTable",
"payload": {
"Item": {
"Id": "foo",
"number": 5
}
}
}
Run the test-invoke-method Amazon API Gateway command to send an HTTPS POST method request to
the resource (DynamoDBManager) endpoint with the preceding JSON in the request body.
$ aws apigateway test-invoke-method \
--rest-api-id api-id \
--resource-id resource-id \
--http-method POST \
--path-with-query-string "" \
--body "{\"operation\":\"create\",\"tableName\":\"LambdaTable\",\"payload\":{\"Item\":{\"Id
\":\"1\",\"name\":\"Bob\"}}}"
Or, you can use the following Curl command:
curl -X POST -d "{\"operation\":\"create\",\"tableName\":\"LambdaTable\",\"payload
\":{\"Item\":{\"Id\":\"1\",\"name\":\"Bob\"}}}" https://api-id.execute-api.awsregion.amazonaws.com/prod/DynamoDBManager
To send request for the echo operation that your Lambda function supports, you can use the following
request payload:
{
"operation": "echo",
"payload": {
"somekey1": "somevalue1",
"somekey2": "somevalue2"
}
}
Run the test-invoke-method Amazon API Gateway CLI command to send an HTTPS POST method
request to the resource (DynamoDBManager) endpoint using the preceding JSON in the request body.
$ aws apigateway test-invoke-method \
--rest-api-id api-id \
--resource-id resource-id \
--http-method POST \
--path-with-query-string "" \
--body "{\"operation\":\"echo\",\"payload\":{\"somekey1\":\"somevalue1\",\"somekey2\":
\"somevalue2\"}}"
Or, you can use the following Curl command:
curl -X POST -d "{\"operation\":\"echo\",\"payload\":{\"somekey1\":\"somevalue1\",
\"somekey2\":\"somevalue2\"}}" https://api-id.execute-api.region.amazonaws.com/prod/
DynamoDBManager
Step 4: Deploy With AWS SAM and AWS CloudFormation
In the previous section, you used AWS Lambda APIs to create and update a Lambda function by providing
a deployment package as a ZIP file. However, this mechanism may not be convenient for automating
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deployment steps for functions, or coordinating deployments and updates to other elements of a serverless
application, like event sources and downstream resources.
You can use AWS CloudFormation to easily specify, deploy, and configure serverless applications. AWS
CloudFormation is a service that helps you model and set up your Amazon Web Services resources so
that you can spend less time managing those resources and more time focusing on your applications
that run in AWS. You create a template that describes all the AWS resources that you want (like Lambda
functions and DynamoDB tables), and AWS CloudFormation takes care of provisioning and configuring
those resources for you.
In addition, you can use the AWS Serverless Application Model to express resources that comprise the
serverless application. These resource types, such as Lambda functions and APIs, are fully supported by
AWS CloudFormation and make it easier for you to define and deploy your serverless application.
For more information, see Deploying Lambda-based Applications (p. 133).
Specification for Amazon API Gateway Application
The following contains the SAM template for this application. Copy the text below to a .yaml file and save
it next to the ZIP package you created previously. Note that the Handler and Runtime parameter values
should match the ones you used when you created the function in the previous section.
AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Resources:
LambdaFunctionOverHttps:
Type: AWS::Serverless::Function
Properties:
Handler: handler
Runtime: runtime
Policies: AmazonDynamoDBFullAccess
Events:
HttpPost:
Type: Api
Properties:
Path: 'DynamoDBOperations/DynamoDBManager'
Method: post
Deploying the Serverless Application
For information on how to package and deploy your serverless application using the package and deploy
commands, see Packaging and Deployment (p. 139).
Using AWS Lambda as Mobile Application Backend
(Custom Event Source: Android)
You can use AWS Lambda to host backend logic for mobile applications. That is, some of your mobile app
code can be run as Lambda functions. This allows you to put minimal logic in the mobile application itself
making it easy to scale and update (for example, you only apply code updates to the Lambda function,
instead of having to deploy code updates in your app clients).
After you create the Lambda function, you can invoke it from your mobile app using AWS Mobile SDKs,
such as the AWS SDK for Android. For more information, see Tools for Amazon Web Services.
Note
You can also invoke your Lambda function over HTTP using Amazon API Gateway (instead of
using any of the AWS SDKs). Amazon API Gateway adds an additional layer between your mobile
users and your app logic that enable the following:
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• Ability to throttle individual users or requests.
• Protect against Distributed Denial of Service attacks.
• Provide a caching layer to cache response from your Lambda function.
Note the following about how the mobile application and AWS Lambda integration works:
• Push-event model – This is a model (see Event Source Mapping (p. 116)), where the app invokes the
Lambda function by passing the event data as parameter.
• Synchronous or asynchronous invocation – The app can invoke the Lambda function and get a
response back in real time by specifying RequestResponse as the invocation type (or use the Event
invocation type for asynchronous invocation). For information about invocation types, see Manage
Permissions: Using a Lambda Function Policy (p. 151).
• Event structure – The event your Lambda function receives is defined by your application, and your
Lambda function is the custom code written to process the specific event type.
Note that there are two types of permissions policies that you work with in setting the end-to-end
experience:
• Permissions for your Lambda function – Regardless of what invokes a Lambda function, AWS
Lambda executes the function by assuming the IAM role (execution role) that you specify at the time
you create the Lambda function. Using the permissions policy associated with this role, you grant your
Lambda function the permissions that it needs. For example, if your Lambda function needs to read an
object, you grant permissions for the relevant Amazon S3 actions in the permissions policy. For more
information, see Manage Permissions: Using an IAM Role (Execution Role) (p. 150).
• Permissions for the mobile app to invoke your Lambda function – The application must have valid
security credentials and permissions to invoke a Lambda function. For mobile applications, you can use
the Amazon Cognito service to manage user identities, authentication, and permissions.
The following diagram illustrates the application flow (the illustration assumes a mobile app using AWS
Mobile SDK for Android to make the API calls):
1. The mobile application sends a request to Amazon Cognito with an identity pool ID in the request (you
create the identity pool as part the setup).
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2. Amazon Cognito returns temporary security credentials back to the application.
Amazon Cognito assumes the role associated with the identity pool to generate temporary credentials.
What the application can do using the credentials is limited to the permissions defined in the permissions
policy associated with the role Amazon Cognito used in obtaining the temporary credential.
Note
The AWS SDK can cache the temporary credentials so that the application does not send a
request to Amazon Cognito each time it needs to invoke a Lambda function.
3. The mobile application invokes the Lambda function using temporary credentials (Cognito Identity).
4. AWS Lambda assumes the execution role to execute your Lambda function on your behalf.
5. The Lambda function executes.
6. AWS Lambda returns results to the mobile application, assuming the app invoked the Lambda function
using the RequestResponse invocation type (synchronous invocation).
For a tutorial that walks you through an example setup, see Tutorial: Using AWS Lambda as Mobile
Application Backend (p. 242).
Tutorial: Using AWS Lambda as Mobile Application
Backend
In this tutorial, you create a simple Android mobile application. The primary purpose of this tutorial is to
show you how to hook up various components to enable an Android mobile application to invoke a Lambda
function and process response. The app itself is simple, we will assume following:
• The sample mobile application will generate event data consisting of a name (first name and last name)
in this format:
{ firstName: 'value1', lastName: 'value2' }
• You use Lambda function to process the event. That is, the app (using the AWS Mobile SDK for Android)
invokes a Lambda function (ExampleAndroidEventProcessor) by passing the event data to it. The
Lambda function in this tutorial does the following:
• Logs incoming event data to Amazon CloudWatch Logs.
• Upon successful execution, returns a simple string in the response body. Your mobile app displays the
message using the Android Toast class.
Note
The way that the mobile application invokes a Lambda function as shown in this tutorial is an
example of the AWS Lambda request-response model in which an application invokes a Lambda
function and then receives a response in real time. For more information, see Programming
Model (p. 8).
Implementation Summary
The tutorial is divided into two main sections:
• First, you perform the necessary setup to create a Lambda function and test it by invoking it manually
using sample event data (you don't need mobile app to test your Lambda function).
• Second, you create an Amazon Cognito identity pool to manage authentication and permissions, and
create the example Android application. Then, you run the application and it invokes the Lambda
function. You can then verify the end-to-end experience. In this tutorial example:
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• You use the Amazon Cognito service to manage user identities, authentication, and permissions. The
mobile application must have valid security credentials and permissions to invoke a Lambda function.
As part of the application setup, you create an Amazon Cognito identity pool to store user identities
and define permissions. For more information, see Amazon Cognito
• This mobile application does not require its users to log in. A mobile application can require its users
to log in using public identity providers such as Amazon and Facebook. The scope of this tutorial
is limited and assumes that the mobile application users are unauthenticated. Therefore, when you
configure Amazon Cognito identity pool you will do the following:
• Enable access for unauthenticated identities.
Amazon Cognito provides a unique identifier and temporary AWS credentials for these users to
invoke the Lambda function.
• In the access permissions policy associated with the IAM role for unauthenticated users, add
permissions to invoke the Lambda function. An identity pool has two associated IAM roles, one
for authenticated and one for unauthenticated application users. In this example, Amazon Cognito
assumes the role for unauthenticated users to obtain temporary credentials. When the app uses
these temporary credentials to invoke your Lambda function, it can do so only if has necessary
permissions (that is, credentials may be valid, but you also need permissions). You do this by
updating the permissions policy that Amazon Cognito uses to obtain the temporary credentials.
The following diagram illustrates the application flow:
Now you are ready to start the tutorial.
Next Step
Step 1: Prepare (p. 243)
Step 1: Prepare
Make sure you have completed the following steps:
• Signed up for an AWS account and created an administrator user in the account.
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• Installed and set up the AWS CLI.
For instructions, see Step 1: Set Up an AWS Account and the AWS CLI (p. 155).
Note
The tutorial creates a Lambda function and an Amazon Cognito identity pool in the us-east-1
region. If you want to use a different AWS region, you must create these resources in the same
region. You also need to update the example mobile application code by providing the specific
region that you want to use.
Next Step
Step 2: Create the Lambda Function and Invoke It Manually (Using Sample Event Data) (p. 244)
Step 2: Create the Lambda Function and Invoke It Manually
(Using Sample Event Data)
In this section, you do the following:
• Create a Lambda function deployment package using the sample code provided. The sample Lambda
function code to process your mobile application events is provided in various languages. Select one of
the languages and follow the corresponding instructions to create a deployment package.
Note
To see more examples of using other AWS services within your function, including calling other
Lambda functions, see AWS SDK for JavaScript
• Create an IAM role (execution role). At the time you upload the deployment package, you need to specify
an IAM role (execution role). This is the role that AWS Lambda assumes to invoke your Lambda function
on your behalf.
• Create the Lambda function by uploading the deployment package, and then test it by invoking it
manually using sample event data.
Topics
• Step 2.1: Create a Deployment Package (p. 244)
• Step 2.2: Create the Execution Role (IAM Role) (p. 246)
• Step 2.3: Create the Lambda Function and Invoke It Manually (Using Sample Event Data) (p. 247)
Step 2.1: Create a Deployment Package
From the Filter View list, choose the language you want to use for your Lambda function. The appropriate
section appears with code and specific instructions for creating a deployment package.
Node.js
Follow the instructions to create a AWS Lambda function deployment package.
1.
Open a text editor, and then copy the following code.
exports.handler = function(event, context, callback) {
console.log("Received event: ", event);
var data = {
"greetings": "Hello, " + event.firstName + " " + event.lastName + "."
};
callback(null, data);
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}
Note
2.
The code sample is compliant with the Node.js runtimes v6.10 or v4.3. For more information,
see Programming Model (Node.js) (p. 9)
Save the file as AndroidBackendLambdaFunction.js.
3.
Zip the AndroidBackendLambdaFunction.js file as AndroidBackendLambdaFunction.zip.
Next Step
Step 2.2: Create the Execution Role (IAM Role) (p. 246)
Java
Use the following Java code to create your Lambda function (AndroidBackendLambdaFunction). The code
receives Android app event data as the first parameter to the handler. Then, the code processes event
data (for illustration this code writes some of the event data to CloudWatch Logs and returns a string in
response).
In the code, the handler (myHandler) uses the RequestClass and ResponseClass types for the input and
output. The code provides implementation for these types.
Important
You use the same classes (POJOs) to handle the input and output data when you create the
sample mobile application in the next section.
package example;
import com.amazonaws.services.lambda.runtime.Context;
public class HelloPojo {
// Define two classes/POJOs for use with Lambda function.
public static class RequestClass {
String firstName;
String lastName;
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public RequestClass(String firstName, String lastName) {
this.firstName = firstName;
this.lastName = lastName;
}
public RequestClass() {
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}
}
public static class ResponseClass {
String greetings;
public String getGreetings() {
return greetings;
}
public void setGreetings(String greetings) {
this.greetings = greetings;
}
public ResponseClass(String greetings) {
this.greetings = greetings;
}
public ResponseClass() {
}
}
public static ResponseClass myHandler(RequestClass request, Context context){
String greetingString = String.format("Hello %s, %s.", request.firstName,
request.lastName);
context.getLogger().log(greetingString);
return new ResponseClass(greetingString);
}
}
Save the preceding code in a file (HelloPojo.java). Your can now create a deployment package. You
need to include the following dependency:
• aws-lambda-java-core
Your deployment package can be a .zip file or a standalone .jar. You can use any build and packaging
tool you are familiar with to create a deployment package. For examples of how to use the Maven build
tool to create a standalone .jar, see Creating a .jar Deployment Package Using Maven without any IDE
(Java) (p. 64) and Creating a .jar Deployment Package Using Maven and Eclipse IDE (Java) (p. 66). For an
example of how to use the Gradle build tool to create a .zip file, see Creating a .zip Deployment Package
(Java) (p. 68).
After you verify that your deployment package (lambda-java-example-1.0-SNAPSHOT.jar) is created, go to
the next section to create an IAM role (execution role). You specify the role when you create your Lambda
function.
Next Step
Step 2.2: Create the Execution Role (IAM Role) (p. 246)
Step 2.2: Create the Execution Role (IAM Role)
In this section, you create an IAM role using the following predefined role type and access policy:
• AWS service role of the type AWS Lambda – This role grants AWS Lambda permissions to assume the
role.
• AWSLambdaBasicExecute – This is the access permissions policy that you attach to the role.
This Lambda function only writes logs to CloudWatch Logs. So it only needs permission for specific
CloudWatch actions. This policy provides these permissions.
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For more information about IAM roles, see IAM Roles in the IAM User Guide. Use the following procedure
to create the IAM role.
To create an IAM role (execution role)
1.
2.
Sign in to the IAM console at https://console.aws.amazon.com/iam/.
Follow the steps in Creating a Role to Delegate Permissions to an AWS Service in the IAM User Guide
to create an IAM role (execution role). As you follow the steps to create a role, note the following:
• In Role Name, use a name that is unique within your AWS account (for example, lambda-androidexecution-role).
• In Select Role Type, choose AWS Service Roles, and then choose AWS Lambda. This grants the
AWS Lambda service permissions to assume the role.
• In Attach Policy, choose AWSLambdaBasicExecute. The permissions in this policy are sufficient
for the Lambda function in this tutorial.
3.
Write down the role ARN. You will need it in the next step when you create your Lambda function.
Next Step
Step 2.3: Create the Lambda Function and Invoke It Manually (Using Sample Event Data) (p. 247)
Step 2.3: Create the Lambda Function and Invoke It Manually (Using Sample
Event Data)
In this section, you do the following:
• Create a Lambda function, by uploading the deployment package.
• Test the Lambda function by invoking it manually. Instead of creating an event source, you use sample
event data. In the next section, you create an Android mobile app and test the end-to-end experience.
Step 2.3.1: Create a Lambda Function (Upload the Deployment Package)
In this step, you upload the deployment package using the AWS CLI.
At the command prompt, run the following Lambda CLI create-function command using the adminuser
profile.
You need to update the command by providing the .zip file path and the execution role ARN. The -runtime parameter value can be nodejs6.10, nodejs4.3, or java8, depending on the language you chose
to author your code.
$ aws lambda create-function \
--region us-east-1 \
--function-name AndroidBackendLambdaFunction \
--zip-file fileb://file-path-to-jar-or-zip-deployment-package \
--role execution-role-arn \
--handler handler-name \
--runtime runtime-value \
--profile adminuser
Optionally, you can upload the .zip file to an Amazon S3 bucket in the same AWS region, and then specify
the bucket and object name in the preceding command. You need to replace the --zip-file parameter by
the --code parameter, as shown following:
--code S3Bucket=bucket-name,S3Key=zip-file-object-key
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Note
You can create the Lambda function using the AWS Lambda console, in which case note the value
of the create-function AWS CLI command parameters. You provide the same values in the
console UI.
Step 2.3.2: Test the Lambda Function (Invoke Manually)
Invoke the function manually using the sample event data. We recommend that you invoke the function
using the console because the console UI provides a user-friendly interface for reviewing the execution
results, including the execution summary, logs written by your code, and the results returned by the function
(because the console always performs synchronous execution—invokes the Lambda function using the
RequestResponse invocation type).
To test the Lambda function (AWS Management Console)
1.
Follow the steps in the Getting Started exercise to create and invoke the Lambda function at Step 2.2:
Invoke the Lambda Function Manually and Verify Results, Logs, and Metrics (p. 162). After you choose
the Lambda function, choose Configure test event from the Actions menu to specify the following
sample event data:
{
2.
"firstName": "first-name",
"lastName": "last-name" }
Verify the results in the console.
• Execution result should be Succeeded with the following return value:
{
"greetings": "Hello first-name, last-name."
}
• Review the Summary and the Log output sections.
To test the Lambda function (AWS CLI)
1.
Save the following sample event JSON in a file, input.txt.
{
2.
"firstName": "first-name",
"lastName": "last-name" }
Execute the following invoke command:
$ aws lambda invoke \
--invocation-type Event \
--function-name AndroidBackendLambdaFunction \
--region us-east-1 \
--payload file://file-path/input.txt \
--profile adminuser
outputfile.txt
Note
In this tutorial example, the message is saved in the outputfile.txt file. If you request
synchronous execution (RequestResponse as the invocation type), the function returns the
string message in the response body.
For Node.js, it could be one of the following (whatever one you specify in the code):
context.succeed("message")
context.fail("message")
context.done(null, "message)
For Java, it is the message in the return statement:
return "message"
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Next Step
Step 3: Create an Amazon Cognito Identity Pool (p. 249)
Step 3: Create an Amazon Cognito Identity Pool
In this section, you create an Amazon Cognito identity pool. The identity pool has two IAM
roles. You update the IAM role for unauthenticated users and grant permissions to execute the
AndroidBackendLambdaFunction Lambda function.
For more information about IAM roles, see IAM Roles in the IAM User Guide. For more information about
Amazon Cognito services, see the Amazon Cognito product detail page.
To create an identity pool
1.
Using the IAM User Sign-In URL, sign in to the Amazon Cognito console as adminuser.
2.
Create a new identity pool called JavaFunctionAndroidEventHandlerPool. Before you follow the
procedure to create an identity pool, note the following:
• The identity pool you are creating must allow access to unauthenticated identities because
our example mobile application does not require a user log in (the application users are
unauthenticated). Therefore, make sure to select the Enable access to unauthenticated
identities option.
• The unauthenticated application users need permission to invoke the Lambda function. To
enable this, you will add the following statement to the permission policy associated with the
unauthenticated identities (it allows permission for the for the lambda:InvokeFunction action on the
specific Lambda function (you must update the resource ARN by providing your account ID).
{
"Effect": "Allow",
"Action": [
"lambda:InvokeFunction"
],
"Resource": [
"arn:aws:lambda:us-east-1:accountid:function:AndroidBackendLambdaFunction"
]
}
The resulting policy will be as follows:
{
"Version":"2012-10-17",
"Statement":[
{
"Effect":"Allow",
"Action":[
"mobileanalytics:PutEvents",
"cognito-sync:*"
],
"Resource":[
"*"
]
},
{
"Effect":"Allow",
"Action":[
"lambda:invokefunction"
],
"Resource":[
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"arn:aws:lambda:us-east-1:accountid:function:AndroidBackendLambdaFunction"
]
}
]
}
Note
You can update policy at the time of creating the identity pool. You can also update the
policy after you create the identity pool, in which case make sure you write down the IAM
role name for the unauthenticated users from the Amazon Cognito console. Then, go to the
IAM console and search for the specific role and edit the access permissions policy.
For instructions about how to create an identity pool, log in to the Amazon Cognito console and follow
the New Identity Pool wizard.
3.
Note down the identity pool ID. You specify this ID in your mobile application you create in the next
section. The app uses this ID when it sends request to Amazon Cognito to request for temporary
security credentials.
Next Step
Step 4: Create a Mobile Application for Android (p. 250)
Step 4: Create a Mobile Application for Android
Now you can create a simple Android mobile application that generates events and invokes Lambda
functions by passing the event data as parameters.
The following instructions have been verified using Android studio.
1.
Create a new Android project called AndroidEventGenerator using the following configuration:
• Select the Phone and Tablet platform.
• Choose Blank Activity.
2.
In the build.gradle (Module:app) file, add the following in the dependencies section:
compile 'com.amazonaws:aws-android-sdk-core:2.2.+'
compile 'com.amazonaws:aws-android-sdk-lambda:2.2.+'
3.
Build the project so that the required dependencies are downloaded, as needed.
4.
In the Android application manifest (AndroidManifest.xml), add the following permissions so that your
application can connect to the Internet. You can add them just before the </manifest> end tag.
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
5.
In MainActivity, add the following imports:
import com.amazonaws.mobileconnectors.lambdainvoker.*;
import com.amazonaws.auth.CognitoCachingCredentialsProvider;
import com.amazonaws.regions.Regions;
6.
In the package section, add the following two classes (RequestClass and ResponseClass). Note that
the POJO is same as the POJO you created in your Lambda function in the preceding section.
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• RequestClass. The instances of this class act as the POJO (Plain Old Java Object) for event data
which consists of first and last name. If you are using Java example for your Lambda function you
created in the preceding section, this POJO is same as the POJO you created in your Lambda
function code.
package com.example....lambdaeventgenerator;
public class RequestClass {
String firstName;
String lastName;
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public RequestClass(String firstName, String lastName) {
this.firstName = firstName;
this.lastName = lastName;
}
public RequestClass() {
}
}
• ResponseClass
package com.example....lambdaeventgenerator;
public class ResponseClass {
String greetings;
public String getGreetings() {
return greetings;
}
public void setGreetings(String greetings) {
this.greetings = greetings;
}
public ResponseClass(String greetings) {
this.greetings = greetings;
}
public ResponseClass() {
}
}
7.
In the same package, create interface called MyInterface for invoking the
AndroidBackendLambdaFunction Lambda function.
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Note
The @LambdaFunction annotation in the code maps the specific client method to the samename Lambda function. For more information about this annotation, see AWS Lambda in the
AWS Mobile SDK for Android Developer Guide.
package com.example.....lambdaeventgenerator;
import com.amazonaws.mobileconnectors.lambdainvoker.LambdaFunction;
public interface MyInterface {
/**
* Invoke the Lambda function "AndroidBackendLambdaFunction".
* The function name is the method name.
*/
@LambdaFunction
ResponseClass AndroidBackendLambdaFunction(RequestClass request);
}
8.
To keep the application simple, we are going to add code to invoke the Lambda function in the
onCreate() event handler. In MainActivity, add the following code toward the end of the onCreate()
code.
// Create an instance of CognitoCachingCredentialsProvider
CognitoCachingCredentialsProvider cognitoProvider = new
CognitoCachingCredentialsProvider(
this.getApplicationContext(), "identity-pool-id", Regions.US_WEST_2);
// Create LambdaInvokerFactory, to be used to instantiate the Lambda proxy.
LambdaInvokerFactory factory = new LambdaInvokerFactory(this.getApplicationContext(),
Regions.US_WEST_2, cognitoProvider);
// Create the Lambda proxy object with a default Json data binder.
// You can provide your own data binder by implementing
// LambdaDataBinder.
final MyInterface myInterface = factory.build(MyInterface.class);
RequestClass request = new RequestClass("John", "Doe");
// The Lambda function invocation results in a network call.
// Make sure it is not called from the main thread.
new AsyncTask<RequestClass, Void, ResponseClass>() {
@Override
protected ResponseClass doInBackground(RequestClass... params) {
// invoke "echo" method. In case it fails, it will throw a
// LambdaFunctionException.
try {
return myInterface.AndroidBackendLambdaFunction(params[0]);
} catch (LambdaFunctionException lfe) {
Log.e("Tag", "Failed to invoke echo", lfe);
return null;
}
}
@Override
protected void onPostExecute(ResponseClass result) {
if (result == null) {
return;
}
// Do a toast
Toast.makeText(MainActivity.this, result.getGreetings(),
Toast.LENGTH_LONG).show();
}
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}.execute(request);
9.
Run the code and verify it as follows:
• The Toast.makeText() displays the response returned.
• Verify that CloudWatch Logs shows the log created by the Lambda function. It should show the
event data (first name and last name). You can also verify this in the AWS Lambda console.
Using AWS Lambda with Scheduled Events
You can create a Lambda function and direct AWS Lambda to execute it on a regular schedule. You can
specify a fixed rate (for example, execute a Lambda function every hour or 15 minutes), or you can specify
a Cron expression. For more information on expressions schedules, see Schedule Expressions Using Rate
or Cron (p. 257).
This functionality is available when you create a Lambda function using the AWS Lambda console or the
AWS CLI. To configure it using the AWS CLI, see Run an AWS Lambda Function on a Schedule Using the
AWS CLI. The console provides the CloudWatch Events - Schedule as an event source. At the time of
creating a Lambda function, you choose this event source and specify a time interval.
If you have made any manual changes to the permissions on your function, you may need to reapply the
scheduled event access to your function. You can do that by using the following CLI command.
aws lambda add-permission \
--statement-id 'statement id' \
--action 'lambda:InvokeFunction' \
--principal events.amazonaws.com \
--source-arn arn:aws:events:region:account-id:rule/rule_name
--function-name function:MyFunction
--region region
Note
Each AWS account can have up to 50 unique event sources of the CloudWatch Events Schedule source type. Each of these can be the event source for up to five Lambda functions.
That is, you can have up to 250 Lambda functions that can be executing on a schedule in your
AWS account.
The console also provides a blueprint (lambda-canary) that uses the CloudWatch Events - Schedule
source type. Using this blueprint, you can create a sample Lambda function and test this feature. The
example code that the blueprint provides checks for the presence of a specific webpage and specific text
string on the webpage. If either the webpage or the text string is not found, the Lambda function throws an
error.
For a tutorial that walks you through an example setup, see Tutorial: Using AWS Lambda with Scheduled
Events (p. 253).
Tutorial: Using AWS Lambda with Scheduled Events
In this tutorial, you do the following:
• Create a Lambda function using the lambda-canary blueprint. You configure the Lambda function to run
every minute. Note that if the function returns an error, AWS Lambda logs error metrics to CloudWatch.
• Configure a CloudWatch alarm on the Errors metric of your Lambda function to post a message to your
Amazon SNS topic when AWS Lambda emits error metrics to CloudWatch. You subscribe to the Amazon
SNS topics to get email notification. In this tutorial, you do the following to set this up:
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• Create an Amazon SNS topic.
• Subscribe to the topic so you can get email notifications when a new message is posted to the topic.
• In Amazon CloudWatch, set an alarm on the Errors metric of your Lambda function to publish a
message to your SNS topic when errors occur.
Next Step
Step 1: Create a Lambda Function (p. 254)
Step 1: Create a Lambda Function
1.
Sign in to the AWS Management Console and open the AWS Lambda console at https://
console.aws.amazon.com/lambda/.
2.
Choose Create a Lambda function.
3.
In Select blueprint, choose the lambda-canary blueprint.
4.
In Configure triggers:
• Choose CloudWatch Events - Schedule.
• In Rule name, type a name (for example, CheckWebsiteScheduledEvent).
• In Rule description, type a description (for example, CheckWebsiteScheduledEvent trigger).
• In Schedule expression, specify rate(1 minute). Note that you can specify the value as a rate or
in the cron expression format. All schedules use the UTC time zone, and the minimum precision for
schedules is one minute.
Note
When setting a rate expression, the first execution is immediate and subsequent executions
occur based on the rate schedule. In the preceding example, the subsequent execution rate
would be every minute.
For more information on expressions schedules, see Schedule Expressions Using Rate or
Cron (p. 257).
• In Enable trigger, we recommend that you leave the trigger in a disabled state until you have tested
it.
• Choose Next.
5.
In Configure function, do the following:
• Specify your Lambda function name (for example, CheckWebsitePeriodically).
• In Runtime, specify Python 2.7, Node.js 6.10 or Node.js 4.3, depending on your preferred
language.
• Review the code provided by the template. Later in this tutorial, you will update the function code so
that the function will return an error. You can either specify a non-existing URL or replace search text
to a string that is not on the page.
• In Role*, choose Create new role from template(s).
• In Role name, type a name for the role.
• In Policy templates, Lambda provides a list of optional, additional templates that extend the basic
Lambda permissions. For the purpose of this tutorial, you can leave this field blank because your
Lambda function already has the basic execution permission it needs.
• In Advanced settings, leave the default configurations and choose Next.
6.
In Review, review the configuration and then choose Create Function.
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Next Step
Step 2: Test the Lambda Function (Using a Sample Test Event) (p. 255)
Step 2: Test the Lambda Function (Using a Sample Test Event)
1.
Choose the function you created in the previous step and then choose Test.
2.
On the Input sample event page, choose Scheduled Event in the Sample event list.
Note the event time in the sample event. This value will be different when AWS Lambda invokes the
function at scheduled intervals. The sample Lambda function code logs this time to CloudWatch Logs.
3.
Choose Save and test and verify that the Execution result section shows success.
Next Step
Step 3: Create an Amazon SNS Topic and Subscribe to It (p. 255)
Step 3: Create an Amazon SNS Topic and Subscribe to It
1.
Create an SNS topic using the Amazon SNS console. For instructions, see Create a Topic in the
Amazon Simple Notification Service Developer Guide.
2.
Subscribe to the topic. For this exercise, use email as the communication protocol. For instructions,
see Subscribe to a Topic in the Amazon Simple Notification Service Developer Guide.
You use this Amazon SNS topic in the next step when you configure a CloudWatch alarm so that when
AWS Lambda emits an error the alarm will publish a notification to this topic.
Next Step
Step 4: Configure a CloudWatch Alarm (p. 255)
Step 4: Configure a CloudWatch Alarm
To configure a CloudWatch alarm, follow the instructions at Create Alarm in the Amazon CloudWatch
User Guide. As you follow the steps, note the following:
• In Create Alarm (1. Select Metric step), choose Lambda Metrics, and then choose the Errors (Metric
Name is Errors) for the Lambda function you created. Also, on the statistics drop-down, change the
settings from Average to Sum statistics.
• In Create Alarm (2. Define Metric step), set the alarm threshold to Whenever: Errors is >= 1 and select
your Amazon SNS topic from the Send notification to: list.
Next Step
Step 5: Test the Lambda Function Again (p. 255)
Step 5: Test the Lambda Function Again
Now test the Lambda function again. This time, update the code by specifying either a non-existing
webpage URL or a text string. This causes the function to return an error that AWS Lambda sends to
CloudWatch error metrics. CloudWatch posts this message to the Amazon SNS topic and you get an email
notification.
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Step 6: Deploy With AWS SAM and AWS CloudFormation
In the previous section, you used AWS Lambda APIs to create and update a Lambda function by providing
a deployment package as a ZIP file. However, this mechanism may not be convenient for automating
deployment steps for functions, or coordinating deployments and updates to other elements of a serverless
application, like event sources and downstream resources.
You can use AWS CloudFormation to easily specify, deploy, and configure serverless applications. AWS
CloudFormation is a service that helps you model and set up your Amazon Web Services resources so
that you can spend less time managing those resources and more time focusing on your applications
that run in AWS. You create a template that describes all the AWS resources that you want (like Lambda
functions and DynamoDB tables), and AWS CloudFormation takes care of provisioning and configuring
those resources for you.
In addition, you can use the AWS Serverless Application Model to express resources that comprise the
serverless application. These resource types, such as Lambda functions and APIs, are fully supported by
AWS CloudFormation and make it easier for you to define and deploy your serverless application.
For more information, see Deploying Lambda-based Applications (p. 133).
Specification for Scheduled Event Application
The following contains the SAM template for this application. Copy the text below to a .yaml file and save it
next to the ZIP package you created previously. Make sure the Runtime: parameter value matches the one
you chose in the previous section.
AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Parameters:
NotificationEmail:
Type: String
Resources:
CheckWebsitePeriodically:
Type: AWS::Serverless::Function
Properties:
Handler: LambdaFunctionOverHttps.handler
Runtime: runtime
Policies: AmazonDynamoDBFullAccess
Events:
CheckWebsiteScheduledEvent:
Type: Schedule
Properties:
Schedule: rate(1 minute)
AlarmTopic:
Type: AWS::SNS::Topic
Properties:
Subscription:
- Protocol: email
Endpoint: !Ref NotificationEmail
Alarm:
Type: AWS::CloudWatch::Alarm
Properties:
AlarmActions:
- !Ref AlarmTopic
ComparisonOperator: GreaterThanOrEqualToThreshold
Dimensions:
- Name: FunctionName
Value: !Ref CheckWebsitePeriodically
EvaluationPeriods: String
MetricName: Errors
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Namespace: AWS/Lambda
Period: '60'
Statistic: Sum
Threshold: '1'
Deploying the Serverless Application
For information on how to package and deploy your serverless application using the package and deploy
commands, see Packaging and Deployment (p. 139).
Schedule Expressions Using Rate or Cron
Rate expression
rate(Value Unit)
Where:
Value can be a positive integer.
Unit can be minute(s), hour(s), or day(s).
For example:
Example
Cron expression
Invoke Lambda function every 5 minutes
rate(5 minutes)
Invoke Lambda function every hour
rate(1 hour)
Invoke Lambda function every seven days
rate(7 days)
Note the following:
• Rate frequencies of less than one minute are not supported.
• For a singular value the unit must be singular (for example, rate(1 day)), otherwise plural (for example,
rate(5 days)).
Cron expression
cron(Minutes Hours Day-of-month Month Day-of-week Year)
All fields are required and time zone is UTC only. The following table describes these fields.
Field
Values
Wildcards
Minutes
0-59
,-*/
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Field
Values
Wildcards
Hours
0-23
,-*/
Day-of-month
1-31
,-*?/LW
Month
1-12 or JAN-DEC
,-*/
Day-of-week
1-7 or SUN-SAT
,-*?/L#
Year
1970-2199
,-*/
The following table describes the wildcard characters.
Character
Definition
Example
/
Specifies
increments
0/15 in the minutes field directs execution to occur every 15
minutes.
L
Specifies "Last"
If used in Day-of-month field, specifies last day of the month.
If used in Day-of-week field, specifies last day of the week
(Saturday).
W
Specifies Weekday
When used with a date, such as 5/W, specifies the closest
weekday to 5th day of the month. If the 5th falls on a
Saturday, execution occurs on Friday. If the 5th falls on a
Sunday, execution occurs on Monday.
#
Specifies the nd
or nth day of the
month
Specifying 3#2 means the second Tuesday of the month
(Tuesday is the third day of the 7-day week).
*
Specifies All
values
If used in the Day-of-month field, it means all days in the
month.
?
No specified value
Used in conjunction with another specified value. For
example, if a specific date is specified, but you don't care what
day of the week it falls on.
-
Specifies ranges
10-12 would mean 10, 11 and 12
,
Specifies
additional values
SUN, MON, TUE means Sunday, Monday and Tuesday
/
Specifies
increments
5/10 means 5, 15, 25, 35, etc.
The following table lists common examples of cron expressions.
Example
Cron expression
Invoke a Lambda function at
10:00am (UTC) everyday
cron(0 10 * * ? *)
Invoke a Lambda function
12:15pm (UTC) everyday
cron(15 12 * * ? *)
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Example
Cron expression
Invoke a Lambda function at
06:00pm (UTC) every Mon-Fri
cron(0 18 ? * MON-FRI *)
Invoke a Lambda function at
8:00am (UTC) every first day of
the month
Invoke a Lambda function every
10 min Mon-Fri
Invoke a Lambda function every
5 minutes Mon-Fri between
8:00am and 5:55pm (UTC)
Invoke a Lambda function at 9
a.m. (UTC) the first Monday of
each month
cron(0 8 1 * ? *)
cron(0/10 * ? * MON-FRI *)
cron(0/5 8-17 ? * MON-FRI *)
cron(0 9 ? * 2#1 *)
Note the following:
• Cron expressions that lead to rates faster than one minute are not supported.
• One of the day-of-month or day-of-week values must be a question mark (?).
Using AWS Lambda with Custom User Applications
One of the use cases for using AWS Lambda is to process events generated by a user application. For
demonstration purposes, you don't need to write a user application that invokes your Lambda function.
Instead, the tutorial provided in this section provides sample event data that you can use and then you
invoke your Lambda function manually.
When a user application invokes a Lambda function, it's an example of the AWS Lambda request-response
model in which an application invokes a Lambda function and receives a response in real time. For more
information, see How It Works (p. 146).
For a tutorial that walks you through an example setup, see Tutorial: Using AWS Lambda with Custom User
Applications (p. 259).
Tutorial: Using AWS Lambda with Custom User
Applications
In this tutorial, you use the AWS CLI to create and invoke a Lambda function and explore other AWS
Lambda APIs.
You'll do the following:
• Create a Lambda function to process an event it receives as a parameter. You use the following example
Node.js code to create your Lambda function.
console.log('Loading function');
exports.handler = function(event, context, callback) {
console.log('value1 =', event.key1);
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console.log('value2 =', event.key2);
console.log('value3 =', event.key3);
callback(null,"Success");
};
Note
The code sample is compliant with the Node.js runtime v4.3. For more information, see
Programming Model (Node.js) (p. 9)
The function is simple. It processes incoming event data by logging it (these logs are available in Amazon
CloudWatch), and in the request-response model, you can request the log data be returned in the
response.
• Simulate a user application that sends an event to your Lambda function by invoking your Lambda
function manually using the following sample event data.
{
"key1": "value1",
"key2": "value2",
"key3": "value3"
}
Note
This example is similar to the Getting Started exercise (see Getting Started (p. 155)). The
difference is that the Getting Started exercise provides a console-based experience. The console
does many things for you, which simplifies the experience. When using the AWS CLI, you get the
experience of making the API calls, which can help you develop a better understanding of the
AWS Lambda operations. In addition to creating and invoking a Lambda function, you can explore
other Lambda APIs.
Next Step
Step 1: Prepare (p. 260)
Step 1: Prepare
Make sure you have completed the following steps:
• Signed up for an AWS account and created an administrator user in the account.
• Installed and set up the AWS CLI.
For instructions, see Step 1: Set Up an AWS Account and the AWS CLI (p. 155).
Next Step
Step 2: Create a Lambda Function and Invoke It Manually (p. 260)
Step 2: Create a Lambda Function and Invoke It Manually
In this section, you do the following:
• Create a deployment package. A deployment package is a .zip file that contains your code and any
dependencies. For this tutorial there are no dependencies, you only have a simple example code.
• Create an IAM role (execution role). At the time you upload the deployment package, you need to specify
an IAM role (execution role) that Lambda can assume to execute the function on your behalf.
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You also grant this role the permissions that your Lambda function needs. The code in this tutorial writes
logs to Amazon CloudWatch Logs. So you need to grant permissions for CloudWatch actions. For more
information, see AWS Lambda Watch Logs.
• Create a Lambda function (HelloWorld) using the create-function CLI command. For more information
about the underlying API and related parameters, see CreateFunction (p. 322).
Topics
• Step 2.1: Create a Lambda Function Deployment Package (p. 261)
• Step 2.2: Create the Execution Role (IAM Role) (p. 261)
• Step 2.3: Create a Lambda Function (p. 262)
• Next Step (p. 263)
Step 2.1: Create a Lambda Function Deployment Package
Follow the instructions to create an AWS Lambda function deployment package.
1.
Open a text editor, and then copy the following code.
console.log('Loading function');
exports.handler = function(event, context, callback) {
console.log('value1 =', event.key1);
console.log('value2 =', event.key2);
console.log('value3 =', event.key3);
callback(null, "Success");
};
Note
The code sample is compliant with the Node.js runtimes v6.10 ore v4.3. For more information,
see Programming Model (Node.js) (p. 9)
2.
Save the file as helloworld.js.
3.
Zip the helloworld.js file as helloworld.zip.
Note
To see more examples of using other AWS services within your function, including calling other
Lambda functions, see AWS SDK for JavaScript
Step 2.2: Create the Execution Role (IAM Role)
When the Lambda function in this tutorial executes, it needs permissions to write logs to Amazon
CloudWatch. You grant these permissions by creating an IAM role (execution role). AWS Lambda assumes
this role when executing your Lambda function on your behalf. In this section, you create an IAM role using
the following predefined role type and access policy:
• AWS service role of the "AWS Lambda" type. This role grants AWS Lambda permission to assume the
role.
• "AWSLambdaBasicExecutionRole" access policy that you attach to the role. This existing policy grants
permissions that include permissions for Amazon CloudWatch actions that your Lambda function needs.
For more information about IAM roles, see IAM Roles in the IAM User Guide.
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In this section, you create an IAM role using the following predefined role type and access permissions
policy:
• AWS service role of the type AWS Lambda – This role grants AWS Lambda permissions to assume the
role.
• AWSLambdaBasicExecutionRole access permissions policy that you attach to the role.
For more information about IAM roles, see IAM Roles in the IAM User Guide. Use the following procedure
to create the IAM role.
To create an IAM role (execution role)
1.
2.
Sign in to the IAM console at https://console.aws.amazon.com/iam/.
Follow the steps in Creating a Role to Delegate Permissions to an AWS Service in the IAM User Guide
to create an IAM role (execution role). As you follow the steps to create a role, note the following:
• In Role Name, use a name that is unique within your AWS account (for example, lambda-customapp-execution-role).
• In Select Role Type, choose AWS Service Roles, and then choose AWS Lambda. This grants the
AWS Lambda service permissions to assume the role.
• In Attach Policy, choose AWSLambdaBasicExecutionRole.
3.
Write down the role ARN. You will need it in the next step when you create your Lambda function.
Step 2.3: Create a Lambda Function
Execute the following Lambda CLI create-function command to create a Lambda function. You provide
the deployment package and IAM role ARN as parameters. Note that the Runtime parameter uses
nodejs6.10 but you can also specify nodejs4.3.
$ aws lambda create-function \
--region us-west-2 \
--function-name helloworld \
--zip-file fileb://file-path/helloworld.zip \
--role role-arn \
--handler helloworld.handler \
--runtime nodejs6.10 \
--profile adminuser
Optionally, you can upload the .zip file to an Amazon S3 bucket in the same AWS region, and then specify
the bucket and object name in the preceding command. You need to replace the --zip-file parameter by
the --code parameter, as shown following:
--code S3Bucket=bucket-name,S3Key=zip-file-object-key
For more information, see CreateFunction (p. 322). AWS Lambda creates the function and returns
function configuration information as shown in the following example:
{
"FunctionName": "helloworld",
"CodeSize": 351,
"MemorySize": 128,
"FunctionArn": "function-arn",
"Handler": "helloworld.handler",
"Role": "arn:aws:iam::account-id:role/LambdaExecRole",
"Timeout": 3,
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"LastModified": "2015-04-07T22:02:58.854+0000",
"Runtime": "nodejs6.10",
"Description": ""
}
Next Step
Step 3: Invoke the Lambda Function (AWS CLI) (p. 263)
Step 3: Invoke the Lambda Function (AWS CLI)
In this section, you invoke your Lambda function manually using the invoke AWS CLI command.
$ aws lambda invoke \
--invocation-type RequestResponse \
--function-name helloworld \
--region us-west-2 \
--log-type Tail \
--payload '{"key1":"value1", "key2":"value2", "key3":"value3"}' \
--profile adminuser \
outputfile.txt
If you want you can save the payload to a file (for example, input.txt) and provide the file name as a
parameter.
--payload file://input.txt \
The preceding invoke command specifies RequestResponse as the invocation type, which returns a
response immediately in response to the function execution. Alternatively, you can specify Event as the
invocation type to invoke the function asynchronously.
By specifying the --log-type parameter, the command also requests the tail end of the log produced by
the function. The log data in the response is base64-encoded as shown in the following example response:
{
"LogResult": "base64-encoded-log",
"StatusCode": 200
}
On Linux and Mac, you can use the base64 command to decode the log.
$ echo base64-encoded-log | base64 --decode
The following is a decoded version of an example log.
START RequestId: 16d25499-d89f-11e4-9e64-5d70fce44801
2015-04-01T18:44:12.323Z
16d25499-d89f-11e4-9e64-5d70fce44801
value1 = value1
2015-04-01T18:44:12.323Z
16d25499-d89f-11e4-9e64-5d70fce44801
value2 = value2
2015-04-01T18:44:12.323Z
16d25499-d89f-11e4-9e64-5d70fce44801
value3 = value3
2015-04-01T18:44:12.323Z
16d25499-d89f-11e4-9e64-5d70fce44801
result: "value1"
END RequestId: 16d25499-d89f-11e4-9e64-5d70fce44801
REPORT RequestId: 16d25499-d89f-11e4-9e64-5d70fce44801
Duration: 13.35 ms
Billed Duration: 100 ms
Memory Size: 128 MB
Max Memory Used: 9 MB
For more information, see Invoke (p. 351).
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Because you invoked the function using the RequestResponse invocation type, the function executes and
returns the object you passed to the context.succeed() in real time when it is called. In this tutorial, you
see the following text written to the outputfile.txt you specified in the CLI command:
"value1"
Note
You are able to execute this function because you are using the same AWS account to create and
invoke the Lambda function. However, if you want to grant cross-account permissions to another
AWS account or grant permissions to another an AWS service to execute the function, you must
add a permissions to the access permissions policy associated with the function. The Amazon
S3 tutorial, which uses Amazon S3 as the event source (see Tutorial: Using AWS Lambda with
Amazon S3 (p. 171)), grants such permissions to Amazon S3 to invoke the function.
You can monitor the activity of your Lambda function in the AWS Lambda console.
• Sign in to the AWS Management Console and open the AWS Lambda console at https://
console.aws.amazon.com/lambda/.
The AWS Lambda console shows a graphical representation of some of the CloudWatch metrics in the
Cloudwatch Metrics at a glance section for your function.
• For each graph, you can also choose the logs link to view the CloudWatch logs directly.
Next Step
Step 4: Try More CLI Commands (AWS CLI) (p. 264)
Step 4: Try More CLI Commands (AWS CLI)
Step 4.1: List the Lambda Functions in Your Account
In this section, you try AWS Lambda list function operations. Execute the following AWS CLI listfunctions command to retrieve a list of functions that you uploaded.
$ aws lambda list-functions \
--max-items 10 \
--profile adminuser
To illustrate the use of pagination, the command specifies the optional --max-items parameter to limit
the number of functions returned in the response. For more information, see ListFunctions (p. 362). The
following is an example response.
{
"Functions": [
{
"FunctionName": "helloworld",
"MemorySize": 128,
"CodeSize": 412,
"FunctionArn": "arn:aws:lambda:us-east-1:accountid:function:ProcessKinesisRecords",
"Handler": "ProcessKinesisRecords.handler",
"Role": "arn:aws:iam::account-id:role/LambdaExecRole",
"Timeout": 3,
"LastModified": "2015-02-22T21:03:01.172+0000",
"Runtime": "nodejs6.10",
"Description": ""
},
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{
"FunctionName": "ProcessKinesisRecords",
"MemorySize": 128,
"CodeSize": 412,
"FunctionArn": "arn:aws:lambda:us-east-1:accountid:function:ProcessKinesisRecords",
"Handler": "ProcessKinesisRecords.handler",
"Role": "arn:aws:iam::account-id:role/lambda-execute-test-kinesis",
"Timeout": 3,
"LastModified": "2015-02-22T21:03:01.172+0000",
"Runtime": "nodejs6.10",
"Description": ""
},
...
],
"NextMarker": null
}
In response, Lambda returns a list of up to 10 functions. If there are more functions you can retrieve,
NextMarker provides a marker you can use in the next list-functions request; otherwise, the value is
null. The following list-functions AWS CLI command is an example that shows the --next-marker
parameter.
$ aws lambda list-functions \
--max-items 10 \
--marker value-of-NextMarker-from-previous-response \
--profile adminuser
Step 4.2: Get Metadata and a URL to Download Previously Uploaded Lambda
Function Deployment Packages
The Lambda CLI get-function command returns Lambda function metadata and a presigned URL that
you can use to download the function's .zip file (deployment package) that you uploaded to create the
function. For more information, see GetFunction (p. 342).
$ aws lambda get-function \
--function-name helloworld \
--region us-west-2 \
--profile adminuser
The following is an example response.
{
"Code": {
"RepositoryType": "S3",
"Location": "pre-signed-url"
},
"Configuration": {
"FunctionName": "helloworld",
"MemorySize": 128,
"CodeSize": 287,
"FunctionArn": "arn:aws:lambda:us-west-2:account-id:function:helloworld",
"Handler": "helloworld.handler",
"Role": "arn:aws:iam::account-id:role/LambdaExecRole",
"Timeout": 3,
"LastModified": "2015-04-07T22:02:58.854+0000",
"Runtime": "nodejs6.10",
"Description": ""
}
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}
If you want the function configuration information only (not the presigned URL), you can use the Lambda
CLI get-function-configuration command.
$ aws lambda get-function-configuration \
--function-name helloworld \
--region us-west-2 \
--profile adminuser
Next Step
Step 5: Delete the Lambda Function and IAM Role (AWS CLI) (p. 266)
Step 5: Delete the Lambda Function and IAM Role (AWS CLI)
Execute the following delete-function command to delete the helloworld function.
$ aws lambda delete-function \
--function-name helloworld \
--region us-west-2 \
--profile adminuser
Delete the IAM Role
After you delete the Lambda function you can also delete the IAM role you created in the IAM console. For
information about deleting a role, see Deleting Roles or Instance Profiles in the IAM User Guide.
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AWS [email protected] (Preview)
[email protected] (preview) allows you to run Lambda functions at the AWS Edge locations in response
to CloudFront events, without provisioning or managing servers, by using the AWS Lambda serverless
programming model. Before [email protected], while you could use CloudFront to deliver pages faster,
customized processing still required requests to be forwarded back to compute resources at centralized
servers. This slows down the end user experience. You can use [email protected] in response to CloudFront
events and to customize content delivered through CloudFront at reduced network latency with execution at
the AWS edge locations.
Functions deployable to edge locations are written in Node.js. With [email protected], a virtually unlimited set
of solutions is available, including the following:
• Write Lambda functions to inspect cookies to rewrite URLs to different versions of a site for A/B testing.
• Send different objects to your users based on the user-agent header (for example, send images that
have different resolutions to users based on their devices).
• Inspect headers or authorized tokens, inserting a corresponding header and allowing access control
before forwarding a request to the origin.
• Add, drop, and modify headers, and rewrite the URL path to direct users to different objects in cache.
• Generate new HTTP responses to do things like redirect unauthenticated users to login pages, or create
and deliver static webpages right from the edge. For more information, see HTTP Response Generation.
While the runtime (nodejs4.3-edge) is the same as the standard Node environment supported in AWS
Lambda (nodejs4.3), there are some additional restrictions. For example, there are no built-in libraries
available. You can use Lambda functions to respond to four different trigger points for a CloudFront
request:
• When a request is first received from a viewer (viewer request).
• When the Lambda function receives a response from the origin (origin response).
• When the Lambda function forwards a request to the origin (origin request).
• Before the Lambda function responds to the end viewer (viewer response).
For more information about setting up CloudFront with [email protected], see Using CloudFront with
[email protected]
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How It Works
After you have identified a decision that can be made at the AWS Edge location (where all the information
needed to make the decision is available within the function and the request/response itself), first identify
which cache behaviors and at what point in the request flow (viewer request, origin request, origin
response, or viewer response) the logic applies to.
You then create a Lambda function to encapsulate the logic. Functions that run on [email protected] are
written in nodejs4.3; however, instead of selecting the standard nodejs4.3 as the runtime of your Lambda
function, you must select nodejs4.3-edge. Next, you use CloudFront API operations or the AWS Lambda
console to associate the appropriate events (viewer request etc.) for a specific CloudFront distribution
to your Lambda function. This the same model as all other event sources—for example, when triggering
Lambda functions for Amazon S3 events, you associate specific events like Amazon S3 PUT for a specific
bucket. Once saved, the next time an applicable request is made to your distribution, the function is
propagated to the CloudFront edge, scaled, and executed as needed.
Authoring Functions for [email protected]
The programming model for using Node.js with [email protected] is the same as using Lambda in a region.
For more information, see Programming Model (Node.js) (p. 9). You can also include third-party packages.
However, when responding to request events, the request object should be returned as part of callback
so that CloudFront can modify the request. The same applies while responding to response events. The
response object should be returned.
exports.origin_response_handler = function(event, context, callback) {
var headers = event.Records[0].cf.response.headers;
for (var header in headers) {
/* your custom header logic */;
}
callback(null, event.Records[0].cf.response);
}
exports.origin_request_handler = function(event, context, callback) {
var request = event.Records[0].cf.request;
request.uri = /* your custom uri logic */;
var headers = request.headers;
for (var header in headers) {
/* your custom header logic */;
}
callback(null , event.Records[0].cf.request);
}
Note
[email protected] functions will not have write access to write to the local file system, and cannot
make remote network calls to external services.
Permissions
If you are using the AWS CLI, [email protected] requires an additional permission. You will need to add the
following principal to the resource policy, as shown below:
aws lambda add-permission
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--function-name arn
--statement-id statement-id
--action lambda:GetFunction
--principal edgelambda.amazonaws.com
When using the Lambda console, these permissions are added automatically.
Testing and Debugging
[email protected] functions can be tested on the Lambda console with test events modeled after the Request
or Response events. For sample events, see [email protected] Event Structure. However, the testing in the
console only validates logic, and does not apply service limits specific to [email protected] which come into
play if your function is deployed to the AWS Edge. To avoid discrepancies in behavior while testing in a
region, ensure that your function does not make remote calls (either through the AWS SDK or via direct
http/https requests) or use environment variables, and configure the function to approximate its eventual
edge deployment by selecting 128MB and 1 second of duration. Note that the actual duration limit during
the preview is 50ms. For more information, see [email protected] Limits (p. 270). You can create logging
statements for Lambda functions running on [email protected] that will write to CloudWatch Logs. For more
information, see Programming Model for Logs.
Simple Setup
In the Lambda console:
1.
Choose the cloudfront-ab-test blueprint.
2.
In Triggers, choose the CloudFront distribution, cache behavior, and an event type.
• Choose CloudFront from the service list.
• Choose distribution.
• Choose cache behavior identified by the URL pattern.
With [email protected], you associate functions at the cache behavior level. To specify different
caching policies (how long to cache an object, what headers to include in the cache key, which origin
has the content) you have the following options:
• *.jpg
• *.php
• * (default)
• Choose the CloudFront event type.
3.
Choose Edge-Node.js 4.3 as the runtime for your function. Edge-Node.js 4.3 is the only supported
runtime for functions that run on [email protected] today.
4.
Choose Create function. When the specified CloudFront distribution receives a request, the function
is propagated to the edge location, and your function will start triggering to the associated event.
Note
Note that you need to add a special permission to allow [email protected] to propagate your
functions to edge locations. When using the console, these are automatically added. If you create
your functions using the API or AWS CLI, see Permissions (p. 268).
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[email protected] Limits
[email protected] Limits
Due to the constrained execution environment, [email protected] has additional restrictions over and above
the default Lambda limits. Functions running in Edge locations do not count against your concurrency limit
for the region. For more information, see AWS Lambda Limits (p. 275).
Item
Default Limit
Max memory setting
128 MB
Maximum duration
50 ms
Size of code/dependencies that you can zip into a deployment
package (uncompressed zip/jar size)
1 MB
Maximum Global TPS
100
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AWS Lambda Information in CloudTrail
Logging AWS Lambda API Calls By
Using AWS CloudTrail
AWS Lambda is integrated with AWS CloudTrail, a service that captures API calls made by or on behalf
of AWS Lambda in your AWS account and delivers the log files to an Amazon S3 bucket that you specify.
CloudTrail captures API calls made from the AWS Lambda console or from the AWS Lambda API. Using
the information collected by CloudTrail, you can determine what request was made to AWS Lambda, the
source IP address from which the request was made, who made the request, when it was made, and so
on. To learn more about CloudTrail, including how to configure and enable it, see the AWS CloudTrail User
Guide.
AWS Lambda Information in CloudTrail
When CloudTrail logging is enabled in your AWS account, API calls made to AWS Lambda actions are
tracked in log files. AWS Lambda records are written together with other AWS service records in a log file.
CloudTrail determines when to create and write to a new file based on a time period and file size.
The following actions are supported:
• AddPermission (p. 311)
• CreateEventSourceMapping (p. 318)
• CreateFunction (p. 322)
(The ZipFile parameter is omitted from the CloudTrail logs for CreateFunction.)
• DeleteEventSourceMapping (p. 330)
•
•
•
•
•
DeleteFunction (p. 333)
GetEventSourceMapping (p. 339)
GetFunction (p. 342)
GetFunctionConfiguration (p. 345)
GetPolicy (p. 349)
•
•
•
•
ListEventSourceMappings (p. 359)
ListFunctions (p. 362)
RemovePermission (p. 371)
UpdateEventSourceMapping (p. 376)
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• UpdateFunctionCode (p. 379)
(The ZipFile parameter is omitted from the CloudTrail logs for UpdateFunctionCode.)
• UpdateFunctionConfiguration (p. 384)
Every log entry contains information about who generated the request. The user identity information in the
log helps you determine whether the request was made with root or IAM user credentials, with temporary
security credentials for a role or federated user, or by another AWS service. For more information, see the
userIdentity field in the CloudTrail Event Reference.
You can store your log files in your bucket for as long as you want, but you can also define Amazon S3
lifecycle rules to archive or delete log files automatically. By default, your log files are encrypted by using
Amazon S3 server-side encryption (SSE).
You can choose to have CloudTrail publish Amazon SNS notifications when new log files are delivered if
you want to take quick action upon log file delivery. For more information, see Configuring Amazon SNS
Notifications for CloudTrail.
You can also aggregate AWS Lambda log files from multiple AWS regions and multiple AWS accounts into
a single S3 bucket. For more information, see Working with CloudTrail Log Files.
Understanding AWS Lambda Log File Entries
CloudTrail log files contain one or more log entries where each entry is made up of multiple JSONformatted events. A log entry represents a single request from any source and includes information about
the requested action, any parameters, the date and time of the action, and so on. The log entries are not
guaranteed to be in any particular order. That is, they are not an ordered stack trace of the public API calls.
The following example shows CloudTrail log entries for the GetFunction and DeleteFunction actions.
{
"Records": [
{
"eventVersion": "1.03",
"userIdentity": {
"type": "IAMUser",
"principalId": "A1B2C3D4E5F6G7EXAMPLE",
"arn": "arn:aws:iam::999999999999:user/myUserName",
"accountId": "999999999999",
"accessKeyId": "AKIAIOSFODNN7EXAMPLE",
"userName": "myUserName"
},
"eventTime": "2015-03-18T19:03:36Z",
"eventSource": "lambda.amazonaws.com",
"eventName": "GetFunction",
"awsRegion": "us-east-1",
"sourceIPAddress": "127.0.0.1",
"userAgent": "Python-httplib2/0.8 (gzip)",
"errorCode": "AccessDenied",
"errorMessage": "User: arn:aws:iam::999999999999:user/myUserName" is
not authorized to perform: lambda:GetFunction on resource: arn:aws:lambda:uswest-2:999999999999:function:other-acct-function",
"requestParameters": null,
"responseElements": null,
"requestID": "7aebcd0f-cda1-11e4-aaa2-e356da31e4ff",
"eventID": "e92a3e85-8ecd-4d23-8074-843aabfe89bf",
"eventType": "AwsApiCall",
"recipientAccountId": "999999999999"
},
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{
"eventVersion": "1.03",
"userIdentity": {
"type": "IAMUser",
"principalId": "A1B2C3D4E5F6G7EXAMPLE",
"arn": "arn:aws:iam::999999999999:user/myUserName",
"accountId": "999999999999",
"accessKeyId": "AKIAIOSFODNN7EXAMPLE",
"userName": "myUserName"
},
"eventTime": "2015-03-18T19:04:42Z",
"eventSource": "lambda.amazonaws.com",
"eventName": "DeleteFunction",
"awsRegion": "us-east-1",
"sourceIPAddress": "127.0.0.1",
"userAgent": "Python-httplib2/0.8 (gzip)",
"requestParameters": {
"functionName": "basic-node-task"
},
"responseElements": null,
"requestID": "a2198ecc-cda1-11e4-aaa2-e356da31e4ff",
"eventID": "20b84ce5-730f-482e-b2b2-e8fcc87ceb22",
"eventType": "AwsApiCall",
"recipientAccountId": "999999999999"
}
]
}
Note
The eventName may include date and version information, such as "GetFunction20150331", but it
is still referring to the same public API.
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Best Practices for Working with AWS
Lambda Functions
The following are recommended best practices for using AWS Lambda:
• Write your Lambda function code in a stateless style, and ensure there is no affinity between your code
and the underlying compute infrastructure.
• Instantiate AWS clients outside the scope of the handler to take advantage of connection re-use.
• Make sure you have set +rx permissions on your files in the uploaded ZIP to ensure Lambda can
execute code on your behalf.
• Lower costs and improve performance by minimizing the use of startup code not directly related to
processing the current event.
• Use the built-in CloudWatch monitoring of your Lambda functions to view and optimize request latencies.
• Delete old Lambda functions that you are no longer using.
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List of AWS Lambda Limits
AWS Lambda Limits
This section discusses AWS Lambda limits.
Topics
• List of AWS Lambda Limits (p. 275)
• AWS Lambda Limit Errors (p. 276)
List of AWS Lambda Limits
Every Lambda function is allocated with a fixed amount of specific resources regardless of the memory
allocation, and each function is allocated with a fixed amount of code storage per function and per account.
The following table lists the runtime resource limits for a Lambda function per invocation.
AWS Lambda Resource Limits
Resource
Default Limit
Ephemeral disk capacity ("/tmp" space)
512 MB
Number of file descriptors
1,024
Number of processes and threads (combined total)
1,024
Maximum execution duration per request
300 seconds
Invoke (p. 351) request body payload size
(RequestResponse)
6 MB
Invoke (p. 351) request body payload size (Event)
128 K
Invoke (p. 351) response body payload size
(RequestResponse)
6 MB
The following table lists the Lambda account limits per region.
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AWS Lambda Account Limits Per Region
Resource
Default Limit
Concurrent executions (see Lambda Function Concurrent
Executions (p. 147)).
400
To request a limit increase for concurrent execution
1.
Open the AWS Support Center page, sign in, if necessary, and then click Create case.
2.
Under Regarding, select Service Limit Increase.
3.
Under Limit Type, select Lambda, fill in the necessary fields in the form, and then click the button at
the bottom of the page for your preferred method of contact.
Note
AWS may automatically raise the concurrent execution limit on your behalf to enable your function
to match the incoming event rate, as in the case of triggering the function from an Amazon S3
bucket.
The following table lists service limits for deploying a Lambda function.
AWS Lambda Deployment Limits
Item
Default Limit
Lambda function deployment package size (.zip/.jar file)
50 MB
Total size of all the deployment packages that can be
uploaded per region
75 GB
Size of code/dependencies that you can zip into a deployment
package (uncompressed zip/jar size)
250 MB
Total size of environment variables set
4 KB
AWS Lambda Limit Errors
Functions that exceed any of the limits listed in the previous limits tables will fail with an exceeded
limits exception. These limits are fixed and cannot be changed at this time. For example, if you receive
the exception CodeStorageExceededException or an error message similar to "Code storage limit
exceeded" from AWS Lambda, you need to reduce the size of your code storage.
To reduce the size of your code storage
1.
2.
Remove the functions that you no longer use.
Reduce the code size of the functions that you do not want to remove. You can find the code size of
a Lambda function by using the AWS Lambda console, the AWS Command Line Interface, or AWS
SDKs.
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Authentication
Authentication and Access Control for
AWS Lambda
Access to AWS Lambda requires credentials that AWS can use to authenticate your requests. Those
credentials must have permissions to access AWS resources, such as an AWS Lambda function or an
Amazon S3 bucket. The following sections provide details on how you can use AWS Identity and Access
Management (IAM) and Lambda to help secure your resources by controlling who can access them:
• Authentication (p. 277)
• Access Control (p. 278)
Authentication
You can access AWS as any of the following types of identities:
• AWS account root user – When you sign up for AWS, you provide an email address and password that
is associated with your AWS account. These are your root credentials and they provide complete access
to all of your AWS resources.
Important
For security reasons, we recommend that you use the root credentials only to create an
administrator user, which is an IAM user with full permissions to your AWS account. Then, you
can use this administrator user to create other IAM users and roles with limited permissions. For
more information, see IAM Best Practices and Creating an Admin User and Group in the IAM
User Guide.
• IAM user – An IAM user is simply an identity within your AWS account that has specific custom
permissions (for example, permissions to create a function in Lambda). You can use an IAM user name
and password to sign in to secure AWS webpages like the AWS Management Console, AWS Discussion
Forums, or the AWS Support Center.
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Access Control
In addition to a user name and password, you can also generate access keys for each user. You can use
these keys when you access AWS services programmatically, either through one of the several SDKs
or by using the AWS Command Line Interface (CLI). The SDK and CLI tools use the access keys to
cryptographically sign your request. If you don’t use the AWS tools, you must sign the request yourself.
Lambda supports Signature Version 4, a protocol for authenticating inbound API requests. For more
information about authenticating requests, see Signature Version 4 Signing Process in the AWS General
Reference.
• IAM role – An IAM role is another IAM identity you can create in your account that has specific
permissions. It is similar to an IAM user, but it is not associated with a specific person. An IAM role
enables you to obtain temporary access keys that can be used to access AWS services and resources.
IAM roles with temporary credentials are useful in the following situations:
• Federated user access – Instead of creating an IAM user, you can use preexisting user identities from
AWS Directory Service, your enterprise user directory, or a web identity provider. These are known as
federated users. AWS assigns a role to a federated user when access is requested through an identity
provider. For more information about federated users, see Federated Users and Roles in the IAM User
Guide.
• Cross-account access – You can use an IAM role in your account to grant another AWS account
permissions to access your account’s resources. For an example, see Tutorial: Delegate Access
Across AWS Accounts Using IAM Roles in the IAM User Guide.
• AWS service access – You can use an IAM role in your account to grant an AWS service permissions
to access your account’s resources. For example, you can create a role that allows Amazon Redshift
to access an Amazon S3 bucket on your behalf and then load data stored in the bucket into an
Amazon Redshift cluster. For more information, see Creating a Role to Delegate Permissions to an
AWS Service in the IAM User Guide.
• Applications running on Amazon EC2 – Instead of storing access keys within the EC2 instance for
use by applications running on the instance and making AWS API requests, you can use an IAM role
to manage temporary credentials for these applications. To assign an AWS role to an EC2 instance
and make it available to all of its applications, you can create an instance profile that is attached to the
instance. An instance profile contains the role and enables programs running on the EC2 instance to
get temporary credentials. For more information, see Using Roles for Applications on Amazon EC2 in
the IAM User Guide.
Access Control
You can have valid credentials to authenticate your requests, but unless you have permissions you cannot
create or access AWS Lambda resources. For example, you must have permissions to create a Lambda
function, add an event source, and publish a version of your Lambda function.
The following sections describe how to manage permissions for AWS Lambda. We recommend that you
read the overview first.
• Overview of Managing Access Permissions to Your AWS Lambda Resources (p. 279)
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Overview of Managing Access
• Using Identity-Based Policies (IAM Policies) for AWS Lambda (p. 283)
• Using Resource-Based Policies for AWS Lambda (Lambda Function Policies) (p. 295)
Overview of Managing Access Permissions to Your
AWS Lambda Resources
Every AWS resource is owned by an AWS account, and permissions to create or access a resource
are governed by permissions policies. An account administrator can attach permissions policies to IAM
identities (that is, users, groups, and roles), and some services (such as AWS Lambda) also support
attaching permissions policies to resources.
Note
An account administrator (or administrator user) is a user with administrator privileges. For more
information, see IAM Best Practices in the IAM User Guide.
When granting permissions, you decide who is getting the permissions, the resources they get permissions
for, and the specific actions that you want to allow on those resources.
Topics
• AWS Lambda Resources and Operations (p. 279)
• Understanding Resource Ownership (p. 280)
• Managing Access to Resources (p. 280)
• Specifying Policy Elements: Actions, Effects, Resources, and Principals (p. 282)
• Specifying Conditions in a Policy (p. 283)
AWS Lambda Resources and Operations
In AWS Lambda, the primary resources are a Lambda function and an event source mapping. You create
an event source mapping in the AWS Lambda pull model to associate a Lambda function with an event
source. For more information, see Event Source Mapping (p. 116).
AWS Lambda also supports additional resource types, alias and version. However, you can create aliases
and versions only in the context of an existing Lambda function. These are referred to as subresources.
These resources and subresources have unique Amazon Resource Names (ARNs) associated with them
as shown in the following table.
Resource Type
ARN Format
Function
arn:aws:lambda:region:account-id:function:function-name
Function alias
arn:aws:lambda:region:account-id:function:function-name:alias-name
Function version
arn:aws:lambda:region:account-id:function:function-name:version
Event source mapping
arn:aws:lambda:region:account-id:event-source-mapping:eventsource-mapping-id
AWS Lambda provides a set of operations to work with the Lambda resources. For a list of available
operations, see Actions (p. 309).
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Understanding Resource Ownership
Understanding Resource Ownership
A resource owner is the AWS account that created the resource. That is, the resource owner is the AWS
account of the principal entity (the root account, an IAM user, or an IAM role) that authenticates the request
that creates the resource. The following examples illustrate how this works:
• If you use the root account credentials of your AWS account to create a Lambda function, your AWS
account is the owner of the resource (in Lambda, the resource is the Lambda function).
• If you create an IAM user in your AWS account and grant permissions to create a Lambda function
to that user, the user can create a Lambda function. However, your AWS account, to which the user
belongs, owns the Lambda function resource.
• If you create an IAM role in your AWS account with permissions to create a Lambda function, anyone
who can assume the role can create a Lambda function. Your AWS account, to which the role belongs,
owns the Lambda function resource.
Managing Access to Resources
A permissions policy describes who has access to what. The following section explains the available
options for creating permissions policies.
Note
This section discusses using IAM in the context of AWS Lambda. It doesn't provide detailed
information about the IAM service. For complete IAM documentation, see What Is IAM? in the
IAM User Guide. For information about IAM policy syntax and descriptions, see AWS IAM Policy
Reference in the IAM User Guide.
Policies attached to an IAM identity are referred to as identity-based policies (IAM polices) and policies
attached to a resource are referred to as resource-based policies. AWS Lambda supports both identitybased (IAM policies) and resource-based policies.
Topics
• Identity-Based Policies (IAM Policies) (p. 280)
• Resource-Based Policies (Lambda Function Policies) (p. 281)
Identity-Based Policies (IAM Policies)
You can attach policies to IAM identities. For example, you can do the following:
• Attach a permissions policy to a user or a group in your account – An account administrator can
use a permissions policy that is associated with a particular user to grant permissions for that user to
create a Lambda function.
• Attach a permissions policy to a role (grant cross-account permissions) – You can attach an
identity-based permissions policy to an IAM role to grant cross-account permissions. For example, the
administrator in Account A can create a role to grant cross-account permissions to another AWS account
(for example, Account B) or an AWS service as follows:
1. Account A administrator creates an IAM role and attaches a permissions policy to the role that grants
permissions on resources in Account A.
2. Account A administrator attaches a trust policy to the role identifying Account B as the principal who
can assume the role.
3. Account B administrator can then delegate permissions to assume the role to any users in Account B.
Doing this allows users in Account B to create or access resources in Account A. The principal in the
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trust policy can also be an AWS service principal if you want to grant an AWS service permissions to
assume the role.
For more information about using IAM to delegate permissions, see Access Management in the IAM User
Guide.
The following is an example policy that grants permissions for the lambda:ListFunctions action on all
resources. In the current implementation, Lambda doesn't support identifying specific resources using the
resource ARNs (also referred to as resource-level permissions) for some of the API actions, so you must
specify a wildcard character (*).
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "ListExistingFunctions",
"Effect": "Allow",
"Action": [
"lambda:ListFunctions"
],
"Resource": "*"
}
]
}
For more information about using identity-based policies with Lambda, see Using Identity-Based Policies
(IAM Policies) for AWS Lambda (p. 283). For more information about users, groups, roles, and
permissions, see Identities (Users, Groups, and Roles) in the IAM User Guide.
Resource-Based Policies (Lambda Function Policies)
Each Lambda function can have resource-based permissions policies associated with it. For Lambda, a
Lambda function is the primary resource and these policies are referred to as Lambda function policies.
You can use a Lambda function policy to grant cross-account permissions as an alternative to using
identity-based policies with IAM roles. For example, you can grant Amazon S3 permissions to invoke your
Lambda function by simply adding permissions to the Lambda function policy instead of creating an IAM
role.
Important
Lambda function policies are primarily used when you are setting up an event source in AWS
Lambda to grant a service or an event source permissions to invoke your Lambda function (see
Invoke (p. 351)). An exception to this is when an event source (for example, Amazon DynamoDB
or Amazon Kinesis) uses the pull model, where permissions are managed in the Lambda function
execution role instead. For more information, see Event Source Mapping (p. 116).
The following is an example Lambda function policy that has one statement. The statement allows the
Amazon S3 service principal permission for the lambda:InvokeFunction action on a Lambda function
called HelloWorld. The condition ensures that the bucket where the event occurred is owned by the same
account that owns the Lambda function.
{
"Policy":{
"Version":"2012-10-17",
"Statement":[
{
"Effect":"Allow",
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"Principal":{
"Service":"s3.amazonaws.com"
},
"Action":"lambda:InvokeFunction",
"Resource":"arn:aws:lambda:region:account-id:function:HelloWorld",
"Sid":"65bafc90-6a1f-42a8-a7ab-8aa9bc877985",
"Condition":{
"StringEquals":{
"AWS:SourceAccount":"account-id"
},
"ArnLike":{
"AWS:SourceArn":"arn:aws:s3:::ExampleBucket"
}
}
}
]
}
}
For more information about using resource-based policies with Lambda, see Using Resource-Based
Policies for AWS Lambda (Lambda Function Policies) (p. 295). For additional information about using
IAM roles (identity-based policies) as opposed to resource-based policies, see How IAM Roles Differ from
Resource-based Policies in the IAM User Guide.
Specifying Policy Elements: Actions, Effects,
Resources, and Principals
For each AWS Lambda resource (see AWS Lambda Resources and Operations (p. 279)), the service
defines a set of API operations (see Actions (p. 309)). To grant permissions for these API operations,
Lambda defines a set of actions that you can specify in a policy. Note that, performing an API operation
can require permissions for more than one action. When granting permissions for specific actions, you also
identify the resource on which the actions are allowed or denied.
The following are the most basic policy elements:
• Resource – In a policy, you use an Amazon Resource Name (ARN) to identify the resource to which the
policy applies. For more information, see AWS Lambda Resources and Operations (p. 279).
• Action – You use action keywords to identify resource operations that you want to allow or deny. For
example, the lambda:InvokeFunction permission allows the user permissions to perform the AWS
Lambda Invoke operation.
• Effect – You specify the effect when the user requests the specific action—this can be either allow or
deny. If you don't explicitly grant access to (allow) a resource, access is implicitly denied. You can also
explicitly deny access to a resource, which you might do to make sure that a user cannot access it, even
if a different policy grants access.
• Principal – In identity-based policies (IAM policies), the user that the policy is attached to is the implicit
principal. For resource-based policies, you specify the user, account, service, or other entity that you
want to receive permissions (applies to resource-based policies only).
To learn more about IAM policy syntax and descriptions, see AWS IAM Policy Reference in the IAM User
Guide.
For a table showing all of the AWS Lambda API actions and the resources that they apply to, see Lambda
API Permissions: Actions, Resources, and Conditions Reference (p. 299).
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Specifying Conditions in a Policy
When you grant permissions, you can use the IAM policy language to specify the conditions when a policy
should take effect. For example, you might want a policy to be applied only after a specific date. For more
information about specifying conditions in a policy language, see Condition in the IAM User Guide.
To express conditions, you use predefined condition keys. There are no condition keys specific to Lambda.
However, there are AWS-wide condition keys that you can use as appropriate. For a complete list of AWSwide keys, see Available Keys for Conditions in the IAM User Guide.
Using Identity-Based Policies (IAM Policies) for
AWS Lambda
This topic provides examples of identity-based policies in which an account administrator can attach
permissions policies to IAM identities (that is, users, groups, and roles).
Important
We recommend that you first review the introductory topics that explain the basic concepts
and options available for you to manage access to your AWS Lambda resources. For
more information, see Overview of Managing Access Permissions to Your AWS Lambda
Resources (p. 279).
The sections in this topic cover the following:
• Permissions Required to Use the AWS Lambda Console (p. 284)
• AWS Managed (Predefined) Policies for AWS Lambda (p. 284)
• Customer Managed Policy Examples (p. 285)
The following shows an example of a permissions policy.
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "CreateFunctionPermissions",
"Effect": "Allow",
"Action": [
"lambda:CreateFunction"
],
"Resource": "*"
},
{
"Sid": "PermissionToPassAnyRole",
"Effect": "Allow",
"Action": [
"iam:PassRole"
],
"Resource": "arn:aws:iam::account-id:role/*"
}
]
}
The policy has two statements:
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• The first statement grants permissions for the AWS Lambda action (lambda:CreateFunction) on a
resource by using the Amazon Resource Name (ARN) for the Lambda function. Currently, AWS Lambda
doesn't support permissions for this particular action at the resource-level. Therefore, the policy specifies
a wildcard character (*) as the Resource value.
• The second statement grants permissions for the IAM action (iam:PassRole) on IAM roles. The wildcard
character (*) at the end of the Resource value means that the statement allows permission for the
iam:PassRole action on any IAM role. To limit this permission to a specific role, replace the wildcard
character (*) in the resource ARN with the specific role name.
The policy doesn't specify the Principal element because in an identity-based policy you don't specify
the principal who gets the permission. When you attach policy to a user, the user is the implicit principal.
When you attach a permission policy to an IAM role, the principal identified in the role's trust policy gets the
permissions.
For a table showing all of the AWS Lambda API actions and the resources and conditions that they apply
to, see Lambda API Permissions: Actions, Resources, and Conditions Reference (p. 299).
Permissions Required to Use the AWS Lambda
Console
The AWS Lambda console provides an integrated environment for you to create and manage Lambda
functions. The console provides many features and workflows that often require permissions to create a
Lambda function in addition to the API-specific permissions documented in the Lambda API Permissions:
Actions, Resources, and Conditions Reference (p. 299). For more information about these additional
console permissions, see Permissions Required to Use the AWS Lambda Console (p. 288).
AWS Managed (Predefined) Policies for AWS Lambda
AWS addresses many common use cases by providing standalone IAM policies that are created and
administered by AWS. Managed policies grant necessary permissions for common use cases so you
can avoid having to investigate what permissions are needed. For more information, see AWS Managed
Policies in the IAM User Guide.
The following AWS managed policies, which you can attach to users in your account, are specific to AWS
Lambda and are grouped by use case scenario:
• AWSLambdaReadOnlyAccess – Grants read-only access to AWS Lambda resources. Note that this
policy doesn't grant permission for the lambda:InvokeFunction action. If you want a user to invoke a
Lambda function, you can also attach the AWSLambdaRole AWS managed policy.
• AWSLambdaFullAccess – Grants full access to AWS Lambda resources.
• AWSLambdaRole – Grants permissions to invoke any Lambda function.
Note
You can review these permissions policies by signing in to the IAM console and searching for
specific policies there.
In addition, there are other AWS-managed policies that are suitable for use with IAM role (execution role)
you specify at the time of creating a Lambda function. For more information, see AWS Lambda Permissions
Model (p. 150).
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You can also create your own custom IAM policies to allow permissions for AWS Lambda API actions and
resources. You can attach these custom policies to the IAM users or groups that require those permissions
or to custom execution roles (IAM roles) that you create for your Lambda functions.
Customer Managed Policy Examples
The examples in this section provide a group of sample policies that you can attach to a user. If you are
new to creating policies, we recommend that you first create an IAM user in your account and attach the
policies to the user in sequence, as outlined in the steps in this section.
You can use the console to verify the effects of each policy as you attach the policy to the user. Initially,
the user doesn't have permissions and the user won't be able to do anything in the console. As you attach
policies to the user, you can verify that the user can perform various actions in the console.
We recommend that you use two browser windows: one to create the user and grant permissions, and the
other to sign in to the AWS Management Console using the user's credentials and verify permissions as
you grant them to the user.
For examples that show how to create an IAM role that you can use as an execution role for your Lambda
function, see Creating IAM Roles in the IAM User Guide.
Example Steps
• Step 1: Create an IAM User (p. 285)
• Step 2: Allow a User to List Lambda Functions (p. 285)
• Step 3: Allow a User to View Details of a Lambda Function (p. 286)
• Step 4: Allow a User to Invoke a Lambda Function (p. 286)
• Step 5: Allow a User to Monitor a Lambda Function and View CloudWatch Logs (p. 286)
• Step 6: Allow a User to Create a Lambda Function (p. 287)
Step 1: Create an IAM User
First, you need to create an IAM user, add the user to an IAM group with administrative permissions, and
then grant administrative permissions to the IAM user that you created. You can then access AWS using a
special URL and that IAM user's credentials.
For instructions, see Creating Your First IAM User and Administrators Group in the IAM User Guide.
Step 2: Allow a User to List Lambda Functions
An IAM user in your account must have permissions for the lambda:ListFunctions action before the
user can see anything in the console. When you grant these permissions, the console can show the list of
Lambda functions in the AWS account created in the specific AWS Region the user belongs to.
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "ListExistingFunctions",
"Effect": "Allow",
"Action": [
"lambda:ListFunctions"
],
"Resource": "*"
}
]
}
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Step 3: Allow a User to View Details of a Lambda Function
A user can select a Lambda function and view details of the function (such as aliases, versions, and other
configuration information), provided that the user has permissions for the following AWS Lambda actions:
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "DisplayFunctionDetailsPermissions",
"Effect": "Allow",
"Action": [
"lambda:ListVersionsByFunction",
"lambda:ListAliases",
"lambda:GetFunction",
"lambda:GetFunctionConfiguration",
"lambda:ListEventSourceMapping",
"lambda:GetPolicy"
],
"Resource": "*"
}
]
}
Step 4: Allow a User to Invoke a Lambda Function
If you want to allow a user permissions to manually invoke a function, you need to grant permissions for the
lambda:InvokeFunction action, as shown following:
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "InvokePermission",
"Effect": "Allow",
"Action": [
"lambda:InvokeFunction"
],
"Resource": "*"
}
]
}
Step 5: Allow a User to Monitor a Lambda Function and View
CloudWatch Logs
When a user invokes a Lambda function, AWS Lambda executes it and returns results. The user needs
additional permissions to monitor the Lambda function.
To enable the user to see the Lambda function's CloudWatch metrics on the console's Monitoring tab, or
on the grid view on the console home page, you must grant the following permissions:
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "CloudWatchPermission",
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"Effect": "Allow",
"Action": [
"cloudwatch:GetMetricStatistics"
],
"Resource": "*"
}
]
}
To enable a user to click the links to CloudWatch Logs in the AWS Lambda console and view log output in
CloudWatch Logs, you must grant the following permissions:
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "CloudWatchLogsPerms",
"Effect": "Allow",
"Action": [
"cloudwatchlog:DescribeLogGroups",
"cloudwatchlog:DescribeLogStreams",
"cloudwatchlog:GetLogEvents"
],
"Resource": "arn:aws:logs:region:account-id:log-group:/aws/lambda/*"
}
]
}
Step 6: Allow a User to Create a Lambda Function
If you want a user to be able to create a Lambda function, you must grant the following permissions. The
permissions for IAM-related actions are required because when a user creates a Lambda function, the user
needs to select an IAM execution role, which AWS Lambda assumes to execute the Lambda function.
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "ListExistingRolesAndPolicies",
"Effect": "Allow",
"Action": [
"iam:ListRolePolicies",
"iam:ListRoles"
],
"Resource": "*"
},
{
"Sid": "CreateFunctionPermissions",
"Effect": "Allow",
"Action": [
"lambda:CreateFunction"
],
"Resource": "*"
},
{
"Sid": "PermissionToPassAnyRole",
"Effect": "Allow",
"Action": [
"iam:PassRole"
],
"Resource": "arn:aws:iam::account-id:role/*"
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}
]
}
If you want a user to be able to create an IAM role when the user is creating a Lambda function, the user
needs permissions to perform the iam:PutRolePolicy action, as shown following:
{
"Sid": "CreateARole",
"Effect": "Allow",
"Action": [
"iam:CreateRole"
"iam:CreatePolicy"
"iam:AttachRolePolicy"
],
"Resource": "arn:aws:iam::account-id:role/*"
}
Important
Each IAM role has a permissions policy attached to it, which grants specific permissions to the
role. Regardless of whether the user creates a new role or uses an existing role, the user must
have permissions for all of the actions granted in the permissions policy associated with the role.
You must grant the user additional permissions accordingly.
Permissions Required to Use the AWS Lambda
Console
To take advantage of the integrated experience provided by the AWS Lambda console, a user must often
have more permissions than the API-specific permissions described in the references table, depending on
what you want the user to be able to do. For more information about Lambda API operations, see Lambda
API Permissions: Actions, Resources, and Conditions Reference (p. 299).
For example, suppose you allow an IAM user in your account permissions to create a Lambda function
to process Amazon S3 object-created events. To enable the user to configure Amazon S3 as the event
source, the console drop-down list will display a list of your buckets. However, the console can show the
bucket list only if the signed-in user has permissions for the relevant Amazon S3 actions.
The following sections describe required additional permissions for different integration points. For
information about integration points, see How It Works (p. 146).
If you are new to managing permissions, we recommend that you start with the example walkthrough where
you create an IAM user, grant the user incremental permissions, and verify the permissions work using the
AWS Lambda console (see Customer Managed Policy Examples (p. 285)).
Topics
• Amazon API Gateway (p. 289)
• Amazon CloudWatch Events (p. 289)
• Amazon CloudWatch Logs (p. 286)
• Amazon Cognito (p. 291)
• Amazon DynamoDB (p. 291)
• Amazon Kinesis Streams (p. 292)
• Amazon S3 (p. 293)
• Amazon SNS (p. 294)
• AWS IoT (p. 294)
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Note
All of these permissions policies grant the specific AWS services permissions to invoke a Lambda
function. The user who is configuring this integration must have permissions to invoke the Lambda
function. Otherwise, the user can't set the configuration. You can attach the AWSLambdaRole AWS
managed (predefined) permissions policy to the user to provide these permissions.
Amazon API Gateway
When you configure an API endpoint in the console, the console makes several API Gateway API calls.
These calls require permissions for the apigateway:* action, as shown following:
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "ApiGatewayPermissions",
"Effect": "Allow",
"Action": [
"apigateway:*"
],
"Resource": "*"
},
{
"Sid": "AddPermissionToFunctionPolicy",
"Effect": "Allow",
"Action": [
"lambda:AddPermission",
"lambda:RemovePermission",
"lambda:GetPolicy"
],
"Resource": "arn:aws:lambda:region:account-id:function:*"
},
{
"Sid": "ListEventSourcePerm",
"Effect": "Allow",
"Action": [
"lambda:ListEventSourceMappings"
],
"Resource": "*"
}
]
}
Amazon CloudWatch Events
You can schedule when to invoke a Lambda function. After you select an existing CloudWatch Events
rule (or create a new one), AWS Lambda creates a new target in CloudWatch that invokes your Lambda
function. For target creation to work, you need to grant the following additional permissions:
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "EventPerms",
"Effect": "Allow",
"Action": [
"events:PutRule",
"events:ListRules",
"events:ListRuleNamesByTarget",
"events:PutTargets",
"events:RemoveTargets",
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"events:DescribeRule",
"events:TestEventPattern",
"events:ListTargetsByRule",
"events:DeleteRule"
],
"Resource": "arn:aws:events:region:account-id:*"
},
{
"Sid": "AddPermissionToFunctionPolicy",
"Effect": "Allow",
"Action": [
"lambda:AddPermission",
"lambda:RemovePermission",
"lambda:GetPolicy"
],
"Resource": "arn:aws:lambda:region:account-id:function:*"
}
]
}
Amazon CloudWatch Logs
You can have the Amazon CloudWatch Logs service publish events and invoke your Lambda function.
When you configure this service as an event source, the console lists log groups in your account. For this
listing to occur, you need to grant the logs:DescribeLogGroups permissions, as shown following:
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "CloudWatchLogsPerms",
"Effect": "Allow",
"Action": [
"logs:FilterLogEvents",
"logs:DescribeLogGroups",
"logs:PutSubscriptionFilter",
"logs:DescribeSubscriptionFilters",
"logs:DeleteSubscriptionFilter",
"logs:TestMetricFilter"
],
"Resource": "arn:aws:logs:region:account-id:*"
},
{
"Sid": "AddPermissionToFunctionPolicy",
"Effect": "Allow",
"Action": [
"lambda:AddPermission",
"lambda:RemovePermission",
"lambda:GetPolicy"
],
"Resource": "arn:aws:lambda:region:account-id:function:*"
},
{
"Sid": "ListEventSourceMappingsPerms",
"Effect": "Allow",
"Action": [
"lambda:ListEventSourceMappings"
],
"Resource": "*"
}
]
}
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Note
The additional permissions shown are required for managing subscription filters.
Amazon Cognito
The console lists identity pools in your account. After you select a pool, you can configure the pool to have
the Cognito sync trigger as the event source type. To do this, you need to grant the following additional
permissions:
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "CognitoPerms1",
"Effect": "Allow",
"Action": [
"cognito-identity:ListIdentityPools"
],
"Resource": [
"arn:aws:cognito-identity:region:account-id:*"
]
},
{
"Sid": "CognitoPerms2",
"Effect": "Allow",
"Action": [
"cognito-sync:GetCognitoEvents",
"cognito-sync:SetCognitoEvents"
],
"Resource": [
"arn:aws:cognito-sync:region:account-id:*"
]
},
{
"Sid": "AddPermissionToFunctionPolicy",
"Effect": "Allow",
"Action": [
"lambda:AddPermission",
"lambda:RemovePermission",
"lambda:GetPolicy"
],
"Resource": "arn:aws:lambda:region:account-id:function:*"
},
{
"Sid": "ListEventSourcePerms",
"Effect": "Allow",
"Action": [
"lambda:ListEventSourceMappings"
],
"Resource": "*"
}
]
}
Amazon DynamoDB
The console lists all of the tables in your account. After you select a table, the console checks to see if
a DynamoDB stream exists for that table. If not, it creates the stream. If you want the user to be able to
configure a DynamoDB stream as an event source for a Lambda function, you need to grant the following
additional permissions:
{
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"Version": "2012-10-17",
"Statement": [
{
"Sid": "DDBpermissions1",
"Effect": "Allow",
"Action": [
"dynamodb:DescribeStream",
"dynamodb:DescribeTable",
"dynamodb:UpdateTable"
],
"Resource": "arn:aws:dynamodb:region:account-id:table/*"
},
{
"Sid": "DDBpermissions2",
"Effect": "Allow",
"Action": [
"dynamodb:ListStreams",
"dynamodb:ListTables"
],
"Resource": "*"
},
{
"Sid": "LambdaGetPolicyPerm",
"Effect": "Allow",
"Action": [
"lambda:GetPolicy"
],
"Resource": "arn:aws:lambda:region:account-id:function:*"
},
{
"Sid": "LambdaEventSourcePerms",
"Effect": "Allow",
"Action": [
"lambda:CreateEventSourceMapping",
"lambda:DeleteEventSourceMapping",
"lambda:GetEventSourceMapping",
"lambda:ListEventSourceMappings",
"lambda:UpdateEventSourceMapping"
],
"Resource": "*"
}
]
}
Important
For a Lambda function to read from a DynamoDB stream, the execution role associated with the
Lambda function must have the correct permissions. Therefore, the user must also have the same
permissions before you can grant the permissions to the execution role. You can grant these
permissions by attaching the AWSLambdaDynamoDBExecutionRole predefined policy, first to the user
and then to the execution role.
Amazon Kinesis Streams
The console lists all Amazon Kinesis streams in your account. After you select a stream, the console
creates event source mappings in AWS Lambda. For this to work, you need to grant the following additional
permissions:
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "PermissionForDescribeStream",
"Effect": "Allow",
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"Action": [
"kinesis:DescribeStream"
],
"Resource": "arn:aws:kinesis:region:account-id:stream/*"
},
{
"Sid": "PermissionForListStreams",
"Effect": "Allow",
"Action": [
"kinesis:ListStreams"
],
"Resource": "*"
},
{
"Sid": "PermissionForGetFunctionPolicy",
"Effect": "Allow",
"Action": [
"lambda:GetPolicy"
],
"Resource": "arn:aws:lambda:region:account-id:function:*"
},
{
"Sid": "LambdaEventSourcePerms",
"Effect": "Allow",
"Action": [
"lambda:CreateEventSourceMapping",
"lambda:DeleteEventSourceMapping",
"lambda:GetEventSourceMapping",
"lambda:ListEventSourceMappings",
"lambda:UpdateEventSourceMapping"
],
"Resource": "*"
}
]
}
Amazon S3
The console prepopulates the list of buckets in the AWS account and finds the bucket location for each
bucket. When you configure Amazon S3 as an event source, the console updates the bucket notification
configuration. For this to work, you need to grant the following additional permissions:
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "S3Permissions",
"Effect": "Allow",
"Action": [
"s3:GetBucketLocation",
"s3:GetBucketNotification",
"s3:PutBucketNotification",
"s3:ListAllMyBuckets"
],
"Resource": "arn:aws:s3:::*"
},
{
"Sid": "AddPermissionToFunctionPolicy",
"Effect": "Allow",
"Action": [
"lambda:AddPermission",
"lambda:RemovePermission"
],
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"Resource": "arn:aws:lambda:region:account-id:function:*"
}
]
}
Amazon SNS
The console lists Amazon Simple Notification Service (Amazon SNS) topics in your account. After you
select a topic, AWS Lambda subscribes your Lambda function to that Amazon SNS topic. For this work,
you need to grant the following additional permissions:
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "SNSPerms",
"Effect": "Allow",
"Action": [
"sns:ListSubscriptions",
"sns:ListSubscriptionsByTopic",
"sns:ListTopics",
"sns:Subscribe",
"sns:Unsubscribe"
],
"Resource": "arn:aws:sns:region:account-id:*"
},
{
"Sid": "AddPermissionToFunctionPolicy",
"Effect": "Allow",
"Action": [
"lambda:AddPermission",
"lambda:RemovePermission",
"lambda:GetPolicy"
],
"Resource": "arn:aws:lambda:region:account-id:function:*"
},
{
"Sid": "LambdaListESMappingsPerms",
"Effect": "Allow",
"Action": [
"lambda:ListEventSourceMappings"
],
"Resource": "*"
}
]
}
AWS IoT
The console lists all of the AWS IoT rules. After you select a rule, the console populates the rest of the
information associated with that rule in the user interface. If you select an existing rule, the console updates
it with information so that events are sent to AWS Lambda. You can also create a new rule. To do these
things, the user must have the following additional permissions:
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "IoTperms",
"Effect": "Allow",
"Action": [
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"iot:GetTopicRule",
"iot:CreateTopicRule",
"iot:ReplaceTopicRule"
],
"Resource": "arn:aws:iot:region:account-id:*"
},
{
"Sid": "IoTlistTopicRulePerms",
"Effect": "Allow",
"Action": [
"iot:ListTopicRules"
],
"Resource": "*"
},
{
"Sid": "LambdaPerms",
"Effect": "Allow",
"Action": [
"lambda:AddPermission",
"lambda:RemovePermission",
"lambda:GetPolicy"
],
"Resource": "arn:aws:lambda:region:account-id:function:*"
}
]
}
Using Resource-Based Policies for AWS Lambda
(Lambda Function Policies)
A Lambda function is one of the resources in AWS Lambda. You can add permissions to the policy
associated with a Lambda function. Permissions policies attached to Lambda functions are referred to as
resource-based policies (or Lambda function policies in Lambda). You use Lambda function policies to
manage Lambda function invocation permissions (see Invoke (p. 351)).
Important
Before you create resource-based policies, we recommend that you first review the introductory
topics that explain the basic concepts and options available for you to manage access to your
AWS Lambda resources. For more information, see Overview of Managing Access Permissions to
Your AWS Lambda Resources (p. 279).
Lambda function policies are primarily used when you are setting up an event source in AWS Lambda to
grant a service or an event source permissions to invoke your Lambda function (see Invoke (p. 351)).
An exception to this is when an event source (for example, Amazon DynamoDB or Amazon Kinesis) uses
the pull model, where permissions are managed in the Lambda function execution role instead. For more
information, see Event Source Mapping (p. 116).
Lambda function policies also make it easy to grant cross-account permissions to invoke your Lambda
function. Suppose you want to grant cross-account permissions (for example, permissions to Amazon S3)
to invoke your Lambda function. Instead of creating an IAM role to grant cross-account permissions, you
can add the relevant permissions in a Lambda function policy.
Note
If the custom application and the Lambda function it invokes belong to the same AWS account,
you don't need to grant explicit permissions using the policy attached to the Lambda function.
AWS Lambda provides the following API operations to manage a permissions policy associated with a
Lambda function:
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• AddPermission (p. 311)
• GetPolicy (p. 349)
• RemovePermission (p. 371)
Note
The AWS Lambda console is the easiest way to manage event sources and their permissions in
a Lambda function policy. If the AWS service console for the event source supports configuring
event source mapping, you can use that console too. As you configure new event sources
or modify existing event sources, the console automatically modifies the permissions policy
associated with the Lambda function.
You can use the console to view your function policy by choosing the Triggers tab on your function's
details page and then choosing View function policy. The console doesn't support directly modifying
permissions in a function policy. You must use either the AWS CLI or the AWS SDKs. The following are
AWS CLI examples of the API operations listed earlier in this topic:
Examples
• Example 1: Allow Amazon S3 to Invoke a Lambda Function (p. 296)
• Example 2: Allow Amazon API Gateway to Invoke a Lambda Function (p. 297)
• Example 3: Allow a User Application Created by Another AWS Account to Invoke a Lambda Function
(Cross-Account Scenario) (p. 298)
• Example 4: Retrieve a Lambda Function Policy (p. 298)
• Example 5: Remove Permissions from a Lambda Function Policy (p. 298)
• Example 6: Working with Lambda Function Versioning, Aliases, and Permissions (p. 298)
Example 1: Allow Amazon S3 to Invoke a Lambda
Function
To grant Amazon S3 permission to invoke a Lambda function, you configure permissions as follows:
• Specify s3.amazonaws.com as the principal value.
• Specify lambda:InvokeFunction as the action for which you are granting permissions.
To ensure that the event is generated from a specific bucket that is owned by a specific AWS account, you
also specify the following:
• Specify the bucket ARN as the source-arn value to restrict events from a specific bucket.
• Specify the AWS account ID that owns the bucket, to ensure that the named bucket is owned by the
account.
The following example AWS CLI command adds a permission to the helloworld Lambda function policy
granting Amazon S3 permissions to invoke the function.
aws lambda add-permission \
--region us-west-2 \
--function-name helloworld \
--statement-id 1 \
--principal s3.amazonaws.com \
--action lambda:InvokeFunction \
--source-arn arn:aws:s3:::examplebucket \
--source-account 111111111111 \
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--profile adminuser
The example assumes that the adminuser (who has full permissions) is adding this permission. Therefore,
the --profile parameter specifies the adminuser profile.
In response, AWS Lambda returns the following JSON code. The Statement value is a JSON string version
of the statement added to the Lambda function policy.
{
"Statement": "{\"Condition\":{\"StringEquals\":{\"AWS:SourceAccount\":
\"111111111111\"},
\"ArnLike\":{\"AWS:SourceArn\":\"arn:aws:s3:::examplebucket\"}},
\"Action\":[\"lambda:InvokeFunction\"],
\"Resource\":\"arn:aws:lambda:us-west-2:111111111111:function:helloworld
\",
\"Effect\":\"Allow\",\"Principal\":{\"Service\":\"s3.amazonaws.com\"},
\"Sid\":\"1\"}"
}
For information about the push model, see Event Source Mapping (p. 116).
Example 2: Allow Amazon API Gateway to Invoke a
Lambda Function
To grant permissions to allow Amazon API Gateway to invoke a Lambda function, do the following:
• Specify apigateway.amazonaws.com as the principal value.
• Specify lambda:InvokeFunction as the action for which you are granting permissions.
• Specify the API Gateway endpoint ARN as the source-arn value.
The following example AWS CLI command adds a permission to the helloworld Lambda function policy
granting API Gateway permissions to invoke the function.
aws lambda add-permission \
--region us-west-2 \
--function-name helloworld \
--statement-id 5 \
--principal apigateway.amazonaws.com \
--action lambda:InvokeFunction \
--source-arn arn:aws:execute-api:region:account-id:api-id/stage/method/resource-path \
--profile adminuser
In response, AWS Lambda returns the following JSON code. The Statement value is a JSON string version
of the statement added to the Lambda function policy.
{
"Statement": "{\"Condition\":{\"ArnLike\":{\"AWS:SourceArn\":\"arn:aws:apigateway:useast-1::my-api-id:/test/petstorewalkthrough/pets\"}},
\"Action\":[\"lambda:InvokeFunction\"],
\"Resource\":\"arn:aws:lambda:us-west-2:account-id:function:helloworld\",
\"Effect\":\"Allow\",
\"Principal\":{\"Service\":\"apigateway.amazonaws.com\"},
\"Sid\":\"5\"}"
}
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Cross-Account Scenario
Example 3: Allow a User Application Created by
Another AWS Account to Invoke a Lambda Function
(Cross-Account Scenario)
To grant permissions to another AWS account (that is, to create a cross-account scenario), you specify the
AWS account ID as the principal value as shown in the following AWS CLI command:
aws lambda add-permission \
--region us-west-2 \
--function-name helloworld \
--statement-id 3 \
--principal 111111111111 \
--action lambda:InvokeFunction \
--profile adminuser
In response, AWS Lambda returns the following JSON code. The Statement value is a JSON string version
of the statement added to the Lambda function policy.
{
"Statement": "{\"Action\":[\"lambda:InvokeFunction\"],
\"Resource\":\"arn:aws:lambda:us-west-2:account-id:function:helloworld
\",
\"Effect\":\"Allow\",
\"Principal\":{\"AWS\":\"account-id\"},
\"Sid\":\"3\"}"
}
Example 4: Retrieve a Lambda Function Policy
To retrieve your Lambda function policy, you use the get-policy command:
aws lambda get-policy \
--function-name example \
--profile adminuser
Example 5: Remove Permissions from a Lambda
Function Policy
To remove permissions from your Lambda function policy, you use the remove-permission command,
specifying the function name and statement ID:
aws lambda remove-permission \
--function-name example \
--statement-id 1 \
--profile adminuser
Example 6: Working with Lambda Function Versioning,
Aliases, and Permissions
For more information about permissions policies for Lambda function versions and aliases, see Versioning,
Aliases, and Resource Policies (p. 82).
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Lambda API Permissions: Actions, Resources, and
Conditions Reference
When you are setting up Access Control (p. 278) and writing permissions policies that you can attach to
an IAM identity (identity-based policies), you can use the following table as a reference. The list includes
each AWS Lambda API operation, the corresponding actions for which you can grant permissions to
perform the action, the AWS resource for which you can grant the permissions and condition keys for
specified API actions. You specify the actions in the policy's Action field, the resource value in the policy's
Resource field and a condition key in the policy's Condition keys field.
To specify an action, use the lambda: prefix followed by the API operation name (for example,
lambda:CreateFunction).
Note
Permissions for the AWS Lambda Invoke API in the following table can also be granted by using
resource-based policies. For more information, see Using Resource-Based Policies for AWS
Lambda (Lambda Function Policies) (p. 295).
You can use AWS-wide condition keys in your AWS Lambda policies to express conditions. For a complete
list of AWS-wide keys, see Available Keys for Conditions in the IAM User Guide.
AWS Lambda also offers predefined condition keys to a limited set of API operations. For example, you
can:
• Restrict access based on the Lambda function ARN (Amazon Resource Name) to the following
operations:
• CreateEventSourceMapping
• DeleteEventSourceMapping
• UpdateEventSourceMapping
The following is an example policy that applies this condition:
"Version": "2012-10-17",
"Statement": [
{
"Sid": " DeleteEventSourceMappingPolicy",
"Effect": "Allow",
"Action": [
"lambda:DeleteEventSourceMapping"
],
"Resource": "arn:aws:lambda:region:account-id:event-source-mapping:UUID",
"Condition": {"StringEquals": {"lambda:FunctionArn":
"arn:aws:lambda:region:account-id:function:function-name}}
}
]
• Restrict mapping based on the AWS service principal to the following operations:
• AddPermission
• RemovePermission
The following is an example policy that applies this condition:
"Version": "2012-10-17",
"Statement": [
{
"Sid": "AddPermissionPolicy",
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"Effect": "Allow",
"Action": [
"lambda:AddPermission"
],
"Resource": "arn:aws:lambda:region:account-id:function:function-name",
"Condition": {"StringEquals": {"lambda:Principal": "s3.amazonaws.com"}}
}
]
AWS Lambda API and Required Permissions for Actions
AddPermission (p. 311)
Action(s): lambda:AddPermission
Resource: arn:aws:lambda:region:account-id:?/*
CreateEventSourceMapping (p. 318)
Action(s): lambda:CreateEventSourceMapping
Resource: arn:aws:lambda:region:account-id:?
CreateFunction (p. 322)
Action(s): lambda:CreateFunction
Resource: arn:aws:lambda:region:account-id:?
DeleteEventSourceMapping (p. 330)
Action(s): lambda:DeleteEventSourceMapping
Resource: arn:aws:lambda:region:account-id:?
DeleteFunction (p. 333)
Action(s): lambda:DeleteFunction,
Resource: arn:aws:lambda:region:account-id:?
GetEventSourceMapping (p. 339)
Action(s): lambda:GetEventSourceMapping
Resource: arn:aws:lambda:region:account-id:?
GetFunction (p. 342)
Action(s): lambda:GetFunction
Resource: arn:aws:lambda:region:account-id:?
GetFunctionConfiguration (p. 345)
Action(s): lambda:DescribeMountTargetSecurityGroups,
Resource: arn:aws:lambda:region:account-id:?
GetPolicy (p. 349)
Action(s): lambda:DescribeMountTargets
Resource: arn:aws:lambda:region:account-id:?
Invoke (p. 351)
Action(s): lambda:DescribeTags
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Resource: arn:aws:lambda:region:account-id:?
InvokeAsync (p. 355)
Action(s): lambda:ModifyMountTargetSecurityGroups
Resource: arn:aws:lambda:region:account-id:?
ListEventSourceMappings (p. 359)
Action(s): lambda:ListEventSourceMappings
Resource: arn:aws:lambda:region:account-id:?
ListFunctions (p. 362)
Action(s): lambda:ListFunctions
Resource: arn:aws:lambda:region:account-id:?
RemovePermission (p. 371)
Action(s): lambda:RemovePermission
Resource: arn:aws:lambda:region:account-id:?
UpdateEventSourceMapping (p. 376)
Action(s): lambda:UpdateEventSourceMapping
Resource: arn:aws:lambda:region:account-id:?
UpdateFunctionCode (p. 379)
Action(s): lambda:UpdateFunctionCode
Resource: arn:aws:lambda:region:account-id:?
UpdateFunctionConfiguration (p. 384)
Action(s): lambda:UpdateFunctionConfiguration
Resource: arn:aws:lambda:region:account-id:?
Policy Templates
When you create an AWS Lambda function in the console using one of the blueprints, Lambda allows you
to create a role for your function from a list of Lambda policy templates.
By selecting one of these templates, your Lambda function automatically creates the role with the requisite
permissions attached to that policy.
The following lists the permissions that are applied to each policy template in the Policy templates list.
The policy templates are named after the blueprints to which they correspond. Lambda will automatically
populate the placeholder items (such as region and accountID) with the appropriate information. For more
information on creating a Lambda function using policy templates, see Step 2.1: Create a Hello World
Lambda Function (p. 159).
The following templates are automatically applied depending upon the type of Lambda function you are
creating:
Basic: 'Basic Lambda Permissions'
{
"Version":"2012-10-17",
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VPCAccess: 'Lambda VPC Access Permissions'
"Statement":[
{
"Effect":"Allow",
"Action":"logs:CreateLogGroup",
"Resource":"arn:aws:logs:region:accountId:*"
},
{
"Effect":"Allow",
"Action":[
"logs:CreateLogStream",
"logs:PutLogEvents"
],
"Resource":[
"arn:aws:logs:region:accountId:log-group:[[logGroups]]:*"
]
}
]
}
VPCAccess: 'Lambda VPC Access Permissions'
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"ec2:CreateNetworkInterface",
"ec2:DeleteNetworkInterface",
"ec2:DescribeNetworkInterfaces"
],
"Resource": "*"
}
]
}
Kinesis: 'Lambda Kinesis stream poller permissions'
{
"Version":"2012-10-17",
"Statement":[
{
"Effect":"Allow",
"Action":"lambda:InvokeFunction",
"Resource":"arn:aws:lambda:region:accountId:function:functionName*"
},
{
"Effect":"Allow",
"Action":"kinesis:ListStreams",
"Resource":"arn:aws:kinesis:region:accountId:stream/*"
},
{
"Effect":"Allow",
"Action":[
"kinesis:DescribeStream",
"kinesis:GetRecords",
"kinesis:GetShardIterator"
],
"Resource":"arn:aws:kinesis:region:accountId:
stream/streamName"
}
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DynamoDB: 'Lambda DynamoDB stream poller permissions'
]
}
DynamoDB: 'Lambda DynamoDB stream poller
permissions'
{
"Version":"2012-10-17",
"Statement":[
{
"Effect":"Allow",
"Action":"lambda:InvokeFunction",
"Resource":"arn:aws:lambda:region:accountId:function:functionName*"
},
{
"Effect":"Allow",
"Action":[
"dynamodb:DescribeStream",
"dynamodb:GetRecords",
"dynamodb:GetShardIterator",
"dynamodb:ListStreams"
],
"Resource":"arn:aws:dynamodb:region:accountId:table/tableName/stream/*"
}
]
}
Edge: 'Basic Edge Lambda permissions'
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"logs:CreateLogGroup",
"logs:CreateLogStream",
"logs:PutLogEvents"
],
"Resource": [
"arn:aws:logs:*:*:*"
]
}
]
}
RedrivePolicySNS: ‘Dead letter queue SNS
permissions’
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"sns:Publish"
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],
"Resource": "arn:aws:sns:region:accountId:topicName"
}
]
}
RedrivePolicySQS: 'Dead letter queue SQS
permissions'
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"sqs:SendMessage"
],
"Resource": "arn:aws:sqs:region:accountId:queueName"
}
]
}
The following templates are selected depending upon which blueprint you choose. You can also select
them from the dropdown to add extra permissions:
CloudFormation: 'CloudFormation stack read-only
permissions'
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"cloudformation:DescribeStacks"
],
"Resource": "*"
}
]
}
AMI: 'AMI read-only permissions'
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"ec2:DescribeImages"
],
"Resource": "*"
}
]
}
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KMS: 'KMS decryption permissions'
KMS: 'KMS decryption permissions'
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"kms:Decrypt"
],
"Resource": "*"
}
]
}
S3: 'S3 object read-only permissions'
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"s3:GetObject"
],
"Resource": "arn:aws:s3:::*"
}
]
}
Elasticsearch: 'Elasticsearch permissions'
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"es:ESHttpPost"
],
"Resource": "*"
}
]
}
SES: 'SES bounce permissions'
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"ses:SendBounce"
],
"Resource": "*"
}
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TestHarness: 'Test Harness permissions'
]
}
TestHarness: 'Test Harness permissions'
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"dynamodb:PutItem"
],
"Resource": "arn:aws:dynamodb:region:accountId:table/*"
},
{
"Effect": "Allow",
"Action": [
"lambda:InvokeFunction"
],
"Resource": "arn:aws:lambda:region:accountId:function:*"
}
]
}
Microservice: 'Simple Microservice permissions'
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"dynamodb:DeleteItem",
"dynamodb:GetItem",
"dynamodb:PutItem",
"dynamodb:Scan",
"dynamodb:UpdateItem"
],
"Resource": "arn:aws:dynamodb:region:accountId:table/*"
}
]
}
VPN: 'VPN Connection Monitor permissions'
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"cloudwatch:PutMetricData"
],
"Resource": "*"
},
{
"Effect": "Allow",
"Action": [
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SQS: 'SQS Poller permissions'
"ec2:DescribeRegions",
"ec2:DescribeVpnConnections"
],
"Resource": "*"
}
]
}
SQS: 'SQS Poller permissions'
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"sqs:DeleteMessage",
"sqs:ReceiveMessage"
],
"Resource": "arn:aws:sqs:*"
},
{
"Effect": "Allow",
"Action": [
"lambda:InvokeFunction"
],
"Resource": "arn:aws:lambda:region:accountId:function:functionName*"
}
]
}
IoTButton: 'AWS IoT Button permissions'
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"sns:ListSubscriptionsByTopic",
"sns:CreateTopic",
"sns:SetTopicAttributes",
"sns:Subscribe",
"sns:Publish"
],
"Resource": "*"
}
]
}
RekognitionNoDataAccess:'Amazon Rekognition no
data permissions'
{
"Version": "2012-10-17",
"Statement": [
{
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RekognitionReadOnlyAccess: 'Amazon
Rekognition read-only permissions'
"Effect": "Allow",
"Action": [
"rekognition:CompareFaces",
"rekognition:DetectFaces",
"rekognition:DetectLabels"
],
"Resource": "*"
}
]
}
RekognitionReadOnlyAccess: 'Amazon Rekognition
read-only permissions'
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"rekognition:ListCollections",
"rekognition:ListFaces",
"rekognition:SearchFaces",
"rekognition:SearchFacesByImage"
],
"Resource": "*"
}
]
}
RekognitionWriteOnlyAccess: 'Amazon Rekognition
write-only permissions'
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"rekognition:CreateCollection",
"rekognition:IndexFaces"
],
"Resource": "*"
}
]
}
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API Reference
This section contains the AWS Lambda API Reference documentation. When making the API calls, you
will need to authenticate your request by providing a signature. AWS Lambda supports signature version
4. For more information, see Signature Version 4 Signing Process in the Amazon Web Services General
Reference.
For an overview of the service, see What Is AWS Lambda? (p. 1). For information about how the service
works, see How It Works (p. 146).
You can use the AWS CLI to explore the AWS Lambda API. This guide provides several tutorials that use
the AWS CLI.
Topics
• Actions (p. 309)
• Data Types (p. 389)
Actions
The following actions are supported:
• AddPermission (p. 311)
• CreateAlias (p. 315)
• CreateEventSourceMapping (p. 318)
• CreateFunction (p. 322)
• DeleteAlias (p. 328)
• DeleteEventSourceMapping (p. 330)
• DeleteFunction (p. 333)
• GetAccountSettings (p. 335)
• GetAlias (p. 337)
• GetEventSourceMapping (p. 339)
• GetFunction (p. 342)
• GetFunctionConfiguration (p. 345)
• GetPolicy (p. 349)
• Invoke (p. 351)
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Actions
• InvokeAsync (p. 355)
• ListAliases (p. 357)
• ListEventSourceMappings (p. 359)
• ListFunctions (p. 362)
• ListVersionsByFunction (p. 364)
• PublishVersion (p. 367)
• RemovePermission (p. 371)
• UpdateAlias (p. 373)
• UpdateEventSourceMapping (p. 376)
• UpdateFunctionCode (p. 379)
• UpdateFunctionConfiguration (p. 384)
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AddPermission
AddPermission
Adds a permission to the resource policy associated with the specified AWS Lambda function. You use
resource policies to grant permissions to event sources that use push model. In a push model, event
sources (such as Amazon S3 and custom applications) invoke your Lambda function. Each permission you
add to the resource policy allows an event source, permission to invoke the Lambda function.
For information about the push model, see AWS Lambda: How it Works.
If you are using versioning, the permissions you add are specific to the Lambda function version or alias
you specify in the AddPermission request via the Qualifier parameter. For more information about
versioning, see AWS Lambda Function Versioning and Aliases.
This operation requires permission for the lambda:AddPermission action.
Request Syntax
POST /2015-03-31/functions/FunctionName/policy?Qualifier=Qualifier HTTP/1.1
Content-type: application/json
{
"Action": "string",
"EventSourceToken": "string",
"Principal": "string",
"SourceAccount": "string",
"SourceArn": "string",
"StatementId": "string"
}
URI Request Parameters
The request requires the following URI parameters.
FunctionName (p. 311)
Name of the Lambda function whose resource policy you are updating by adding a new permission.
You can specify a function name (for example, Thumbnail) or you can specify Amazon
Resource Name (ARN) of the function (for example, arn:aws:lambda:us-west-2:accountid:function:ThumbNail). AWS Lambda also allows you to specify partial ARN (for example, accountid:Thumbnail). Note that the length constraint applies only to the ARN. If you specify only the function
name, it is limited to 64 characters in length.
Length Constraints: Minimum length of 1. Maximum length of 140.
Pattern: (arn:aws:lambda:)?([a-z]{2}-[a-z]+-\d{1}:)?(\d{12}:)?(function:)?([a-zA-Z0-9_]+)(:(\$LATEST|[a-zA-Z0-9-_]+))?
Qualifier (p. 311)
You can use this optional query parameter to describe a qualified ARN using a function version or an
alias name. The permission will then apply to the specific qualified ARN. For example, if you specify
function version 2 as the qualifier, then permission applies only when request is made using qualified
function ARN:
arn:aws:lambda:aws-region:acct-id:function:function-name:2
If you specify an alias name, for example PROD, then the permission is valid only for requests made
using the alias ARN:
arn:aws:lambda:aws-region:acct-id:function:function-name:PROD
If the qualifier is not specified, the permission is valid only when requests is made using unqualified
function ARN.
arn:aws:lambda:aws-region:acct-id:function:function-name
Length Constraints: Minimum length of 1. Maximum length of 128.
Pattern: (|[a-zA-Z0-9$_-]+)
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Request Body
The request accepts the following data in JSON format.
Action (p. 311)
The AWS Lambda action you want to allow in this statement. Each Lambda action is a string starting
with lambda: followed by the API name (see Actions) . For example, lambda:CreateFunction. You can
use wildcard (lambda:*) to grant permission for all AWS Lambda actions.
Type: String
Pattern: (lambda:[*]|lambda:[a-zA-Z]+|[*])
Required: Yes
EventSourceToken (p. 311)
A unique token that must be supplied by the principal invoking the function. This is currently only used
for Alexa Smart Home functions.
Type: String
Length Constraints: Minimum length of 0. Maximum length of 256.
Pattern: [a-zA-Z0-9._\-]+
Required: No
Principal (p. 311)
The principal who is getting this permission. It can be Amazon S3 service Principal
(s3.amazonaws.com) if you want Amazon S3 to invoke the function, an AWS account ID if you are
granting cross-account permission, or any valid AWS service principal such as sns.amazonaws.com.
For example, you might want to allow a custom application in another AWS account to push events to
AWS Lambda by invoking your function.
Type: String
Pattern: .*
Required: Yes
SourceAccount (p. 311)
This parameter is used for S3. The AWS account ID (without a hyphen) of the source owner. For
example, if the SourceArn identifies a bucket, then this is the bucket owner's account ID. You can use
this additional condition to ensure the bucket you specify is owned by a specific account (it is possible
the bucket owner deleted the bucket and some other AWS account created the bucket). You can also
use this condition to specify all sources (that is, you don't specify the SourceArn) owned by a specific
account.
Type: String
Pattern: \d{12}
Required: No
SourceArn (p. 311)
This is optional; however, when granting a source permission to invoke your function, you should
specify this field with the Amazon Resource Name (ARN) as its value. This ensures that only events
generated from the specified source can invoke the function.
Important
If you add a permission for the source without providing the source ARN, any AWS account
that creates a mapping to your function ARN can send events to invoke your Lambda function
from that source.
Type: String
Pattern: arn:aws:([a-zA-Z0-9\-])+:([a-z]{2}-[a-z]+-\d{1})?:(\d{12})?:(.*)
Required: No
StatementId (p. 311)
A unique statement identifier.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 100.
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Pattern: ([a-zA-Z0-9-_]+)
Required: Yes
Response Syntax
HTTP/1.1 201
Content-type: application/json
{
"Statement": "string"
}
Response Elements
If the action is successful, the service sends back an HTTP 201 response.
The following data is returned in JSON format by the service.
Statement (p. 313)
The permission statement you specified in the request. The response returns the same as a string
using a backslash ("\") as an escape character in the JSON.
Type: String
Errors
InvalidParameterValueException
One of the parameters in the request is invalid. For example, if you provided an IAM role for AWS
Lambda to assume in the CreateFunction or the UpdateFunctionConfiguration API, that AWS
Lambda is unable to assume you will get this exception.
HTTP Status Code: 400
PolicyLengthExceededException
Lambda function access policy is limited to 20 KB.
HTTP Status Code: 400
ResourceConflictException
The resource already exists.
HTTP Status Code: 409
ResourceNotFoundException
The resource (for example, a Lambda function or access policy statement) specified in the request
does not exist.
HTTP Status Code: 404
ServiceException
The AWS Lambda service encountered an internal error.
HTTP Status Code: 500
TooManyRequestsException
HTTP Status Code: 429
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS Command Line Interface
• AWS SDK for .NET
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• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for JavaScript
• AWS SDK for PHP V3
• AWS SDK for Python
• AWS SDK for Ruby V2
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CreateAlias
CreateAlias
Creates an alias that points to the specified Lambda function version. For more information, see
Introduction to AWS Lambda Aliases.
Alias names are unique for a given function. This requires permission for the lambda:CreateAlias action.
Request Syntax
POST /2015-03-31/functions/FunctionName/aliases HTTP/1.1
Content-type: application/json
{
"Description": "string",
"FunctionVersion": "string",
"Name": "string"
}
URI Request Parameters
The request requires the following URI parameters.
FunctionName (p. 315)
Name of the Lambda function for which you want to create an alias. Note that the length constraint
applies only to the ARN. If you specify only the function name, it is limited to 64 characters in length.
Length Constraints: Minimum length of 1. Maximum length of 140.
Pattern: (arn:aws:lambda:)?([a-z]{2}-[a-z]+-\d{1}:)?(\d{12}:)?(function:)?([a-zA-Z0-9_]+)(:(\$LATEST|[a-zA-Z0-9-_]+))?
Request Body
The request accepts the following data in JSON format.
Description (p. 315)
Description of the alias.
Type: String
Length Constraints: Minimum length of 0. Maximum length of 256.
Required: No
FunctionVersion (p. 315)
Lambda function version for which you are creating the alias.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 1024.
Pattern: (\$LATEST|[0-9]+)
Required: Yes
Name (p. 315)
Name for the alias you are creating.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 128.
Pattern: (?!^[0-9]+$)([a-zA-Z0-9-_]+)
Required: Yes
Response Syntax
HTTP/1.1 201
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Content-type: application/json
{
"AliasArn": "string",
"Description": "string",
"FunctionVersion": "string",
"Name": "string"
}
Response Elements
If the action is successful, the service sends back an HTTP 201 response.
The following data is returned in JSON format by the service.
AliasArn (p. 315)
Lambda function ARN that is qualified using the alias name as the suffix. For example, if you create
an alias called BETA that points to a helloworld function version, the ARN is arn:aws:lambda:awsregions:acct-id:function:helloworld:BETA.
Type: String
Pattern: arn:aws:lambda:[a-z]{2}-[a-z]+-\d{1}:\d{12}:function:[a-zA-Z0-9-_]+(:(\$LATEST|
[a-zA-Z0-9-_]+))?
Description (p. 315)
Alias description.
Type: String
Length Constraints: Minimum length of 0. Maximum length of 256.
FunctionVersion (p. 315)
Function version to which the alias points.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 1024.
Pattern: (\$LATEST|[0-9]+)
Name (p. 315)
Alias name.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 128.
Pattern: (?!^[0-9]+$)([a-zA-Z0-9-_]+)
Errors
InvalidParameterValueException
One of the parameters in the request is invalid. For example, if you provided an IAM role for AWS
Lambda to assume in the CreateFunction or the UpdateFunctionConfiguration API, that AWS
Lambda is unable to assume you will get this exception.
HTTP Status Code: 400
ResourceConflictException
The resource already exists.
HTTP Status Code: 409
ResourceNotFoundException
The resource (for example, a Lambda function or access policy statement) specified in the request
does not exist.
HTTP Status Code: 404
ServiceException
The AWS Lambda service encountered an internal error.
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HTTP Status Code: 500
TooManyRequestsException
HTTP Status Code: 429
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS Command Line Interface
• AWS SDK for .NET
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for JavaScript
• AWS SDK for PHP V3
• AWS SDK for Python
• AWS SDK for Ruby V2
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CreateEventSourceMapping
CreateEventSourceMapping
Identifies a stream as an event source for a Lambda function. It can be either an Amazon Kinesis stream or
an Amazon DynamoDB stream. AWS Lambda invokes the specified function when records are posted to
the stream.
This association between a stream source and a Lambda function is called the event source mapping.
Important
This event source mapping is relevant only in the AWS Lambda pull model, where AWS Lambda
invokes the function. For more information, see AWS Lambda: How it Works in the AWS Lambda
Developer Guide.
You provide mapping information (for example, which stream to read from and which Lambda function to
invoke) in the request body.
Each event source, such as an Amazon Kinesis or a DynamoDB stream, can be associated with multiple
AWS Lambda function. A given Lambda function can be associated with multiple AWS event sources.
If you are using versioning, you can specify a specific function version or an alias via the function name
parameter. For more information about versioning, see AWS Lambda Function Versioning and Aliases.
This operation requires permission for the lambda:CreateEventSourceMapping action.
Request Syntax
POST /2015-03-31/event-source-mappings/ HTTP/1.1
Content-type: application/json
{
"BatchSize": number,
"Enabled": boolean,
"EventSourceArn": "string",
"FunctionName": "string",
"StartingPosition": "string",
"StartingPositionTimestamp": number
}
URI Request Parameters
The request does not use any URI parameters.
Request Body
The request accepts the following data in JSON format.
BatchSize (p. 318)
The largest number of records that AWS Lambda will retrieve from your event source at the time of
invoking your function. Your function receives an event with all the retrieved records. The default is 100
records.
Type: Integer
Valid Range: Minimum value of 1. Maximum value of 10000.
Required: No
Enabled (p. 318)
Indicates whether AWS Lambda should begin polling the event source. By default, Enabled is true.
Type: Boolean
Required: No
EventSourceArn (p. 318)
The Amazon Resource Name (ARN) of the Amazon Kinesis or the Amazon DynamoDB stream that is
the event source. Any record added to this stream could cause AWS Lambda to invoke your Lambda
function, it depends on the BatchSize. AWS Lambda POSTs the Amazon Kinesis event, containing
records, to your Lambda function as JSON.
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Type: String
Pattern: arn:aws:([a-zA-Z0-9\-])+:([a-z]{2}-[a-z]+-\d{1})?:(\d{12})?:(.*)
Required: Yes
FunctionName (p. 318)
The Lambda function to invoke when AWS Lambda detects an event on the stream.
You can specify the function name (for example, Thumbnail) or you can specify Amazon
Resource Name (ARN) of the function (for example, arn:aws:lambda:us-west-2:accountid:function:ThumbNail).
If you are using versioning, you can also provide a qualified function ARN (ARN that is qualified with
function version or alias name as suffix). For more information about versioning, see AWS Lambda
Function Versioning and Aliases
AWS Lambda also allows you to specify only the function name with the account ID qualifier (for
example, account-id:Thumbnail).
Note that the length constraint applies only to the ARN. If you specify only the function name, it is
limited to 64 characters in length.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 140.
Pattern: (arn:aws:lambda:)?([a-z]{2}-[a-z]+-\d{1}:)?(\d{12}:)?(function:)?([a-zA-Z0-9_]+)(:(\$LATEST|[a-zA-Z0-9-_]+))?
Required: Yes
StartingPosition (p. 318)
The position in the stream where AWS Lambda should start reading. Valid only for Kinesis streams.
For more information, see ShardIteratorType in the Amazon Kinesis API Reference.
Type: String
Valid Values: TRIM_HORIZON | LATEST | AT_TIMESTAMP
Required: Yes
StartingPositionTimestamp (p. 318)
The timestamp of the data record from which to start reading. Used with shard iterator type
AT_TIMESTAMP. If a record with this exact timestamp does not exist, the iterator returned is for the
next (later) record. If the timestamp is older than the current trim horizon, the iterator returned is for the
oldest untrimmed data record (TRIM_HORIZON). Valid only for Kinesis streams.
Type: Timestamp
Required: No
Response Syntax
HTTP/1.1 202
Content-type: application/json
{
"BatchSize": number,
"EventSourceArn": "string",
"FunctionArn": "string",
"LastModified": number,
"LastProcessingResult": "string",
"State": "string",
"StateTransitionReason": "string",
"UUID": "string"
}
Response Elements
If the action is successful, the service sends back an HTTP 202 response.
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The following data is returned in JSON format by the service.
BatchSize (p. 319)
The largest number of records that AWS Lambda will retrieve from your event source at the time of
invoking your function. Your function receives an event with all the retrieved records.
Type: Integer
Valid Range: Minimum value of 1. Maximum value of 10000.
EventSourceArn (p. 319)
The Amazon Resource Name (ARN) of the Amazon Kinesis stream that is the source of events.
Type: String
Pattern: arn:aws:([a-zA-Z0-9\-])+:([a-z]{2}-[a-z]+-\d{1})?:(\d{12})?:(.*)
FunctionArn (p. 319)
The Lambda function to invoke when AWS Lambda detects an event on the stream.
Type: String
Pattern: arn:aws:lambda:[a-z]{2}-[a-z]+-\d{1}:\d{12}:function:[a-zA-Z0-9-_]+(:(\$LATEST|
[a-zA-Z0-9-_]+))?
LastModified (p. 319)
The UTC time string indicating the last time the event mapping was updated.
Type: Timestamp
LastProcessingResult (p. 319)
The result of the last AWS Lambda invocation of your Lambda function.
Type: String
State (p. 319)
The state of the event source mapping. It can be Creating, Enabled, Disabled, Enabling, Disabling,
Updating, or Deleting.
Type: String
StateTransitionReason (p. 319)
The reason the event source mapping is in its current state. It is either user-requested or an AWS
Lambda-initiated state transition.
Type: String
UUID (p. 319)
The AWS Lambda assigned opaque identifier for the mapping.
Type: String
Errors
InvalidParameterValueException
One of the parameters in the request is invalid. For example, if you provided an IAM role for AWS
Lambda to assume in the CreateFunction or the UpdateFunctionConfiguration API, that AWS
Lambda is unable to assume you will get this exception.
HTTP Status Code: 400
ResourceConflictException
The resource already exists.
HTTP Status Code: 409
ResourceNotFoundException
The resource (for example, a Lambda function or access policy statement) specified in the request
does not exist.
HTTP Status Code: 404
ServiceException
The AWS Lambda service encountered an internal error.
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HTTP Status Code: 500
TooManyRequestsException
HTTP Status Code: 429
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS Command Line Interface
• AWS SDK for .NET
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for JavaScript
• AWS SDK for PHP V3
• AWS SDK for Python
• AWS SDK for Ruby V2
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CreateFunction
CreateFunction
Creates a new Lambda function. The function metadata is created from the request parameters, and the
code for the function is provided by a .zip file in the request body. If the function name already exists, the
operation will fail. Note that the function name is case-sensitive.
If you are using versioning, you can also publish a version of the Lambda function you are creating using
the Publish parameter. For more information about versioning, see AWS Lambda Function Versioning and
Aliases.
This operation requires permission for the lambda:CreateFunction action.
Request Syntax
POST /2015-03-31/functions HTTP/1.1
Content-type: application/json
{
"Code": {
"S3Bucket": "string",
"S3Key": "string",
"S3ObjectVersion": "string",
"ZipFile": blob
},
"DeadLetterConfig": {
"TargetArn": "string"
},
"Description": "string",
"Environment": {
"Variables": {
"string" : "string"
}
},
"FunctionName": "string",
"Handler": "string",
"KMSKeyArn": "string",
"MemorySize": number,
"Publish": boolean,
"Role": "string",
"Runtime": "string",
"Timeout": number,
"VpcConfig": {
"SecurityGroupIds": [ "string" ],
"SubnetIds": [ "string" ]
}
}
URI Request Parameters
The request does not use any URI parameters.
Request Body
The request accepts the following data in JSON format.
Code (p. 322)
The code for the Lambda function.
Type: FunctionCode (p. 399) object
Required: Yes
DeadLetterConfig (p. 322)
The parent object that contains the target Amazon Resource Name (ARN) of an Amazon SQS queue
or Amazon SNS topic.
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Type: DeadLetterConfig (p. 393) object
Required: No
Description (p. 322)
A short, user-defined function description. Lambda does not use this value. Assign a meaningful
description as you see fit.
Type: String
Length Constraints: Minimum length of 0. Maximum length of 256.
Required: No
Environment (p. 322)
The parent object that contains your environment's configuration settings.
Type: Environment (p. 394) object
Required: No
FunctionName (p. 322)
The name you want to assign to the function you are uploading. The function names appear in the
console and are returned in the ListFunctions (p. 362) API. Function names are used to specify
functions to other AWS Lambda API operations, such as Invoke (p. 351). Note that the length
constraint applies only to the ARN. If you specify only the function name, it is limited to 64 characters in
length.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 140.
Pattern: (arn:aws:lambda:)?([a-z]{2}-[a-z]+-\d{1}:)?(\d{12}:)?(function:)?([a-zA-Z0-9_]+)(:(\$LATEST|[a-zA-Z0-9-_]+))?
Required: Yes
Handler (p. 322)
The function within your code that Lambda calls to begin execution. For Node.js, it is the modulename.export value in your function. For Java, it can be package.class-name::handler or
package.class-name. For more information, see Lambda Function Handler (Java).
Type: String
Length Constraints: Maximum length of 128.
Pattern: [^\s]+
Required: Yes
KMSKeyArn (p. 322)
The Amazon Resource Name (ARN) of the KMS key used to encrypt your function's environment
variables. If not provided, AWS Lambda will use a default service key.
Type: String
Pattern: (arn:aws:[a-z0-9-.]+:.*)|()
Required: No
MemorySize (p. 322)
The amount of memory, in MB, your Lambda function is given. Lambda uses this memory size to
infer the amount of CPU and memory allocated to your function. Your function use-case determines
your CPU and memory requirements. For example, a database operation might need less memory
compared to an image processing function. The default value is 128 MB. The value must be a multiple
of 64 MB.
Type: Integer
Valid Range: Minimum value of 128. Maximum value of 1536.
Required: No
Publish (p. 322)
This boolean parameter can be used to request AWS Lambda to create the Lambda function and
publish a version as an atomic operation.
Type: Boolean
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Required: No
Role (p. 322)
The Amazon Resource Name (ARN) of the IAM role that Lambda assumes when it executes your
function to access any other Amazon Web Services (AWS) resources. For more information, see AWS
Lambda: How it Works.
Type: String
Pattern: arn:aws:iam::\d{12}:role/?[a-zA-Z_0-9+=,[email protected]\-_/]+
Required: Yes
Runtime (p. 322)
The runtime environment for the Lambda function you are uploading.
To use the Node.js runtime v6.10, set the value to "nodejs6.10". To use the Node.js runtime v4.3, set
the value to "nodejs4.3".
Note
You can no longer create functions using the v0.10.42 runtime version as of November, 2016.
Existing functions will be supported until early 2017, but we recommend you migrate them to
either nodejs6.10 or nodejs4.3 runtime version as soon as possible.
Type: String
Valid Values: nodejs | nodejs4.3 | nodejs6.10 | java8 | python2.7 | dotnetcore1.0 |
nodejs4.3-edge
Required: Yes
Timeout (p. 322)
The function execution time at which Lambda should terminate the function. Because the execution
time has cost implications, we recommend you set this value based on your expected execution time.
The default is 3 seconds.
Type: Integer
Valid Range: Minimum value of 1.
Required: No
VpcConfig (p. 322)
If your Lambda function accesses resources in a VPC, you provide this parameter identifying the list
of security group IDs and subnet IDs. These must belong to the same VPC. You must provide at least
one security group and one subnet ID.
Type: VpcConfig (p. 404) object
Required: No
Response Syntax
HTTP/1.1 201
Content-type: application/json
{
"CodeSha256": "string",
"CodeSize": number,
"DeadLetterConfig": {
"TargetArn": "string"
},
"Description": "string",
"Environment": {
"Error": {
"ErrorCode": "string",
"Message": "string"
},
"Variables": {
"string" : "string"
}
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},
"FunctionArn": "string",
"FunctionName": "string",
"Handler": "string",
"KMSKeyArn": "string",
"LastModified": "string",
"MemorySize": number,
"Role": "string",
"Runtime": "string",
"Timeout": number,
"Version": "string",
"VpcConfig": {
"SecurityGroupIds": [ "string" ],
"SubnetIds": [ "string" ],
"VpcId": "string"
}
}
Response Elements
If the action is successful, the service sends back an HTTP 201 response.
The following data is returned in JSON format by the service.
CodeSha256 (p. 324)
It is the SHA256 hash of your function deployment package.
Type: String
CodeSize (p. 324)
The size, in bytes, of the function .zip file you uploaded.
Type: Long
DeadLetterConfig (p. 324)
The parent object that contains the target Amazon Resource Name (ARN) of an Amazon SQS queue
or Amazon SNS topic.
Type: DeadLetterConfig (p. 393) object
Description (p. 324)
The user-provided description.
Type: String
Length Constraints: Minimum length of 0. Maximum length of 256.
Environment (p. 324)
The parent object that contains your environment's configuration settings.
Type: EnvironmentResponse (p. 396) object
FunctionArn (p. 324)
The Amazon Resource Name (ARN) assigned to the function.
Type: String
Pattern: arn:aws:lambda:[a-z]{2}-[a-z]+-\d{1}:\d{12}:function:[a-zA-Z0-9-_]+(:(\$LATEST|
[a-zA-Z0-9-_]+))?
FunctionName (p. 324)
The name of the function. Note that the length constraint applies only to the ARN. If you specify only
the function name, it is limited to 64 characters in length.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 140.
Pattern: (arn:aws:lambda:)?([a-z]{2}-[a-z]+-\d{1}:)?(\d{12}:)?(function:)?([a-zA-Z0-9_]+)(:(\$LATEST|[a-zA-Z0-9-_]+))?
Handler (p. 324)
The function Lambda calls to begin executing your function.
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Type: String
Length Constraints: Maximum length of 128.
Pattern: [^\s]+
KMSKeyArn (p. 324)
The Amazon Resource Name (ARN) of the KMS key used to encrypt your function's environment
variables. If empty, it means you are using the AWS Lambda default service key.
Type: String
Pattern: (arn:aws:[a-z0-9-.]+:.*)|()
LastModified (p. 324)
The time stamp of the last time you updated the function.
Type: String
MemorySize (p. 324)
The memory size, in MB, you configured for the function. Must be a multiple of 64 MB.
Type: Integer
Valid Range: Minimum value of 128. Maximum value of 1536.
Role (p. 324)
The Amazon Resource Name (ARN) of the IAM role that Lambda assumes when it executes your
function to access any other Amazon Web Services (AWS) resources.
Type: String
Pattern: arn:aws:iam::\d{12}:role/?[a-zA-Z_0-9+=,[email protected]\-_/]+
Runtime (p. 324)
The runtime environment for the Lambda function.
Type: String
Valid Values: nodejs | nodejs4.3 | nodejs6.10 | java8 | python2.7 | dotnetcore1.0 |
nodejs4.3-edge
Timeout (p. 324)
The function execution time at which Lambda should terminate the function. Because the execution
time has cost implications, we recommend you set this value based on your expected execution time.
The default is 3 seconds.
Type: Integer
Valid Range: Minimum value of 1.
Version (p. 324)
The version of the Lambda function.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 1024.
Pattern: (\$LATEST|[0-9]+)
VpcConfig (p. 324)
VPC configuration associated with your Lambda function.
Type: VpcConfigResponse (p. 405) object
Errors
CodeStorageExceededException
You have exceeded your maximum total code size per account. Limits
HTTP Status Code: 400
InvalidParameterValueException
One of the parameters in the request is invalid. For example, if you provided an IAM role for AWS
Lambda to assume in the CreateFunction or the UpdateFunctionConfiguration API, that AWS
Lambda is unable to assume you will get this exception.
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HTTP Status Code: 400
ResourceConflictException
The resource already exists.
HTTP Status Code: 409
ResourceNotFoundException
The resource (for example, a Lambda function or access policy statement) specified in the request
does not exist.
HTTP Status Code: 404
ServiceException
The AWS Lambda service encountered an internal error.
HTTP Status Code: 500
TooManyRequestsException
HTTP Status Code: 429
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS Command Line Interface
• AWS SDK for .NET
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for JavaScript
• AWS SDK for PHP V3
• AWS SDK for Python
• AWS SDK for Ruby V2
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DeleteAlias
DeleteAlias
Deletes the specified Lambda function alias. For more information, see Introduction to AWS Lambda
Aliases.
This requires permission for the lambda:DeleteAlias action.
Request Syntax
DELETE /2015-03-31/functions/FunctionName/aliases/Name HTTP/1.1
URI Request Parameters
The request requires the following URI parameters.
FunctionName (p. 328)
The Lambda function name for which the alias is created. Deleting an alias does not delete the function
version to which it is pointing. Note that the length constraint applies only to the ARN. If you specify
only the function name, it is limited to 64 characters in length.
Length Constraints: Minimum length of 1. Maximum length of 140.
Pattern: (arn:aws:lambda:)?([a-z]{2}-[a-z]+-\d{1}:)?(\d{12}:)?(function:)?([a-zA-Z0-9_]+)(:(\$LATEST|[a-zA-Z0-9-_]+))?
Name (p. 328)
Name of the alias to delete.
Length Constraints: Minimum length of 1. Maximum length of 128.
Pattern: (?!^[0-9]+$)([a-zA-Z0-9-_]+)
Request Body
The request does not have a request body.
Response Syntax
HTTP/1.1 204
Response Elements
If the action is successful, the service sends back an HTTP 204 response with an empty HTTP body.
Errors
InvalidParameterValueException
One of the parameters in the request is invalid. For example, if you provided an IAM role for AWS
Lambda to assume in the CreateFunction or the UpdateFunctionConfiguration API, that AWS
Lambda is unable to assume you will get this exception.
HTTP Status Code: 400
ServiceException
The AWS Lambda service encountered an internal error.
HTTP Status Code: 500
TooManyRequestsException
HTTP Status Code: 429
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See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS Command Line Interface
• AWS SDK for .NET
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for JavaScript
• AWS SDK for PHP V3
• AWS SDK for Python
• AWS SDK for Ruby V2
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DeleteEventSourceMapping
DeleteEventSourceMapping
Removes an event source mapping. This means AWS Lambda will no longer invoke the function for events
in the associated source.
This operation requires permission for the lambda:DeleteEventSourceMapping action.
Request Syntax
DELETE /2015-03-31/event-source-mappings/UUID HTTP/1.1
URI Request Parameters
The request requires the following URI parameters.
UUID (p. 330)
The event source mapping ID.
Request Body
The request does not have a request body.
Response Syntax
HTTP/1.1 202
Content-type: application/json
{
"BatchSize": number,
"EventSourceArn": "string",
"FunctionArn": "string",
"LastModified": number,
"LastProcessingResult": "string",
"State": "string",
"StateTransitionReason": "string",
"UUID": "string"
}
Response Elements
If the action is successful, the service sends back an HTTP 202 response.
The following data is returned in JSON format by the service.
BatchSize (p. 330)
The largest number of records that AWS Lambda will retrieve from your event source at the time of
invoking your function. Your function receives an event with all the retrieved records.
Type: Integer
Valid Range: Minimum value of 1. Maximum value of 10000.
EventSourceArn (p. 330)
The Amazon Resource Name (ARN) of the Amazon Kinesis stream that is the source of events.
Type: String
Pattern: arn:aws:([a-zA-Z0-9\-])+:([a-z]{2}-[a-z]+-\d{1})?:(\d{12})?:(.*)
FunctionArn (p. 330)
The Lambda function to invoke when AWS Lambda detects an event on the stream.
Type: String
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Pattern: arn:aws:lambda:[a-z]{2}-[a-z]+-\d{1}:\d{12}:function:[a-zA-Z0-9-_]+(:(\$LATEST|
[a-zA-Z0-9-_]+))?
LastModified (p. 330)
The UTC time string indicating the last time the event mapping was updated.
Type: Timestamp
LastProcessingResult (p. 330)
The result of the last AWS Lambda invocation of your Lambda function.
Type: String
State (p. 330)
The state of the event source mapping. It can be Creating, Enabled, Disabled, Enabling, Disabling,
Updating, or Deleting.
Type: String
StateTransitionReason (p. 330)
The reason the event source mapping is in its current state. It is either user-requested or an AWS
Lambda-initiated state transition.
Type: String
UUID (p. 330)
The AWS Lambda assigned opaque identifier for the mapping.
Type: String
Errors
InvalidParameterValueException
One of the parameters in the request is invalid. For example, if you provided an IAM role for AWS
Lambda to assume in the CreateFunction or the UpdateFunctionConfiguration API, that AWS
Lambda is unable to assume you will get this exception.
HTTP Status Code: 400
ResourceNotFoundException
The resource (for example, a Lambda function or access policy statement) specified in the request
does not exist.
HTTP Status Code: 404
ServiceException
The AWS Lambda service encountered an internal error.
HTTP Status Code: 500
TooManyRequestsException
HTTP Status Code: 429
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS Command Line Interface
• AWS SDK for .NET
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for JavaScript
• AWS SDK for PHP V3
• AWS SDK for Python
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• AWS SDK for Ruby V2
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DeleteFunction
DeleteFunction
Deletes the specified Lambda function code and configuration.
If you are using the versioning feature and you don't specify a function version in your DeleteFunction
request, AWS Lambda will delete the function, including all its versions, and any aliases pointing to the
function versions. To delete a specific function version, you must provide the function version via the
Qualifier parameter. For information about function versioning, see AWS Lambda Function Versioning
and Aliases.
When you delete a function the associated resource policy is also deleted. You will need to delete the event
source mappings explicitly.
This operation requires permission for the lambda:DeleteFunction action.
Request Syntax
DELETE /2015-03-31/functions/FunctionName?Qualifier=Qualifier HTTP/1.1
URI Request Parameters
The request requires the following URI parameters.
FunctionName (p. 333)
The Lambda function to delete.
You can specify the function name (for example, Thumbnail) or you can specify Amazon
Resource Name (ARN) of the function (for example, arn:aws:lambda:us-west-2:accountid:function:ThumbNail). If you are using versioning, you can also provide a qualified function ARN
(ARN that is qualified with function version or alias name as suffix). AWS Lambda also allows you to
specify only the function name with the account ID qualifier (for example, account-id:Thumbnail).
Note that the length constraint applies only to the ARN. If you specify only the function name, it is
limited to 64 characters in length.
Length Constraints: Minimum length of 1. Maximum length of 140.
Pattern: (arn:aws:lambda:)?([a-z]{2}-[a-z]+-\d{1}:)?(\d{12}:)?(function:)?([a-zA-Z0-9_]+)(:(\$LATEST|[a-zA-Z0-9-_]+))?
Qualifier (p. 333)
Using this optional parameter you can specify a function version (but not the $LATEST version) to direct
AWS Lambda to delete a specific function version. If the function version has one or more aliases
pointing to it, you will get an error because you cannot have aliases pointing to it. You can delete
any function version but not the $LATEST, that is, you cannot specify $LATEST as the value of this
parameter. The $LATEST version can be deleted only when you want to delete all the function versions
and aliases.
You can only specify a function version, not an alias name, using this parameter. You cannot delete a
function version using its alias.
If you don't specify this parameter, AWS Lambda will delete the function, including all of its versions
and aliases.
Length Constraints: Minimum length of 1. Maximum length of 128.
Pattern: (|[a-zA-Z0-9$_-]+)
Request Body
The request does not have a request body.
Response Syntax
HTTP/1.1 204
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Response Elements
If the action is successful, the service sends back an HTTP 204 response with an empty HTTP body.
Errors
InvalidParameterValueException
One of the parameters in the request is invalid. For example, if you provided an IAM role for AWS
Lambda to assume in the CreateFunction or the UpdateFunctionConfiguration API, that AWS
Lambda is unable to assume you will get this exception.
HTTP Status Code: 400
ResourceConflictException
The resource already exists.
HTTP Status Code: 409
ResourceNotFoundException
The resource (for example, a Lambda function or access policy statement) specified in the request
does not exist.
HTTP Status Code: 404
ServiceException
The AWS Lambda service encountered an internal error.
HTTP Status Code: 500
TooManyRequestsException
HTTP Status Code: 429
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS Command Line Interface
• AWS SDK for .NET
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for JavaScript
• AWS SDK for PHP V3
• AWS SDK for Python
• AWS SDK for Ruby V2
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GetAccountSettings
GetAccountSettings
Returns a customer's account settings.
You can use this operation to retrieve Lambda limits information, such as code size and concurrency
limits. For more information about limits, see AWS Lambda Limits. You can also retrieve resource usage
statistics, such as code storage usage and function count.
Request Syntax
GET /2016-08-19/account-settings/ HTTP/1.1
URI Request Parameters
The request does not use any URI parameters.
Request Body
The request does not have a request body.
Response Syntax
HTTP/1.1 200
Content-type: application/json
{
"AccountLimit": {
"CodeSizeUnzipped": number,
"CodeSizeZipped": number,
"ConcurrentExecutions": number,
"TotalCodeSize": number
},
"AccountUsage": {
"FunctionCount": number,
"TotalCodeSize": number
}
}
Response Elements
If the action is successful, the service sends back an HTTP 200 response.
The following data is returned in JSON format by the service.
AccountLimit (p. 335)
Provides limits of code size and concurrency associated with the current account and region.
Type: AccountLimit (p. 390) object
AccountUsage (p. 335)
Provides code size usage and function count associated with the current account and region.
Type: AccountUsage (p. 391) object
Errors
ServiceException
The AWS Lambda service encountered an internal error.
HTTP Status Code: 500
TooManyRequestsException
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HTTP Status Code: 429
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS Command Line Interface
• AWS SDK for .NET
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for JavaScript
• AWS SDK for PHP V3
• AWS SDK for Python
• AWS SDK for Ruby V2
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GetAlias
GetAlias
Returns the specified alias information such as the alias ARN, description, and function version it is pointing
to. For more information, see Introduction to AWS Lambda Aliases.
This requires permission for the lambda:GetAlias action.
Request Syntax
GET /2015-03-31/functions/FunctionName/aliases/Name HTTP/1.1
URI Request Parameters
The request requires the following URI parameters.
FunctionName (p. 337)
Function name for which the alias is created. An alias is a subresource that exists only in the context
of an existing Lambda function so you must specify the function name. Note that the length constraint
applies only to the ARN. If you specify only the function name, it is limited to 64 characters in length.
Length Constraints: Minimum length of 1. Maximum length of 140.
Pattern: (arn:aws:lambda:)?([a-z]{2}-[a-z]+-\d{1}:)?(\d{12}:)?(function:)?([a-zA-Z0-9_]+)(:(\$LATEST|[a-zA-Z0-9-_]+))?
Name (p. 337)
Name of the alias for which you want to retrieve information.
Length Constraints: Minimum length of 1. Maximum length of 128.
Pattern: (?!^[0-9]+$)([a-zA-Z0-9-_]+)
Request Body
The request does not have a request body.
Response Syntax
HTTP/1.1 200
Content-type: application/json
{
"AliasArn": "string",
"Description": "string",
"FunctionVersion": "string",
"Name": "string"
}
Response Elements
If the action is successful, the service sends back an HTTP 200 response.
The following data is returned in JSON format by the service.
AliasArn (p. 337)
Lambda function ARN that is qualified using the alias name as the suffix. For example, if you create
an alias called BETA that points to a helloworld function version, the ARN is arn:aws:lambda:awsregions:acct-id:function:helloworld:BETA.
Type: String
Pattern: arn:aws:lambda:[a-z]{2}-[a-z]+-\d{1}:\d{12}:function:[a-zA-Z0-9-_]+(:(\$LATEST|
[a-zA-Z0-9-_]+))?
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Description (p. 337)
Alias description.
Type: String
Length Constraints: Minimum length of 0. Maximum length of 256.
FunctionVersion (p. 337)
Function version to which the alias points.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 1024.
Pattern: (\$LATEST|[0-9]+)
Name (p. 337)
Alias name.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 128.
Pattern: (?!^[0-9]+$)([a-zA-Z0-9-_]+)
Errors
InvalidParameterValueException
One of the parameters in the request is invalid. For example, if you provided an IAM role for AWS
Lambda to assume in the CreateFunction or the UpdateFunctionConfiguration API, that AWS
Lambda is unable to assume you will get this exception.
HTTP Status Code: 400
ResourceNotFoundException
The resource (for example, a Lambda function or access policy statement) specified in the request
does not exist.
HTTP Status Code: 404
ServiceException
The AWS Lambda service encountered an internal error.
HTTP Status Code: 500
TooManyRequestsException
HTTP Status Code: 429
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS Command Line Interface
• AWS SDK for .NET
• AWS SDK for C++
• AWS SDK for Go
•
•
•
•
AWS SDK for Java
AWS SDK for JavaScript
AWS SDK for PHP V3
AWS SDK for Python
• AWS SDK for Ruby V2
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GetEventSourceMapping
GetEventSourceMapping
Returns configuration information for the specified event source mapping (see
CreateEventSourceMapping (p. 318)).
This operation requires permission for the lambda:GetEventSourceMapping action.
Request Syntax
GET /2015-03-31/event-source-mappings/UUID HTTP/1.1
URI Request Parameters
The request requires the following URI parameters.
UUID (p. 339)
The AWS Lambda assigned ID of the event source mapping.
Request Body
The request does not have a request body.
Response Syntax
HTTP/1.1 200
Content-type: application/json
{
"BatchSize": number,
"EventSourceArn": "string",
"FunctionArn": "string",
"LastModified": number,
"LastProcessingResult": "string",
"State": "string",
"StateTransitionReason": "string",
"UUID": "string"
}
Response Elements
If the action is successful, the service sends back an HTTP 200 response.
The following data is returned in JSON format by the service.
BatchSize (p. 339)
The largest number of records that AWS Lambda will retrieve from your event source at the time of
invoking your function. Your function receives an event with all the retrieved records.
Type: Integer
Valid Range: Minimum value of 1. Maximum value of 10000.
EventSourceArn (p. 339)
The Amazon Resource Name (ARN) of the Amazon Kinesis stream that is the source of events.
Type: String
Pattern: arn:aws:([a-zA-Z0-9\-])+:([a-z]{2}-[a-z]+-\d{1})?:(\d{12})?:(.*)
FunctionArn (p. 339)
The Lambda function to invoke when AWS Lambda detects an event on the stream.
Type: String
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Pattern: arn:aws:lambda:[a-z]{2}-[a-z]+-\d{1}:\d{12}:function:[a-zA-Z0-9-_]+(:(\$LATEST|
[a-zA-Z0-9-_]+))?
LastModified (p. 339)
The UTC time string indicating the last time the event mapping was updated.
Type: Timestamp
LastProcessingResult (p. 339)
The result of the last AWS Lambda invocation of your Lambda function.
Type: String
State (p. 339)
The state of the event source mapping. It can be Creating, Enabled, Disabled, Enabling, Disabling,
Updating, or Deleting.
Type: String
StateTransitionReason (p. 339)
The reason the event source mapping is in its current state. It is either user-requested or an AWS
Lambda-initiated state transition.
Type: String
UUID (p. 339)
The AWS Lambda assigned opaque identifier for the mapping.
Type: String
Errors
InvalidParameterValueException
One of the parameters in the request is invalid. For example, if you provided an IAM role for AWS
Lambda to assume in the CreateFunction or the UpdateFunctionConfiguration API, that AWS
Lambda is unable to assume you will get this exception.
HTTP Status Code: 400
ResourceNotFoundException
The resource (for example, a Lambda function or access policy statement) specified in the request
does not exist.
HTTP Status Code: 404
ServiceException
The AWS Lambda service encountered an internal error.
HTTP Status Code: 500
TooManyRequestsException
HTTP Status Code: 429
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS Command Line Interface
• AWS SDK for .NET
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for JavaScript
• AWS SDK for PHP V3
• AWS SDK for Python
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• AWS SDK for Ruby V2
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GetFunction
GetFunction
Returns the configuration information of the Lambda function and a presigned URL link to the .zip file you
uploaded with CreateFunction (p. 322) so you can download the .zip file. Note that the URL is valid for up
to 10 minutes. The configuration information is the same information you provided as parameters when
uploading the function.
Using the optional Qualifier parameter, you can specify a specific function version for which you want
this information. If you don't specify this parameter, the API uses unqualified function ARN which return
information about the $LATEST version of the Lambda function. For more information, see AWS Lambda
Function Versioning and Aliases.
This operation requires permission for the lambda:GetFunction action.
Request Syntax
GET /2015-03-31/functions/FunctionName?Qualifier=Qualifier HTTP/1.1
URI Request Parameters
The request requires the following URI parameters.
FunctionName (p. 342)
The Lambda function name.
You can specify a function name (for example, Thumbnail) or you can specify Amazon
Resource Name (ARN) of the function (for example, arn:aws:lambda:us-west-2:accountid:function:ThumbNail). AWS Lambda also allows you to specify a partial ARN (for example,
account-id:Thumbnail). Note that the length constraint applies only to the ARN. If you specify only the
function name, it is limited to 64 characters in length.
Length Constraints: Minimum length of 1. Maximum length of 140.
Pattern: (arn:aws:lambda:)?([a-z]{2}-[a-z]+-\d{1}:)?(\d{12}:)?(function:)?([a-zA-Z0-9_]+)(:(\$LATEST|[a-zA-Z0-9-_]+))?
Qualifier (p. 342)
Using this optional parameter to specify a function version or an alias name. If you specify function
version, the API uses qualified function ARN for the request and returns information about the specific
Lambda function version. If you specify an alias name, the API uses the alias ARN and returns
information about the function version to which the alias points. If you don't provide this parameter, the
API uses unqualified function ARN and returns information about the $LATEST version of the Lambda
function.
Length Constraints: Minimum length of 1. Maximum length of 128.
Pattern: (|[a-zA-Z0-9$_-]+)
Request Body
The request does not have a request body.
Response Syntax
HTTP/1.1 200
Content-type: application/json
{
"Code": {
"Location": "string",
"RepositoryType": "string"
},
"Configuration": {
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"CodeSha256": "string",
"CodeSize": number,
"DeadLetterConfig": {
"TargetArn": "string"
},
"Description": "string",
"Environment": {
"Error": {
"ErrorCode": "string",
"Message": "string"
},
"Variables": {
"string" : "string"
}
},
"FunctionArn": "string",
"FunctionName": "string",
"Handler": "string",
"KMSKeyArn": "string",
"LastModified": "string",
"MemorySize": number,
"Role": "string",
"Runtime": "string",
"Timeout": number,
"Version": "string",
"VpcConfig": {
"SecurityGroupIds": [ "string" ],
"SubnetIds": [ "string" ],
"VpcId": "string"
}
}
}
Response Elements
If the action is successful, the service sends back an HTTP 200 response.
The following data is returned in JSON format by the service.
Code (p. 342)
The object for the Lambda function location.
Type: FunctionCodeLocation (p. 400) object
Configuration (p. 342)
A complex type that describes function metadata.
Type: FunctionConfiguration (p. 401) object
Errors
InvalidParameterValueException
One of the parameters in the request is invalid. For example, if you provided an IAM role for AWS
Lambda to assume in the CreateFunction or the UpdateFunctionConfiguration API, that AWS
Lambda is unable to assume you will get this exception.
HTTP Status Code: 400
ResourceNotFoundException
The resource (for example, a Lambda function or access policy statement) specified in the request
does not exist.
HTTP Status Code: 404
ServiceException
The AWS Lambda service encountered an internal error.
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GetFunction
HTTP Status Code: 500
TooManyRequestsException
HTTP Status Code: 429
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS Command Line Interface
• AWS SDK for .NET
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for JavaScript
• AWS SDK for PHP V3
• AWS SDK for Python
• AWS SDK for Ruby V2
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GetFunctionConfiguration
GetFunctionConfiguration
Returns the configuration information of the Lambda function. This the same information you provided as
parameters when uploading the function by using CreateFunction (p. 322).
If you are using the versioning feature, you can retrieve this information for a specific function version
by using the optional Qualifier parameter and specifying the function version or alias that points to it.
If you don't provide it, the API returns information about the $LATEST version of the function. For more
information about versioning, see AWS Lambda Function Versioning and Aliases.
This operation requires permission for the lambda:GetFunctionConfiguration operation.
Request Syntax
GET /2015-03-31/functions/FunctionName/configuration?Qualifier=Qualifier HTTP/1.1
URI Request Parameters
The request requires the following URI parameters.
FunctionName (p. 345)
The name of the Lambda function for which you want to retrieve the configuration information.
You can specify a function name (for example, Thumbnail) or you can specify Amazon
Resource Name (ARN) of the function (for example, arn:aws:lambda:us-west-2:accountid:function:ThumbNail). AWS Lambda also allows you to specify a partial ARN (for example,
account-id:Thumbnail). Note that the length constraint applies only to the ARN. If you specify only the
function name, it is limited to 64 characters in length.
Length Constraints: Minimum length of 1. Maximum length of 140.
Pattern: (arn:aws:lambda:)?([a-z]{2}-[a-z]+-\d{1}:)?(\d{12}:)?(function:)?([a-zA-Z0-9_]+)(:(\$LATEST|[a-zA-Z0-9-_]+))?
Qualifier (p. 345)
Using this optional parameter you can specify a function version or an alias name. If you specify
function version, the API uses qualified function ARN and returns information about the specific
function version. If you specify an alias name, the API uses the alias ARN and returns information
about the function version to which the alias points.
If you don't specify this parameter, the API uses unqualified function ARN, and returns information
about the $LATEST function version.
Length Constraints: Minimum length of 1. Maximum length of 128.
Pattern: (|[a-zA-Z0-9$_-]+)
Request Body
The request does not have a request body.
Response Syntax
HTTP/1.1 200
Content-type: application/json
{
"CodeSha256": "string",
"CodeSize": number,
"DeadLetterConfig": {
"TargetArn": "string"
},
"Description": "string",
"Environment": {
"Error": {
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"ErrorCode": "string",
"Message": "string"
},
"Variables": {
"string" : "string"
}
},
"FunctionArn": "string",
"FunctionName": "string",
"Handler": "string",
"KMSKeyArn": "string",
"LastModified": "string",
"MemorySize": number,
"Role": "string",
"Runtime": "string",
"Timeout": number,
"Version": "string",
"VpcConfig": {
"SecurityGroupIds": [ "string" ],
"SubnetIds": [ "string" ],
"VpcId": "string"
}
}
Response Elements
If the action is successful, the service sends back an HTTP 200 response.
The following data is returned in JSON format by the service.
CodeSha256 (p. 345)
It is the SHA256 hash of your function deployment package.
Type: String
CodeSize (p. 345)
The size, in bytes, of the function .zip file you uploaded.
Type: Long
DeadLetterConfig (p. 345)
The parent object that contains the target Amazon Resource Name (ARN) of an Amazon SQS queue
or Amazon SNS topic.
Type: DeadLetterConfig (p. 393) object
Description (p. 345)
The user-provided description.
Type: String
Length Constraints: Minimum length of 0. Maximum length of 256.
Environment (p. 345)
The parent object that contains your environment's configuration settings.
Type: EnvironmentResponse (p. 396) object
FunctionArn (p. 345)
The Amazon Resource Name (ARN) assigned to the function.
Type: String
Pattern: arn:aws:lambda:[a-z]{2}-[a-z]+-\d{1}:\d{12}:function:[a-zA-Z0-9-_]+(:(\$LATEST|
[a-zA-Z0-9-_]+))?
FunctionName (p. 345)
The name of the function. Note that the length constraint applies only to the ARN. If you specify only
the function name, it is limited to 64 characters in length.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 140.
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Pattern: (arn:aws:lambda:)?([a-z]{2}-[a-z]+-\d{1}:)?(\d{12}:)?(function:)?([a-zA-Z0-9_]+)(:(\$LATEST|[a-zA-Z0-9-_]+))?
Handler (p. 345)
The function Lambda calls to begin executing your function.
Type: String
Length Constraints: Maximum length of 128.
Pattern: [^\s]+
KMSKeyArn (p. 345)
The Amazon Resource Name (ARN) of the KMS key used to encrypt your function's environment
variables. If empty, it means you are using the AWS Lambda default service key.
Type: String
Pattern: (arn:aws:[a-z0-9-.]+:.*)|()
LastModified (p. 345)
The time stamp of the last time you updated the function.
Type: String
MemorySize (p. 345)
The memory size, in MB, you configured for the function. Must be a multiple of 64 MB.
Type: Integer
Valid Range: Minimum value of 128. Maximum value of 1536.
Role (p. 345)
The Amazon Resource Name (ARN) of the IAM role that Lambda assumes when it executes your
function to access any other Amazon Web Services (AWS) resources.
Type: String
Pattern: arn:aws:iam::\d{12}:role/?[a-zA-Z_0-9+=,[email protected]\-_/]+
Runtime (p. 345)
The runtime environment for the Lambda function.
Type: String
Valid Values: nodejs | nodejs4.3 | nodejs6.10 | java8 | python2.7 | dotnetcore1.0 |
nodejs4.3-edge
Timeout (p. 345)
The function execution time at which Lambda should terminate the function. Because the execution
time has cost implications, we recommend you set this value based on your expected execution time.
The default is 3 seconds.
Type: Integer
Valid Range: Minimum value of 1.
Version (p. 345)
The version of the Lambda function.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 1024.
Pattern: (\$LATEST|[0-9]+)
VpcConfig (p. 345)
VPC configuration associated with your Lambda function.
Type: VpcConfigResponse (p. 405) object
Errors
InvalidParameterValueException
One of the parameters in the request is invalid. For example, if you provided an IAM role for AWS
Lambda to assume in the CreateFunction or the UpdateFunctionConfiguration API, that AWS
Lambda is unable to assume you will get this exception.
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GetFunctionConfiguration
HTTP Status Code: 400
ResourceNotFoundException
The resource (for example, a Lambda function or access policy statement) specified in the request
does not exist.
HTTP Status Code: 404
ServiceException
The AWS Lambda service encountered an internal error.
HTTP Status Code: 500
TooManyRequestsException
HTTP Status Code: 429
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS Command Line Interface
• AWS SDK for .NET
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for JavaScript
• AWS SDK for PHP V3
• AWS SDK for Python
• AWS SDK for Ruby V2
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GetPolicy
GetPolicy
Returns the resource policy associated with the specified Lambda function.
If you are using the versioning feature, you can get the resource policy associated with the specific Lambda
function version or alias by specifying the version or alias name using the Qualifier parameter. For more
information about versioning, see AWS Lambda Function Versioning and Aliases.
For information about adding permissions, see AddPermission (p. 311).
You need permission for the lambda:GetPolicy action.
Request Syntax
GET /2015-03-31/functions/FunctionName/policy?Qualifier=Qualifier HTTP/1.1
URI Request Parameters
The request requires the following URI parameters.
FunctionName (p. 349)
Function name whose resource policy you want to retrieve.
You can specify the function name (for example, Thumbnail) or you can specify Amazon
Resource Name (ARN) of the function (for example, arn:aws:lambda:us-west-2:accountid:function:ThumbNail). If you are using versioning, you can also provide a qualified function ARN
(ARN that is qualified with function version or alias name as suffix). AWS Lambda also allows you to
specify only the function name with the account ID qualifier (for example, account-id:Thumbnail).
Note that the length constraint applies only to the ARN. If you specify only the function name, it is
limited to 64 characters in length.
Length Constraints: Minimum length of 1. Maximum length of 140.
Pattern: (arn:aws:lambda:)?([a-z]{2}-[a-z]+-\d{1}:)?(\d{12}:)?(function:)?([a-zA-Z0-9_]+)(:(\$LATEST|[a-zA-Z0-9-_]+))?
Qualifier (p. 349)
You can specify this optional query parameter to specify a function version or an alias name in which
case this API will return all permissions associated with the specific qualified ARN. If you don't provide
this parameter, the API will return permissions that apply to the unqualified function ARN.
Length Constraints: Minimum length of 1. Maximum length of 128.
Pattern: (|[a-zA-Z0-9$_-]+)
Request Body
The request does not have a request body.
Response Syntax
HTTP/1.1 200
Content-type: application/json
{
"Policy": "string"
}
Response Elements
If the action is successful, the service sends back an HTTP 200 response.
The following data is returned in JSON format by the service.
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Policy (p. 349)
The resource policy associated with the specified function. The response returns the same as a string
using a backslash ("\") as an escape character in the JSON.
Type: String
Errors
InvalidParameterValueException
One of the parameters in the request is invalid. For example, if you provided an IAM role for AWS
Lambda to assume in the CreateFunction or the UpdateFunctionConfiguration API, that AWS
Lambda is unable to assume you will get this exception.
HTTP Status Code: 400
ResourceNotFoundException
The resource (for example, a Lambda function or access policy statement) specified in the request
does not exist.
HTTP Status Code: 404
ServiceException
The AWS Lambda service encountered an internal error.
HTTP Status Code: 500
TooManyRequestsException
HTTP Status Code: 429
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS Command Line Interface
• AWS SDK for .NET
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for JavaScript
• AWS SDK for PHP V3
• AWS SDK for Python
• AWS SDK for Ruby V2
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Invoke
Invokes a specific Lambda function. For an example, see Create the Lambda Function and Test It
Manually.
If you are using the versioning feature, you can invoke the specific function version by providing function
version or alias name that is pointing to the function version using the Qualifier parameter in the request.
If you don't provide the Qualifier parameter, the $LATEST version of the Lambda function is invoked.
Invocations occur at least once in response to an event and functions must be idempotent to handle this.
For information about the versioning feature, see AWS Lambda Function Versioning and Aliases.
This operation requires permission for the lambda:InvokeFunction action.
Request Syntax
POST /2015-03-31/functions/FunctionName/invocations?Qualifier=Qualifier HTTP/1.1
X-Amz-Invocation-Type: InvocationType
X-Amz-Log-Type: LogType
X-Amz-Client-Context: ClientContext
Payload
URI Request Parameters
The request requires the following URI parameters.
ClientContext (p. 351)
Using the ClientContext you can pass client-specific information to the Lambda function you are
invoking. You can then process the client information in your Lambda function as you choose through
the context variable. For an example of a ClientContext JSON, see PutEvents in the Amazon Mobile
Analytics API Reference and User Guide.
The ClientContext JSON must be base64-encoded.
FunctionName (p. 351)
The Lambda function name.
You can specify a function name (for example, Thumbnail) or you can specify Amazon
Resource Name (ARN) of the function (for example, arn:aws:lambda:us-west-2:accountid:function:ThumbNail). AWS Lambda also allows you to specify a partial ARN (for example,
account-id:Thumbnail). Note that the length constraint applies only to the ARN. If you specify only the
function name, it is limited to 64 characters in length.
Length Constraints: Minimum length of 1. Maximum length of 140.
Pattern: (arn:aws:lambda:)?([a-z]{2}-[a-z]+-\d{1}:)?(\d{12}:)?(function:)?([a-zA-Z0-9_]+)(:(\$LATEST|[a-zA-Z0-9-_]+))?
InvocationType (p. 351)
By default, the Invoke API assumes RequestResponse invocation type. You can optionally request
asynchronous execution by specifying Event as the InvocationType. You can also use this parameter
to request AWS Lambda to not execute the function but do some verification, such as if the caller is
authorized to invoke the function and if the inputs are valid. You request this by specifying DryRun as
the InvocationType. This is useful in a cross-account scenario when you want to verify access to a
function without running it.
Valid Values: Event | RequestResponse | DryRun
LogType (p. 351)
You can set this optional parameter to Tail in the request only if you specify the InvocationType
parameter with value RequestResponse. In this case, AWS Lambda returns the base64-encoded last 4
KB of log data produced by your Lambda function in the x-amz-log-result header.
Valid Values: None | Tail
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Qualifier (p. 351)
You can use this optional parameter to specify a Lambda function version or alias name. If you specify
a function version, the API uses the qualified function ARN to invoke a specific Lambda function. If you
specify an alias name, the API uses the alias ARN to invoke the Lambda function version to which the
alias points.
If you don't provide this parameter, then the API uses unqualified function ARN which results in
invocation of the $LATEST version.
Length Constraints: Minimum length of 1. Maximum length of 128.
Pattern: (|[a-zA-Z0-9$_-]+)
Request Body
The request accepts the following data in JSON format.
Payload (p. 351)
JSON that you want to provide to your Lambda function as input.
Type: Binary data object
Required: No
Response Syntax
HTTP/1.1 StatusCode
X-Amz-Function-Error: FunctionError
X-Amz-Log-Result: LogResult
Payload
Response Elements
If the action is successful, the service sends back the following HTTP response.
StatusCode (p. 352)
The HTTP status code will be in the 200 range for successful request. For the RequestResonse
invocation type this status code will be 200. For the Event invocation type this status code will be 202.
For the DryRun invocation type the status code will be 204.
The response returns the following HTTP headers.
FunctionError (p. 352)
Indicates whether an error occurred while executing the Lambda function. If an error occurred this field
will have one of two values; Handled or Unhandled. Handled errors are errors that are reported by the
function while the Unhandled errors are those detected and reported by AWS Lambda. Unhandled
errors include out of memory errors and function timeouts. For information about how to report an
Handled error, see Programming Model.
LogResult (p. 352)
It is the base64-encoded logs for the Lambda function invocation. This is present only if the invocation
type is RequestResponse and the logs were requested.
The response returns the following as the HTTP body.
<varlistentry> Payload (p. 352)
It is the JSON representation of the object returned by the Lambda function. This is present only if the
invocation type is RequestResponse.
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In the event of a function error this field contains a message describing the error. For the Handled errors the
Lambda function will report this message. For Unhandled errors AWS Lambda reports the message.
</varlistentry>
Errors
EC2AccessDeniedException
HTTP Status Code: 502
EC2ThrottledException
AWS Lambda was throttled by Amazon EC2 during Lambda function initialization using the execution
role provided for the Lambda function.
HTTP Status Code: 502
EC2UnexpectedException
AWS Lambda received an unexpected EC2 client exception while setting up for the Lambda function.
HTTP Status Code: 502
ENILimitReachedException
AWS Lambda was not able to create an Elastic Network Interface (ENI) in the VPC, specified as part of
Lambda function configuration, because the limit for network interfaces has been reached.
HTTP Status Code: 502
InvalidParameterValueException
One of the parameters in the request is invalid. For example, if you provided an IAM role for AWS
Lambda to assume in the CreateFunction or the UpdateFunctionConfiguration API, that AWS
Lambda is unable to assume you will get this exception.
HTTP Status Code: 400
InvalidRequestContentException
The request body could not be parsed as JSON.
HTTP Status Code: 400
InvalidSecurityGroupIDException
The Security Group ID provided in the Lambda function VPC configuration is invalid.
HTTP Status Code: 502
InvalidSubnetIDException
The Subnet ID provided in the Lambda function VPC configuration is invalid.
HTTP Status Code: 502
InvalidZipFileException
AWS Lambda could not unzip the function zip file.
HTTP Status Code: 502
KMSAccessDeniedException
Lambda was unable to decrypt the environment variables because KMS access was denied. Check the
Lambda function's KMS permissions.
HTTP Status Code: 502
KMSDisabledException
Lambda was unable to decrypt the environment variables because the KMS key used is disabled.
Check the Lambda function's KMS key settings.
HTTP Status Code: 502
KMSInvalidStateException
Lambda was unable to decrypt the environment variables because the KMS key used is in an invalid
state for Decrypt. Check the function's KMS key settings.
HTTP Status Code: 502
KMSNotFoundException
Lambda was unable to decrypt the environment variables because the KMS key was not found. Check
the function's KMS key settings.
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HTTP Status Code: 502
RequestTooLargeException
The request payload exceeded the Invoke request body JSON input limit. For more information, see
Limits.
HTTP Status Code: 413
ResourceNotFoundException
The resource (for example, a Lambda function or access policy statement) specified in the request
does not exist.
HTTP Status Code: 404
ServiceException
The AWS Lambda service encountered an internal error.
HTTP Status Code: 500
SubnetIPAddressLimitReachedException
AWS Lambda was not able to set up VPC access for the Lambda function because one or more
configured subnets has no available IP addresses.
HTTP Status Code: 502
TooManyRequestsException
HTTP Status Code: 429
UnsupportedMediaTypeException
The content type of the Invoke request body is not JSON.
HTTP Status Code: 415
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS Command Line Interface
• AWS SDK for .NET
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for JavaScript
• AWS SDK for PHP V3
• AWS SDK for Python
• AWS SDK for Ruby V2
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InvokeAsync
InvokeAsync
Important
This API is deprecated. We recommend you use Invoke API (see Invoke (p. 351)).
Submits an invocation request to AWS Lambda. Upon receiving the request, Lambda executes the
specified function asynchronously. To see the logs generated by the Lambda function execution, see the
CloudWatch Logs console.
This operation requires permission for the lambda:InvokeFunction action.
Request Syntax
POST /2014-11-13/functions/FunctionName/invoke-async/ HTTP/1.1
InvokeArgs
URI Request Parameters
The request requires the following URI parameters.
FunctionName (p. 355)
The Lambda function name. Note that the length constraint applies only to the ARN. If you specify only
the function name, it is limited to 64 characters in length.
Length Constraints: Minimum length of 1. Maximum length of 140.
Pattern: (arn:aws:lambda:)?([a-z]{2}-[a-z]+-\d{1}:)?(\d{12}:)?(function:)?([a-zA-Z0-9_]+)(:(\$LATEST|[a-zA-Z0-9-_]+))?
Request Body
The request accepts the following data in JSON format.
InvokeArgs (p. 355)
JSON that you want to provide to your Lambda function as input.
Type: Binary data object
Required: Yes
Response Syntax
HTTP/1.1 Status
Response Elements
If the action is successful, the service sends back the following HTTP response.
Status (p. 355)
It will be 202 upon success.
Errors
InvalidRequestContentException
The request body could not be parsed as JSON.
HTTP Status Code: 400
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ResourceNotFoundException
The resource (for example, a Lambda function or access policy statement) specified in the request
does not exist.
HTTP Status Code: 404
ServiceException
The AWS Lambda service encountered an internal error.
HTTP Status Code: 500
Example
Invoke a Lambda function
The following example uses a POST request to invoke a Lambda function.
Sample Request
POST /2014-11-13/functions/helloworld/invoke-async/ HTTP/1.1
[input json]
Sample Response
HTTP/1.1 202 Accepted
x-amzn-requestid: f037bc5c-5a08-11e4-b02e-af446c3f9d0d
content-length: 0
connection: keep-alive
date: Wed, 22 Oct 2014 16:31:55 GMT
content-type: application/json
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS Command Line Interface
• AWS SDK for .NET
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for JavaScript
• AWS SDK for PHP V3
• AWS SDK for Python
• AWS SDK for Ruby V2
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ListAliases
ListAliases
Returns list of aliases created for a Lambda function. For each alias, the response includes information
such as the alias ARN, description, alias name, and the function version to which it points. For more
information, see Introduction to AWS Lambda Aliases.
This requires permission for the lambda:ListAliases action.
Request Syntax
GET /2015-03-31/functions/FunctionName/aliases?
FunctionVersion=FunctionVersion&Marker=Marker&MaxItems=MaxItems HTTP/1.1
URI Request Parameters
The request requires the following URI parameters.
FunctionName (p. 357)
Lambda function name for which the alias is created. Note that the length constraint applies only to the
ARN. If you specify only the function name, it is limited to 64 characters in length.
Length Constraints: Minimum length of 1. Maximum length of 140.
Pattern: (arn:aws:lambda:)?([a-z]{2}-[a-z]+-\d{1}:)?(\d{12}:)?(function:)?([a-zA-Z0-9_]+)(:(\$LATEST|[a-zA-Z0-9-_]+))?
FunctionVersion (p. 357)
If you specify this optional parameter, the API returns only the aliases that are pointing to the specific
Lambda function version, otherwise the API returns all of the aliases created for the Lambda function.
Length Constraints: Minimum length of 1. Maximum length of 1024.
Pattern: (\$LATEST|[0-9]+)
Marker (p. 357)
Optional string. An opaque pagination token returned from a previous ListAliases operation. If
present, indicates where to continue the listing.
MaxItems (p. 357)
Optional integer. Specifies the maximum number of aliases to return in response. This parameter value
must be greater than 0.
Valid Range: Minimum value of 1. Maximum value of 10000.
Request Body
The request does not have a request body.
Response Syntax
HTTP/1.1 200
Content-type: application/json
{
"Aliases": [
{
"AliasArn": "string",
"Description": "string",
"FunctionVersion": "string",
"Name": "string"
}
],
"NextMarker": "string"
}
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Response Elements
If the action is successful, the service sends back an HTTP 200 response.
The following data is returned in JSON format by the service.
Aliases (p. 357)
A list of aliases.
Type: array of AliasConfiguration (p. 392) objects
NextMarker (p. 357)
A string, present if there are more aliases.
Type: String
Errors
InvalidParameterValueException
One of the parameters in the request is invalid. For example, if you provided an IAM role for AWS
Lambda to assume in the CreateFunction or the UpdateFunctionConfiguration API, that AWS
Lambda is unable to assume you will get this exception.
HTTP Status Code: 400
ResourceNotFoundException
The resource (for example, a Lambda function or access policy statement) specified in the request
does not exist.
HTTP Status Code: 404
ServiceException
The AWS Lambda service encountered an internal error.
HTTP Status Code: 500
TooManyRequestsException
HTTP Status Code: 429
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS Command Line Interface
• AWS SDK for .NET
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for JavaScript
• AWS SDK for PHP V3
• AWS SDK for Python
• AWS SDK for Ruby V2
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ListEventSourceMappings
ListEventSourceMappings
Returns a list of event source mappings you created using the CreateEventSourceMapping (see
CreateEventSourceMapping (p. 318)).
For each mapping, the API returns configuration information. You can optionally specify filters to retrieve
specific event source mappings.
If you are using the versioning feature, you can get list of event source mappings for a specific Lambda
function version or an alias as described in the FunctionName parameter. For information about the
versioning feature, see AWS Lambda Function Versioning and Aliases.
This operation requires permission for the lambda:ListEventSourceMappings action.
Request Syntax
GET /2015-03-31/event-source-mappings/?
EventSourceArn=EventSourceArn&FunctionName=FunctionName&Marker=Marker&MaxItems=MaxItems
HTTP/1.1
URI Request Parameters
The request requires the following URI parameters.
EventSourceArn (p. 359)
The Amazon Resource Name (ARN) of the Amazon Kinesis stream. (This parameter is optional.)
Pattern: arn:aws:([a-zA-Z0-9\-])+:([a-z]{2}-[a-z]+-\d{1})?:(\d{12})?:(.*)
FunctionName (p. 359)
The name of the Lambda function.
You can specify the function name (for example, Thumbnail) or you can specify Amazon
Resource Name (ARN) of the function (for example, arn:aws:lambda:us-west-2:accountid:function:ThumbNail). If you are using versioning, you can also provide a qualified function ARN
(ARN that is qualified with function version or alias name as suffix). AWS Lambda also allows you to
specify only the function name with the account ID qualifier (for example, account-id:Thumbnail).
Note that the length constraint applies only to the ARN. If you specify only the function name, it is
limited to 64 characters in length.
Length Constraints: Minimum length of 1. Maximum length of 140.
Pattern: (arn:aws:lambda:)?([a-z]{2}-[a-z]+-\d{1}:)?(\d{12}:)?(function:)?([a-zA-Z0-9_]+)(:(\$LATEST|[a-zA-Z0-9-_]+))?
Marker (p. 359)
Optional string. An opaque pagination token returned from a previous ListEventSourceMappings
operation. If present, specifies to continue the list from where the returning call left off.
MaxItems (p. 359)
Optional integer. Specifies the maximum number of event sources to return in response. This value
must be greater than 0.
Valid Range: Minimum value of 1. Maximum value of 10000.
Request Body
The request does not have a request body.
Response Syntax
HTTP/1.1 200
Content-type: application/json
{
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"EventSourceMappings": [
{
"BatchSize": number,
"EventSourceArn": "string",
"FunctionArn": "string",
"LastModified": number,
"LastProcessingResult": "string",
"State": "string",
"StateTransitionReason": "string",
"UUID": "string"
}
],
"NextMarker": "string"
}
Response Elements
If the action is successful, the service sends back an HTTP 200 response.
The following data is returned in JSON format by the service.
EventSourceMappings (p. 359)
An array of EventSourceMappingConfiguration objects.
Type: array of EventSourceMappingConfiguration (p. 397) objects
NextMarker (p. 359)
A string, present if there are more event source mappings.
Type: String
Errors
InvalidParameterValueException
One of the parameters in the request is invalid. For example, if you provided an IAM role for AWS
Lambda to assume in the CreateFunction or the UpdateFunctionConfiguration API, that AWS
Lambda is unable to assume you will get this exception.
HTTP Status Code: 400
ResourceNotFoundException
The resource (for example, a Lambda function or access policy statement) specified in the request
does not exist.
HTTP Status Code: 404
ServiceException
The AWS Lambda service encountered an internal error.
HTTP Status Code: 500
TooManyRequestsException
HTTP Status Code: 429
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS Command Line Interface
• AWS SDK for .NET
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
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• AWS SDK for JavaScript
• AWS SDK for PHP V3
• AWS SDK for Python
• AWS SDK for Ruby V2
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ListFunctions
ListFunctions
Returns a list of your Lambda functions. For each function, the response includes the function configuration
information. You must use GetFunction (p. 342) to retrieve the code for your function.
This operation requires permission for the lambda:ListFunctions action.
If you are using versioning feature, the response returns list of $LATEST versions of your functions. For
information about the versioning feature, see AWS Lambda Function Versioning and Aliases.
Request Syntax
GET /2015-03-31/functions/?Marker=Marker&MaxItems=MaxItems HTTP/1.1
URI Request Parameters
The request requires the following URI parameters.
Marker (p. 362)
Optional string. An opaque pagination token returned from a previous ListFunctions operation. If
present, indicates where to continue the listing.
MaxItems (p. 362)
Optional integer. Specifies the maximum number of AWS Lambda functions to return in response. This
parameter value must be greater than 0.
Valid Range: Minimum value of 1. Maximum value of 10000.
Request Body
The request does not have a request body.
Response Syntax
HTTP/1.1 200
Content-type: application/json
{
"Functions": [
{
"CodeSha256": "string",
"CodeSize": number,
"DeadLetterConfig": {
"TargetArn": "string"
},
"Description": "string",
"Environment": {
"Error": {
"ErrorCode": "string",
"Message": "string"
},
"Variables": {
"string" : "string"
}
},
"FunctionArn": "string",
"FunctionName": "string",
"Handler": "string",
"KMSKeyArn": "string",
"LastModified": "string",
"MemorySize": number,
"Role": "string",
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"Runtime": "string",
"Timeout": number,
"Version": "string",
"VpcConfig": {
"SecurityGroupIds": [ "string" ],
"SubnetIds": [ "string" ],
"VpcId": "string"
}
}
],
"NextMarker": "string"
}
Response Elements
If the action is successful, the service sends back an HTTP 200 response.
The following data is returned in JSON format by the service.
Functions (p. 362)
A list of Lambda functions.
Type: array of FunctionConfiguration (p. 401) objects
NextMarker (p. 362)
A string, present if there are more functions.
Type: String
Errors
ServiceException
The AWS Lambda service encountered an internal error.
HTTP Status Code: 500
TooManyRequestsException
HTTP Status Code: 429
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS Command Line Interface
• AWS SDK for .NET
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for JavaScript
• AWS SDK for PHP V3
• AWS SDK for Python
• AWS SDK for Ruby V2
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ListVersionsByFunction
ListVersionsByFunction
List all versions of a function. For information about the versioning feature, see AWS Lambda Function
Versioning and Aliases.
Request Syntax
GET /2015-03-31/functions/FunctionName/versions?Marker=Marker&MaxItems=MaxItems HTTP/1.1
URI Request Parameters
The request requires the following URI parameters.
FunctionName (p. 364)
Function name whose versions to list. You can specify a function name (for example, Thumbnail) or
you can specify Amazon Resource Name (ARN) of the function (for example, arn:aws:lambda:uswest-2:account-id:function:ThumbNail). AWS Lambda also allows you to specify a partial ARN
(for example, account-id:Thumbnail). Note that the length constraint applies only to the ARN. If you
specify only the function name, it is limited to 64 characters in length.
Length Constraints: Minimum length of 1. Maximum length of 140.
Pattern: (arn:aws:lambda:)?([a-z]{2}-[a-z]+-\d{1}:)?(\d{12}:)?(function:)?([a-zA-Z0-9_]+)(:(\$LATEST|[a-zA-Z0-9-_]+))?
Marker (p. 364)
Optional string. An opaque pagination token returned from a previous ListVersionsByFunction
operation. If present, indicates where to continue the listing.
MaxItems (p. 364)
Optional integer. Specifies the maximum number of AWS Lambda function versions to return in
response. This parameter value must be greater than 0.
Valid Range: Minimum value of 1. Maximum value of 10000.
Request Body
The request does not have a request body.
Response Syntax
HTTP/1.1 200
Content-type: application/json
{
"NextMarker": "string",
"Versions": [
{
"CodeSha256": "string",
"CodeSize": number,
"DeadLetterConfig": {
"TargetArn": "string"
},
"Description": "string",
"Environment": {
"Error": {
"ErrorCode": "string",
"Message": "string"
},
"Variables": {
"string" : "string"
}
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},
"FunctionArn": "string",
"FunctionName": "string",
"Handler": "string",
"KMSKeyArn": "string",
"LastModified": "string",
"MemorySize": number,
"Role": "string",
"Runtime": "string",
"Timeout": number,
"Version": "string",
"VpcConfig": {
"SecurityGroupIds": [ "string" ],
"SubnetIds": [ "string" ],
"VpcId": "string"
}
}
]
}
Response Elements
If the action is successful, the service sends back an HTTP 200 response.
The following data is returned in JSON format by the service.
NextMarker (p. 364)
A string, present if there are more function versions.
Type: String
Versions (p. 364)
A list of Lambda function versions.
Type: array of FunctionConfiguration (p. 401) objects
Errors
InvalidParameterValueException
One of the parameters in the request is invalid. For example, if you provided an IAM role for AWS
Lambda to assume in the CreateFunction or the UpdateFunctionConfiguration API, that AWS
Lambda is unable to assume you will get this exception.
HTTP Status Code: 400
ResourceNotFoundException
The resource (for example, a Lambda function or access policy statement) specified in the request
does not exist.
HTTP Status Code: 404
ServiceException
The AWS Lambda service encountered an internal error.
HTTP Status Code: 500
TooManyRequestsException
HTTP Status Code: 429
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS Command Line Interface
• AWS SDK for .NET
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• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for JavaScript
• AWS SDK for PHP V3
• AWS SDK for Python
• AWS SDK for Ruby V2
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PublishVersion
PublishVersion
Publishes a version of your function from the current snapshot of $LATEST. That is, AWS Lambda takes a
snapshot of the function code and configuration information from $LATEST and publishes a new version.
The code and configuration cannot be modified after publication. For information about the versioning
feature, see AWS Lambda Function Versioning and Aliases.
Request Syntax
POST /2015-03-31/functions/FunctionName/versions HTTP/1.1
Content-type: application/json
{
"CodeSha256": "string",
"Description": "string"
}
URI Request Parameters
The request requires the following URI parameters.
FunctionName (p. 367)
The Lambda function name. You can specify a function name (for example, Thumbnail) or you
can specify Amazon Resource Name (ARN) of the function (for example, arn:aws:lambda:uswest-2:account-id:function:ThumbNail). AWS Lambda also allows you to specify a partial ARN
(for example, account-id:Thumbnail). Note that the length constraint applies only to the ARN. If you
specify only the function name, it is limited to 64 characters in length.
Length Constraints: Minimum length of 1. Maximum length of 140.
Pattern: (arn:aws:lambda:)?([a-z]{2}-[a-z]+-\d{1}:)?(\d{12}:)?(function:)?([a-zA-Z0-9_]+)(:(\$LATEST|[a-zA-Z0-9-_]+))?
Request Body
The request accepts the following data in JSON format.
CodeSha256 (p. 367)
The SHA256 hash of the deployment package you want to publish. This provides validation on the
code you are publishing. If you provide this parameter value must match the SHA256 of the $LATEST
version for the publication to succeed.
Type: String
Required: No
Description (p. 367)
The description for the version you are publishing. If not provided, AWS Lambda copies the description
from the $LATEST version.
Type: String
Length Constraints: Minimum length of 0. Maximum length of 256.
Required: No
Response Syntax
HTTP/1.1 201
Content-type: application/json
{
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"CodeSha256": "string",
"CodeSize": number,
"DeadLetterConfig": {
"TargetArn": "string"
},
"Description": "string",
"Environment": {
"Error": {
"ErrorCode": "string",
"Message": "string"
},
"Variables": {
"string" : "string"
}
},
"FunctionArn": "string",
"FunctionName": "string",
"Handler": "string",
"KMSKeyArn": "string",
"LastModified": "string",
"MemorySize": number,
"Role": "string",
"Runtime": "string",
"Timeout": number,
"Version": "string",
"VpcConfig": {
"SecurityGroupIds": [ "string" ],
"SubnetIds": [ "string" ],
"VpcId": "string"
}
}
Response Elements
If the action is successful, the service sends back an HTTP 201 response.
The following data is returned in JSON format by the service.
CodeSha256 (p. 367)
It is the SHA256 hash of your function deployment package.
Type: String
CodeSize (p. 367)
The size, in bytes, of the function .zip file you uploaded.
Type: Long
DeadLetterConfig (p. 367)
The parent object that contains the target Amazon Resource Name (ARN) of an Amazon SQS queue
or Amazon SNS topic.
Type: DeadLetterConfig (p. 393) object
Description (p. 367)
The user-provided description.
Type: String
Length Constraints: Minimum length of 0. Maximum length of 256.
Environment (p. 367)
The parent object that contains your environment's configuration settings.
Type: EnvironmentResponse (p. 396) object
FunctionArn (p. 367)
The Amazon Resource Name (ARN) assigned to the function.
Type: String
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Pattern: arn:aws:lambda:[a-z]{2}-[a-z]+-\d{1}:\d{12}:function:[a-zA-Z0-9-_]+(:(\$LATEST|
[a-zA-Z0-9-_]+))?
FunctionName (p. 367)
The name of the function. Note that the length constraint applies only to the ARN. If you specify only
the function name, it is limited to 64 characters in length.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 140.
Pattern: (arn:aws:lambda:)?([a-z]{2}-[a-z]+-\d{1}:)?(\d{12}:)?(function:)?([a-zA-Z0-9_]+)(:(\$LATEST|[a-zA-Z0-9-_]+))?
Handler (p. 367)
The function Lambda calls to begin executing your function.
Type: String
Length Constraints: Maximum length of 128.
Pattern: [^\s]+
KMSKeyArn (p. 367)
The Amazon Resource Name (ARN) of the KMS key used to encrypt your function's environment
variables. If empty, it means you are using the AWS Lambda default service key.
Type: String
Pattern: (arn:aws:[a-z0-9-.]+:.*)|()
LastModified (p. 367)
The time stamp of the last time you updated the function.
Type: String
MemorySize (p. 367)
The memory size, in MB, you configured for the function. Must be a multiple of 64 MB.
Type: Integer
Valid Range: Minimum value of 128. Maximum value of 1536.
Role (p. 367)
The Amazon Resource Name (ARN) of the IAM role that Lambda assumes when it executes your
function to access any other Amazon Web Services (AWS) resources.
Type: String
Pattern: arn:aws:iam::\d{12}:role/?[a-zA-Z_0-9+=,[email protected]\-_/]+
Runtime (p. 367)
The runtime environment for the Lambda function.
Type: String
Valid Values: nodejs | nodejs4.3 | nodejs6.10 | java8 | python2.7 | dotnetcore1.0 |
nodejs4.3-edge
Timeout (p. 367)
The function execution time at which Lambda should terminate the function. Because the execution
time has cost implications, we recommend you set this value based on your expected execution time.
The default is 3 seconds.
Type: Integer
Valid Range: Minimum value of 1.
Version (p. 367)
The version of the Lambda function.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 1024.
Pattern: (\$LATEST|[0-9]+)
VpcConfig (p. 367)
VPC configuration associated with your Lambda function.
Type: VpcConfigResponse (p. 405) object
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Errors
CodeStorageExceededException
You have exceeded your maximum total code size per account. Limits
HTTP Status Code: 400
InvalidParameterValueException
One of the parameters in the request is invalid. For example, if you provided an IAM role for AWS
Lambda to assume in the CreateFunction or the UpdateFunctionConfiguration API, that AWS
Lambda is unable to assume you will get this exception.
HTTP Status Code: 400
ResourceNotFoundException
The resource (for example, a Lambda function or access policy statement) specified in the request
does not exist.
HTTP Status Code: 404
ServiceException
The AWS Lambda service encountered an internal error.
HTTP Status Code: 500
TooManyRequestsException
HTTP Status Code: 429
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS Command Line Interface
• AWS SDK for .NET
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for JavaScript
• AWS SDK for PHP V3
• AWS SDK for Python
• AWS SDK for Ruby V2
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RemovePermission
RemovePermission
You can remove individual permissions from an resource policy associated with a Lambda function by
providing a statement ID that you provided when you added the permission.
If you are using versioning, the permissions you remove are specific to the Lambda function version or
alias you specify in the AddPermission request via the Qualifier parameter. For more information about
versioning, see AWS Lambda Function Versioning and Aliases.
Note that removal of a permission will cause an active event source to lose permission to the function.
You need permission for the lambda:RemovePermission action.
Request Syntax
DELETE /2015-03-31/functions/FunctionName/policy/StatementId?Qualifier=Qualifier HTTP/1.1
URI Request Parameters
The request requires the following URI parameters.
FunctionName (p. 371)
Lambda function whose resource policy you want to remove a permission from.
You can specify a function name (for example, Thumbnail) or you can specify Amazon
Resource Name (ARN) of the function (for example, arn:aws:lambda:us-west-2:accountid:function:ThumbNail). AWS Lambda also allows you to specify a partial ARN (for example,
account-id:Thumbnail). Note that the length constraint applies only to the ARN. If you specify only the
function name, it is limited to 64 characters in length.
Length Constraints: Minimum length of 1. Maximum length of 140.
Pattern: (arn:aws:lambda:)?([a-z]{2}-[a-z]+-\d{1}:)?(\d{12}:)?(function:)?([a-zA-Z0-9_]+)(:(\$LATEST|[a-zA-Z0-9-_]+))?
Qualifier (p. 371)
You can specify this optional parameter to remove permission associated with a specific function
version or function alias. If you don't specify this parameter, the API removes permission associated
with the unqualified function ARN.
Length Constraints: Minimum length of 1. Maximum length of 128.
Pattern: (|[a-zA-Z0-9$_-]+)
StatementId (p. 371)
Statement ID of the permission to remove.
Length Constraints: Minimum length of 1. Maximum length of 100.
Pattern: ([a-zA-Z0-9-_]+)
Request Body
The request does not have a request body.
Response Syntax
HTTP/1.1 204
Response Elements
If the action is successful, the service sends back an HTTP 204 response with an empty HTTP body.
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Errors
InvalidParameterValueException
One of the parameters in the request is invalid. For example, if you provided an IAM role for AWS
Lambda to assume in the CreateFunction or the UpdateFunctionConfiguration API, that AWS
Lambda is unable to assume you will get this exception.
HTTP Status Code: 400
ResourceNotFoundException
The resource (for example, a Lambda function or access policy statement) specified in the request
does not exist.
HTTP Status Code: 404
ServiceException
The AWS Lambda service encountered an internal error.
HTTP Status Code: 500
TooManyRequestsException
HTTP Status Code: 429
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS Command Line Interface
• AWS SDK for .NET
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for JavaScript
• AWS SDK for PHP V3
• AWS SDK for Python
• AWS SDK for Ruby V2
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UpdateAlias
UpdateAlias
Using this API you can update the function version to which the alias points and the alias description. For
more information, see Introduction to AWS Lambda Aliases.
This requires permission for the lambda:UpdateAlias action.
Request Syntax
PUT /2015-03-31/functions/FunctionName/aliases/Name HTTP/1.1
Content-type: application/json
{
"Description": "string",
"FunctionVersion": "string"
}
URI Request Parameters
The request requires the following URI parameters.
FunctionName (p. 373)
The function name for which the alias is created. Note that the length constraint applies only to the
ARN. If you specify only the function name, it is limited to 64 characters in length.
Length Constraints: Minimum length of 1. Maximum length of 140.
Pattern: (arn:aws:lambda:)?([a-z]{2}-[a-z]+-\d{1}:)?(\d{12}:)?(function:)?([a-zA-Z0-9_]+)(:(\$LATEST|[a-zA-Z0-9-_]+))?
Name (p. 373)
The alias name.
Length Constraints: Minimum length of 1. Maximum length of 128.
Pattern: (?!^[0-9]+$)([a-zA-Z0-9-_]+)
Request Body
The request accepts the following data in JSON format.
Description (p. 373)
You can change the description of the alias using this parameter.
Type: String
Length Constraints: Minimum length of 0. Maximum length of 256.
Required: No
FunctionVersion (p. 373)
Using this parameter you can change the Lambda function version to which the alias points.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 1024.
Pattern: (\$LATEST|[0-9]+)
Required: No
Response Syntax
HTTP/1.1 200
Content-type: application/json
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{
"AliasArn": "string",
"Description": "string",
"FunctionVersion": "string",
"Name": "string"
}
Response Elements
If the action is successful, the service sends back an HTTP 200 response.
The following data is returned in JSON format by the service.
AliasArn (p. 373)
Lambda function ARN that is qualified using the alias name as the suffix. For example, if you create
an alias called BETA that points to a helloworld function version, the ARN is arn:aws:lambda:awsregions:acct-id:function:helloworld:BETA.
Type: String
Pattern: arn:aws:lambda:[a-z]{2}-[a-z]+-\d{1}:\d{12}:function:[a-zA-Z0-9-_]+(:(\$LATEST|
[a-zA-Z0-9-_]+))?
Description (p. 373)
Alias description.
Type: String
Length Constraints: Minimum length of 0. Maximum length of 256.
FunctionVersion (p. 373)
Function version to which the alias points.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 1024.
Pattern: (\$LATEST|[0-9]+)
Name (p. 373)
Alias name.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 128.
Pattern: (?!^[0-9]+$)([a-zA-Z0-9-_]+)
Errors
InvalidParameterValueException
One of the parameters in the request is invalid. For example, if you provided an IAM role for AWS
Lambda to assume in the CreateFunction or the UpdateFunctionConfiguration API, that AWS
Lambda is unable to assume you will get this exception.
HTTP Status Code: 400
ResourceNotFoundException
The resource (for example, a Lambda function or access policy statement) specified in the request
does not exist.
HTTP Status Code: 404
ServiceException
The AWS Lambda service encountered an internal error.
HTTP Status Code: 500
TooManyRequestsException
HTTP Status Code: 429
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See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS Command Line Interface
• AWS SDK for .NET
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for JavaScript
• AWS SDK for PHP V3
• AWS SDK for Python
• AWS SDK for Ruby V2
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UpdateEventSourceMapping
UpdateEventSourceMapping
You can update an event source mapping. This is useful if you want to change the parameters of the
existing mapping without losing your position in the stream. You can change which function will receive the
stream records, but to change the stream itself, you must create a new mapping.
If you are using the versioning feature, you can update the event source mapping to map to a specific
Lambda function version or alias as described in the FunctionName parameter. For information about the
versioning feature, see AWS Lambda Function Versioning and Aliases.
If you disable the event source mapping, AWS Lambda stops polling. If you enable again, it will resume
polling from the time it had stopped polling, so you don't lose processing of any records. However, if you
delete event source mapping and create it again, it will reset.
This operation requires permission for the lambda:UpdateEventSourceMapping action.
Request Syntax
PUT /2015-03-31/event-source-mappings/UUID HTTP/1.1
Content-type: application/json
{
"BatchSize": number,
"Enabled": boolean,
"FunctionName": "string"
}
URI Request Parameters
The request requires the following URI parameters.
UUID (p. 376)
The event source mapping identifier.
Request Body
The request accepts the following data in JSON format.
BatchSize (p. 376)
The maximum number of stream records that can be sent to your Lambda function for a single
invocation.
Type: Integer
Valid Range: Minimum value of 1. Maximum value of 10000.
Required: No
Enabled (p. 376)
Specifies whether AWS Lambda should actively poll the stream or not. If disabled, AWS Lambda will
not poll the stream.
Type: Boolean
Required: No
FunctionName (p. 376)
The Lambda function to which you want the stream records sent.
You can specify a function name (for example, Thumbnail) or you can specify Amazon
Resource Name (ARN) of the function (for example, arn:aws:lambda:us-west-2:accountid:function:ThumbNail). AWS Lambda also allows you to specify a partial ARN (for example,
account-id:Thumbnail). Note that the length constraint applies only to the ARN. If you specify only the
function name, it is limited to 64 characters in length.
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If you are using versioning, you can also provide a qualified function ARN (ARN that is qualified with
function version or alias name as suffix). For more information about versioning, see AWS Lambda
Function Versioning and Aliases
Note that the length constraint applies only to the ARN. If you specify only the function name, it is
limited to 64 character in length.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 140.
Pattern: (arn:aws:lambda:)?([a-z]{2}-[a-z]+-\d{1}:)?(\d{12}:)?(function:)?([a-zA-Z0-9_]+)(:(\$LATEST|[a-zA-Z0-9-_]+))?
Required: No
Response Syntax
HTTP/1.1 202
Content-type: application/json
{
"BatchSize": number,
"EventSourceArn": "string",
"FunctionArn": "string",
"LastModified": number,
"LastProcessingResult": "string",
"State": "string",
"StateTransitionReason": "string",
"UUID": "string"
}
Response Elements
If the action is successful, the service sends back an HTTP 202 response.
The following data is returned in JSON format by the service.
BatchSize (p. 377)
The largest number of records that AWS Lambda will retrieve from your event source at the time of
invoking your function. Your function receives an event with all the retrieved records.
Type: Integer
Valid Range: Minimum value of 1. Maximum value of 10000.
EventSourceArn (p. 377)
The Amazon Resource Name (ARN) of the Amazon Kinesis stream that is the source of events.
Type: String
Pattern: arn:aws:([a-zA-Z0-9\-])+:([a-z]{2}-[a-z]+-\d{1})?:(\d{12})?:(.*)
FunctionArn (p. 377)
The Lambda function to invoke when AWS Lambda detects an event on the stream.
Type: String
Pattern: arn:aws:lambda:[a-z]{2}-[a-z]+-\d{1}:\d{12}:function:[a-zA-Z0-9-_]+(:(\$LATEST|
[a-zA-Z0-9-_]+))?
LastModified (p. 377)
The UTC time string indicating the last time the event mapping was updated.
Type: Timestamp
LastProcessingResult (p. 377)
The result of the last AWS Lambda invocation of your Lambda function.
Type: String
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State (p. 377)
The state of the event source mapping. It can be Creating, Enabled, Disabled, Enabling, Disabling,
Updating, or Deleting.
Type: String
StateTransitionReason (p. 377)
The reason the event source mapping is in its current state. It is either user-requested or an AWS
Lambda-initiated state transition.
Type: String
UUID (p. 377)
The AWS Lambda assigned opaque identifier for the mapping.
Type: String
Errors
InvalidParameterValueException
One of the parameters in the request is invalid. For example, if you provided an IAM role for AWS
Lambda to assume in the CreateFunction or the UpdateFunctionConfiguration API, that AWS
Lambda is unable to assume you will get this exception.
HTTP Status Code: 400
ResourceConflictException
The resource already exists.
HTTP Status Code: 409
ResourceNotFoundException
The resource (for example, a Lambda function or access policy statement) specified in the request
does not exist.
HTTP Status Code: 404
ServiceException
The AWS Lambda service encountered an internal error.
HTTP Status Code: 500
TooManyRequestsException
HTTP Status Code: 429
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS Command Line Interface
• AWS SDK for .NET
• AWS SDK for C++
• AWS SDK for Go
•
•
•
•
•
AWS SDK for Java
AWS SDK for JavaScript
AWS SDK for PHP V3
AWS SDK for Python
AWS SDK for Ruby V2
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UpdateFunctionCode
UpdateFunctionCode
Updates the code for the specified Lambda function. This operation must only be used on an existing
Lambda function and cannot be used to update the function configuration.
If you are using the versioning feature, note this API will always update the $LATEST version of your
Lambda function. For information about the versioning feature, see AWS Lambda Function Versioning and
Aliases.
This operation requires permission for the lambda:UpdateFunctionCode action.
Request Syntax
PUT /2015-03-31/functions/FunctionName/code HTTP/1.1
Content-type: application/json
{
"Publish": boolean,
"S3Bucket": "string",
"S3Key": "string",
"S3ObjectVersion": "string",
"ZipFile": blob
}
URI Request Parameters
The request requires the following URI parameters.
FunctionName (p. 379)
The existing Lambda function name whose code you want to replace.
You can specify a function name (for example, Thumbnail) or you can specify Amazon
Resource Name (ARN) of the function (for example, arn:aws:lambda:us-west-2:accountid:function:ThumbNail). AWS Lambda also allows you to specify a partial ARN (for example,
account-id:Thumbnail). Note that the length constraint applies only to the ARN. If you specify only the
function name, it is limited to 64 characters in length.
Length Constraints: Minimum length of 1. Maximum length of 140.
Pattern: (arn:aws:lambda:)?([a-z]{2}-[a-z]+-\d{1}:)?(\d{12}:)?(function:)?([a-zA-Z0-9_]+)(:(\$LATEST|[a-zA-Z0-9-_]+))?
Request Body
The request accepts the following data in JSON format.
Publish (p. 379)
This boolean parameter can be used to request AWS Lambda to update the Lambda function and
publish a version as an atomic operation.
Type: Boolean
Required: No
S3Bucket (p. 379)
Amazon S3 bucket name where the .zip file containing your deployment package is stored. This bucket
must reside in the same AWS Region where you are creating the Lambda function.
Type: String
Length Constraints: Minimum length of 3. Maximum length of 63.
Pattern: ^[0-9A-Za-z\.\-_]*(?<!\.)$
Required: No
S3Key (p. 379)
The Amazon S3 object (the deployment package) key name you want to upload.
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Type: String
Length Constraints: Minimum length of 1. Maximum length of 1024.
Required: No
S3ObjectVersion (p. 379)
The Amazon S3 object (the deployment package) version you want to upload.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 1024.
Required: No
ZipFile (p. 379)
The contents of your zip file containing your deployment package. If you are using the web API directly,
the contents of the zip file must be base64-encoded. If you are using the AWS SDKs or the AWS
CLI, the SDKs or CLI will do the encoding for you. For more information about creating a .zip file, see
Execution Permissions in the AWS Lambda Developer Guide.
Type: Base64-encoded binary data object
Required: No
Response Syntax
HTTP/1.1 200
Content-type: application/json
{
"CodeSha256": "string",
"CodeSize": number,
"DeadLetterConfig": {
"TargetArn": "string"
},
"Description": "string",
"Environment": {
"Error": {
"ErrorCode": "string",
"Message": "string"
},
"Variables": {
"string" : "string"
}
},
"FunctionArn": "string",
"FunctionName": "string",
"Handler": "string",
"KMSKeyArn": "string",
"LastModified": "string",
"MemorySize": number,
"Role": "string",
"Runtime": "string",
"Timeout": number,
"Version": "string",
"VpcConfig": {
"SecurityGroupIds": [ "string" ],
"SubnetIds": [ "string" ],
"VpcId": "string"
}
}
Response Elements
If the action is successful, the service sends back an HTTP 200 response.
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The following data is returned in JSON format by the service.
CodeSha256 (p. 380)
It is the SHA256 hash of your function deployment package.
Type: String
CodeSize (p. 380)
The size, in bytes, of the function .zip file you uploaded.
Type: Long
DeadLetterConfig (p. 380)
The parent object that contains the target Amazon Resource Name (ARN) of an Amazon SQS queue
or Amazon SNS topic.
Type: DeadLetterConfig (p. 393) object
Description (p. 380)
The user-provided description.
Type: String
Length Constraints: Minimum length of 0. Maximum length of 256.
Environment (p. 380)
The parent object that contains your environment's configuration settings.
Type: EnvironmentResponse (p. 396) object
FunctionArn (p. 380)
The Amazon Resource Name (ARN) assigned to the function.
Type: String
Pattern: arn:aws:lambda:[a-z]{2}-[a-z]+-\d{1}:\d{12}:function:[a-zA-Z0-9-_]+(:(\$LATEST|
[a-zA-Z0-9-_]+))?
FunctionName (p. 380)
The name of the function. Note that the length constraint applies only to the ARN. If you specify only
the function name, it is limited to 64 characters in length.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 140.
Pattern: (arn:aws:lambda:)?([a-z]{2}-[a-z]+-\d{1}:)?(\d{12}:)?(function:)?([a-zA-Z0-9_]+)(:(\$LATEST|[a-zA-Z0-9-_]+))?
Handler (p. 380)
The function Lambda calls to begin executing your function.
Type: String
Length Constraints: Maximum length of 128.
Pattern: [^\s]+
KMSKeyArn (p. 380)
The Amazon Resource Name (ARN) of the KMS key used to encrypt your function's environment
variables. If empty, it means you are using the AWS Lambda default service key.
Type: String
Pattern: (arn:aws:[a-z0-9-.]+:.*)|()
LastModified (p. 380)
The time stamp of the last time you updated the function.
Type: String
MemorySize (p. 380)
The memory size, in MB, you configured for the function. Must be a multiple of 64 MB.
Type: Integer
Valid Range: Minimum value of 128. Maximum value of 1536.
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Role (p. 380)
The Amazon Resource Name (ARN) of the IAM role that Lambda assumes when it executes your
function to access any other Amazon Web Services (AWS) resources.
Type: String
Pattern: arn:aws:iam::\d{12}:role/?[a-zA-Z_0-9+=,[email protected]\-_/]+
Runtime (p. 380)
The runtime environment for the Lambda function.
Type: String
Valid Values: nodejs | nodejs4.3 | nodejs6.10 | java8 | python2.7 | dotnetcore1.0 |
nodejs4.3-edge
Timeout (p. 380)
The function execution time at which Lambda should terminate the function. Because the execution
time has cost implications, we recommend you set this value based on your expected execution time.
The default is 3 seconds.
Type: Integer
Valid Range: Minimum value of 1.
Version (p. 380)
The version of the Lambda function.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 1024.
Pattern: (\$LATEST|[0-9]+)
VpcConfig (p. 380)
VPC configuration associated with your Lambda function.
Type: VpcConfigResponse (p. 405) object
Errors
CodeStorageExceededException
You have exceeded your maximum total code size per account. Limits
HTTP Status Code: 400
InvalidParameterValueException
One of the parameters in the request is invalid. For example, if you provided an IAM role for AWS
Lambda to assume in the CreateFunction or the UpdateFunctionConfiguration API, that AWS
Lambda is unable to assume you will get this exception.
HTTP Status Code: 400
ResourceNotFoundException
The resource (for example, a Lambda function or access policy statement) specified in the request
does not exist.
HTTP Status Code: 404
ServiceException
The AWS Lambda service encountered an internal error.
HTTP Status Code: 500
TooManyRequestsException
HTTP Status Code: 429
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS Command Line Interface
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• AWS SDK for .NET
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for JavaScript
• AWS SDK for PHP V3
• AWS SDK for Python
• AWS SDK for Ruby V2
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UpdateFunctionConfiguration
UpdateFunctionConfiguration
Updates the configuration parameters for the specified Lambda function by using the values provided in
the request. You provide only the parameters you want to change. This operation must only be used on an
existing Lambda function and cannot be used to update the function's code.
If you are using the versioning feature, note this API will always update the $LATEST version of your
Lambda function. For information about the versioning feature, see AWS Lambda Function Versioning and
Aliases.
This operation requires permission for the lambda:UpdateFunctionConfiguration action.
Request Syntax
PUT /2015-03-31/functions/FunctionName/configuration HTTP/1.1
Content-type: application/json
{
"DeadLetterConfig": {
"TargetArn": "string"
},
"Description": "string",
"Environment": {
"Variables": {
"string" : "string"
}
},
"Handler": "string",
"KMSKeyArn": "string",
"MemorySize": number,
"Role": "string",
"Runtime": "string",
"Timeout": number,
"VpcConfig": {
"SecurityGroupIds": [ "string" ],
"SubnetIds": [ "string" ]
}
}
URI Request Parameters
The request requires the following URI parameters.
FunctionName (p. 384)
The name of the Lambda function.
You can specify a function name (for example, Thumbnail) or you can specify Amazon
Resource Name (ARN) of the function (for example, arn:aws:lambda:us-west-2:accountid:function:ThumbNail). AWS Lambda also allows you to specify a partial ARN (for example,
account-id:Thumbnail). Note that the length constraint applies only to the ARN. If you specify only the
function name, it is limited to 64 character in length.
Length Constraints: Minimum length of 1. Maximum length of 140.
Pattern: (arn:aws:lambda:)?([a-z]{2}-[a-z]+-\d{1}:)?(\d{12}:)?(function:)?([a-zA-Z0-9_]+)(:(\$LATEST|[a-zA-Z0-9-_]+))?
Request Body
The request accepts the following data in JSON format.
DeadLetterConfig (p. 384)
The parent object that contains the target Amazon Resource Name (ARN) of an Amazon SQS queue
or Amazon SNS topic.
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Type: DeadLetterConfig (p. 393) object
Required: No
Description (p. 384)
A short user-defined function description. AWS Lambda does not use this value. Assign a meaningful
description as you see fit.
Type: String
Length Constraints: Minimum length of 0. Maximum length of 256.
Required: No
Environment (p. 384)
The parent object that contains your environment's configuration settings.
Type: Environment (p. 394) object
Required: No
Handler (p. 384)
The function that Lambda calls to begin executing your function. For Node.js, it is the modulename.export value in your function.
Type: String
Length Constraints: Maximum length of 128.
Pattern: [^\s]+
Required: No
KMSKeyArn (p. 384)
The Amazon Resource Name (ARN) of the KMS key used to encrypt your function's environment
variables. If you elect to use the AWS Lambda default service key, pass in an empty string ("") for this
parameter.
Type: String
Pattern: (arn:aws:[a-z0-9-.]+:.*)|()
Required: No
MemorySize (p. 384)
The amount of memory, in MB, your Lambda function is given. AWS Lambda uses this memory size to
infer the amount of CPU allocated to your function. Your function use-case determines your CPU and
memory requirements. For example, a database operation might need less memory compared to an
image processing function. The default value is 128 MB. The value must be a multiple of 64 MB.
Type: Integer
Valid Range: Minimum value of 128. Maximum value of 1536.
Required: No
Role (p. 384)
The Amazon Resource Name (ARN) of the IAM role that Lambda will assume when it executes your
function.
Type: String
Pattern: arn:aws:iam::\d{12}:role/?[a-zA-Z_0-9+=,[email protected]\-_/]+
Required: No
Runtime (p. 384)
The runtime environment for the Lambda function.
To use the Node.js runtime v6.10, set the value to "nodejs6.10". To use the Node.js runtime v4.3, set
the value to "nodejs4.3".
Note
You can no longer downgrade to the v0.10.42 runtime version. This version will no longer be
supported as of early 2017.
Type: String
Valid Values: nodejs | nodejs4.3 | nodejs6.10 | java8 | python2.7 | dotnetcore1.0 |
nodejs4.3-edge
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UpdateFunctionConfiguration
Required: No
Timeout (p. 384)
The function execution time at which AWS Lambda should terminate the function. Because the
execution time has cost implications, we recommend you set this value based on your expected
execution time. The default is 3 seconds.
Type: Integer
Valid Range: Minimum value of 1.
Required: No
VpcConfig (p. 384)
If your Lambda function accesses resources in a VPC, you provide this parameter identifying the list
of security group IDs and subnet IDs. These must belong to the same VPC. You must provide at least
one security group and one subnet ID.
Type: VpcConfig (p. 404) object
Required: No
Response Syntax
HTTP/1.1 200
Content-type: application/json
{
"CodeSha256": "string",
"CodeSize": number,
"DeadLetterConfig": {
"TargetArn": "string"
},
"Description": "string",
"Environment": {
"Error": {
"ErrorCode": "string",
"Message": "string"
},
"Variables": {
"string" : "string"
}
},
"FunctionArn": "string",
"FunctionName": "string",
"Handler": "string",
"KMSKeyArn": "string",
"LastModified": "string",
"MemorySize": number,
"Role": "string",
"Runtime": "string",
"Timeout": number,
"Version": "string",
"VpcConfig": {
"SecurityGroupIds": [ "string" ],
"SubnetIds": [ "string" ],
"VpcId": "string"
}
}
Response Elements
If the action is successful, the service sends back an HTTP 200 response.
The following data is returned in JSON format by the service.
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UpdateFunctionConfiguration
CodeSha256 (p. 386)
It is the SHA256 hash of your function deployment package.
Type: String
CodeSize (p. 386)
The size, in bytes, of the function .zip file you uploaded.
Type: Long
DeadLetterConfig (p. 386)
The parent object that contains the target Amazon Resource Name (ARN) of an Amazon SQS queue
or Amazon SNS topic.
Type: DeadLetterConfig (p. 393) object
Description (p. 386)
The user-provided description.
Type: String
Length Constraints: Minimum length of 0. Maximum length of 256.
Environment (p. 386)
The parent object that contains your environment's configuration settings.
Type: EnvironmentResponse (p. 396) object
FunctionArn (p. 386)
The Amazon Resource Name (ARN) assigned to the function.
Type: String
Pattern: arn:aws:lambda:[a-z]{2}-[a-z]+-\d{1}:\d{12}:function:[a-zA-Z0-9-_]+(:(\$LATEST|
[a-zA-Z0-9-_]+))?
FunctionName (p. 386)
The name of the function. Note that the length constraint applies only to the ARN. If you specify only
the function name, it is limited to 64 characters in length.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 140.
Pattern: (arn:aws:lambda:)?([a-z]{2}-[a-z]+-\d{1}:)?(\d{12}:)?(function:)?([a-zA-Z0-9_]+)(:(\$LATEST|[a-zA-Z0-9-_]+))?
Handler (p. 386)
The function Lambda calls to begin executing your function.
Type: String
Length Constraints: Maximum length of 128.
Pattern: [^\s]+
KMSKeyArn (p. 386)
The Amazon Resource Name (ARN) of the KMS key used to encrypt your function's environment
variables. If empty, it means you are using the AWS Lambda default service key.
Type: String
Pattern: (arn:aws:[a-z0-9-.]+:.*)|()
LastModified (p. 386)
The time stamp of the last time you updated the function.
Type: String
MemorySize (p. 386)
The memory size, in MB, you configured for the function. Must be a multiple of 64 MB.
Type: Integer
Valid Range: Minimum value of 128. Maximum value of 1536.
Role (p. 386)
The Amazon Resource Name (ARN) of the IAM role that Lambda assumes when it executes your
function to access any other Amazon Web Services (AWS) resources.
Type: String
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UpdateFunctionConfiguration
Pattern: arn:aws:iam::\d{12}:role/?[a-zA-Z_0-9+=,[email protected]\-_/]+
Runtime (p. 386)
The runtime environment for the Lambda function.
Type: String
Valid Values: nodejs | nodejs4.3 | nodejs6.10 | java8 | python2.7 | dotnetcore1.0 |
nodejs4.3-edge
Timeout (p. 386)
The function execution time at which Lambda should terminate the function. Because the execution
time has cost implications, we recommend you set this value based on your expected execution time.
The default is 3 seconds.
Type: Integer
Valid Range: Minimum value of 1.
Version (p. 386)
The version of the Lambda function.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 1024.
Pattern: (\$LATEST|[0-9]+)
VpcConfig (p. 386)
VPC configuration associated with your Lambda function.
Type: VpcConfigResponse (p. 405) object
Errors
InvalidParameterValueException
One of the parameters in the request is invalid. For example, if you provided an IAM role for AWS
Lambda to assume in the CreateFunction or the UpdateFunctionConfiguration API, that AWS
Lambda is unable to assume you will get this exception.
HTTP Status Code: 400
ResourceNotFoundException
The resource (for example, a Lambda function or access policy statement) specified in the request
does not exist.
HTTP Status Code: 404
ServiceException
The AWS Lambda service encountered an internal error.
HTTP Status Code: 500
TooManyRequestsException
HTTP Status Code: 429
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS Command Line Interface
• AWS SDK for .NET
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for JavaScript
• AWS SDK for PHP V3
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Data Types
• AWS SDK for Python
• AWS SDK for Ruby V2
Data Types
The following data types are supported:
• AccountLimit (p. 390)
• AccountUsage (p. 391)
• AliasConfiguration (p. 392)
• DeadLetterConfig (p. 393)
• Environment (p. 394)
• EnvironmentError (p. 395)
• EnvironmentResponse (p. 396)
• EventSourceMappingConfiguration (p. 397)
• FunctionCode (p. 399)
• FunctionCodeLocation (p. 400)
• FunctionConfiguration (p. 401)
• VpcConfig (p. 404)
• VpcConfigResponse (p. 405)
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AccountLimit
AccountLimit
Provides limits of code size and concurrency associated with the current account and region.
Contents
CodeSizeUnzipped
Size, in bytes, of code/dependencies that you can zip into a deployment package (uncompressed zip/
jar size) for uploading. The default limit is 250 MB.
Type: Long
Required: No
CodeSizeZipped
Size, in bytes, of a single zipped code/dependencies package you can upload for your Lambda
function(.zip/.jar file). Try using Amazon S3 for uploading larger files. Default limit is 50 MB.
Type: Long
Required: No
ConcurrentExecutions
Number of simultaneous executions of your function per region. For more information or to request a
limit increase for concurrent executions, see Lambda Function Concurrent Executions. The default limit
is 100.
Type: Integer
Required: No
TotalCodeSize
Maximum size, in bytes, of a code package you can upload per region. The default size is 75 GB.
Type: Long
Required: No
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for Ruby V2
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AccountUsage
AccountUsage
Provides code size usage and function count associated with the current account and region.
Contents
FunctionCount
The number of your account's existing functions per region.
Type: Long
Required: No
TotalCodeSize
Total size, in bytes, of the account's deployment packages per region.
Type: Long
Required: No
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for Ruby V2
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AliasConfiguration
AliasConfiguration
Provides configuration information about a Lambda function version alias.
Contents
AliasArn
Lambda function ARN that is qualified using the alias name as the suffix. For example, if you create
an alias called BETA that points to a helloworld function version, the ARN is arn:aws:lambda:awsregions:acct-id:function:helloworld:BETA.
Type: String
Pattern: arn:aws:lambda:[a-z]{2}-[a-z]+-\d{1}:\d{12}:function:[a-zA-Z0-9-_]+(:(\$LATEST|
[a-zA-Z0-9-_]+))?
Required: No
Description
Alias description.
Type: String
Length Constraints: Minimum length of 0. Maximum length of 256.
Required: No
FunctionVersion
Function version to which the alias points.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 1024.
Pattern: (\$LATEST|[0-9]+)
Required: No
Name
Alias name.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 128.
Pattern: (?!^[0-9]+$)([a-zA-Z0-9-_]+)
Required: No
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for Ruby V2
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DeadLetterConfig
DeadLetterConfig
The parent object that contains the target Amazon Resource Name (ARN) of an Amazon SQS queue or
Amazon SNS topic.
Contents
TargetArn
The Amazon Resource Name (ARN) of an Amazon SQS queue or Amazon SNS topic you specify as
your Dead Letter Queue (DLQ).
Type: String
Pattern: (arn:aws:[a-z0-9-.]+:.*)|()
Required: No
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for Ruby V2
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Environment
Environment
The parent object that contains your environment's configuration settings.
Contents
Variables
The key-value pairs that represent your environment's configuration settings. The value you specify
cannot contain a ",".
Type: String to String map
Pattern: [^,]*
Required: No
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for Ruby V2
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EnvironmentError
EnvironmentError
The parent object that contains error information associated with your configuration settings.
Contents
ErrorCode
The error code returned by the environment error object.
Type: String
Required: No
Message
The message returned by the environment error object.
Type: String
Required: No
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for Ruby V2
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EnvironmentResponse
EnvironmentResponse
The parent object returned that contains your environment's configuration settings or any error information
associated with your configuration settings.
Contents
Error
The parent object that contains error information associated with your configuration settings.
Type: EnvironmentError (p. 395) object
Required: No
Variables
The key-value pairs returned that represent your environment's configuration settings or error
information.
Type: String to String map
Pattern: [^,]*
Required: No
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for Ruby V2
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EventSourceMappingConfiguration
EventSourceMappingConfiguration
Describes mapping between an Amazon Kinesis stream and a Lambda function.
Contents
BatchSize
The largest number of records that AWS Lambda will retrieve from your event source at the time of
invoking your function. Your function receives an event with all the retrieved records.
Type: Integer
Valid Range: Minimum value of 1. Maximum value of 10000.
Required: No
EventSourceArn
The Amazon Resource Name (ARN) of the Amazon Kinesis stream that is the source of events.
Type: String
Pattern: arn:aws:([a-zA-Z0-9\-])+:([a-z]{2}-[a-z]+-\d{1})?:(\d{12})?:(.*)
Required: No
FunctionArn
The Lambda function to invoke when AWS Lambda detects an event on the stream.
Type: String
Pattern: arn:aws:lambda:[a-z]{2}-[a-z]+-\d{1}:\d{12}:function:[a-zA-Z0-9-_]+(:(\$LATEST|
[a-zA-Z0-9-_]+))?
Required: No
LastModified
The UTC time string indicating the last time the event mapping was updated.
Type: Timestamp
Required: No
LastProcessingResult
The result of the last AWS Lambda invocation of your Lambda function.
Type: String
Required: No
State
The state of the event source mapping. It can be Creating, Enabled, Disabled, Enabling, Disabling,
Updating, or Deleting.
Type: String
Required: No
StateTransitionReason
The reason the event source mapping is in its current state. It is either user-requested or an AWS
Lambda-initiated state transition.
Type: String
Required: No
UUID
The AWS Lambda assigned opaque identifier for the mapping.
Type: String
Required: No
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS SDK for C++
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EventSourceMappingConfiguration
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for Ruby V2
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FunctionCode
FunctionCode
The code for the Lambda function.
Contents
S3Bucket
Amazon S3 bucket name where the .zip file containing your deployment package is stored. This bucket
must reside in the same AWS region where you are creating the Lambda function.
Type: String
Length Constraints: Minimum length of 3. Maximum length of 63.
Pattern: ^[0-9A-Za-z\.\-_]*(?<!\.)$
Required: No
S3Key
The Amazon S3 object (the deployment package) key name you want to upload.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 1024.
Required: No
S3ObjectVersion
The Amazon S3 object (the deployment package) version you want to upload.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 1024.
Required: No
ZipFile
The contents of your zip file containing your deployment package. If you are using the web API directly,
the contents of the zip file must be base64-encoded. If you are using the AWS SDKs or the AWS
CLI, the SDKs or CLI will do the encoding for you. For more information about creating a .zip file, see
Execution Permissions in the AWS Lambda Developer Guide.
Type: Base64-encoded binary data object
Required: No
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for Ruby V2
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FunctionCodeLocation
FunctionCodeLocation
The object for the Lambda function location.
Contents
Location
The presigned URL you can use to download the function's .zip file that you previously uploaded. The
URL is valid for up to 10 minutes.
Type: String
Required: No
RepositoryType
The repository from which you can download the function.
Type: String
Required: No
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for Ruby V2
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FunctionConfiguration
FunctionConfiguration
A complex type that describes function metadata.
Contents
CodeSha256
It is the SHA256 hash of your function deployment package.
Type: String
Required: No
CodeSize
The size, in bytes, of the function .zip file you uploaded.
Type: Long
Required: No
DeadLetterConfig
The parent object that contains the target Amazon Resource Name (ARN) of an Amazon SQS queue
or Amazon SNS topic.
Type: DeadLetterConfig (p. 393) object
Required: No
Description
The user-provided description.
Type: String
Length Constraints: Minimum length of 0. Maximum length of 256.
Required: No
Environment
The parent object that contains your environment's configuration settings.
Type: EnvironmentResponse (p. 396) object
Required: No
FunctionArn
The Amazon Resource Name (ARN) assigned to the function.
Type: String
Pattern: arn:aws:lambda:[a-z]{2}-[a-z]+-\d{1}:\d{12}:function:[a-zA-Z0-9-_]+(:(\$LATEST|
[a-zA-Z0-9-_]+))?
Required: No
FunctionName
The name of the function. Note that the length constraint applies only to the ARN. If you specify only
the function name, it is limited to 64 characters in length.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 140.
Pattern: (arn:aws:lambda:)?([a-z]{2}-[a-z]+-\d{1}:)?(\d{12}:)?(function:)?([a-zA-Z0-9_]+)(:(\$LATEST|[a-zA-Z0-9-_]+))?
Required: No
Handler
The function Lambda calls to begin executing your function.
Type: String
Length Constraints: Maximum length of 128.
Pattern: [^\s]+
Required: No
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FunctionConfiguration
KMSKeyArn
The Amazon Resource Name (ARN) of the KMS key used to encrypt your function's environment
variables. If empty, it means you are using the AWS Lambda default service key.
Type: String
Pattern: (arn:aws:[a-z0-9-.]+:.*)|()
Required: No
LastModified
The time stamp of the last time you updated the function.
Type: String
Required: No
MemorySize
The memory size, in MB, you configured for the function. Must be a multiple of 64 MB.
Type: Integer
Valid Range: Minimum value of 128. Maximum value of 1536.
Required: No
Role
The Amazon Resource Name (ARN) of the IAM role that Lambda assumes when it executes your
function to access any other Amazon Web Services (AWS) resources.
Type: String
Pattern: arn:aws:iam::\d{12}:role/?[a-zA-Z_0-9+=,[email protected]\-_/]+
Required: No
Runtime
The runtime environment for the Lambda function.
Type: String
Valid Values: nodejs | nodejs4.3 | nodejs6.10 | java8 | python2.7 | dotnetcore1.0 |
nodejs4.3-edge
Required: No
Timeout
The function execution time at which Lambda should terminate the function. Because the execution
time has cost implications, we recommend you set this value based on your expected execution time.
The default is 3 seconds.
Type: Integer
Valid Range: Minimum value of 1.
Required: No
Version
The version of the Lambda function.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 1024.
Pattern: (\$LATEST|[0-9]+)
Required: No
VpcConfig
VPC configuration associated with your Lambda function.
Type: VpcConfigResponse (p. 405) object
Required: No
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS SDK for C++
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FunctionConfiguration
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for Ruby V2
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VpcConfig
VpcConfig
If your Lambda function accesses resources in a VPC, you provide this parameter identifying the list of
security group IDs and subnet IDs. These must belong to the same VPC. You must provide at least one
security group and one subnet ID.
Contents
SecurityGroupIds
A list of one or more security groups IDs in your VPC.
Type: array of Strings
Array Members: Maximum number of 5 items.
Required: No
SubnetIds
A list of one or more subnet IDs in your VPC.
Type: array of Strings
Array Members: Maximum number of 16 items.
Required: No
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for Ruby V2
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VpcConfigResponse
VpcConfigResponse
VPC configuration associated with your Lambda function.
Contents
SecurityGroupIds
A list of security group IDs associated with the Lambda function.
Type: array of Strings
Array Members: Maximum number of 5 items.
Required: No
SubnetIds
A list of subnet IDs associated with the Lambda function.
Type: array of Strings
Array Members: Maximum number of 16 items.
Required: No
VpcId
The VPC ID associated with you Lambda function.
Type: String
Required: No
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
• AWS SDK for C++
• AWS SDK for Go
• AWS SDK for Java
• AWS SDK for Ruby V2
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Document History
The following table describes the important changes to the AWS Lambda Developer Guide.
Relevant Dates to this History:
• Current product version: 2015-03-31
• Last documentation update: March 28, 2017
Change
Description
Date
Asia Pacific (Mumbai)
Region
AWS Lambda is now available in the Asia Pacific (Mumbai)
Region. For more information about Lambda regions and
endpoints, see Regions and Endpoints in the AWS General
Reference.
March 28,
2017
AWS Lambda now
AWS Lambda added support for Node.js runtime v6.10. For
supports Node.js runtime more information, see Programming Model (Node.js) (p. 9).
v6.10
March 22,
2017
EU (London) Region
February 1,
2017
AWS Lambda is now available in the EU (London) Region. For
more information about Lambda regions and endpoints, see
Regions and Endpoints in the AWS General Reference.
Introduced AWS
AWS Lambda introduces the following features:
December
Lambda support for
3, 2016
• AWS Lambda added support for C#. For more information,
the .NET runtime,
see Programming Model for Authoring Lambda Functions in
[email protected]
C# (p. 48).
(Preview), Dead Letter
Queues and automated
• [email protected] (Preview) allows you to run Lambda functions
deployment of serverless
at the AWS Edge locations in response to CloudFront
applications.
events. For more information, see AWS [email protected]
(Preview) (p. 267).
• Added a tutorial for automating deployment of serverless
applications using AWS CodePipeline, AWS CodeBuild and
AWS CloudFormation. For more information, see Automating
Deployment of Lambda-based Applications (p. 141).
• Updated Troubleshooting and Monitoring AWS Lambda
Functions with Amazon CloudWatch (p. 103) to include a
section on Dead Letter Queues (p. 109), which you can
406
AWS Lambda Developer Guide
Change
Description
Date
configure to retrieve information on failed asynchronous
invocations of Lambda functions.
AWS Lambda adds
Amazon Lex as a
supported event source.
Using Lambda and Amazon Lex, you can quickly build chat
bots for various services like Slack and Facebook. For more
information, see Amazon Lex (p. 125).
November
30, 2016
US West (N. California)
Region
AWS Lambda is now available in the US West (N. California)
Region. For more information about Lambda regions and
endpoints, see Regions and Endpoints in the AWS General
Reference.
November
21, 2016
Introduced the AWS
Serverless Application
Model for creating and
deploying Lambdabased applications
and using environment
variables for Lambda
function configuration
settings.
AWS Lambda introduces the following features in this release.
November
18, 2016
Added a tutorial under
Getting Started (p. 155)
for creating an Amazon
API Gateway endpoint
using the Lambda
console
The tutorial instructs how to seamlessly integrate a Lambda
function with an API via new features introduced in Configure
Proxy Integration for a Proxy Resource. For more information,
see Step 3: Create a Simple Microservice using Lambda and
API Gateway (p. 166).
August 29,
2016
Asia Pacific (Seoul)
Region
AWS Lambda is now available in the Asia Pacific (Seoul)
Region. For more information about Lambda regions and
endpoints, see Regions and Endpoints in the AWS General
Reference.
August 29,
2016
Asia Pacific (Sydney)
Region
Lambda is now available in the Asia Pacific (Sydney) Region.
For more information about Lambda regions and endpoints, see
Regions and Endpoints in the AWS General Reference.
June 23,
2016
Updates to the Lambda
console
The Lambda console has been updated to simplify the rolecreation process. For more information, see Step 2.1: Create a
Hello World Lambda Function (p. 159).
June 23,
2016
• AWS Serverless Application Model: You can now use the
AWS SAM to define the syntax for expressing resources
within a serverless application. In order to deploy your
application, simply specify the resources you need as part
of your application, along with their associated permissions
policies in a AWS CloudFormation template file (written in
either JSON or YAML), package your deployment artifacts,
and deploy the template. For more information, see Deploying
Lambda-based Applications (p. 133).
• Environment variables: You can use environment variables
to specify configuration settings for your Lambda function
outside of your function code. For more information, see
Environment Variables (p. 85).
AWS Lambda now
AWS Lambda added support for Node.js runtime v4.3. For more
supports Node.js runtime information, see Programming Model (Node.js) (p. 9).
v4.3
April 07,
2016
EU (Frankfurt) region
March 14,
2016
Lambda is now available in the EU (Frankfurt) region. For more
information about Lambda regions and endpoints, see Regions
and Endpoints in the AWS General Reference.
407
AWS Lambda Developer Guide
Change
Description
Date
VPC support
You can now configure a Lambda function to access resources
in your VPC. For more information, see Configuring a Lambda
Function to Access Resources in an Amazon VPC (p. 92). For
example walkthroughs, see Tutorials: Configuring a Lambda
Function to Access Resources in an Amazon VPC (p. 94).
February
11, 2016
Content reorganization
The reorganized content now provides the following:
December
9, 2015
• Getting Started (p. 155) – Contains a console-based exercise
in which you create a Hello World Lambda function. You
explore the AWS Lambda console features, including
blueprints that enable you to create Lambda functions with
just a few clicks.
• Use Cases (p. 169) – Provides examples of how to use AWS
Lambda with other AWS services or your custom applications
as event sources, invoke over HTTPS, and set up AWS
Lambda to invoke your Lambda function at scheduled
interval.
• Programming Model (p. 8) – Explains programming model
core concepts and describes language-specific details.
Regardless of the language you choose, there is a common
pattern to writing code for a Lambda function.
• Creating a Deployment Package (p. 58) – Explains how to
create deployment packages for Lambda function code that is
authored in languages supported by AWS Lambda (Python,
Java, and Node.js).
AWS Lambda runtime
has been updated.
AWS Lambda runtime has been updated with the following SDK
and Linux kernel versions in this release:
• AWS SDK for JavaScript: 2.2.12
• Boto SDK: 1.2.1
• Linux kernel version: 3.14.48-33.39.amzn1.x86_6.
For more information, see Lambda Execution Environment and
Available Libraries (p. 152).
408
November
4, 2015
AWS Lambda Developer Guide
Change
Description
Date
Versioning support,
Python for developing
code for Lambda
functions, scheduled
events, and increase in
execution time
AWS Lambda introduces the following features in this release.
October 08,
2015
• Python: You can now develop your Lambda function code
using Python. For more information, see Programming
Model (p. 8).
• Versioning: You can maintain one or more versions of
your Lambda function. Versioning allows you to control
which Lambda function version is executed in different
environments (for example, development, testing, or
production). For more information, see AWS Lambda
Function Versioning and Aliases (p. 73).
• Scheduled events: You can also set up AWS Lambda
to invoke your code on a regular, scheduled basis using
the AWS Lambda console. You can specify a fixed rate
(number of hours, days, or weeks) or you can specify a cron
expression. For an example, see Using AWS Lambda with
Scheduled Events (p. 253).
• Increase in execution time: You can now set up your Lambda
functions to run for up to five minutes allowing longer running
functions such as large volume data ingestion and processing
jobs.
Two new walkthroughs
The following new walkthroughs are added. They both use Java
Lambda function.
August 27,
2015
Tutorial: Using AWS Lambda with Amazon DynamoDB (p. 197)
Using AWS Lambda as Mobile Application Backend (Custom
Event Source: Android) (p. 240)
Support for DynamoDB
Streams
DynamoDB Streams is now generally available and you can
use it in all the regions where DynamoDB is available. You can
enable DynamoDB Streams for your table and use a Lambda
function as a trigger for the table. Triggers are custom actions
you take in response to updates made to the DynamoDB table.
For an example walkthrough, see Tutorial: Using AWS Lambda
with Amazon DynamoDB (p. 197) .
409
July 14,
2015
AWS Lambda Developer Guide
Change
Description
Date
AWS Lambda now
supports invoking
Lambda functions
with REST-compatible
clients.
Until now, to invoke your Lambda function from your web,
mobile, or IoT application you needed the AWS SDKs (for
example, AWS SDK for Java, AWS SDK for Android, or AWS
SDK for iOS). Now, AWS Lambda supports invoking a Lambda
function with REST-compatible clients through a customized
API that you can create using Amazon API Gateway. You can
send requests to your Lambda function endpoint URL. You
can configure security on the endpoint to allow open access,
leverage AWS Identity and Access Management (IAM) to
authorize access, or use API keys to meter access to your
Lambda functions by others.
July 09,
2015
For an example Getting Started exercise, see Using AWS
Lambda with Amazon API Gateway (On-Demand Over
HTTPS) (p. 227).
For more information about the Amazon API Gateway, see
https://aws.amazon.com/api-gateway/.
The AWS Lambda
console now provides
blueprints to easily
create Lambda functions
and test them.
AWS Lambda console provides a set of blueprints. Each
blueprint provides a sample event source configuration and
sample code for your Lambda function that you can use to
easily create Lambda-based applications. All of the AWS
Lambda Getting Started exercises now use the blueprints. For
more information, see Getting Started (p. 155).
In this
release
AWS Lambda now
supports Java to author
your Lambda functions.
You can now author Lambda code in Java. For more
information, see Programming Model (p. 8).
June 15,
2015
AWS Lambda now
supports specifying an
Amazon S3 object as
the function .zip when
creating or updating a
Lambda function.
You can upload a Lambda function deployment package (.zip
file) to an Amazon S3 bucket in the same region where you
want to create a Lambda function. Then, you can specify the
bucket name and object key name when you create or update a
Lambda function.
May 28,
2015
410
AWS Lambda Developer Guide
Change
Description
Date
AWS Lambda now
generally available with
added support for mobile
backends
AWS Lambda is now generally available for production use.
The release also introduces new features that make it easier to
build mobile, tablet, and Internet of Things (IoT) backends using
AWS Lambda that scale automatically without provisioning
or managing infrastructure. AWS Lambda now supports
both real-time (synchronous) and asynchronous events.
Additional features include easier event source configuration
and management. The permission model and the programming
model have been simplified by the introduction of resource
policies for your Lambda functions.
April 9,
2015
The documentation has been updated accordingly. For
information, see the following topics:
How It Works (p. 146)
Getting Started (p. 155)
AWS Lambda
Preview release
Preview release of the AWS Lambda Developer Guide.
411
November
13, 2014
AWS Lambda Developer Guide
AWS Glossary
For the latest AWS terminology, see the AWS Glossary in the AWS General Reference.
412
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