Elastic Load Balancing Developer Guide

Elastic Load Balancing Developer Guide
Elastic Load Balancing
Developer Guide
Elastic Load Balancing Developer Guide
Elastic Load Balancing: Developer Guide
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Elastic Load Balancing Developer Guide
Table of Contents
What Is Elastic Load Balancing? ...................................................................................................... 1
Features of Elastic Load Balancing ........................................................................................... 1
How to Get Started with Elastic Load Balancing .......................................................................... 2
Accessing Elastic Load Balancing ............................................................................................ 2
PCI DSS Compliance ............................................................................................................. 2
Pricing ................................................................................................................................. 3
Related Services ................................................................................................................... 3
How Elastic Load Balancing Works ........................................................................................... 3
Request Routing ........................................................................................................... 4
Availability Zones and Instances ...................................................................................... 4
Related Topics .............................................................................................................. 5
Setting Up .................................................................................................................................... 6
Sign Up ............................................................................................................................... 6
Prepare Your VPC and Back-end Instances ................................................................................ 6
Access Elastic Load Balancing Using the AWS Management Console ............................................ 7
Access Elastic Load Balancing Using the AWS CLI ..................................................................... 8
Getting Started ............................................................................................................................. 9
Before You Begin ................................................................................................................... 9
Step 1: Define Your Load Balancer .......................................................................................... 10
Step 2: Assign Security Groups to Your Load Balancer in a VPC .................................................. 11
Step 3: Configure Security Settings (Optional) .......................................................................... 11
Step 4: Configure Health Checks for Your EC2 Instances ............................................................ 12
Step 5: Register EC2 Instances with Your Load Balancer ............................................................ 12
Step 6: Tag Your Load Balancer (Optional) ................................................................................ 13
Step 7: Create and Verify Your Load Balancer ........................................................................... 13
Step 8: Delete Your Load Balancer (Optional) ............................................................................ 13
Internet-Facing Load Balancers ...................................................................................................... 15
Public DNS Names for Your Load Balancer ............................................................................... 15
Create an Internet-Facing Load Balancer ................................................................................. 16
Internal Load Balancers ................................................................................................................ 17
Public DNS Name for Your Load Balancer ................................................................................ 18
Create an Internal Load Balancer ........................................................................................... 18
Prerequisites .............................................................................................................. 18
Create an Internal Load Balancer Using the Console ......................................................... 18
Create an Internal Load Balancer Using the AWS CLI ........................................................ 19
HTTPS Load Balancers ................................................................................................................ 22
SSL Certificates .................................................................................................................. 22
Creating an SSL Certificate Using AWS Certificate Manager ............................................... 23
Creating an SSL Certificate Using SSL/TLS Tools ............................................................. 23
SSL Negotiation Configurations .............................................................................................. 28
SSL Protocols ............................................................................................................. 28
SSL Ciphers ............................................................................................................... 29
Server Order Preference ............................................................................................... 29
SSL Security Policies ................................................................................................... 29
Predefined SSL Security Policies .................................................................................... 30
Create an HTTPS Load Balancer ........................................................................................... 34
Prerequisites .............................................................................................................. 34
Create an HTTPS/SSL Load Balancer Using the Console ................................................... 34
Create an HTTPS/SSL Load Balancer Using the AWS CLI .................................................. 40
Configure an HTTPS Listener ................................................................................................ 48
Prerequisites .............................................................................................................. 49
Add an HTTPS Listener Using the Console ...................................................................... 49
Add an HTTPS Listener Using the AWS CLI ..................................................................... 50
Replace the SSL Certificate ................................................................................................... 51
Prerequisites .............................................................................................................. 52
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Replace the SSL Certificate Using the Console .................................................................
Replace the SSL Certificate Using the AWS CLI ...............................................................
Update the SSL Negotiation Configuration ...............................................................................
Update the SSL Negotiation Configuration Using the Console .............................................
Update the SSL Negotiation Configuration Using the AWS CLI ............................................
Back-end Instances ......................................................................................................................
Best Practices for Your Back-end Instances ..............................................................................
Configure Health Checks ......................................................................................................
Health Check Configuration ...........................................................................................
Update the Health Check Configuration ...........................................................................
Check the Health of Your Instances .................................................................................
Troubleshoot Health Checks ..........................................................................................
Configure Security Groups ....................................................................................................
Security Groups for Load Balancers in a VPC ...................................................................
Security Groups for Back-end Instances in a VPC .............................................................
Network ACLs for Load Balancers in a VPC ......................................................................
Security Groups for Back-end Instances in EC2-Classic .....................................................
Add or Remove Availability Zones ...........................................................................................
Add an Availability Zone ................................................................................................
Remove an Availability Zone ..........................................................................................
Add or Remove Subnets .......................................................................................................
Requirements .............................................................................................................
Add a Subnet ..............................................................................................................
Remove a Subnet ........................................................................................................
Register or De-register Instances ...........................................................................................
Prerequisites ..............................................................................................................
Register an Instance ....................................................................................................
De-register an Instance .................................................................................................
Listeners ....................................................................................................................................
Protocols ............................................................................................................................
TCP/SSL Protocol ........................................................................................................
HTTP/HTTPS Protocol .................................................................................................
HTTPS/SSL Listeners ..........................................................................................................
SSL Server Certificates ................................................................................................
SSL Negotiation ..........................................................................................................
Back-End Server Authentication .....................................................................................
Listener Configurations .........................................................................................................
X-Forwarded Headers ..........................................................................................................
X-Forwarded-For .........................................................................................................
X-Forwarded-Proto ......................................................................................................
X-Forwarded-Port ........................................................................................................
Configure Your Load Balancer ........................................................................................................
Configure the Idle Timeout ....................................................................................................
Configure the Idle Timeout Using the Console ..................................................................
Configure the Idle Timeout Using the AWS CLI .................................................................
Configure Cross-Zone Load Balancing ....................................................................................
Enable Cross-Zone Load Balancing ................................................................................
Disable Cross-Zone Load Balancing ...............................................................................
Configure Connection Draining ..............................................................................................
Enable Connection Draining ..........................................................................................
Disable Connection Draining ..........................................................................................
Configure Proxy Protocol ......................................................................................................
Proxy Protocol Header ..................................................................................................
Prerequisites for Enabling Proxy Protocol .........................................................................
Enable Proxy Protocol Using the AWS CLI .......................................................................
Disable Proxy Protocol Using the AWS CLI ......................................................................
Configure Sticky Sessions .....................................................................................................
Duration-Based Session Stickiness .................................................................................
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Application-Controlled Session Stickiness ........................................................................ 94
Tag Your Load Balancer ........................................................................................................ 96
Tag Restrictions ........................................................................................................... 96
Add a Tag ................................................................................................................... 97
Remove a Tag ............................................................................................................. 97
Configure the Domain Name .................................................................................................. 98
Associating Your Custom Domain Name with Your Load Balancer Name ................................ 98
Configure DNS Failover for Your Load Balancer ................................................................. 99
Disassociating Your Custom Domain Name from Your Load Balancer .................................. 100
Monitor Your Load Balancer ......................................................................................................... 101
Monitor CloudWatch Metrics ................................................................................................ 101
Elastic Load Balancing Metrics ..................................................................................... 102
Statistics for Elastic Load Balancing Metrics ................................................................... 105
Dimensions for Elastic Load Balancing Metrics ................................................................ 105
View CloudWatch Metrics for Your Load Balancer ............................................................ 106
Create CloudWatch Alarms for Your Load Balancer .......................................................... 106
Log Load Balancer Requests ............................................................................................... 107
Access Log Files ........................................................................................................ 108
Access Log Entries .................................................................................................... 109
Processing Access Logs ............................................................................................. 111
Enable Access Logs ................................................................................................... 111
Disable Access Logs .................................................................................................. 115
Log API Calls .................................................................................................................... 116
Configure CloudTrail Event Logging ............................................................................... 117
Elastic Load Balancing Event Entries in CloudTrail Log Files .............................................. 117
Control Access to Your Load Balancer ........................................................................................... 119
Using an IAM Policy to Grant Permissions .............................................................................. 119
Actions for Elastic Load Balancing ........................................................................................ 120
Resource-Level Permissions for Elastic Load Balancing ............................................................ 121
Condition Keys for Elastic Load Balancing .............................................................................. 122
Example IAM Policies for Elastic Load Balancing ..................................................................... 122
Troubleshoot Your Load Balancer .................................................................................................. 125
API Errors ......................................................................................................................... 126
CertificateNotFound: undefined .................................................................................... 126
OutofService: A Transient Error Occurred ....................................................................... 127
HTTP Errors ..................................................................................................................... 127
HTTP 400: BAD_REQUEST ........................................................................................ 127
HTTP 405: METHOD_NOT_ALLOWED ......................................................................... 127
HTTP 408: Request Timeout ........................................................................................ 128
HTTP 502: Bad Gateway ............................................................................................. 128
HTTP 503: Service Unavailable .................................................................................... 128
HTTP 504: Gateway Timeout ....................................................................................... 128
Response Code Metrics ...................................................................................................... 129
HTTPCode_ELB_4XX ................................................................................................ 129
HTTPCode_ELB_5XX ................................................................................................ 129
HTTPCode_Backend_2XX .......................................................................................... 129
HTTPCode_Backend_3XX .......................................................................................... 130
HTTPCode_Backend_4XX .......................................................................................... 130
HTTPCode_Backend_5XX .......................................................................................... 130
Health Checks ................................................................................................................... 130
Connection to the instances has timed out ...................................................................... 131
Connection to your Internet-facing load balancer launched in a VPC has timed out ................ 131
Health check target page error ..................................................................................... 132
Public key authentication is failing ................................................................................. 132
Instance is not receiving traffic from the load balancer ...................................................... 132
Ports on instance are not open ..................................................................................... 132
Instances in an Auto Scaling group are failing the ELB health check .................................... 133
Instance Registration .......................................................................................................... 133
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Taking too long to register an EC2 instance ....................................................................
Unable to register an instance launched from a paid AMI ..................................................
Limits .......................................................................................................................................
Document History ......................................................................................................................
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Features of Elastic Load Balancing
What Is Elastic Load Balancing?
Elastic Load Balancing automatically distributes incoming traffic across multiple EC2 instances. You
create a load balancer and register instances with the load balancer in one or more Availability Zones.
The load balancer serves as a single point of contact for clients. This enables you to increase the availability
of your application. You can add and remove EC2 instances from your load balancer as your needs
change, without disrupting the overall flow of information. If an EC2 instance fails, Elastic Load Balancing
automatically reroutes the traffic to the remaining running EC2 instances. If a failed EC2 instance is
restored, Elastic Load Balancing restores the traffic to that instance. Elastic Load Balancing can also
serve as the first line of defense against attacks on your network. You can offload the work of encryption
and decryption to your load balancer so that your EC2 instances can focus on their main work.
For more information, see Elastic Load Balancing.
Features of Elastic Load Balancing
Elastic Load Balancing provides the following features:
• You can use the operating systems and instance types supported by Amazon EC2. You can configure
your EC2 instances to accept traffic only from your load balancer.
• You can configure the load balancer to accept traffic using the following protocols: HTTP, HTTPS
(secure HTTP), TCP, and SSL (secure TCP).
• You can configure your load balancer to distribute requests to EC2 instances in multiple Availability
Zones, minimizing the risk of overloading one single instance. If an entire Availability Zone goes offline,
the load balancer routes traffic to instances in other Availability Zones.
• There is no limit on the number of connections that your load balancer can attempt to make with your
EC2 instances. The number of connections scales with the number of concurrent requests that the
load balancer receives.
• You can configure the health checks that Elastic Load Balancing uses to monitor the health of the EC2
instances registered with the load balancer so that it can send requests only to the healthy instances.
• You can use end-to-end traffic encryption on those networks that use secure (HTTPS/SSL) connections.
• [EC2-VPC] You can create an Internet-facing load balancer, which takes requests from clients over
the Internet and routes them to your EC2 instances, or an internal-facing load balancer, which takes
requests from clients in your VPC and routes them to EC2 instances in your private subnets. Load
balancers in EC2-Classic are always Internet-facing.
• [EC2-Classic] Load balancers for EC2-Classic support both IPv4 and IPv6 addresses. Load balancers
for a VPC do not support IPv6 addresses.
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How to Get Started with Elastic Load Balancing
• You can monitor your load balancer using CloudWatch metrics, access logs, and AWS CloudTrail.
• You can associate your Internet-facing load balancer with your domain name. Because the load balancer
receives all requests from clients, you don't need to create and manage public domain names for the
EC2 instances to which the load balancer routes traffic. You can point the instance's domain records
at the load balancer instead and scale as needed (either adding or removing capacity) without having
to update the records with each scaling activity.
How to Get Started with Elastic Load Balancing
• Before you explore Elastic Load Balancing, you must sign up for AWS and prepare to create your load
balancer. For more information, see Setting Up Elastic Load Balancing (p. 6).
• To learn how to create a basic load balancer and register EC2 instances with your load balancer, see
Getting Started with Elastic Load Balancing (p. 9).
• To learn how to create an HTTPS load balancer and register EC2 instances with your load balancer,
see Create an HTTPS Load Balancer (p. 34).
• To learn how to use the various features supported by Elastic Load Balancing, see Configure Your
Load Balancer (p. 82).
Accessing Elastic Load Balancing
You can create, access, and manage your load balancers using any of the following interfaces:
• AWS Management Console— Provides a web interface that you can use to access Elastic Load
Balancing.
• AWS Command Line Interface (CLI) — Provides commands for a broad set of AWS services, including
Elastic Load Balancing, and is supported on Windows, Mac, and Linux. For more information, see AWS
Command Line Interface.
• AWS SDKs — Provides language-specific APIs and takes care of many of the connection details, such
as calculating signatures, handling request retries, and error handling. For more information, see AWS
SDKs.
• Query API— Provides low-level APIs that you call using HTTPS requests. Using the Query API is the
most direct way to access Elastic Load Balancing, but it requires that your application handle low-level
details such as generating the hash to sign the request, and error handling. For more information, see
the Elastic Load Balancing API Reference.
• SOAP API— Provides access to the Elastic Load Balancing web service using the SOAP web services
messaging protocol. This interface is described by a Web Services Description Language (WSDL)
document that defines the operations and security model. The WSDL references an XML schema
document, which strictly defines the data types that might appear in SOAP requests and responses.
For more information, see the Elastic Load Balancing API Reference.
• Elastic Load Balancing Command Line Interface (CLI) — Provides commands to access Elastic
Load Balancing.
Important
We are no longer adding new functionality to the ELB CLI. We recommend that you use the
AWS CLI instead.
PCI DSS Compliance
Elastic Load Balancing supports the processing, storage, and transmission of credit card data by a
merchant or service provider, and has been validated as being compliant with Payment Card Industry
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Elastic Load Balancing Developer Guide
Pricing
(PCI) Data Security Standard (DSS). For more information about PCI DSS, including how to request a
copy of the AWS PCI Compliance Package, see PCI DSS Level 1.
Pricing
With Amazon Web Services, you pay only for what you use. For Elastic Load Balancing, you pay for each
hour or portion of an hour that the service is running, and you pay for each gigabyte of data that is
transferred through your load balancer. For current pricing information, see Elastic Load Balancing Pricing.
If your AWS account is less than 12 months old, you are eligible to use the free tier. The free tier includes
750 hours per month of Amazon EC2 usage, and 750 hours per month of Elastic Load Balancing, plus
15 GB of data processing. For more information, see AWS Free Tier.
Related Services
Elastic Load Balancing works with the following services to improve the availability and scalability of your
applications.
• Amazon EC2 — Virtual servers that run your applications in the cloud. For more information, see the
Amazon EC2 User Guide for Linux Instances or the Amazon EC2 User Guide for Microsoft Windows
Instances.
• Auto Scaling — Ensures that you are running your desired number of instances, even if an instance
fails, and enables you to automatically increase or decrease the number of instances as the demand
on your instances changes. If you enable Auto Scaling with Elastic Load Balancing, instances that are
launched by Auto Scaling are automatically registered with the load balancer, and instances that are
terminated by Auto Scaling are automatically de-registered from the load balancer. For more information,
see Load Balance Your Auto Scaling Group in the Auto Scaling Developer Guide.
• Amazon CloudWatch — Enables you to monitor the health state of your instances and take action as
needed. For more information, see the Amazon CloudWatch Developer Guide.
• Amazon Route 53 — Provides a reliable and cost-effective way to route visitors to websites by
translating domain names (such as www.example.com) into the numeric IP addresses (such as
192.0.2.1) that computers use to connect to each other. AWS assigns URLs to your AWS resources,
such as your load balancers. However, you might want a URL that is easy for your users to remember.
For example, you can map your domain name to your load balancer. If you don't have a domain name,
you can search for available domains and register them using Amazon Route 53. If you have an existing
domain name, you can transfer it to Amazon Route 53. For more information, see the Amazon Route 53
Developer Guide.
How Elastic Load Balancing Works
A load balancer accepts incoming traffic from clients and routes requests to its registered EC2 instances
in one or more Availability Zones. The load balancer also monitors the health of its registered instances
and ensures that it routes traffic only to healthy instances. When the load balancer detects an unhealthy
instance, it stops routing traffic to that instance, and then resumes routing traffic to that instance when it
detects that the instance is healthy again.
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Request Routing
You configure your load balancer to accept incoming traffic by specifying one or more listeners. A listener
is a process that checks for connection requests. It is configured with a protocol and port number for
connections from clients to the load balancer and a protocol and port number for connections from the
load balancer to the instances.
When you attach an Availability Zone to your load balancer, Elastic Load Balancing creates a load balancer
node in the Availability Zone that forwards traffic to the healthy registered instances in that Availability
Zone. We recommend that you configure your load balancer across multiple Availability Zones. If one
Availability Zone becomes unavailable or has no healthy instances, the load balancer can route traffic to
the healthy registered instances in another Availability Zone.
Request Routing
Before a client sends a request to your load balancer, it resolves the load balancer's domain name using
a Domain Name System (DNS) server. The DNS entry is controlled by Amazon, because your instances
are in the amazonaws.com domain. The Amazon DNS servers return one or more IP addresses to the
client. These are the IP addresses of the load balancer nodes for your load balancer. As traffic to your
application changes over time, Elastic Load Balancing scales your load balancer and updates the DNS
entry. Note that the DNS entry also specifies the time-to-live (TTL) as 60 seconds, which ensures that
the IP addresses can be remapped quickly in response to changing traffic.
The client uses DNS round robin to determine which IP address to use to send the request to the load
balancer. The load balancer node that receives the request uses a routing algorithm to select a healthy
instance. It uses the round robin routing algorithm for TCP listeners, and the least outstanding requests
routing algorithm (favors the instances with the fewest outstanding requests) for HTTP and HTTPS
listeners.
The cross-zone load balancing setting also determines how the load balancer selects an instance. If
cross-zone load balancing is disabled, the load balancer node selects the instance from the same
Availability Zone that it is in. If cross-zone load balancing is enabled, the load balancer node selects the
instance regardless of Availability Zone. The load balancer node routes the client request to the selected
instance.
Availability Zones and Instances
To ensure that your back-end instances are able to handle the request load in each Availability Zone, it
is important to keep approximately the same number of instances in each Availability Zone registered
with the load balancer. For example, if you have ten instances in Availability Zone us-west-2a and two
instances in us-west-2b, the requests are distributed evenly between the two Availability Zones. As a
result, the two instances in us-west-2b serve the same amount of traffic as the ten instances in us-west-2a.
Instead, you should have six instances in each Availability Zone.
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Related Topics
To distribute traffic evenly across all back-end instances, regardless of the Availability Zone, enable
cross-zone load balancing on your load balancer. However, we still recommend that you maintain
approximately equivalent numbers of instances in each Availability Zone for better fault tolerance.
Related Topics
For more information about Elastic Load Balancing, see the following documentation:
• Internet-Facing Load Balancers (p. 15)
• Internal Load Balancers (p. 17)
• Listeners for Your Load Balancer (p. 76)
• Configure Health Checks (p. 59)
• Configure Your Load Balancer (p. 82)
• Monitor Your Load Balancer (p. 101)
• Troubleshoot Your Load Balancer (p. 125)
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Elastic Load Balancing Developer Guide
Sign Up
Setting Up Elastic Load Balancing
Complete the following tasks to get ready to use Elastic Load Balancing.
Tasks
• Sign Up for Amazon Web Services (AWS) (p. 6)
• Prepare Your VPC and Back-end Instances (p. 6)
• Access Elastic Load Balancing Using the AWS Management Console (p. 7)
• Access Elastic Load Balancing Using the AWS CLI (p. 8)
Sign Up for Amazon Web Services (AWS)
When you sign up for AWS, we automatically sign up your AWS account for all services, including Elastic
Load Balancing. You pay only for the services that you use.
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 sign up for an AWS account
1.
2.
Open http://aws.amazon.com/, and then choose Create an AWS Account.
Follow the online instructions.
Part of the sign-up procedure involves receiving a phone call and entering a PIN using the phone
keypad.
Prepare Your VPC and Back-end Instances
If you haven't used Amazon EC2 before, complete the tasks described in the Amazon EC2 documentation.
For more information, see Setting Up with Amazon EC2 in the Amazon EC2 User Guide for Linux Instances
or Setting Up with Amazon EC2 in the Amazon EC2 User Guide for Microsoft Windows Instances,
depending on which operating system you plan to use for your EC2 instances.
Load Balancers in a VPC
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Access Elastic Load Balancing Using the AWS
Management Console
Amazon Virtual Private Cloud (Amazon VPC) enables you to define a virtual networking environment in
a private, isolated section of the AWS cloud. Within this virtual private cloud (VPC), you can launch AWS
resources such as load balancers and EC2 instances. For more information, see the Amazon VPC User
Guide.
We recommend that you launch your instances and create your load balancer in a VPC. If you have a
new AWS account or plan to use a region that you haven't used before, you have a default VPC. You
can use a default VPC if you have one, or create your own VPC.
Subnets for Your Load Balancer
To ensure that your load balancer can scale properly, verify that each subnet for your load balancer has
a CIDR block with at least a /27 bitmask (for example, 10.0.0.0/27) and has at least 8 free IP addresses.
Your load balancer uses these IP addresses to establish connections with the back-end instances.
Create a subnet in each Availability Zone where you want to launch instances. Depending on your
application, you can launch your instances in public subnets, private subnets, or a combination of public
and private subnets. A public subnet has a route to an Internet gateway. Note that default VPCs have
one public subnet per Availability Zone by default.
When you create a load balancer, you must attach one or more public subnets to the load balancer. If
your instances are in private subnets, create public subnets in the same Availability Zones as the subnets
with your instances; you will attach these public subnets to the load balancer.
Security Groups
You must ensure that the load balancer can communicate with your back-end instances on both the
listener port and the health check port. For more information, see Security Groups for Load Balancers in
a VPC (p. 62). The security group for your instances must allow traffic in both directions on both ports
for each subnet attached to your load balancer. For more information, see Security Groups for Back-end
Instances in a VPC (p. 64).
Network ACLs
The network ACLs for your VPC must allow traffic in both directions on the listener port and the health
check port. For more information, see Network ACLs for Load Balancers in a VPC (p. 64).
ClassicLink
ClassicLink enables your EC2-Classic instances to communicate with VPC instances using private IP
addresses, provided that the VPC security groups allow it. If you plan to register linked EC2-Classic
instances with your load balancer, you must enable ClassicLink for your VPC, and then create your load
balancer in the ClassicLink-enabled VPC. For more information, see ClassicLink Basics and Working
with ClassicLink in the Amazon EC2 User Guide for Linux Instances.
Access Elastic Load Balancing Using the AWS
Management Console
The AWS Management Console is a point-and-click web-based interface you can use to access Elastic
Load Balancing and other AWS products. You can access Elastic Load Balancing resources using the
Amazon EC2 console.
To access Elastic Load Balancing using the Amazon EC2 console
1.
Sign in to the AWS Management Console and open the Amazon EC2 console at https://
console.aws.amazon.com/ec2/.
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Access Elastic Load Balancing Using the AWS CLI
2.
From the navigation bar, select a region. Each load balancer is tied to the region in which you create
it. You can select any region that's available to you, regardless of your location.
3.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
To learn how to create a load balancer using the AWS Management Console, see Getting Started with
Elastic Load Balancing (p. 9).
Access Elastic Load Balancing Using the AWS
CLI
The AWS CLI provides commands for a broad set of AWS products, including Elastic Load Balancing,
and is supported on Windows, Mac, and Linux.
To get started using the AWS CLI, see the AWS Command Line Interface User Guide. For details about
the commands for Elastic Load Balancing, see AWS CLI elb.
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Elastic Load Balancing Developer Guide
Before You Begin
Getting Started with Elastic Load
Balancing
This tutorial provides a hands-on introduction to using Elastic Load Balancing through the AWS
Management Console, a point-and-click web-based interface. You'll create a load balancer that receives
public HTTP traffic and sends it to your EC2 instances.
Note that you can create your load balancer for use with EC2-Classic or a VPC. Some of the tasks
described in this tutorial apply only to load balancers in a VPC.
Tasks
• Before You Begin (p. 9)
• Step 1: Define Your Load Balancer (p. 10)
• Step 2: Assign Security Groups to Your Load Balancer in a VPC (p. 11)
• Step 3: Configure Security Settings (Optional) (p. 11)
• Step 4: Configure Health Checks for Your EC2 Instances (p. 12)
• Step 5: Register EC2 Instances with Your Load Balancer (p. 12)
• Step 6: Tag Your Load Balancer (Optional) (p. 13)
• Step 7: Create and Verify Your Load Balancer (p. 13)
• Step 8: Delete Your Load Balancer (Optional) (p. 13)
Before You Begin
• Complete the steps in Setting Up Elastic Load Balancing (p. 6).
• Launch the EC2 instances that you plan to register with your load balancer in the Availability Zones
that you plan to use for your load balancer. Ensure that the security groups for these instances allow
HTTP access on port 80.
• Install a web server, such as Apache or Internet Information Services (IIS), on the EC2 instances that
you plan to register with your load balancer.
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Step 1: Define Your Load Balancer
Step 1: Define Your Load Balancer
First, provide some basic configuration information for your load balancer, such as a name, a network,
and a listener.
A listener is a process that checks for connection requests. It is configured with a protocol and a port for
front-end (client to load balancer) connections, and a protocol and a port for back-end (load balancer to
back-end instance) connections. In this tutorial, you configure a listener that accepts HTTP requests on
port 80 and sends them to the back-end instances on port 80 using HTTP.
To define your load balancer
1.
2.
3.
4.
5.
6.
7.
8.
9.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
From the navigation bar, select a region for your load balancers. Be sure to select the same region
that you selected for your EC2 instances.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
Click Create Load Balancer.
In Load Balancer name, enter a name for your load balancer.
The name of your load balancer must be unique within your set of load balancers for the region, can
have a maximum of 32 characters, and can contain only alphanumeric characters and hyphens.
From Create LB inside, select the same network that you selected for your instances: EC2-Classic
or a specific VPC.
[Default VPC] If you selected a default VPC and would like to choose the subnets for your load
balancer, select Enable advanced VPC configuration.
Leave the default listener configuration.
[EC2-VPC] Under Select Subnets, select at least one available public subnet. To improve the
availability of your load balancer, select more than one public subnet.
Note
If you selected EC2-Classic as your network, or you have a default VPC but did not select
Enable advanced VPC configuration, you do not see Select Subnets.
The available subnets for the VPC for your load balancer are displayed under Available Subnets.
Select public subnets that are in the same Availability Zones as your instances. Click the icon in the
Action column for each subnet to attach. These subnets are moved under Selected Subnets. You
can select at most one subnet per Availability Zone. If you select a subnet from an Availability Zone
where there is already a selected subnet, this subnet replaces the currently selected subnet for the
Availability Zone.
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Step 2: Assign Security Groups to Your Load Balancer
in a VPC
10. Click Next: Assign Security Groups.
Step 2: Assign Security Groups to Your Load
Balancer in a VPC
If you selected a VPC as your network, you must assign your load balancer a security group that allows
inbound traffic to the ports that you specified for your load balancer and the health checks for your load
balancer.
Note
If you selected EC2-Classic as your network, you can continue to the next step. By default,
Elastic Load Balancing provides a security group for load balancers in EC2-Classic.
To assign security group to your load balancer
1.
2.
On the Assign Security Groups page, select Create a new security group.
Enter a name and description for your security group, or leave the default name and description.
This new security group contains a rule that allows traffic to the port that you configured your load
balancer to use.
3.
Click Next: Configure Security Settings.
Step 3: Configure Security Settings (Optional)
For this tutorial, you can click Next: Configure Health Check to continue to the next step. For more
information about creating a HTTPS load balancer and using additional security features, see HTTPS
Load Balancers (p. 22).
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Step 4: Configure Health Checks for Your EC2 Instances
Step 4: Configure Health Checks for Your EC2
Instances
Elastic Load Balancing automatically checks the health of the EC2 instances for your load balancer. If
Elastic Load Balancing finds an unhealthy instance, it stops sending traffic to the instance and reroutes
traffic to healthy instances. In this step, you customize the health checks for your load balancer.
To configure health checks for your instances
1.
2.
On the Configure Health Check page, do the following:
a.
Leave Ping Protocol set to its default value, HTTP.
b.
Leave Ping Port set to its default value, 80.
c.
In the Ping Path field, replace the default value with a single forward slash ("/"). This tells Elastic
Load Balancing to send health check queries to the default home page for your web server,
such as index.html or default.html.
d.
Leave the other fields set to their default values.
Click Next: Add EC2 Instances.
Step 5: Register EC2 Instances with Your Load
Balancer
Your load balancer distributes traffic between the instances that are registered to it.
Note
When you register an instance with an elastic network interface (ENI) attached, the load balancer
routes traffic to the primary IP address of the primary interface (eth0) of the instance.
To register EC2 instances with your load balancer
1.
2.
On the Add EC2 Instances page, select the instances to register with your load balancer.
Click Next: Add Tags.
Alternatively, you can register instances with your load balancer later on using the following options:
• Select running instances after you create the load balancer. For more information, see Register Instances
with Your Load Balancer (p. 73).
• Set up Auto Scaling to register the instances automatically when it launches them. For more information,
see Set Up a Scaled and Load-Balanced Application in the Auto Scaling Developer Guide.
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Step 6: Tag Your Load Balancer (Optional)
Step 6: Tag Your Load Balancer (Optional)
You can tag your load balancer, or continue to the next step. Note that you can tag your load balancer
later on; for more information, see Tag Your Load Balancer (p. 96).
To add tags to your load balancer
1.
On the Add Tags page, specify a key and a value for the tag.
2.
3.
To add another tag, click Create Tag and specify a key and a value for the tag.
After you are finished adding tags, click Review and Create.
Step 7: Create and Verify Your Load Balancer
Before you create the load balancer, review the settings that you selected. After creating the load balancer,
you can verify that it's sending traffic to your EC2 instances.
To finish creating your load balancer
1.
2.
3.
4.
5.
6.
On the Review page, check your settings. If you need to make changes, click the corresponding link
to edit the settings.
Click Create to create your load balancer.
After you are notified that your load balancer was created, click Close.
Select your new load balancer.
In the bottom pane, on the Description tab, check the Status row. If it indicates that some of your
instances are not in service, its probably because they are still in the registration process. For more
information, see Troubleshooting Elastic Load Balancing: Instance Registration (p. 133).
(Optional) After you've verified that at least one of your EC2 instances is InService, you can test
your load balancer. Copy the string from the DNS Name field and paste it into the address field of
an Internet-connected web browser. (For example,
my-load-balancer-1234567890.us-west-2.elb.amazonaws.com.) If your load balancer is
working, you see the default page of your HTTP server.
Step 8: Delete Your Load Balancer (Optional)
As soon as your load balancer becomes available, you are billed for each hour or partial hour that you
keep it running. When you no longer need a load balancer, you can delete it. As soon as the load balancer
is deleted, you stop incurring charges for it. Note that deleting a load balancer does not affect the instances
registered with the load balancer.
To delete your load balancer
1.
2.
3.
If you have a CNAME record for your domain that points to your load balancer, point it to a new
location and wait for the DNS change to take effect before deleting your load balancer.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
4.
5.
Select the load balancer.
Click Actions, and then click Delete.
6.
7.
When prompted for confirmation, click Yes, Delete.
(Optional) After you delete a load balancer, the EC2 instances associated with the load balancer
continue to run, and you are billed for each hour or partial hour that you keep them running. For
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Step 8: Delete Your Load Balancer (Optional)
information about stopping or terminating your instances, see Stop and Start Your Instance or
Terminate Your Instance in the Amazon EC2 User Guide for Linux Instances.
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Public DNS Names for Your Load Balancer
Internet-Facing Load Balancers
An Internet-facing load balancer takes requests from clients over the Internet and distributes them across
the EC2 instances that are registered with the load balancer.
If a load balancer is in a VPC with ClassicLink enabled, its instances can be linked EC2-Classic instances.
If a load balancer is in EC2-Classic, its instances must be in EC2-Classic.
Contents
• Public DNS Names for Your Load Balancer (p. 15)
• Create an Internet-Facing Load Balancer (p. 16)
Public DNS Names for Your Load Balancer
When your load balancer is created, it receives a public DNS name that clients can use to send requests.
The DNS servers resolve the DNS name of your load balancer to the public IP addresses of the load
balancer nodes for your load balancer. Each load balancer node is connected to the back-end instances.
EC2-VPC
Load balancers in a VPC support IPv4 addresses only. The console displays a public DNS name with
the following form:
name-1234567890.region.elb.amazonaws.com
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Create an Internet-Facing Load Balancer
EC2-Classic
Load balancers in EC2-Classic support both IPv4 and IPv6 addresses. The console displays the following
public DNS names:
name-123456789.region.elb.amazonaws.com
ipv6.name-123456789.region.elb.amazonaws.com
dualstack.name-123456789.region.elb.amazonaws.com
The base public DNS name returns only IPv4 records. The public DNS name with the ipv6 prefix returns
only IPv6 records. The public DNS name with the dualstack prefix returns both IPv4 and IPv6 records.
We recommend that you enable IPv6 support by using the DNS name with the dualstack prefix to
ensure that clients can access the load balancer using either IPv4 or IPv6.
Clients can connect to your load balancer in EC2-Classic using either IPv4 or IPv6. However,
communication between the load balancer and its back-end instances uses only IPv4, regardless of how
the client communicates with your load balancer.
Create an Internet-Facing Load Balancer
When you create a load balancer in a VPC, you can make it an internal load balancer or an Internet-facing
load balancer. You create an Internet-facing load balancer in a public subnet. Load balancers in
EC2-Classic are always Internet-facing load balancers.
When you create your load balancer, you configure listeners, configure health checks, and register
back-end instances. You configure a listener by specifying a protocol and a port for front-end (client to
load balancer) connections, and a protocol and a port for back-end (load balancer to back-end instances)
connections. You can configure multiple listeners for your load balancer.
To create a basic Internet-facing load balancer, see Getting Started with Elastic Load Balancing (p. 9).
To create an HTTPS load balancer, see Create an HTTPS Load Balancer (p. 34).
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Internal Load Balancers
When you create a load balancer in a VPC, you can make it an internal load balancer or an Internet-facing
load balancer.
An Internet-facing load balancer routes traffic from clients over the Internet to your EC2 instances. For
more information, see Internet-Facing Load Balancers (p. 15).
An internal load balancer routes traffic to your EC2 instances in private subnets using private IP addresses.
If your application has multiple tiers, for example web servers that must be connected to the Internet and
database servers that are only connected to the web servers, you can design an architecture that uses
both internal and Internet-facing load balancers. Create an Internet-facing load balancer and register the
web servers with it. Create an internal load balancer and register the database servers with it. The web
servers receive requests from the Internet-facing load balancer and send requests for the database
servers to the internal load balancer. The database servers receive requests from the internal load
balancer.
Contents
• Public DNS Name for Your Load Balancer (p. 18)
• Create an Internal Load Balancer (p. 18)
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Elastic Load Balancing Developer Guide
Public DNS Name for Your Load Balancer
Public DNS Name for Your Load Balancer
When an internal load balancer is created, it receives a public DNS name with the following form:
internal-name-123456789.region.elb.amazonaws.com
The DNS servers resolve the DNS name of your load balancer to the private IP addresses of the load
balancer nodes for your internal load balancer. Each load balancer node is connected to the private IP
addresses of the back-end instances that are in its Availability Zone using elastic network interfaces.
Create an Internal Load Balancer
You can create an internal load balancer to distribute traffic to your EC2 instances in private subnets.
Contents
• Prerequisites (p. 18)
• Create an Internal Load Balancer Using the Console (p. 18)
• Create an Internal Load Balancer Using the AWS CLI (p. 19)
Prerequisites
• If you have not yet created a VPC for your load balancer, you must create it before you get started.
For more information, see Prepare Your VPC and Back-end Instances (p. 6).
• Launch the EC2 instances that you plan to register with your internal load balancer. Ensure that you
launch them in private subnets in the VPC intended for the load balancer.
Create an Internal Load Balancer Using the
Console
By default, Elastic Load Balancing creates an Internet-facing load balancer. Use the following procedure
to create an internal load balancer and register your EC2 instances with the newly created internal load
balancer.
To create an internal load balancer
1.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
2.
3.
4.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
Click Create Load Balancer.
On the Define Load Balancer page, do the following:
a.
In Load Balancer name, enter a name for your load balancer.
b.
The name of your load balancer must be unique within your set of load balancers for the region,
can have a maximum of 32 characters, and can contain only alphanumeric characters and
hyphens.
From Create LB inside, select a VPC for your load balancer.
c.
Click Create an internal load balancer.
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Create an Internal Load Balancer Using the AWS CLI
d.
e.
f.
[Default VPC] If you selected a default VPC and would like to choose the subnets for your load
balancer, select Enable advanced VPC configuration.
Leave the default listener configuration.
Under Select Subnets, select private subnets that are in the same Availability Zone as your
instances. Note that selecting multiple subnets improves the availability of your load balancer.
Note
If you select a default VPC as your network, but did not select Enable advanced VPC
configuration, you do not see Select Subnets.
The available subnets for the VPC for your load balancer are displayed under Available Subnets.
Select private subnets that are in the same Availability Zones as your instances. Click the icon
in the Action column for each subnet to attach. These subnets are moved under Selected
Subnets. You can select at most one subnet per Availability Zone. If you select a subnet from
an Availability Zone where there is already a selected subnet, this subnet replaces the currently
selected subnet for the Availability Zone.
g.
5.
6.
7.
8.
Click Next: Assign Security Groups.
On the Assign Security Groups page, click Create a new security group. Enter a name and
description for your security group, or leave the default name and description. This new security
group contains a rule that allows traffic to the port that you configured your load balancer to use. If
you specified a different port for the health checks, you must click Add Rule to add a rule that allows
inbound traffic to that port as well. Click Next: Configure Security Settings.
On the Configure Security Settings page, click Next: Configure Health Check to continue to the
next step. If you prefer to create a HTTPS load balancer, see HTTPS Load Balancers (p. 22).
On the Configure Health Check page, configure the health check settings that your application
requires, and then click Next: Add EC2 Instances.
On the Add EC2 Instances page, select the instances to register with your load balancer, and then
click Next: Add Tags.
Note
When you register an instance with an elastic network interface (ENI) attached, the load
balancer routes traffic to the primary IP address of the primary interface (eth0) of the instance.
9.
(Optional) You can add tags to your load balancer. When you are finished adding tags, click Review
and Create.
10. On the Review page, check your settings. If you need to make changes, click the corresponding link
to edit the settings. When you are finished, click Create to create your load balancer.
11. After you are notified that your load balancer was created, click Close.
12. Select your new load balancer.
13. In the bottom pane, on the Description tab, note that DNS Name and Scheme indicate that the load
balancer is internal.
Check the Status row. If it indicates that some of your instances are not in service, its probably
because they are still in the registration process. For more information, see Troubleshooting Elastic
Load Balancing: Instance Registration (p. 133).
Create an Internal Load Balancer Using the AWS
CLI
By default, Elastic Load Balancing creates an Internet-facing load balancer. Use the following procedure
to create an internal load balancer and register your EC2 instances with the newly created internal load
balancer.
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Create an Internal Load Balancer Using the AWS CLI
To create an internal load balancer
1.
Use the create-load-balancer command with the --scheme option set to internal, as follows:
aws elb create-load-balancer --load-balancer-name my-internal-loadbalancer
--listeners Protocol=HTTP,LoadBalancerPort=80,InstanceProtocol=HTTP,Instan
cePort=80
--subnets subnet-4e05f721 --scheme internal --security-groups sg-b9ffedd5
The following is an example response. Note that the name indicates that this is an internal load
balancer.
{
"DNSName": "internal-my-internal-loadbalancer-786501203.us-west2.elb.amazonaws.com"
}
2.
Use the following register-instances-with-load-balancer command to add instances:
aws elb register-instances-with-load-balancer --load-balancer-name my-intern
al-loadbalancer --instances i-4f8cf126 i-0bb7ca62
The following is an example response:
{
"Instances": [
{
"InstanceId": "i-4f8cf126"
},
{
"InstanceId": "i-0bb7ca62"
}
]
}
3.
(Optional) Use the following describe-load-balancers command to verify the internal load balancer:
aws elb describe-load-balancers --load-balancer-name my-internal-loadbalancer
The response includes the DNSName and Scheme fields, which indicate that this is an internal load
balancer.
{
"LoadBalancerDescriptions": [
{
...
"DNSName": "internal-my-internal-loadbalancer-1234567890.uswest-2.elb.amazonaws.com",
"SecurityGroups": [
"sg-b9ffedd5"
],
"Policies": {
"LBCookieStickinessPolicies": [],
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Create an Internal Load Balancer Using the AWS CLI
"AppCookieStickinessPolicies": [],
"OtherPolicies": []
},
"LoadBalancerName": "my-internal-loadbalancer",
"CreatedTime": "2014-05-22T20:32:19.920Z",
"AvailabilityZones": [
"us-west-2a"
],
"Scheme": "internal",
...
}
]
}
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SSL Certificates
HTTPS Load Balancers
You can create a load balancer that uses the SSL/TLS protocol for encrypted connections (also known
as SSL offload). This feature enables traffic encryption between your load balancer and the clients that
initiate HTTPS sessions, and for connections between your load balancer and your back-end instances.
Elastic Load Balancing provides Secure Sockets Layer (SSL) negotiation configurations, known as security
policy, to negotiate connections between the clients and the load balancer. When you use HTTPS/SSL
for your front-end connection, you can use either a predefined security policy or a custom security policy.
You must deploy an SSL certificate on your load balancer. The load balancer uses this certificate to
terminate the connection and then decrypt requests from clients before sending them to the back-end
instances. You can optionally choose to enable authentication on your back-end instances.
Elastic Load Balancing does not support Server Name Indication (SNI) on your load balancer. You can
use one of the following alternatives instead:
• Deploy one certificate on the load balancer, and add a Subject Alternative Name (SAN) for each
additional website. SANs enable you to protect multiple host names using a single certificate. Check
with your certificate provider for more information about the number of SANs they support per certificate
and how to add and remove SANs.
• Use TCP listeners on port 443 for the front-end and back-end connections. The load balancer passes
the request through, with the SNI certificate as is. You can handle the HTTPS termination from the
EC2 instance.
Contents
• SSL Certificates for Elastic Load Balancing (p. 22)
• SSL Negotiation Configurations for Elastic Load Balancing (p. 28)
• Create an HTTPS Load Balancer (p. 34)
• Configure an HTTPS Listener for Your Load Balancer (p. 48)
• Replace the SSL Certificate for Your Load Balancer (p. 51)
• Update the SSL Negotiation Configuration of Your Load Balancer (p. 53)
SSL Certificates for Elastic Load Balancing
If you use HTTPS or SSL for your front-end listener, you must deploy an SSL/TLS certificate on your load
balancer. The load balancer uses the certificate to terminate the connection and then decrypt requests
from clients before sending them to the back-end instances.
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Creating an SSL Certificate Using AWS Certificate
Manager
The SSL protocol uses an X.509 certificate (SSL server certificate) to authenticate both the client and
the back-end application. An X.509 certificate is a digital form of identification issued by a certificate
authority (CA) and contains identification information, a validity period, a public key, a serial number, and
the digital signature of the issuer.
You can create a certificate using AWS Certificate Manager or a tool that supports the SSL and TLS
protocols, such as OpenSSL.You will specify this certificate when you create or update an HTTPS listener
for your load balancer.
Contents
• Creating an SSL Certificate Using AWS Certificate Manager (p. 23)
• Creating an SSL Certificate Using SSL/TLS Tools (p. 23)
Creating an SSL Certificate Using AWS Certificate
Manager
You can use AWS Certificate Manager (ACM) to request and manage certificates. ACM integrates with
Elastic Load Balancing so that you can deploy the certificate on your load balancer. To deploy a certificate
on your load balancer, the certificate must be in the same region as the load balancer.
To allow an IAM user to deploy the certificate on your load balancer using the AWS Management Console,
you must grant access to the ListCertificates API action. For more information, see Listing Certificates
in the AWS Certificate Manager User Guide.
For more information, see Request a Certificate in the AWS Certificate Manager User Guide.
Creating an SSL Certificate Using SSL/TLS Tools
Before you can deploy a certificate on your load balancer, you must create the certificate, get the certificate
signed by a CA, and then upload the certificate using the AWS Identity and Access Management (IAM)
service, which manages SSL certificates that are not created using AWS Certificate Manager. By default,
IAM allows 20 certificates per AWS account. For more information about this limit and how to request an
increase, see Limitations on IAM Entities in IAM User Guide.
Contents
• Prerequisite: Install Certificate Tools (p. 23)
• Step 1: Create a Server Certificate (p. 24)
• Step 2: Upload the Certificate (p. 25)
• Step 3: Verify the Server Certificate (p. 28)
Prerequisite: Install Certificate Tools
Creating a server certificate requires a tool that supports the SSL and TLS protocols.
Linux
OpenSSL is an open-source tool that provides extensive cryptographic functions. To check whether this
tool is already installed, run openssl version. If OpenSSL is not installed, you must install it. For more
information, see the documentation for your Linux distribution.
Windows
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Elastic Load Balancing Developer Guide
Creating an SSL Certificate Using SSL/TLS Tools
There are several tools that you can use, such as IIS Manager, SelfSSL, OpenSSL, Windows PowerShell
cmdlets. If you don't have one of these tools already, select a tool and install it.
Step 1: Create a Server Certificate
To create an SSL server certificate, you must generate an RSA private key and create a Certificate Signing
Request (CSR). Next, either have your certificate signed by a Certificate Authority (CA), or generate a
self-signed certificate so that you can test your SSL implementation while waiting for the CA to sign your
certificate. Follow the directions for the tool that you are using. In this example, we provide directions for
OpenSSL, and pointers to directions for IIS Manager.
To create a server certificate using OpenSSL
1.
Create a private key and save it in a secure place, as there is no way to get your private key if you
lose it.
Private keys are created using standard key algorithms. Choose the algorithm based on the ciphers
that you plan to use when negotiating SSL connections from the client to your load balancer.
RSA-based Ciphers
Use the following genrsa command. Note that AWS supports RSA keys that are 1024, 2048, and
4096 bits. However, we recommend that you specify 2048 bits.
openssl genrsa -out my-private-key.pem 2048
ECDHE-ECDSA-based Ciphers
Use the following ecparam command:
openssl ecparam -name prime256v1 -out my-private-key.pem -genkey
2.
Create a CSR using the following req command:
openssl req -sha256 -new -key my-private-key.pem -out csr.pem
The command runs interactively, prompting you to enter the following information:
Country Name
The two-letter ISO code for your country. For example, US.
State or Province Name
The full name of the state or province where your organization is located. Do not use an
abbreviation.
Locality Name
The name of the city where your organization is located.
Organization Name
The full legal name of your organization.
Organizational Unit Name
(Optional) Additional information, such as a product name or division.
Common Name
The fully-qualified domain name for your CNAME. This name must be an exact match. For
example, www.mycompany.com, mycompany.com, or *.mycompany.com.
Email Address
The server administrator's email address.
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Elastic Load Balancing Developer Guide
Creating an SSL Certificate Using SSL/TLS Tools
3.
You can either apply to have your certificate signed by a CA, or generate a self-signed certificate to
use for testing purposes.
• To apply for a server certificate, send your CSR to an CA. Your CSR contains information that
identifies you. The CA might require other credentials or proof of identity. Upon success, the CA
returns a public (identity) certificate and possibly a chain certificate that is digitally signed. AWS
does not recommend a specific CA. For a partial listing of available CAs, see Third-Party Certificate
Authorities.
• To create a self-signed certificate, use the following command:
openssl x509 -req -days 365 -in csr.pem -signkey my-private-key.pem -out
my-certificate.pem
To create a server certificate using IIS Manager
For information about using IIS Manager to create a certificate, see Request an Internet Server Certificate
or Create a Self-Signed Server Certificate in the Microsoft TechNet Library.
Step 2: Upload the Certificate
Typically the certificate authority (CA) sends you a public certificate, one or more intermediate certificates,
and a root certificate. The intermediate certificates and the root certificate can come bundled in a file or
as separate files. The file names may vary depending on the type of SSL certificate you purchase and
the certificate authority. Your public certificate is the domain-specific file.
Prerequisites
• The private key must be created using the algorithm based on the ciphers you plan to use for negotiating
SSL connections and must be in PEM format.
RSA-based Ciphers
Use the following command to convert a private key generated for RSA based ciphers:
openssl rsa -in my-private-key -outform PEM
ECDHE-ECDSA-based Ciphers
Use the following command to convert a private key generated for ECDHE-ECDSA based ciphers:
openssl ec -in my-private-key -outform PEM
• The private key cannot be encrypted with a password.
• When you receive your server certificate from the CA, the files might not be in the PEM format that is
required by IAM. For more information about the PEM format, see pem DESCRIPTION.
• Use the following command to convert the server certificate you received from the CA:
openssl x509 -inform PEM -in my-certificate
• Use the following command to convert your certificate chain:
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Elastic Load Balancing Developer Guide
Creating an SSL Certificate Using SSL/TLS Tools
openssl x509 -inform PEM -in my-certificate-chain
• The current date must be between the certificate's start and end dates.
• The public and private certificate files must contain a single certificate.
• The private key must match the public key in the certificate.
• The certificate chain must include all of your CA's intermediary certificates that lead to the root certificate,
and can optionally end with your CA's root certificate. Typically, both intermediate and root certificates
are provided by the CA in a bundled file with the proper chained order. The order of intermediate
certificates should be documented by the CA. Although the root certificate is optional, you can include
it so that you can run a full chain of trust verification, such as SSL Checker.
If a certificate bundle is not available or not available in the required order, you can create your own
certificate chain file using the intermediary certificates, as shown in Example RSA Private Key (p. 27).
Uploading the Server Certificate
After you have your certificate files in PEM format, use the following upload-server-certificate command
to upload them:
aws iam upload-server-certificate --server-certificate-name my-server-cert
--certificate-body file://my-certificate.pem --private-key file://my-privatekey.pem
--certificate-chain file://my-certificate-chain.pem
Note that if you are uploading a self-signed certificate, you do not need to specify a certificate chain.
When you upload your certificates, IAM validates them. If you get an error, ensure that your files meet
the prerequisites and then try uploading them again.
The following are examples of the server certificates, private keys, and certificate chains accepted by
IAM.
Example Server Certificate
The server certificate associates your public key with your identity. When you submit your CSR to a
certificate authority (CA), the CA returns a server certificate.
-----BEGIN CERTIFICATE----MIIE+TCCA+GgAwIBAgIQU306HIX4KsioTW1s2A2krTANBgkqhkiG9w0BAQUFADCB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Elastic Load Balancing Developer Guide
Creating an SSL Certificate Using SSL/TLS Tools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-----END CERTIFICATE-----
Example RSA Private Key
The private key enables you to decrypt messages that are encrypted with your public key.
-----BEGIN RSA PRIVATE KEY----MIICiTCCAfICCQD6m7oRw0uXOjANBgkqhkiG9w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-----END RSA PRIVATE KEY-----
Example Certificate Chain
The certificate chain enables a browser to build a certificate chain to a root certificate that it trusts. As a
result, the browser can implicitly trust your certificate.
The certificate chain includes the intermediate certificates and optionally the root certificate, one after the
other without any blank lines, as shown in the following example. If you include the root certificate, your
certificate chain must start with intermediate certificates and end with the root certificate. Use the
intermediate certificates that were provided by your CA. Do not include any intermediaries that are not
in the chain of trust path.
-----BEGIN CERTIFICATE----Intermediate certificate 2
-----END CERTIFICATE---------BEGIN CERTIFICATE----Intermediate certificate 1
-----END CERTIFICATE---------BEGIN CERTIFICATE----Optional: Root certificate
-----END CERTIFICATE-----
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Elastic Load Balancing Developer Guide
SSL Negotiation Configurations
Step 3: Verify the Server Certificate
After the server certificate is uploaded, you can verify that the information is stored in IAM. Each certificate
object has a unique Amazon Resource Name (ARN) and ID.
Use the following get-server-certificate command to verify the certificate object:
aws iam get-server-certificate --server-certificate-name my-server-certificate
The following is an example response. The first line is the ARN of the server certificate and the second
line is the ID.
arn:aws:iam::123456789012:server-certificate/my-server-certificate
ASCACexampleKEZUQ4K
SSL Negotiation Configurations for Elastic Load
Balancing
Elastic Load Balancing uses an Secure Socket Layer (SSL) negotiation configuration, known as a security
policy, to negotiate SSL connections between a client and the load balancer. A security policy is a
combination of SSL protocols, SSL ciphers, and the Server Order Preference option. For more information
about configuring an SSL connection for your load balancer, see Listeners for Your Load Balancer (p. 76).
Contents
• SSL Protocols (p. 28)
• SSL Ciphers (p. 29)
• Server Order Preference (p. 29)
• SSL Security Policies for Elastic Load Balancing (p. 29)
• Predefined SSL Security Policies for Elastic Load Balancing (p. 30)
SSL Protocols
Secure Sockets Layer (SSL) and Transport Layer Security (TLS) are cryptographic protocols that are
used to encrypt confidential data over insecure networks such as the Internet. The TLS protocol is a
newer version of the SSL protocol. In the Elastic Load Balancing documentation, we refer to both SSL
and TLS protocols as the SSL protocol.
The SSL protocol establishes a secure connection between a client and a server and ensures that all the
data passed between the client and your load balancer is private.
Elastic Load Balancing supports the following versions of the SSL protocol:
• TLS 1.2
• TLS 1.1
• TLS 1.0
• SSL 3.0
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Elastic Load Balancing Developer Guide
SSL Ciphers
SSL Ciphers
An SSL cipher is an encryption algorithm that uses encryption keys to create a coded message. SSL
protocols use several SSL ciphers to encrypt data over the Internet. For information about the SSL ciphers
and SSL protocols supported by Elastic Load Balancing, see Predefined SSL Security Policies (p. 30).
Note that a certificate provided by AWS Certificate Manager (ACM) contains an RSA public key. Therefore,
you must include a cipher suite that uses RSA in your security policy if you use a certificate provided by
ACM; otherwise, the TLS connection fails.
Server Order Preference
Elastic Load Balancing supports the Server Order Preference option for negotiating connections between
a client and a load balancer. During the SSL connection negotiation process, the client and the load
balancer present a list of ciphers and protocols that they each support, in order of preference. By default,
the first cipher on the client's list that matches any one of the load balancer's ciphers is selected for the
SSL connection. If the load balancer is configured to support Server Order Preference, then the load
balancer selects the first cipher in its list that is in the client's list of ciphers. This ensures that the load
balancer determines which cipher is used for SSL connection. If you do not enable Server Order Preference,
the order of ciphers presented by the client is used to negotiate connections between the client and the
load balancer.
For information about the order of ciphers used by Elastic Load Balancing, see Predefined SSL Security
Policies (p. 30).
SSL Security Policies for Elastic Load Balancing
A security policy determines which ciphers and protocols are supported during SSL negotiations between
a client and a load balancer. Elastic Load Balancing supports configuring your load balancer to use either
predefined or custom security policies.
Contents
• Predefined Security Policies (p. 29)
• Custom Security Policy (p. 30)
Predefined Security Policies
You can use the predefined SSL negotiation configurations provided by Elastic Load Balancing. The
naming convention of a predefined security policy includes version information based on the year and
month that it was released. For example, the current predefined security policy is
ELBSecurityPolicy-2015-05. Note that some of the older predefined security policies do not follow
this naming convention.
Whenever a new predefined security policy is related, you can update your configuration to use the current
version.
Elastic Load Balancing provides the following predefined security policies:
• ELBSecurityPolicy-2015-05
• ELBSecurityPolicy-2015-03
• ELBSecurityPolicy-2015-02
• ELBSecurityPolicy-2014-10
• ELBSecurityPolicy-2014-01
• ELBSecurityPolicy-2011-08
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Elastic Load Balancing Developer Guide
Predefined SSL Security Policies
• ELBSample-ELBDefaultNegotiationPolicy or ELBSample-ELBDefaultCipherPolicy
• ELBSample-OpenSSLDefaultNegotiationPolicy or ELBSample-OpenSSLDefaultCipherPolicy
For information about the SSL protocols, SSL ciphers, and SSL option enabled for the predefined security
policies, see Predefined SSL Security Policies (p. 30).
Custom Security Policy
You can create a custom negotiation configuration with the ciphers and protocols that you need. Note
that Some security compliance standards (such as PCI, SOX, and so on) might require a specific set of
protocols and ciphers to ensure that the security standards are met. In such cases, you can create a
custom security policy to meet those standards.
For example, a certificate provided by AWS Certificate Manager (ACM) contains an RSA public key.
Therefore, you must include a cipher suite that uses RSA in your security policy if you use a certificate
provided by ACM; otherwise, the TLS connection fails.
For information about the protocols and ciphers supported by Elastic Load Balancing, see Predefined
SSL Security Policies (p. 30).
Predefined SSL Security Policies for Elastic Load
Balancing
We recommend that you always use the current predefined security policy. For more information about
updating the SSL negotiation configuration for your HTTPS/SSL listener, see Update the SSL Negotiation
Configuration of Your Load Balancer (p. 53).
The RSA- and DSA-based ciphers are specific to the signing algorithm used to create SSL certificate.
Make sure to create an SSL certificate using the signing algorithm that is based on the ciphers that are
enabled for your security policy.
The following table describes the most recent predefined security policies, including their enabled SSL
protocols and SSL ciphers. If you select a policy that is enabled for Server Order Preference, the load
balancer uses the ciphers in the order that they are specified in this table to negotiate connections between
the client and load balancer. Otherwise, the load balancer uses the ciphers in the order that they are
presented by the client.
To describe all predefined policies, including the deprecated ones, use the describe-load-balancer-policies
command or the DescribeLoadBalancerPolicies action.
Security Policy
2015-05 2015-03 2015-02 2014-10 2014-01 2011-08
SSL Protocols
Protocol-SSLv3
♦
♦
♦
Protocol-TLSv1
♦
♦
♦
♦
♦
Protocol-TLSv1.1
♦
♦
♦
♦
♦
Protocol-TLSv1.2
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
SSL Options
Server Order Preference
SSL Ciphers
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Elastic Load Balancing Developer Guide
Predefined SSL Security Policies
Security Policy
2015-05 2015-03 2015-02 2014-10 2014-01 2011-08
ECDHE-ECDSA-AES128-GCM-SHA256
♦
♦
♦
♦
♦
ECDHE-RSA-AES128-GCM-SHA256
♦
♦
♦
♦
♦
ECDHE-ECDSA-AES128-SHA256
♦
♦
♦
♦
♦
ECDHE-RSA-AES128-SHA256
♦
♦
♦
♦
♦
ECDHE-ECDSA-AES128-SHA
♦
♦
♦
♦
♦
ECDHE-RSA-AES128-SHA
♦
♦
♦
♦
♦
♦
♦
♦
♦
DHE-RSA-AES128-SHA
♦
ECDHE-ECDSA-AES256-GCM-SHA384
♦
♦
♦
♦
♦
ECDHE-RSA-AES256-GCM-SHA384
♦
♦
♦
♦
♦
ECDHE-ECDSA-AES256-SHA384
♦
♦
♦
♦
♦
ECDHE-RSA-AES256-SHA384
♦
♦
♦
♦
♦
ECDHE-RSA-AES256-SHA
♦
♦
♦
♦
♦
ECDHE-ECDSA-AES256-SHA
♦
♦
♦
♦
♦
AES128-GCM-SHA256
♦
♦
♦
♦
♦
AES128-SHA256
♦
♦
♦
♦
♦
AES128-SHA
♦
♦
♦
♦
♦
AES256-GCM-SHA384
♦
♦
♦
♦
♦
AES256-SHA256
♦
♦
♦
♦
♦
AES256-SHA
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
DHE-DSS-AES128-SHA
♦
CAMELLIA128-SHA
♦
EDH-RSA-DES-CBC3-SHA
♦
DES-CBC3-SHA
♦
♦
♦
ECDHE-RSA-RC4-SHA
♦
♦
RC4-SHA
♦
♦
♦
ECDHE-ECDSA-RC4-SHA
DHE-DSS-AES256-GCM-SHA384
DHE-RSA-AES256-GCM-SHA384
DHE-RSA-AES256-SHA256
DHE-DSS-AES256-SHA256
DHE-RSA-AES256-SHA
♦
DHE-DSS-AES256-SHA
♦
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Elastic Load Balancing Developer Guide
Predefined SSL Security Policies
Security Policy
2015-05 2015-03 2015-02 2014-10 2014-01 2011-08
DHE-RSA-CAMELLIA256-SHA
♦
DHE-DSS-CAMELLIA256-SHA
♦
CAMELLIA256-SHA
♦
EDH-DSS-DES-CBC3-SHA
♦
DHE-DSS-AES128-GCM-SHA256
DHE-RSA-AES128-GCM-SHA256
DHE-RSA-AES128-SHA256
DHE-DSS-AES128-SHA256
DHE-RSA-CAMELLIA128-SHA
♦
DHE-DSS-CAMELLIA128-SHA
♦
ADH-AES128-GCM-SHA256
ADH-AES128-SHA
ADH-AES128-SHA256
ADH-AES256-GCM-SHA384
ADH-AES256-SHA
ADH-AES256-SHA256
ADH-CAMELLIA128-SHA
ADH-CAMELLIA256-SHA
ADH-DES-CBC3-SHA
ADH-DES-CBC-SHA
ADH-RC4-MD5
ADH-SEED-SHA
DES-CBC-SHA
DHE-DSS-SEED-SHA
DHE-RSA-SEED-SHA
EDH-DSS-DES-CBC-SHA
EDH-RSA-DES-CBC-SHA
IDEA-CBC-SHA
RC4-MD5
SEED-SHA
DES-CBC3-MD5
DES-CBC-MD5
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Elastic Load Balancing Developer Guide
Predefined SSL Security Policies
Security Policy
2015-05 2015-03 2015-02 2014-10 2014-01 2011-08
Deprecated SSL Ciphers
RC2-CBC-MD5
PSK-AES256-CBC-SHA
PSK-3DES-EDE-CBC-SHA
KRB5-DES-CBC3-SHA
KRB5-DES-CBC3-MD5
PSK-AES128-CBC-SHA
PSK-RC4-SHA
KRB5-RC4-SHA
KRB5-RC4-MD5
KRB5-DES-CBC-SHA
KRB5-DES-CBC-MD5
EXP-EDH-RSA-DES-CBC-SHA
EXP-EDH-DSS-DES-CBC-SHA
EXP-ADH-DES-CBC-SHA
EXP-DES-CBC-SHA
EXP-RC2-CBC-MD5
EXP-KRB5-RC2-CBC-SHA
EXP-KRB5-DES-CBC-SHA
EXP-KRB5-RC2-CBC-MD5
EXP-KRB5-DES-CBC-MD5
EXP-ADH-RC4-MD5
EXP-RC4-MD5
EXP-KRB5-RC4-SHA
EXP-KRB5-RC4-MD5
Deprecated SSL Ciphers: If you had previously enabled these ciphers in a custom policy or
ELBSample-OpenSSLDefaultCipherPolicy, we recommend that you update your security policy to
the current predefined security policy.
Deprecated SSL Protocol: If you had previously enabled the SSLv2 protocol in a custom policy, we
recommend that you update your security policy to the current predefined security policy.
33
Elastic Load Balancing Developer Guide
Create an HTTPS Load Balancer
Create an HTTPS Load Balancer
A load balancer takes requests from clients and distributes them across the EC2 instances that are
registered with the load balancer (also known as back-end instances).
You can create a load balancer that listens on both the HTTP (80) and HTTPS (443) ports. If you specify
that the HTTPS listener sends requests to the back-end instances on port 80, the load balancer terminates
the requests and communication from the load balancer to the back-end instances is not encrypted. If
the HTTPS listener sends requests to the back-end instances on port 443, communication from the load
balancer to the back-end instances is encrypted.
If your load balancer uses an encrypted connection to communicate with the back-end instances, you
can optionally enable authentication of the back-end instances. This ensures that the load balancer
communicates with a back-end instance only if its public key matches the key that you specified to the
load balancer for this purpose.
For information about adding an HTTPS listener to an existing load balancer, see Configure an HTTPS
Listener for Your Load Balancer (p. 48).
Contents
• Prerequisites (p. 34)
• Create an HTTPS/SSL Load Balancer Using the Console (p. 34)
• Create an HTTPS/SSL Load Balancer Using the AWS CLI (p. 40)
Prerequisites
Before you get started, be sure that you've met the following prerequisites:
• Complete the steps in Setting Up Elastic Load Balancing (p. 6).
• Launch the EC2 instances that you plan to register with your load balancer in the Availability Zones
you plan to use for your load balancer. These instances must be configured to receive requests from
the load balancer.
• The EC2 instances must respond to the target of the health check with an HTTP status code 200. For
more information, see Configure Health Checks (p. 59).
• If you plan to enable the keep-alive option on your EC2 instances, we recommend that you set the
keep-alive settings to at least the idle timeout settings of your load balancer. If you want to ensure that
the load balancer is responsible for closing the connections to your back-end instance, make sure that
the value set on your instance for the keep-alive time is greater than the idle timeout setting on your
load balancer. For more information, see Configure the Idle Connection Timeout for Your Load
Balancer (p. 82).
• To enable HTTPS support for our listeners, you must deploy an SSL certificate on your load balancer.
The load balancer uses the certificate to terminate and then decrypt requests before sending them to
the back-end instances. If you don't have an SSL certificate, you can create one. For more information,
see SSL Certificates for Elastic Load Balancing (p. 22).
Create an HTTPS/SSL Load Balancer Using the
Console
To create an HTTPS/SSL load balancer, complete the following tasks.
Tasks
• Step 1: Define Your Load Balancer (p. 35)
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Elastic Load Balancing Developer Guide
Create an HTTPS/SSL Load Balancer Using the Console
• Step 2: Assign Security Groups to Your Load Balancer in a VPC (p. 36)
• Step 3: Configure Security Settings (p. 37)
• Step 4: Configure Health Checks (p. 38)
• Step 5: Register EC2 Instances with Your Load Balancer (p. 38)
• Step 6: Tag Your Load Balancer (Optional) (p. 39)
• Step 7: Create and Verify Your Load Balancer (p. 39)
• Step 8: Delete Your Load Balancer (Optional) (p. 39)
Step 1: Define Your Load Balancer
First, provide some basic configuration information for your load balancer, such as a name, a network,
and one or more listeners.
A listener is a process that checks for connection requests. It is configured with a protocol and a port for
front-end (client to load balancer) connections and a protocol and a port for back-end (load balancer to
back-end instance) connections. For information about the ports, protocols, and listener configurations
supported by Elastic Load Balancing, see Listeners for Your Load Balancer (p. 76).
In this example, you configure two listeners for your load balancer. The first listener accepts HTTP requests
on port 80 and sends them to the back-end instances on port 80 using HTTP. The second listener accepts
HTTPS requests on port 443 and sends them to the back-end instances using HTTP on port 80 (or using
HTTPS on port 443 if you want to configure back-end authentication).
To define your load balancer
1.
2.
3.
4.
5.
6.
7.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
Click Create Load Balancer.
In Load Balancer name, enter a name for your load balancer.
The name of your load balancer must be unique within your set of load balancers for the region, can
have a maximum of 32 characters, and can contain only alphanumeric characters and hyphens.
From Create LB inside, select the same network that you selected for your instances: EC2-Classic
or a specific VPC.
[Default VPC] If you selected a default VPC and would like to choose the subnets for your load
balancer, select Enable advanced VPC configuration.
Under Listener Configuration, leave the default listener, and click Add to add another listener.
From the Load Balancer Protocol column for the new listener, select HTTPS (Secure HTTP).
This updates the Load Balancer Port, Instance Protocol, and Instance Port columns.
By default, Instance Protocol is set to HTTP and Instance Port is set to 80.
If you want to set up back-end instance authentication (later, in Step 3: Configure Security
Settings (p. 37)), change the instance protocol to HTTPS (Security HTTP). This also updates the
Instance Port column.
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Elastic Load Balancing Developer Guide
Create an HTTPS/SSL Load Balancer Using the Console
8.
[EC2-VPC] Under Select Subnets, select at least one available subnet. To improve the availability
of your load balancer, select more than one subnet.
Note
If you selected EC2-Classic as your network, or you have a default VPC but did not select
Enable advanced VPC configuration, you do not see Select Subnets.
The available subnets for the VPC for your load balancer are displayed under Available Subnets.
Select subnets that are in the same Availability Zones as your instances. If your load balancer is an
Internet-facing load balancer, select public subnets. If you load balancer is an internal load balancer,
select private subnets. Click the icon in the Action column for each subnet to attach. These subnets
are moved under Selected Subnets. You can select at most one subnet per Availability Zone. If you
select a subnet from an Availability Zone where there is already a selected subnet, this replaces the
currently selected subnet for that Availability Zone.
9.
Click Next: Assign Security Groups.
Step 2: Assign Security Groups to Your Load Balancer in a
VPC
If you selected a VPC as your network, you must assign your load balancer a security group that allows
inbound traffic to the ports that you specified for your load balancer and the health checks for your load
balancer.
Note
If you selected EC2-Classic as your network, you can continue to the next step. By default,
Elastic Load Balancing provides a security group for load balancers in EC2-Classic.
To assign security group to your load balancer
1.
2.
On the Assign Security Groups page, select Create a new security group.
Enter a name and description for your security group, or leave the default name and description.
This new security group contains a rule that allows traffic to the ports that you configured your load
balancer to use.
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Elastic Load Balancing Developer Guide
Create an HTTPS/SSL Load Balancer Using the Console
3.
Click Next: Configure Security Settings.
Step 3: Configure Security Settings
When you use HTTPS or SSL for your front-end listener, you must deploy an SSL certificate on your load
balancer. The load balancer uses the certificate to terminate the connection and then decrypt requests
from clients before sending them to the back-end instances.
You must also specify a security policy. Elastic Load Balancing provides security policies that have
predefined SSL negotiation configurations, or you can create your own custom security policy.
If you configured HTTPS/SSL on the back-end connection, you can enable authentication of your back-end
instances.
To configure security settings
1.
Under Select Certificate, do one of the following:
•
If you have a certificate from AWS Certificate Manager, select Choose an existing certificate
from AWS Certificate Manager (ACM), select the certificate from ACM Certificate, and then
click Save.
Note
This option is available only in regions that support AWS Certificate Manager. For more
information, see Supported Regions in the AWS Certificate Manager User Guide.
•
•
If you have already uploaded a certificate using IAM, select Choose an existing certificate
from AWS Identity and Access Management (IAM), select your certificate from Certificate
Name, and then click Save.
If you have a certificate ready to upload, select Upload a new SSL Certificate to AWS Identity
and Access Management (IAM). Enter the name of the certificate. In Private Key, copy and
paste the contents of the private key file (PEM-encoded). In Public Key Certificate, copy and
paste the contents of the public key certificate file (PEM-encoded). In Certificate Chain, copy
and paste the contents of the certificate chain file (PEM-encoded), unless you are using a
self-signed certificate and it's not important that browsers implicitly accept the certificate.
2.
Under Select a Cipher, verify that Predefined Security Policy is selected and set to
ELBSecurityPolicy-2015-05. We recommend that you always use the latest predefined security
policy. If you need to use a different predefined security policy or create a custom policy, see Update
the SSL Negotiation Configuration (p. 54).
3.
(Optional) If you configured the HTTPS listener to communicate with back-end instances using an
encrypted connection, you can optionally set up authentication of the back-end instances.
a.
Under Backend Certificate, select Enable backend authentication.
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Note
If you do not see the Backend Certificate section, go back to Listener Configuration
and select HTTPS (Security HTTP) from Instance Protocol.
b.
In Certificate Name, enter the name of the public key certificate.
c.
In Certificate Body (pem encoded), copy and paste the contents of the certificate. The load
balancer communicates with a back-end instance only if its public key matches this key.
To add another certificate, click Add another backend certificate.
d.
4.
Click Next: Configure Health Check.
Step 4: Configure Health Checks
Elastic Load Balancing automatically checks the health of the registered EC2 instances for your load
balancer. If Elastic Load Balancing finds an unhealthy instance, it stops sending traffic to the instance
and reroutes traffic to the healthy instances. For more information about configuring health checks, see
Configure Health Checks (p. 59).
To configure health checks for your instances
1.
2.
On the Configure Health Check page, select a ping protocol and ping port. Your EC2 instances
must accept the specified traffic on the specified ping port.
In the Ping Path field, replace the default value with a single forward slash ("/"). This tells Elastic
Load Balancing to send health check queries to the default home page for your web server, such as
index.html or default.html.
3.
4.
Leave the other fields at their default values.
Click Next: Add EC2 Instances.
Step 5: Register EC2 Instances with Your Load Balancer
Your load balancer distributes traffic between the instances that are registered to it. You can select EC2
instances in a single Availability Zone or multiple Availability Zones within the same region as the load
balancer. For more information, see Back-end Instances for Your Load Balancer (p. 58).
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Note
When you register an instance with an elastic network interface (ENI) attached, the load balancer
routes traffic to the primary IP address of the primary interface (eth0) of the instance.
To register EC2 instances with your load balancer
1.
On the Add EC2 Instances page, select the instances to register with your load balancer.
2.
Click Next: Add Tags.
Step 6: Tag Your Load Balancer (Optional)
You can tag your load balancer, or continue to the next step.
To add tags to your load balancer
1.
2.
On the Add Tags page, specify a key and a value for the tag.
To add another tag, click Create Tag and specify a key and a value for the tag.
3.
After you are finished adding tags, click Review and Create.
Step 7: Create and Verify Your Load Balancer
Before you create the load balancer, review the settings that you selected. After creating the load balancer,
you can verify that it's sending traffic to your EC2 instances.
To finish creating your load balancer
1.
2.
3.
4.
5.
6.
On the Review page, check your settings. If you need to make changes, click the corresponding link
to edit the settings.
Click Create to create your load balancer.
After you are notified that your load balancer was created, click Close.
Select your new load balancer.
In the bottom pane, on the Description tab, check the Status row. If it indicates that some of your
instances are not in service, its probably because they are still in the registration process. For more
information, see Troubleshooting Elastic Load Balancing: Instance Registration (p. 133).
(Optional) After you've verified that at least one of your EC2 instances is InService, you can test
your load balancer. Copy the string from the DNS Name field and paste it into the address field of
an Internet-connected web browser. (For example,
my-load-balancer-1234567890.us-west-2.elb.amazonaws.com.) If your load balancer is
working, you see the default page of your HTTP server.
Step 8: Delete Your Load Balancer (Optional)
As soon as your load balancer becomes available, you are billed for each hour or partial hour that you
keep it running. When you no longer need a load balancer, you can delete it. As soon as the load balancer
is deleted, you stop incurring charges for it.
To delete your load balancer
1.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
2.
3.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
Select the load balancer.
4.
Click Actions, and then click Delete.
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5.
6.
When prompted for confirmation, click Yes, Delete.
(Optional) After you delete a load balancer, the EC2 instances associated with the load balancer
continue to run, and you are billed for each hour or partial hour that you keep them running. For
information about stopping or terminating your instances, see Stop and Start Your Instance or
Terminate Your Instance in the Amazon EC2 User Guide for Linux Instances.
Create an HTTPS/SSL Load Balancer Using the
AWS CLI
Use the following instructions to create an HTTPS/SSL load balancer using the AWS CLI.
Tasks
• Step 1: Configure Listeners (p. 40)
•
•
•
•
•
•
Step 2: Configure the SSL Security Policy (p. 41)
Step 3: Configure Back-end Instance Authentication (Optional) (p. 45)
Step 4: Configure Health Checks (Optional) (p. 46)
Step 5: Register EC2 Instances (p. 47)
Step 6: Verify the Instances (p. 47)
Step 7: Delete Your Load Balancer (Optional) (p. 48)
Step 1: Configure Listeners
A listener is a process that checks for connection requests. It is configured with a protocol and a port for
front-end (client to load balancer) connections and a protocol and port for back-end (load balancer to
back-end instance) connections. For information about the ports, protocols, and listener configurations
supported by Elastic Load Balancing, see Listeners for Your Load Balancer (p. 76).
In this example, you configure two listeners for your load balancer by specifying the ports and protocols
to use for front-end and back-end connections. The first listener accepts HTTP requests on port 80 and
sends the requests to the back-end instances on port 80 using HTTP.The second listener accepts HTTPS
requests on port 443 and sends requests to back-end instances using HTTP on port 80.
Because the second listener uses HTTPS for the front-end connection, you must deploy an SSL sever
certificate on your load balancer. The load balancer uses the certificate to terminate and then decrypt
requests before sending them to the back-end instances.
To configure listeners for your load balancer
1.
Get the Amazon Resource Name (ARN) of the SSL certificate. For example:
ACM
arn:aws:acm:region:123456789012:certificate/12345678-1234-1234-1234123456789012
IAM
arn:aws:iam::123456789012:server-certificate/my-server-certificate
2.
Use the following create-load-balancer command to configure the load balancer with the two listeners:
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aws elb create-load-balancer --load-balancer-name my-load-balancer -listeners "Protocol=http,LoadBalancerPort=80,InstanceProtocol=http,Instan
cePort=80" "Protocol=https,LoadBalancerPort=443,InstanceProtocol=http,Instan
cePort=80,SSLCertificateId="ARN" --availability-zones us-west-2a
The following is an example response:
{
"DNSName": "my-loadbalancer-012345678.us-west-2.elb.amazonaws.com"
}
3.
(Optional) Use the following describe-load-balancers command to view the details of your load
balancer:
aws elb describe-load-balancers --load-balancer-name my-load-balancer
Step 2: Configure the SSL Security Policy
You can select one of the predefined security policies, or you can create your own custom security policy.
By default, Elastic Load Balancing configures your load balancer with the current predefined security
policy, ELBSecurityPolicy-2015-05. We recommend that you use the default security policy. For
more information about security policies, see SSL Negotiation Configurations for Elastic Load
Balancing (p. 28).
To verify that your load balancer is associated with the default security policy
Use the following describe-load-balancers command:
aws elb describe-load-balancers --load-balancer-name my-loadbalancer
The following is an example response. Note that ELBSecurityPolicy-2015-05 is associated with the
load balancer on port 443.
{
"LoadBalancerDescriptions": [
{
...
"ListenerDescriptions": [
{
"Listener": {
"InstancePort": 80,
"SSLCertificateId": "ARN",
"LoadBalancerPort": 443,
"Protocol": "HTTPS",
"InstanceProtocol": "HTTP"
},
"PolicyNames": [
"ELBSecurityPolicy-2015-05"
]
},
{
"Listener": {
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"InstancePort": 80,
"LoadBalancerPort": 80,
"Protocol": "HTTP",
"InstanceProtocol": "HTTP"
},
"PolicyNames": []
}
],
...
}
]
}
If you prefer, you can configure the SSL security policy for your load balancer instead of using the default
security policy.
(Optional) To use a predefined SSL security policy
1.
Use the following describe-load-balancer-policies command to list the names of the predefined
security policies:
aws elb describe-load-balancer-policies
2.
For information about the configuration for the predefined security policies, see Predefined SSL
Security Policies (p. 30).
Use the following create-load-balancer-policy command to create an SSL negotiation policy using
one of the predefined security policies that you described in the previous step:
aws elb create-load-balancer-policy --load-balancer-name my-loadbalancer
--policy-name my-SSLNegotiation-policy --policy-type-name SSLNegotiationPoli
cyType
--policy-attributes AttributeName=Reference-Security-Policy,AttributeValue=pre
defined-policy
3.
(Optional) Use the following describe-load-balancer-policies command to verify that the policy is
created:
aws elb describe-load-balancer-policies --load-balancer-name my-loadbalancer
--policy-name my-SSLNegotiation-policy
4.
The response includes the description of the policy.
Use the following set-load-balancer-policies-of-listener command to enable the policy on load balancer
port 443:
aws elb set-load-balancer-policies-of-listener --load-balancer-name myloadbalancer --load-balancer-port 443 --policy-names my-SSLNegotiation-policy
Note
The set-load-balancer-policies-of-listener command replaces the current set
of policies for the specified load balancer port with the specified set of policies. The
--policy-names list must include all policies to be enabled. If you omit a policy that is
currently enabled, it is disabled.
5.
(Optional) Use the following describe-load-balancers command to verify that the policy is enabled:
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aws elb describe-load-balancers --load-balancer-name my-loadbalancer
The following is an example response showing that the policy is enabled on port 443.
{
"LoadBalancerDescriptions": [
{
....
"ListenerDescriptions": [
{
"Listener": {
"InstancePort": 80,
"SSLCertificateId": "ARN",
"LoadBalancerPort": 443,
"Protocol": "HTTPS",
"InstanceProtocol": "HTTP"
},
"PolicyNames": [
"my-SSLNegotiation-policy"
]
},
{
"Listener": {
"InstancePort": 80,
"LoadBalancerPort": 80,
"Protocol": "HTTP",
"InstanceProtocol": "HTTP"
},
"PolicyNames": []
}
],
...
}
]
}
When you create a custom security policy, you must enable at least one protocol and one cipher. The
DSA and RSA ciphers are specific to the signing algorithm and are used to create the SSL certificate. If
you already have your SSL certificate, make sure to enable the cipher that was used to create your
certificate. The name of your custom policy must not begin with ELBSecurityPolicy- or ELBSample-,
as these prefixes are reserved for the names of the predefined security policies.
(Optional) To use a custom SSL security policy
1.
Use the create-load-balancer-policy command to create an SSL negotiation policy using a custom
security policy. For example:
aws elb create-load-balancer-policy --load-balancer-name my-loadbalancer
--policy-name my-SSLNegotiation-policy --policy-type-name SSLNegotiation
PolicyType
--policy-attributes AttributeName=Protocol-TLSv1.2,AttributeValue=true
AttributeName=Protocol-TLSv1.1,AttributeValue=true
AttributeName=DHE-RSA-AES256-SHA256,AttributeValue=true
AttributeName=Server-Defined-Cipher-Order,AttributeValue=true
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2.
(Optional) Use the following describe-load-balancer-policies command to verify that the policy is
created:
aws elb describe-load-balancer-policies --load-balancer-name my-loadbalancer
--policy-name my-SSLNegotiation-policy
3.
The response includes the description of the policy.
Use the following set-load-balancer-policies-of-listener command to enable the policy on load balancer
port 443:
aws elb set-load-balancer-policies-of-listener --load-balancer-name myloadbalancer --load-balancer-port 443 --policy-names my-SSLNegotiation-policy
Note
The set-load-balancer-policies-of-listener command replaces the current set
of policies for the specified load balancer port with the specified set of policies. The
--policy-names list must include all policies to be enabled. If you omit a policy that is
currently enabled, it is disabled.
4.
(Optional) Use the following describe-load-balancers command to verify that the policy is enabled:
aws elb describe-load-balancers --load-balancer-name my-loadbalancer
The following is an example response showing that the policy is enabled on port 443.
{
"LoadBalancerDescriptions": [
{
....
"ListenerDescriptions": [
{
"Listener": {
"InstancePort": 80,
"SSLCertificateId": "ARN",
"LoadBalancerPort": 443,
"Protocol": "HTTPS",
"InstanceProtocol": "HTTP"
},
"PolicyNames": [
"my-SSLNegotiation-policy"
]
},
{
"Listener": {
"InstancePort": 80,
"LoadBalancerPort": 80,
"Protocol": "HTTP",
"InstanceProtocol": "HTTP"
},
"PolicyNames": []
}
],
...
}
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]
}
Step 3: Configure Back-end Instance Authentication
(Optional)
If you set up HTTPS/SSL on the back-end connection, you can optionally set up authentication of your
back-end instances.
When you set up back-end instance authentication, you create a public key policy. Next, you use this
public key policy to create a back-end instance authentication policy. Finally, you set the back-end instance
authentication policy with the instance port for the HTTPS protocol.
The load balancer communicates with a back-end instance only if the public key that the instance presents
to the load balancer matches a public key in the authentication policy for your load balancer.
To configure back-end instance authentication
1.
Use the following command to retrieve the public key:
openssl x509 -in your X509 certificate PublicKey -pubkey -noout
2.
Use the following create-load-balancer-policy command to create a public key policy:
aws elb create-load-balancer-policy --load-balancer-name my-loadbalancer -policy-name my-PublicKey-policy --policy-type-name PublicKeyPolicyType -policy-attributes AttributeName=PublicKey,AttributeValue=MIICiTCCAfIC
CQD6m7oRw0uXOjANBgkqhkiG9w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Note
To specify a public key value for --policy-attributes, remove the first and last lines
of the public key (the line containing "-----BEGIN PUBLIC KEY-----" and the line
containing "-----END PUBLIC KEY-----"). The AWS CLI does not accept white space
characters in --policy-attributes.
3.
Use the following create-load-balancer-policy command to create a back-end instance authentication
policy using my-PublicKey-policy.
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aws elb create-load-balancer-policy --load-balancer-name my-loadbalancer -policy-name my-authentication-policy --policy-type-name BackendServerAu
thenticationPolicyType --policy-attributes AttributeName=PublicKeyPolicy
Name,AttributeValue=my-PublicKey-policy
4.
You can optionally use multiple public key policies. The load balancer tries all the keys, one at a
time. If the public key presented by a back-end instance matches one of these public keys, the
instance is authenticated.
Use the following set-load-balancer-policies-for-backend-server command to set
my-authentication-policy to the instance port for HTTPS. In this example, the instance port
is port 443.
aws elb set-load-balancer-policies-for-backend-server --load-balancer-name
my-loadbalancer --instance-port 443 --policy-names my-authentication-policy
5.
(Optional) Use the following describe-load-balancer-policies command to list all the policies for your
load balancer:
aws elb describe-load-balancer-policies --load-balancer-name my-loadbalancer
6.
(Optional) Use the following describe-load-balancer-policies command to view details of the policy:
aws elb describe-load-balancer-policies --load-balancer-name my-loadbalancer
--policy-names my-authentication-policy
Step 4: Configure Health Checks (Optional)
Elastic Load Balancing regularly checks the health of each registered EC2 instance based on the health
checks that you configured. If Elastic Load Balancing finds an unhealthy instance, it stops sending traffic
to the instance and routes traffic to the healthy instances. For more information, see Configure Health
Checks (p. 59).
When you create your load balancer, Elastic Load Balancing uses default settings for the health checks.
If you prefer, you can change the health check configuration for your load balancer instead of using the
default settings.
To configure the health checks for your back-end instances
Use the following configure-health-check command:
aws elb configure-health-check --load-balancer-name my-loadbalancer --healthcheck Target=HTTP:80/ping,Interval=30,Un
healthyThreshold=2,HealthyThreshold=2,Timeout=3
The following is an example response:
{
"HealthCheck": {
"HealthyThreshold": 2,
"Interval": 30,
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"Target": "HTTP:80/ping",
"Timeout": 3,
"UnhealthyThreshold": 2
}
}
Step 5: Register EC2 Instances
After you create your load balancer, you must register your EC2 instances with the load balancer. You
can select EC2 instances from a single Availability Zone or multiple Availability Zones within the same
region as the load balancer. For more information, see Back-end Instances for Your Load Balancer (p. 58).
Use the register-instances-with-load-balancer command as follows:
aws elb register-instances-with-load-balancer --load-balancer-name my-loadbal
ancer --instances i-4f8cf126 i-0bb7ca62
The following is an example response:
{
"Instances": [
{
"InstanceId": "i-4f8cf126"
},
{
"InstanceId": "i-0bb7ca62"
}
]
}
Step 6: Verify the Instances
Your load balancer is usable as soon as any one of your registered instances is in the InService state.
To check the state of your newly registered EC2 instances, use the following describe-instance-health
command:
aws elb describe-instance-health
stances i-4f8cf126 i-0bb7ca62
--load-balancer-name my-loadbalancer --in
The following is an example response:
{
"InstanceStates": [
{
"InstanceId": "i-4f8cf126",
"ReasonCode": "N/A",
"State": "InService",
"Description": "N/A"
},
{
"InstanceId": "i-0bb7ca62",
"ReasonCode": "Instance",
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"State": "OutOfService",
"Description": "Instance registration is still in progress"
}
]
}
If the State field for an instance is OutOfService, it's probably because your instances are still
registering. For more information, see Troubleshooting Elastic Load Balancing: Instance
Registration (p. 133).
After the state of at least one of your instances is InService, you can test your load balancer. To test
your load balancer, copy the DNS name of the load balancer and paste it into the address field of an
Internet-connected web browser. If your load balancer is working, you see the default page of your HTTP
server.
Step 7: Delete Your Load Balancer (Optional)
Deleting a the load balancer automatically de-registers its associated EC2 instances. As soon as the load
balancer is deleted, you stop incurring charges for that load balancer. However, the EC2 instances
continue run and you continue to incur charges.
To delete your load balancer, use the following delete-load-balancer command:
aws elb delete-load-balancer --load-balancer-name my-loadbalancer
To stop your EC2 instances, use the stop-instances command. To terminate your EC2 instances, use
the terminate-instances command.
Configure an HTTPS Listener for Your Load
Balancer
A listener is a process that checks for connection requests. It is configured with a protocol and a port for
front-end (client to load balancer) connections and a protocol and a port for back-end (load balancer to
back-end instance) connections. For information about the ports, protocols, and listener configurations
supported by Elastic Load Balancing, see Listeners for Your Load Balancer (p. 76).
If you have a load balancer with a listener that accepts HTTP requests on port 80, you can add a listener
that accepts HTTPS requests on port 443. If you specify that the HTTPS listener sends requests to the
back-end instances on port 80, the load balancer terminates the SSL requests and communication from
the load balancer to the back-end instances is not encrypted. If the HTTPS listener sends requests to
the back-end instances on port 443, communication from the load balancer to the back-end instances is
encrypted.
If your load balancer uses an encrypted connection to communicate with back-end instances, you can
optionally enable authentication of the back-end instances. This ensures that the load balancer
communicates with a back-end instance only if its public key matches the key that you specified to the
load balancer for this purpose.
For information about creating a new HTTPS listener, see Create an HTTPS Load Balancer (p. 34).
Contents
• Prerequisites (p. 49)
• Add an HTTPS Listener Using the Console (p. 49)
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Prerequisites
• Add an HTTPS Listener Using the AWS CLI (p. 50)
Prerequisites
To enable HTTPS support for an HTTPS listener, you must deploy an SSL server certificate on your load
balancer. The load balancer uses the certificate to terminate and then decrypt requests before sending
them to the back-end instances. If you do not have an SSL certificate, you can create one. For more
information, see SSL Certificates for Elastic Load Balancing (p. 22).
Add an HTTPS Listener Using the Console
You can add an HTTPS listener to an existing load balancer.
To add an HTTPS listener to your load balancer
1.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
2.
3.
4.
5.
6.
7.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
Select your load balancer.
In the bottom pane, select the Listeners tab.
Click Edit.
In the Edit listeners dialog box, click Add.
In the Load Balancer Protocol column, select HTTPS (Secure HTTP). This updates the Load
Balancer Port, Instance Protocol, and Instance Port columns.
Important
By default, Instance Protocol is set to HTTP. If you want to set up back-end instance
authentication, change the instance protocol to HTTPS (Secure HTTP). This also updates
the Instance Port column.
8.
9.
Under Select a Cipher, verify that Predefined Security Policy is selected and set to
ELBSecurityPolicy-2015-05. We recommend that you always use the latest predefined security
policy. If you need to use a different predefined security policy or create a custom policy, see Update
the SSL Negotiation Configuration (p. 54).
If you already have a certificate deployed on your load balancer and want to continue using it, you
can skip this step.
In the SSL Certificate column, click Change, and then do one of the following:
•
If you have a certificate from AWS Certificate Manager, select Choose an existing certificate
from AWS Certificate Manager (ACM), select the certificate from ACM Certificate, and then
click Save.
Note
This option is available only in regions that support AWS Certificate Manager.
•
If you have already uploaded a certificate using IAM, select Choose an existing certificate
from AWS Identity and Access Management (IAM), select the certificate from Certificate
Name, and then click Save.
•
If you have an SSL certificate to upload, select Upload a new SSL Certificate to AWS Identity
and Access Management (IAM). Enter the name of the certificate. In Private Key, copy and
paste the contents of the private key file (PEM-encoded). In Public Key Certificate, copy and
paste the contents of the public key certificate file (PEM-encoded). In Certificate Chain, copy
and paste the contents of the certificate chain file (PEM-encoded), unless you are using a
self-signed certificate and it's not important that browsers implicitly accept the certificate.
10. (Optional) Click Add to add additional listeners.
11. Click Save to add the listeners you just configured.
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12. (Optional) To set up back-end instance authentication for an existing load balancer, you must use
the AWS CLI or an API, as this task is not supported using the console. For more information, see
Configure Back-end Instance Authentication (p. 45).
Add an HTTPS Listener Using the AWS CLI
You can add an HTTPS listener to an existing load balancer.
To add an HTTPS listener to your load balancer using the AWS CLI
1.
Get the Amazon Resource Name (ARN) of the SSL certificate. For example:
ACM
arn:aws:acm:region:123456789012:certificate/12345678-1234-1234-1234123456789012
IAM
arn:aws:iam::123456789012:server-certificate/my-server-certificate
2.
Use the following create-load-balancer-listeners command to add a listener to your load balancer
that accepts HTTPS requests on port 443 and sends the requests to the back-end instances on port
80 using HTTP:
aws elb create-load-balancer-listeners --load-balancer-name my-load-balancer
--listeners Protocol=HTTPS,LoadBalancerPort=443,InstanceProtocol=HTTP,In
stancePort=80,SSLCertificateId=ARN
If you want to set up back-end instance authentication, use the following command to add a listener
that accepts HTTPS requests on port 443 and sends the requests to the back-end instances on port
443 using HTTPS:
aws elb create-load-balancer-listeners --load-balancer-name my-load-balancer
--listeners Protocol=HTTPS,LoadBalancerPort=443,InstanceProtocol=HTTPS,In
stancePort=443,SSLCertificateId=ARN
3.
(Optional) You can use the following describe-load-balancers command to view the updated details
of your load balancer:
aws elb describe-load-balancers --load-balancer-name my-load-balancer
The following is an example response:
{
"LoadBalancerDescriptions": [
{
...
"ListenerDescriptions": [
{
"Listener": {
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Elastic Load Balancing Developer Guide
Replace the SSL Certificate
"InstancePort": 80,
"SSLCertificateId": "ARN",
"LoadBalancerPort": 443,
"Protocol": "HTTPS",
"InstanceProtocol": "HTTP"
},
"PolicyNames": [
"ELBSecurityPolicy-2015-05"
]
},
{
"Listener": {
"InstancePort": 80,
"LoadBalancerPort": 80,
"Protocol": "HTTP",
"InstanceProtocol": "HTTP"
},
"PolicyNames": []
}
],
...
}
]
}
4.
5.
(Optional) Your HTTPS listener was created using the default security policy. If you want to specify
a different predefined security policy or a custom security policy, use the create-load-balancer-policy
and set-load-balancer-policies-of-listener commands. For more information, see Update the SSL
Negotiation Configuration Using the AWS CLI (p. 54).
(Optional) To set up back-end instance authentication, use the
set-load-balancer-policies-for-backend-server command. For more information, see Configure
Back-end Instance Authentication (p. 45).
Replace the SSL Certificate for Your Load
Balancer
If you have an HTTPS listener, you deployed an SSL server certificate on your load balancer when you
created the listener. Each certificate comes with a validity period. You must ensure that you renew or
replace the certificate before its validity period ends.
Certificates provided by AWS Certificate Manager and deployed on your load balancer can be renewed
automatically. ACM attempts to renew certificates before they expire. For more information, see Managed
Renewal in the AWS Certificate Manager User Guide.
To replace a certificate, you must first create a new certificate by following the same steps you used when
you created the current certificate. For more information about creating an SSL certificate and uploading
it, see SSL Certificates for Elastic Load Balancing (p. 22). Then, you can replace the certificate as
described in the next sections. Note that replacing a certificate does not affect requests that were received
by a load balancer node and are pending routing to a healthy instance, but the new certificate will be
used with subsequent requests that are received.
Contents
• Prerequisites (p. 52)
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Elastic Load Balancing Developer Guide
Prerequisites
• Replace the SSL Certificate Using the Console (p. 52)
• Replace the SSL Certificate Using the AWS CLI (p. 52)
Prerequisites
Verify that your certificate meets the prerequisites (p. 25).
Replace the SSL Certificate Using the Console
You can replace the certificate deployed on your load balancer with a certificate provided by ACM or a
certificate uploaded to IAM.
To replace the SSL certificate for an HTTPS load balancer
1.
2.
3.
4.
5.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
Select your load balancer.
In the Listeners tab, click Change in the SSL Certificate column for the certificate.
In the Select Certificate dialog box, do one of the following:
• If you have a certificate from AWS Certificate Manager, select Choose an existing certificate
from AWS Certificate Manager (ACM), select the certificate from ACM Certificate, and then
click Save.
Note
This option is available only in regions that support AWS Certificate Manager.
• If you have already uploaded a certificate using IAM, select Choose an existing certificate from
AWS Identity and Access Management (IAM), select the certificate from Certificate Name, and
then click Save.
• If you have an SSL certificate to upload, select Upload a new SSL Certificate to AWS Identity
and Access Management (IAM). Enter a name for the certificate, copy the required information
to the form, and then click Save. Note that the certificate chain is not required if the certificate is
a self-signed certificate.
Replace the SSL Certificate Using the AWS CLI
You can replace the certificate deployed on your load balancer with a certificate provided by ACM or a
certificate uploaded to IAM.
To replace an SSL certificate with a certificate provided by ACM
1.
Use the following request-certificate command to request a new certificate:
aws acm request-certificate --domain-name www.example.com
2.
Use the following set-load-balancer-listener-ssl-certificate command to set the certificate:
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aws elb set-load-balancer-listener-ssl-certificate --load-balancer-name myload-balancer --load-balancer-port 443 --ssl-certificate-id arn:aws:acm:re
gion:123456789012:certificate/12345678-1234-1234-1234-123456789012
To replace an SSL certificate with a certificate uploaded to IAM
1.
2.
If you have an SSL certificate but have not uploaded it, complete the instructions described in Upload
the Certificate (p. 25).
Use the following get-server-certificate command to get the ARN of the certificate:
aws iam get-server-certificate --server-certificate-name my-new-certificate
3.
Use the following set-load-balancer-listener-ssl-certificate command to set the certificate:
aws elb set-load-balancer-listener-ssl-certificate --load-balancer-name myload-balancer --load-balancer-port 443 --ssl-certificate-id
arn:aws:iam::123456789012:server-certificate/my-new-certificate
Update the SSL Negotiation Configuration of
Your Load Balancer
Elastic Load Balancing provides security policies that have predefined SSL negotiation configurations to
use to negotiate SSL connections between clients and your load balancer. If you are using the HTTPS/SSL
protocol for your listener, you can use one of the predefined security policies, or use your own custom
security policy.
For more information about the security policies, see SSL Negotiation Configurations for Elastic Load
Balancing (p. 28). For information about the configurations of the security policies provided by Elastic
Load Balancing, see Predefined SSL Security Policies (p. 30).
If you create an HTTPS/SSL listener without associating a security policy, Elastic Load Balancing associates
the current predefined security policy, ELBSecurityPolicy-2015-05, with your load balancer.
If you have an existing load balancer with an SSL negotiation configuration that does not use the latest
protocols and ciphers, we recommend that you update your load balancer to use
ELBSecurityPolicy-2015-05. If you prefer, you can create a custom configuration. We strongly recommend
that you test the new security policies before you upgrade your load balancer configuration.
The following examples show you how to update the SSL negotiation configuration for an HTTPS/SSL
listener. Note that the change does not affect requests that were received by a load balancer node and
are pending routing to a healthy instance, but the updated configuration will be used with new requests
that are received.
Contents
• Update the SSL Negotiation Configuration Using the Console (p. 54)
• Update the SSL Negotiation Configuration Using the AWS CLI (p. 54)
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Elastic Load Balancing Developer Guide
Update the SSL Negotiation Configuration Using the
Console
Update the SSL Negotiation Configuration Using
the Console
By default, Elastic Load Balancing associates the latest predefined policy with your load balancer. When
a new predefined policy is added, we recommend that you update your load balancer to use the new
predefined policy. Alternatively, you can select a different predefined security policy or create a custom
policy.
To update SSL negotiation configuration for an HTTPS/SSL load balancer
1.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
2.
3.
4.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
Select your load balancer.
In the bottom pane, select the Listeners tab.
5.
6.
In the Cipher column of the listener to be updated, click Change.
In the Select a Cipher dialog box, select a security policy using one of the following options:
•
(Recommended) Select Predefined Security Policy and then select
ELBSecurityPolicy-2015-05.
•
Click Predefined Security Policy, select one of the predefined policies from the list, and then
click Save.
•
Click Custom Security Policy and enable at least one protocol and one cipher.
a.
b.
c.
d.
Under SSL Protocols, select one or more protocols to enable.
Under SSL Options, select Server Order Preference to use the order listed in the
Predefined SSL Security Policies (p. 30) for SSL negotiation.
Under SSL Ciphers, select one or more ciphers to enable. If you already have an SSL
certificate, you must enable the cipher that was used to create the certificate, because DSA
and RSA ciphers are specific to the signing algorithm.
Click Save.
Update the SSL Negotiation Configuration Using
the AWS CLI
You can use the current predefined security policy, ELBSecurityPolicy-2015-05, a different predefined
security policy, or a custom security policy.
To use a predefined SSL security policy
1.
Use the following describe-load-balancer-policies command to list the predefined security policies
provided by Elastic Load Balancing:
aws elb describe-load-balancer-policies --query "PolicyDescriptions[?Poli
cyTypeName==`SSLNegotiationPolicyType`].{PolicyName:PolicyName}" --output
table
The following is example output:
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Update the SSL Negotiation Configuration Using the
AWS CLI
-----------------------------------------|
DescribeLoadBalancerPolicies
|
+----------------------------------------+
|
PolicyName
|
+----------------------------------------+
| ELBSecurityPolicy-2015-05
|
| ELBSecurityPolicy-2015-03
|
| ELBSecurityPolicy-2015-02
|
| ELBSecurityPolicy-2014-10
|
| ELBSecurityPolicy-2014-01
|
| ELBSecurityPolicy-2011-08
|
| ELBSample-ELBDefaultCipherPolicy
|
| ELBSample-OpenSSLDefaultCipherPolicy |
+----------------------------------------+
To determine which ciphers are enabled for a policy, use the following command:
aws elb describe-load-balancer-policies --policy-names ELBSecurityPolicy2015-05 --output table
2.
For information about the configuration for the predefined security policies, see Predefined SSL
Security Policies (p. 30).
Use the create-load-balancer-policy command to create an SSL negotiation policy using one of the
predefined security policies that you described in the previous step. For example, the following
command uses the current predefined security policy:
aws elb create-load-balancer-policy --load-balancer-name my-loadbalancer
--policy-name my-SSLNegotiation-policy --policy-type-name SSLNegotiation
PolicyType
--policy-attributes AttributeName=Reference-Security-Policy,AttributeValue=ELB
SecurityPolicy-2015-05
3.
(Optional) Use the following describe-load-balancer-policies command to verify that the policy is
created:
aws elb describe-load-balancer-policies --load-balancer-name my-loadbalancer
--policy-name my-SSLNegotiation-policy
4.
The response includes the description of the policy.
Use the following set-load-balancer-policies-of-listener command to enable the policy on load balancer
port 443:
aws elb set-load-balancer-policies-of-listener --load-balancer-name myloadbalancer --load-balancer-port 443 --policy-names my-SSLNegotiation-policy
Note
The set-load-balancer-policies-of-listener command replaces the current set
of policies for the specified load balancer port with the the specified set of policies. The
--policy-names list must include all policies to be enabled. If you omit a policy that is
currently enabled, it is disabled.
5.
(Optional) Use the following describe-load-balancers command to verify that the new policy is enabled
for the load balancer port:
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Update the SSL Negotiation Configuration Using the
AWS CLI
aws elb describe-load-balancers --load-balancer-name my-loadbalancer
The response shows that the policy is enabled on port 443.
...
{
"Listener": {
"InstancePort": 443,
"SSLCertificateId": "ARN",
"LoadBalancerPort": 443,
"Protocol": "HTTPS",
"InstanceProtocol": "HTTPS"
},
"PolicyNames": [
"my-SSLNegotiation-policy"
]
}
...
When you create a custom security policy, you must enable at least one protocol and one cipher. The
DSA and RSA ciphers are specific to the signing algorithm and are used to create the SSL certificate. If
you already have an SSL certificate, be sure to enable the cipher that was used to create the certificate.
The name of your custom policy must not begin with ELBSecurityPolicy- or ELBSample-, as these
prefixes are reserved for the names of the predefined security policies.
To use a custom SSL security policy
1.
Use the create-load-balancer-policy command to create an SSL negotiation policy using a custom
security policy. For example:
aws elb create-load-balancer-policy --load-balancer-name my-loadbalancer
--policy-name my-SSLNegotiation-policy --policy-type-name SSLNegotiation
PolicyType
--policy-attributes AttributeName=Protocol-TLSv1.2,AttributeValue=true
AttributeName=Protocol-TLSv1.1,AttributeValue=true
AttributeName=DHE-RSA-AES256-SHA256,AttributeValue=true
AttributeName=Server-Defined-Cipher-Order,AttributeValue=true
2.
(Optional) Use the following describe-load-balancer-policies command to verify that the policy is
created:
aws elb describe-load-balancer-policies --load-balancer-name my-loadbalancer
--policy-name my-SSLNegotiation-policy
3.
The response includes the description of the policy.
Use the following set-load-balancer-policies-of-listener command to enable the policy on load balancer
port 443:
aws elb set-load-balancer-policies-of-listener --load-balancer-name myloadbalancer --load-balancer-port 443 --policy-names my-SSLNegotiation-policy
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Elastic Load Balancing Developer Guide
Update the SSL Negotiation Configuration Using the
AWS CLI
Note
The set-load-balancer-policies-of-listener command replaces the current set
of policies for the specified load balancer port with the the specified set of policies. The
--policy-names list must include all policies to be enabled. If you omit a policy that is
currently enabled, it is disabled.
4.
(Optional) Use the following describe-load-balancers command to verify that the new policy is enabled
for the load balancer port:
aws elb describe-load-balancers --load-balancer-name my-loadbalancer
The response shows that the policy is enabled on port 443.
...
{
"Listener": {
"InstancePort": 443,
"SSLCertificateId": "ARN",
"LoadBalancerPort": 443,
"Protocol": "HTTPS",
"InstanceProtocol": "HTTPS"
},
"PolicyNames": [
"my-SSLNegotiation-policy"
]
}
...
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Elastic Load Balancing Developer Guide
Best Practices for Your Back-end Instances
Back-end Instances for Your Load
Balancer
After you've created your load balancer, you must register your EC2 instances with the load balancer.
You can select EC2 instances from a single Availability Zone or multiple Availability Zones within the
same region as the load balancer. Elastic Load Balancing routinely performs health checks on registered
EC2 instances, and automatically distributes incoming requests to the DNS name of your load balancer
across the registered, healthy EC2 instances.
Contents
• Best Practices for Your Back-end Instances (p. 58)
• Configure Health Checks (p. 59)
• Configure Security Groups for Your Load Balancer (p. 61)
• Add or Remove Availability Zones for Your Load Balancer in EC2-Classic (p. 68)
• Add or Remove Subnets for Your Load Balancer in a VPC (p. 70)
• Register or De-Register EC2 Instances for Your Load Balancer (p. 73)
Best Practices for Your Back-end Instances
• Install a web server, such as Apache or Internet Information Services (IIS), on all instances that you
plan to register with your load balancer.
• For HTTP and HTTPS listeners, we recommend that you enable the keep-alive option in your EC2
instances, which enables the load balancer to re-use the connections to your instances for multiple
client requests. This reduces the load on your web server and improves the throughput of the load
balancer. The keep-alive timeout should be at least 60 seconds to ensure that the load balancer is
responsible for closing the connection to your instance.
• Elastic Load Balancing supports Path Maximum Transmission Unit (MTU) Discovery. To ensure that
Path MTU Discovery can function correctly, you must ensure that the security group for your instance
allows ICMP fragmentation required (type 3, code 4) messages. For more information, see Path MTU
Discovery in the Amazon EC2 User Guide for Linux Instances.
• The security group for your back-end instances should have inbound rules for the listener port and the
health check port for your load balancer, with the source as the security group for your load balancer.
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Configure Health Checks
Configure Health Checks
To discover the availability of your EC2 instances, the load balancer periodically sends pings, attempts
connections, or sends requests to test the EC2 instances. These tests are called health checks. The
status of the instances that are healthy at the time of the health check is InService. The status of any
instances that are unhealthy at the time of the health check is OutOfService. The load balancer performs
health checks on all registered instances, whether the instance is in a healthy state or an unhealthy state.
The load balancer routes requests only to the healthy instances. When the load balancer determines that
an instance is unhealthy, it stops routing requests to that instance. The load balancer resumes routing
requests to the instance when it has been restored to a healthy state.
The load balancer checks the health of the registered instances using either the default health check
configuration provided by Elastic Load Balancing or a health check configuration that you configure.
If you have associated your Auto Scaling group with a load balancer, you can use the load balancer health
check to determine the health state of instances in your Auto Scaling group. By default, an Auto Scaling
group periodically determines the health state of each instance. For more information, see Add an Elastic
Load Balancing Health Check to Your Auto Scaling Group in the Auto Scaling Developer Guide.
Contents
• Health Check Configuration (p. 59)
• Update the Health Check Configuration (p. 60)
• Check the Health of Your Instances (p. 61)
• Troubleshoot Health Checks (p. 61)
Health Check Configuration
A health configuration contains the information that a load balancer uses to determine the health state
of the registered instances. The following table describes the health check configuration fields.
Field
Description
Ping Protocol
The protocol to use to connect with the instance.
Valid values: TCP, HTTP, HTTPS, and SSL
Console default: HTTP
CLI/API default: TCP
Ping Port
The port to use to connect with the instance, as a protocol:port pair. If the load balancer fails to connect with
the instance at the specified port within the configured response timeout period, the instance is considered unhealthy.
Ping protocols: TCP, HTTP, HTTPS, and SSL
Ping port range: 1 to 65535
Console default: HTTP:80
CLI/API default: TCP:80
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Elastic Load Balancing Developer Guide
Update the Health Check Configuration
Field
Description
Ping Path
The destination for the HTTP or HTTPS request.
An HTTP or HTTPS GET request is issued to the instance
on the ping port and the ping path. If the load balancer receives any response other than "200 OK" within the response
timeout period, the instance is considered unhealthy. If the
response includes a body, your application must either set
the Content-Length header to a value greater than or equal
to zero, or specify Transfer-Encoding with a value set to
'chunked'.
Default: /index.html
Response Timeout
The amount of time to wait when receiving a response from
the health check, in seconds.
Valid values: 2 to 60
Default: 5
HealthCheck Interval
The amount of time between health checks of an individual
instance, in seconds.
Valid values: 5 to 300
Default: 30
Unhealthy Threshold
The number of consecutive failed health checks that must
occur before declaring an EC2 instance unhealthy.
Valid values: 2 to 10
Default: 2
Healthy Threshold
The number of consecutive successful health checks that
must occur before declaring an EC2 instance healthy.
Valid values: 2 to 10
Default: 10
The load balancer sends a request to each registered instance at the ping port and ping path every
Interval seconds. It waits for the instance to respond within the response timeout period. If the health
checks exceed the threshold for consecutive failed responses, the load balancer takes the instance out
of service. When the health checks exceed the threshold for consecutive successful responses, the load
balancer puts the instance back in service.
Update the Health Check Configuration
You can update the health check configuration for your load balancer at any time.
To update the health check configuration for your load balancer using the console
1.
2.
3.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
Select your load balancer.
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Check the Health of Your Instances
4.
5.
On the Health Check tab, click Edit Health Check.
In the Configure Health Check dialog box, update the settings as needed.
6.
Click Save.
To update the health check configuration for your load balancer using the AWS CLI
Use the following configure-health-check command:
aws elb configure-health-check --load-balancer-name my-load-balancer --healthcheck Target=HTTP:80/ping,Interval=30,Un
healthyThreshold=2,HealthyThreshold=2,Timeout=3
Check the Health of Your Instances
You can check the health status of your registered instances.
To check the health status of your instances using the console
1.
2.
3.
4.
5.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
Select your load balancer.
On the Description tab, find the Status row. The status message indicates how many instances are
in service.
On the Instances tab, the Status column indicates the status of the instance.
To check the health status of your instances using the AWS CLI
Use the following describe-instance-health command:
aws elb describe-instance-health --load-balancer-name my-load-balancer
Troubleshoot Health Checks
Your registered instances can fail the load balancer health check for several reasons. The most common
reasons for failing a health check are where EC2 instances close connections to your load balancer or
where the response from the EC2 instances times out. For information about potential causes and steps
you can take to resolve failed health check issues, see Troubleshooting Elastic Load Balancing: Health
Checks (p. 130).
Configure Security Groups for Your Load
Balancer
A security group acts as a firewall that controls the traffic allowed to and from one or more instances.
When you launch an EC2 instance, you can associate one or more security groups with the instance.
For each security group, you add one or more rules to allow traffic.You can modify the rules for a security
group at any time; the new rules are automatically applied to all instances associated with the security
group. For more information, see Amazon EC2 Security Groups in the Amazon EC2 User Guide for Linux
Instances.
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Elastic Load Balancing Developer Guide
Security Groups for Load Balancers in a VPC
There is a significant difference between the way Elastic Load Balancing supports security groups in
EC2-Classic and in a VPC. In EC2-Classic, Elastic Load Balancing provides a special source security
group that you can use to ensure that back-end instances receives traffic only from your load balancer.
You can't modify this source security group. In a VPC, you provide the security group for your load
balancer, which enables you to choose the ports and protocols to allow. For example, you can open
Internet Control Message Protocol (ICMP) connections for the load balancer to respond to ping requests
(however, ping requests are not forwarded to any back-end instances).
In both EC2-Classic and in a VPC, you must ensure that the security groups for your instances allow the
load balancer to communicate with your back-end instances on both the listener port and the health check
port. In a VPC, your security groups and network access control lists (ACL) must allow traffic in both
directions on these ports.
Contents
• Security Groups for Load Balancers in a VPC (p. 62)
• Security Groups for Back-end Instances in a VPC (p. 64)
• Network ACLs for Load Balancers in a VPC (p. 64)
• Security Groups for Back-end Instances in EC2-Classic (p. 66)
Security Groups for Load Balancers in a VPC
When you use the AWS Management Console to create a load balancer in a VPC, you can choose an
existing security group for the VPC or create a new security group for the VPC. If you choose an existing
security group, it must allow traffic in both directions to the listener and health check ports for the load
balancer. If you choose to create a security group, the console automatically adds rules to allow all traffic
on these ports.
[Nondefault VPC] If you use the AWS CLI or API create a load balancer in a nondefault VPC, but you
don't specify a security group, your load balancer is automatically associated with the default security
group for the VPC.
[Default VPC] If you use the AWS CLI or API to create a load balancer in your default VPC, you can't
choose an existing security group for your load balancer. Instead, Elastic Load Balancing provides a
security group with rules to allow all traffic on the ports specified for the load balancer. Elastic Load
Balancing creates only one such security group per AWS account, with a name of the form default_elb_id
(for example, default_elb_fc5fbed3-0405-3b7d-a328-ea290EXAMPLE). Subsequent load balancers
that you create in the default VPC also use this security group. Be sure to review the security group rules
to ensure that they allow traffic on the listener and health check ports for the new load balancer. When
you delete your load balancer, this security group is not deleted automatically.
If you add a listener to an existing load balancer, you must review your security groups to ensure they
allow traffic on the new listener port in both directions.
Contents
• Recommended Rules for Load Balancer Security Groups (p. 62)
• Manage Security Groups Using the Console (p. 63)
• Manage Security Groups Using the AWS CLI (p. 63)
Recommended Rules for Load Balancer Security Groups
The security groups for your load balancers must allow them to communicate with your back-end instances.
The recommended rules depend on the type of load balancer (Internet-facing or internal).
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Security Groups for Load Balancers in a VPC
Internet-facing Load Balancer: Recommended Rules
Inbound
Source
Protocol
Port Range
Comment
0.0.0.0/0
TCP
listener
Allow all inbound traffic on the load balancer listener port
Protocol
Port Range
Comment
instance secur- TCP
ity group
instance
listener
Allow outbound traffic to back-end instances on the instance listener port
instance secur- TCP
ity group
health check
Allow outbound traffic to back-end instances on the health check port
Outbound
Destination
Internal Load Balancer: Recommended Rules
Inbound
Source
Protocol
Port Range
Comment
VPC CIDR
TCP
listener
Allow inbound traffic from the VPC CIDR
on the load balancer listener port
Protocol
Port Range
Comment
instance secur- TCP
ity group
instance
listener
Allow outbound traffic to back-end instances on the instance listener port
instance secur- TCP
ity group
health check
Allow outbound traffic to back-end instances on the health check port
Outbound
Destination
Manage Security Groups Using the Console
Use the following procedure to change the security group associated with your load balancer in a VPC.
To update a security group assigned to your load balancer
1.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
2.
3.
4.
5.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
Select your load balancer.
Select the Security tab.
Click Edit.
6.
Select the security group and then click Save.
Manage Security Groups Using the AWS CLI
Use the following apply-security-groups-to-load-balancer command to assign an additional security group
to a load balancer in a VPC:
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Elastic Load Balancing Developer Guide
Security Groups for Back-end Instances in a VPC
aws elb apply-security-groups-to-load-balancer --load-balancer-name my-loadbal
ancer --security-groups sg-53fae93f
The following is an example response:
{
"SecurityGroups": [
"sg-fc448899"
"sg-53fae93f"
]
}
Security Groups for Back-end Instances in a VPC
The security groups for your back-end instances must allow them to communicate with the load balancer.
Back-end Instances: Recommended Rules
Inbound
Source
Protocol
Port Range
Comment
load balancer security
group
TCP
instance
listener
Allow traffic from the load balancer on
the instance listener port
load balancer security
group
TCP
health
check
Allow traffic from the load balancer on
the health check port
Network ACLs for Load Balancers in a VPC
The default network access control list (ACL) for the VPC allows all inbound and outbound traffic. If you
create custom network ACLs, you must add rules that allow the load balancer and back-end instances
to communicate.
The recommended rules for the subnet for your load balancer depend on the type of load balancer
(Internet-facing or internal).
Internet-Facing Load Balancer: Recommended Rules
Inbound
Source
Protocol
Port
Comment
0.0.0.0/0
TCP
listener
Allow all inbound traffic on the load balancer listener port
VPC CIDR
TCP
1024-65535
Allow inbound traffic from the VPC CIDR
on the ephemeral ports
Destination
Protocol
Port
Comment
0.0.0.0/0
TCP
instance
listener
Allow all outbound traffic on the instance
listener port
Outbound
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0.0.0.0/0
TCP
health check
Allow all outbound traffic on the health
check port
0.0.0.0/0
TCP
1024-65535
Allow all outbound traffic on the ephemeral ports
Internal Load Balancer: Recommended Rules
Inbound
Source
Protocol
Port
Comment
VPC CIDR
TCP
listener
Allow inbound traffic from the VPC CIDR
on the load balancer listener port
VPC CIDR
TCP
1024-65535
Allow inbound traffic from the VPC CIDR
on the ephemeral ports
Destination
Protocol
Port
Comment
VPC CIDR
TCP
instance
listener
Allow outbound traffic to the VPC CIDR
on the instance listener port
VPC CIDR
TCP
health check
Allow outbound traffic to the VPC CIDR
on the health check port
VPC CIDR
TCP
1024-65535
Allow outbound traffic to the VPC CIDR
on the ephemeral ports
Outbound
The recommended rules for the subnet for your back-end instances depend on whether the subnet is
private or public. The following rules are for a private subnet. If your back-end instances are in a public
subnet, change the source and destination from the CIDR of the VPC to 0.0.0.0/0.
Back-End Instances: Recommended Rules
Inbound
Source
Protocol
Port
Comment
VPC CIDR
TCP
instance
listener
Allow inbound traffic from the VPC CIDR
on the instance listener port
VPC CIDR
TCP
health check
Allow inbound traffic from the VPC CIDR
on the health check port
Destination
Protocol
Port
Comment
VPC CIDR
TCP
1024-65535
Allow outbound traffic to the VPC CIDR
on the ephemeral ports
Outbound
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Security Groups for Back-end Instances in EC2-Classic
Security Groups for Back-end Instances in
EC2-Classic
To allow communication between your load balancer and your back-end instances launched in EC2-Classic,
create an inbound rule for the security group for your back-end instances that allows inbound traffic from
either all IP addresses (using the 0.0.0.0/0 CIDR block) or only from the load balancer (using the
source security group provided by Elastic Load Balancing).
Use the following procedure to lock down traffic between your load balancer and your back-end instances
in EC2-Classic.
To lock down traffic between your load balancer and instances using the console
1.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
2.
3.
4.
5.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
Select your load balancer.
Select the Security tab.
Copy the name of the source security group.
6.
Add a rule to the security group for your back-end instances as follows:
a.
b.
c.
d.
e.
f.
On the Instances tab, click the instance ID of one of the instances registered with your load
balancer.
On the Description tab, find Security groups, and then click the name of the security group.
On the Inbound tab, click Edit, and then click Add Rule.
From the Type column, select the protocol type. The Protocol and Port Range columns are
populated.
From the Source column, select Custom IP. In the box, paste the name of the source security
group that you copied earlier (for example, amazon-elb/amazon-elb-sg).
(Optional) If your security group has rules that are less restrictive than the rule you just added,
remove the less restrictive rule by clicking its delete icon.
Important
If you need to connect to your back-end instances, do not delete the inbound rules that
allow traffic on port 22 (SSH) or port 3389 (RDP).
g.
Click Save.
To lock down traffic between your load balancer and instances using the AWS CLI
1.
Use the following describe-load-balancers command to display the name and owner of the source
security group for your load balancer:
aws elb describe-load-balancers --load-balancer-name my-loadbalancer
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The response includes the name and owner in the SourceSecurityGroup field. For example:
{
"LoadBalancerDescriptions": [
{
...
"SourceSecurityGroup": {
"OwnerAlias": "amazon-elb",
"GroupName": "amazon-elb-sg"
}
}
]
}
2.
Add a rule to the security group for your back-end instances as follows:
a.
If you do not know the name of the security group for your back-end instances, use the following
describe-instances command to get the name and ID of the security group for the specified
back-end instance:
aws ec2 describe-instances --instance-ids i-315b7e51
b.
The response includes the name and ID of the security group in the SecurityGroups field.
Make a note of the name of the security group; you'll use it in the next step.
Use the following authorize-security-group-ingress command to add a rule to the security group
for your back-end instance to allow traffic from your load balancer:
aws ec2 authorize-security-group-ingress --group-name my-security-group
--source-security-group-name amazon-elb-sg --source-security-groupowner-id amazon-elb
3.
(Optional) Use the following describe-security-groups command to verify that the security group has
the new rule:
aws ec2 describe-security-groups --group-names my-security-group
The response includes a UserIdGroupPairs data structure that lists the security groups that are
granted permissions to access the instance.
{
"SecurityGroups": [
{
...
"IpPermissions": [
{
"IpRanges": [],
"FromPort": -1,
"IpProtocol": "icmp",
"ToPort": -1,
"UserIdGroupPairs": [
{
"GroupName": "amazon-elb-sg",
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"GroupId": "sg-5a9c116a",
"UserId": "amazon-elb"
}
]
},
{
"IpRanges": [],
"FromPort": 1,
"IpProtocol": "tcp",
"ToPort": 65535,
"UserIdGroupPairs": [
{
"GroupName": "amazon-elb-sg",
"GroupId": "sg-5a9c116a",
"UserId": "amazon-elb"
}
]
},
{
"IpRanges": [],
"FromPort": 1,
"IpProtocol": "udp",
"ToPort": 65535,
"UserIdGroupPairs": [
{
"GroupName": "amazon-elb-sg",
"GroupId": "sg-5a9c116a",
"UserId": "amazon-elb"
}
]
},
. . .
}
4.
(Optional) If your security group has rules that are less restrictive than the rule you just added, use
the revoke-security-group-ingress command to remove the less restrictive rules. For example, the
following command removes a rule that allows TCP traffic from everyone (CIDR range 0.0.0.0/0):
aws ec2 revoke-security-group-ingress --group-name my-security-group --pro
tocol tcp --port 80 --cidr 0.0.0.0/0
Important
If you need to connect to your back-end instances, do not delete the inbound rules that allow
traffic on port 22 (SSH) or port 3389 (RDP).
Add or Remove Availability Zones for Your Load
Balancer in EC2-Classic
When you attach an Availability Zone to your load balancer, Elastic Load Balancing creates a load balancer
node in the Availability Zone. Load balancer nodes accept traffic from clients and forward requests to the
healthy registered instances in one or more Availability Zones.
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Add an Availability Zone
You can set up your load balancer in EC2-Classic to distribute incoming requests across EC2 instances
in a single Availability Zone or multiple Availability Zones. First, launch EC2 instances in all the Availability
Zones that you plan to use. Next, register these instances with your load balancer. Finally, attach the
Availability Zones to your load balancer. After you attach an Availability Zone, the load balancer starts
routing requests to the registered instances in that Availability Zone. Note that you can modify the
Availability Zones attached to your load balancer at any time.
By default, the load balancer routes requests evenly across its attached Availability Zones. To route
requests evenly across the registered instances in the attached Availability Zones, enable cross-zone
load balancing. For more information, see Configure Cross-Zone Load Balancing for Your Load
Balancer (p. 83).
You might want to detach an Availability Zone from your load balancer temporarily when it has no healthy
registered instances or when you want to troubleshoot or update the registered instances. After you've
detached an Availability Zone, the load balancer stops routing requests to the registered instances in this
Availability Zone but continues to route requests to the registered instances in the remaining attached
Availability Zones.
If your load balancer is in a VPC, see Add or Remove Subnets for Your Load Balancer in a VPC (p. 70).
Contents
• Add an Availability Zone (p. 69)
• Remove an Availability Zone (p. 70)
Add an Availability Zone
You can expand the availability of your application to an additional Availability Zone. Register the instances
in this Availability Zone with the load balancer, then attach the Availability Zone. For more information,
see Register or De-Register EC2 Instances for Your Load Balancer (p. 73).
To add an Availability Zone using the console
1.
2.
3.
4.
5.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
Select your load balancer.
In the bottom pane, select the Instances tab.
Click Edit Availability Zones.
6.
In the Add and Remove Availability Zones dialog box, select the new Availability Zone, and then
click Save.
To add an Availability Zone using the AWS CLI
Use the following enable-availability-zones-for-load-balancer command to attach an Availability Zone:
aws elb enable-availability-zones-for-load-balancer --load-balancer-name myloadbalancer --availability-zones us-west-2b
The response lists all attached Availability Zones for the load balancer. For example:
{
"AvailabilityZones": [
"us-west-2a",
"us-west-2b"
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]
}
Remove an Availability Zone
You can detach an Availability Zone from your load balancer. Note that after you detach an Availability
Zone, the back-end instances in that Availability Zone remain registered with the load balancer. For more
information, see Register or De-Register EC2 Instances for Your Load Balancer (p. 73).
To remove an Availability Zone using the console
1.
2.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
3.
4.
5.
6.
Select your load balancer.
In the bottom pane, select the Instances tab.
Click Edit Availability Zones.
In the Add and Remove Availability Zones dialog box, deselect the Availability Zone, and then
click Save.
To remove an Availability Zone using the AWS CLI
Use the following disable-availability-zones-for-load-balancer command:
aws elb disable-availability-zones-for-load-balancer --load-balancer-name myloadbalancer --availability-zones us-west-2a
The response lists the remaining attached Availability Zones for the load balancer. For example:
{
"AvailabilityZones": [
"us-west-2b"
]
}
Add or Remove Subnets for Your Load Balancer
in a VPC
When you attach a subnet to your load balancer, Elastic Load Balancing creates a load balancer node
in the Availability Zone. Load balancer nodes accept traffic from clients and forward requests to the healthy
registered instances in one or more Availability Zones. For load balancers in a VPC, we recommend that
you attach one subnet per Availability Zone for at least two Availability Zones. This improves the availability
of your load balancer. Note that you can modify the subnets attached to your load balancer at any time.
Select subnets from the same Availability Zones as your instances. If your load balancer is an
Internet-facing load balancer, you must select public subnets in order for your back-end instances to
receive traffic from the load balancer (even if the back-end instances are in private subnets). If you load
balancer is an internal load balancer, we recommend that you select private subnets. For more information
about subnets for your load balancer, see Prepare Your VPC and Back-end Instances (p. 6).
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Requirements
After you attach a subnet, the load balancer starts routing requests to the registered instances in the
corresponding Availability Zone. By default, the load balancer routes requests evenly across the Availability
Zones for its attached subnets. To route requests evenly across the registered instances in the Availability
Zones for its attached subnets, enable cross-zone load balancing. For more information, see Configure
Cross-Zone Load Balancing for Your Load Balancer (p. 83).
You might want to detach a subnet from your load balancer temporarily when its Availability Zone has no
healthy registered instances, or when you want to troubleshoot or update the registered instances. After
you've detached a subnet, the load balancer stops routing requests to the registered instances in its
Availability Zone, but continues to route requests to the registered instances in the Availability Zones for
the remaining attached subnets.
If your load balancer is in EC2-Classic, see Add or Remove Availability Zones for Your Load Balancer in
EC2-Classic (p. 68).
Contents
• Requirements (p. 71)
• Add a Subnet (p. 71)
• Remove a Subnet (p. 72)
Requirements
When you update the subnets for your load balancer, you must meet the following requirements:
• The load balancer must have at least one attached subnet at all times.
• You can attach at most one subnet per Availability Zone.
Because there are separate APIs to attach and detach subnets from a load balancer, you must consider
the order of operations carefully when swapping the attached subnets for new subnets in order to meet
these requirements. Also, you must temporarily attach a subnet from another Availability Zone if you need
to swap all attached subnets for your load balancer. For example, if your load balancer has a single
Availability Zone and you need to swap its subnet for another subnet, you must first attach a subnet from
a second Availability Zone. Then you can detach the subnet from the original Availability Zone (without
going below one attached subnet), attach a new subnet from the original Availability Zone (without
exceeding one subnet per Availability Zone), and then detach the subnet from the second Availability
Zone (if it is only needed to perform the swap).
Add a Subnet
You can expand the availability of your load balancer to an additional subnet. Register the instances in
this subnet with the load balancer, then attach a subnet to the load balancer that is from the same
Availability Zone as the instances. For more information, see Register or De-Register EC2 Instances for
Your Load Balancer (p. 73).
To attach a subnet to your load balancer using the console
1.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
2.
3.
4.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
Select your load balancer.
In the bottom pane, select the Instances tab.
5.
6.
Click Edit Availability Zones.
In the Add and Remove Subnets dialog box, under Available Subnets, click the icon in the Action
column for the subnet to attach. The subnets are moved under Selected Subnets.
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Remove a Subnet
7.
Note that you can select at most one subnet per Availability Zone. If you select a subnet from an
Availability Zone where there is already a selected subnet, this subnet replaces the currently selected
subnet for the Availability Zone.
Click Save.
To attach a subnet to your load balancer using the CLI
Use the following attach-load-balancer-to-subnets command to attach two subnets to your load balancer:
aws elb attach-load-balancer-to-subnets --load-balancer-name my-load-balancer
--subnets subnet-dea770a9 subnet-fb14f6a2
The response lists all attached subnets for the load balancer. For example:
{
"Subnets": [
"subnet-5c11033e",
"subnet-dea770a9",
"subnet-fb14f6a2"
]
}
Remove a Subnet
You can detach a subnet from your load balancer. Note that after you detach a subnet, the back-end
instances in that subnet remain registered with the load balancer. For more information, see Register or
De-Register EC2 Instances for Your Load Balancer (p. 73).
To detach a subnet using the console
1.
2.
3.
4.
5.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
Select your load balancer.
In the bottom pane, select the Instances tab.
Click Edit Availability Zones.
6.
In the Add and Remove Subnets dialog box, under Selected Subnets, click the icon in the Action
column for the subnet to detach. The subnets are moved under Available Subnets.
Click Save.
7.
To detach a subnet using the AWS CLI
Use the following detach-load-balancer-from-subnets command as to detach the specified subnets from
the specified load balancer:
aws elb detach-load-balancer-from-subnets --load-balancer-name my-loadbalancer
--subnets subnet-450f5127
The response lists the remaining attached subnets for the load balancer. For example:
{
"Subnets": [
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Register or De-register Instances
"subnet-15aaab61"
]
}
Register or De-Register EC2 Instances for Your
Load Balancer
Registering an EC2 instance adds it to your load balancer. The load balancer continuously monitors the
health of registered instances in its enabled Availability Zones, and routes requests to the instances that
are healthy. If demand on your instances increases, you can register additional instances with the load
balancer to handle the demand.
De-registering an EC2 instance removes it from your load balancer. The load balancer stops routing
requests to an instance as soon as it is de-registered. If demand decreases, or you need to service your
instances, you can de-register instances from the load balancer. A de-registered instance remains running,
but no longer receives traffic from the load balancer, and you can register it with the load balancer again
when you are ready.
When you de-register an instance, Elastic Load Balancing waits until in-flight requests have completed
if connection draining is enabled. For more information, see Configure Connection Draining for Your Load
Balancer (p. 86).
If your load balancer is attached to an Auto Scaling group, instances added to the group are automatically
registered with the load balancer and instances removed from the group are automatically de-registered
from the load balancer. For more information, see Load Balance Your Auto Scaling Group.
Elastic Load Balancing registers your EC2 instance with your load balancer using its IP address.
[EC2-VPC] When you register an instance with an elastic network interface (ENI) attached, the load
balancer routes requests to the primary IP address of the primary interface (eth0) of the instance.
Contents
• Prerequisites (p. 73)
• Register an Instance (p. 73)
• De-register an Instance (p. 74)
Prerequisites
The instance must be a running instance in the same network as the load balancer (EC2-Classic or the
same VPC). If you have EC2-Classic instances and a load balancer in a VPC with ClassicLink enabled,
you can link the EC2-Classic instances to that VPC and then register them with a load balancer in the
VPC.
Register an Instance
When you are ready, register your instance with your load balancer. If the instance is an in Availability
Zone that is enabled for the load balancer, the instance is ready to receive traffic from the load balancer
as soon as it passes the required number of health checks.
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De-register an Instance
To register your instances using the console
1.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
2.
3.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
Select your load balancer.
4.
5.
6.
In the bottom pane, select the Instances tab.
Click Edit Instances.
Select the instance to register with your load balancer.
7.
Click Save.
To register your instances using the AWS CLI
Use the following register-instances-with-load-balancer command:
aws elb register-instances-with-load-balancer --load-balancer-name my-loadbal
ancer --instances i-4e05f721
The following is an example response that lists the instances registered with the load balancer:
{
"Instances": [
{
"InstanceId": "i-315b7e51"
},
{
"InstanceId": "i-4e05f721"
}
]
}
De-register an Instance
You can de-register a back-end instance from your load balancer if you no longer need the capacity or
if you need to service the instance.
To de-register your instances using the console
1.
2.
3.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
Select your load balancer.
4.
5.
In the bottom pane, select the Instances tab.
In Actions column for the instance to de-register, click Remove from Load Balancer.
6.
When prompted for confirmation, click Yes, Remove.
To de-register your instances using the AWS CLI
Use the following deregister-instances-from-load-balancer command:
aws elb deregister-instances-from-load-balancer --load-balancer-name my-loadbal
ancer --instances i-4e05f721
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De-register an Instance
The following is an example response that lists the remaining instances registered with the load balancer:
{
"Instances": [
{
"InstanceId": "i-315b7e51"
}
]
}
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Listeners for Your Load Balancer
Before you start using Elastic Load Balancing, you must configure one or more listeners for your load
balancer. A listener is a process that checks for connection requests. It is configured with a protocol and
a port for front-end (client to load balancer) connections, and a protocol and a port for back-end (load
balancer to back-end instance) connections.
Elastic Load Balancing supports the following protocols:
•
•
•
•
HTTP
HTTPS (secure HTTP)
TCP
SSL (secure TCP)
The HTTPS protocol uses the SSL protocol to establish secure connections over the HTTP layer. You
can also use the SSL protocol to establish secure connections over the TCP layer.
If the front-end connection uses TCP or SSL, then your back-end connections can use either TCP or
SSL. If the front-end connection uses HTTP or HTTPS, then your back-end connections can use either
HTTP or HTTPS.
Back-end instances can listen on ports 1-65535.
Load balancers can listen on the following ports:
• [EC2-VPC] 1-65535
• [EC2-Classic] 25, 80, 443, 465, 587, 1024-65535
Contents
• Protocols (p. 77)
• HTTPS/SSL Listeners (p. 78)
• Listener Configurations for Your Load Balancer (p. 78)
• X-Forwarded Headers for Elastic Load Balancing (p. 80)
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Protocols
Protocols
Communication for a typical web application goes through layers of hardware and software. Each layer
provides a specific communication function. The control over the communication function is passed from
one layer to the next, in sequence. The Open System Interconnection (OSI) defines a model framework
for implementing a standard format for communication, called a protocol, in these layers. For more
information, see OSI model in Wikipedia.
When you use Elastic Load Balancing, you need a basic understanding of layer 4 and layer 7. Layer 4
is the transport layer that describes the Transmission Control Protocol (TCP) connection between the
client and your back-end instance, through the load balancer. Layer 4 is the lowest level that is configurable
for your load balancer. Layer 7 is the application layer that describes the use of Hypertext Transfer Protocol
(HTTP) and HTTPS (secure HTTP) connections from clients to the load balancer and from the load
balancer to your back-end instance.
The Secure Sockets Layer (SSL) protocol is primarily used to encrypt confidential data over insecure
networks such as the Internet. The SSL protocol establishes a secure connection between a client and
the back-end server, and ensures that all the data passed between your client and your server is private
and integral.
TCP/SSL Protocol
When you use TCP (layer 4) for both front-end and back-end connections, your load balancer forwards
the request to the back-end instances without modifying the headers. After your load balancer receives
the request, it attempts to open a TCP connection to the back-end instance on the port specified in the
listener configuration.
Because load balancers intercept traffic between clients and your back-end instances, the access logs
for your back-end instance contain the IP address of the load balancer instead of the originating client.
You can enable Proxy Protocol, which adds a header with the connection information of the client, such
as the source IP address, destination IP address, and port numbers. The header is then sent to the
back-end instance as a part of the request. You can parse the first line in the request to retrieve the
connection information. For more information, see Configure Proxy Protocol Support for Your Load
Balancer (p. 88).
Using this configuration, you do not receive cookies for session stickiness or X-Forwarded headers.
HTTP/HTTPS Protocol
When you use HTTP (layer 7) for both front-end and back-end connections, your load balancer parses
the headers in the request and terminates the connection before sending the request to the back-end
instances.
For every registered and healthy instance behind an HTTP/HTTPS load balancer, Elastic Load Balancing
opens and maintains one or more TCP connections. These connections ensure that there is always an
established connection ready to receive HTTP/HTTPS requests.
The HTTP requests and HTTP responses use header fields to send information about HTTP messages.
Elastic Load Balancing supports X-Forwarded-For headers. Because load balancers intercept traffic
between clients and servers, your server access logs contain only the IP address of the load balancer.
To see the IP address of the client, use the X-Forwarded-For request header. For more information,
see X-Forwarded-For (p. 80).
When you use HTTP/HTTPS, you can enable sticky sessions on your load balancer. A sticky session
binds a user's session to a specific back-end instance. This ensures that all requests coming from the
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HTTPS/SSL Listeners
user during the session are sent to the same back-end instance. For more information, see Configure
Sticky Sessions for Your Load Balancer (p. 92).
Not all HTTP extensions are supported in the load balancer. You may need to use a TCP listener if the
load balancer is not able to terminate the request due to unexpected methods, response codes, or other
non-standard HTTP 1.0/1.1 implementations.
HTTPS/SSL Listeners
You can create an HTTPS load balancer with the following security features.
SSL Server Certificates
If you use HTTPS or SSL for your front-end listener, you must deploy an X.509 certificate (SSL server
certificate) on your load balancer. The load balancer decrypts requests from clients before sending them
to the back-end instances (known as SSL termination). For more information, see SSL Certificates for
Elastic Load Balancing (p. 22).
SSL Negotiation
Elastic Load Balancing provides predefined SSL negotiation configurations that are used for SSL negotiation
when a connection is established between a client and your load balancer. The SSL negotiation
configurations provide compatibility with a broad range of clients and use high-strength cryptographic
algorithms called ciphers. However, some use cases might require all data on the network to be encrypted
and allow only specific ciphers. Some security compliance standards (such as PCI, SOX, and so on)
might require a specific set of protocols and ciphers from clients to ensure that the security standards are
met. In such cases, you can create a custom SSL negotiation configuration, based on your specific
requirements. Your ciphers and protocols should take effect within 30 seconds. For more information,
see SSL Negotiation Configurations for Elastic Load Balancing (p. 28).
Back-End Server Authentication
If you want to use SSL, but don't want to the load balancer to handle the SSL termination (known as SSL
offloading), you can use TCP for connections from the client to your load balancer, use the SSL protocol
for connections from the load balancer to your back-end application, and deploy certificates on the
back-end instances handling requests.
If you use an HTTPS/SSL connection for your back end, you can enable authentication of your back-end
instances.You can use the authentication process to ensure that back-end instances accept only encrypted
communication, and to ensure that each back-end instance has the correct certificate.
You can deploy any certificate on your back-end instances, including a self-signed certificate.
For more information, see Configure Back-end Server Authentication (p. 45).
Listener Configurations for Your Load Balancer
The following tables summarizes the listener settings that you can use to configure your load balancer.
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Listener Configurations
HTTP/HTTPS Load Balancer
Use Case
Front-End Pro- Front-End Optocol
tions
Back-End
Protocol
Back-End Options
Notes
Basic HTTP
load balancer
HTTP
NA
HTTP
NA
• Supports the
X-ForwardFor (p. 80)
header
Secure webHTTPS
site or application using
Elastic Load
Balancing to
offload SSL
decryption
SSL negotiation (p. 28)
HTTP
NA
• Supports the
X-ForwardFor (p. 80)
header
• Requires an
SSL certificate (p. 22)
deployed on
the load balancer
Secure webHTTPS
site or application using endto-end encryption
SSL negotiation (p. 28)
HTTPS
Back-end authentication
• Supports the
X-ForwardFor (p. 80)
header
• Requires SSL
certificates (p. 22)
deployed on
the load balancer and the
registered instances
TCP/SSL Load Balancer
Use Case
Front-End Pro- Front-End Optocol
tions
Back-End
Protocol
Back-End Options
Notes
Basic TCP
load balancer
TCP
TCP
NA
• Supports the
Proxy Protocol (p. 88)
header
NA
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Elastic Load Balancing Developer Guide
X-Forwarded Headers
Use Case
Front-End Pro- Front-End Optocol
tions
Back-End
Protocol
Back-End Options
Notes
Secure webSSL
site or application using
Elastic Load
Balancing to
offload SSL
decryption
SSL negotiation (p. 28)
TCP
NA
• Requires an
SSL certificate (p. 22)
deployed on
the load balancer
Secure webSSL
site or application using endto-end encryption with Elastic Load Balancing
SSL negotiation (p. 28)
SSL
Back-end authentication
• Requires SSL
certificates (p. 22)
deployed on
the load balancer and the
registered instances
• Elastic Load
Balancing
does not insert SNI
headers on
back-end
SSL connections.
X-Forwarded Headers for Elastic Load Balancing
HTTP requests and HTTP responses use header fields to send information about the HTTP messages.
Header fields are colon-separated name-value pairs that are separated by a carriage return (CR) and a
line feed (LF). A standard set of HTTP header fields is defined in RFC 2616, Message Headers. There
are also non-standard HTTP headers available that are widely used by the applications. Some of the
non-standard HTTP headers have a X-Forwarded prefix. Elastic Load Balancing supports the following
X-Forwarded headers.
Headers
• X-Forwarded-For (p. 80)
• X-Forwarded-Proto (p. 81)
• X-Forwarded-Port (p. 81)
X-Forwarded-For
The X-Forwarded-For request header helps you identify the IP address of a client when you use an
HTTP or HTTPS load balancer. Because load balancers intercept traffic between clients and servers,
your server access logs contain only the IP address of the load balancer. To see the IP address of the
client, use the X-Forwarded-For request header. Elastic Load Balancing stores the IP address of the
client in the X-Forwarded-For request header and passes the header to your server.
The X-Forwarded-For request header takes the following form:
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Elastic Load Balancing Developer Guide
X-Forwarded-Proto
X-Forwarded-For: clientIPAddress
The following is an example X-Forwarded-For request header for a client with an IP address of
203.0.113.7.
X-Forwarded-For: 203.0.113.7
The following is an example X-Forwarded-For request header for a client with an IPv6 address of
2001:DB8::21f:5bff:febf:ce22:8a2e.
X-Forwarded-For: 2001:DB8::21f:5bff:febf:ce22:8a2e
If a request goes through multiple proxies, the clientIPAddress in the X-Forwarded-For request
header is followed by the IP addresses of each successive proxy that the request goes through before it
reaches your load balancer. Therefore, the right-most IP address is the IP address of the most recent
proxy and the left-most IP address is the IP address of the originating client. In such cases, the
X-Forwarded-For request header takes the following form:
X-Forwarded-For: OriginatingClientIPAddress, proxy1-IPAddress, proxy2-IPAddress
X-Forwarded-Proto
The X-Forwarded-Proto request header helps you identify the protocol (HTTP or HTTPS) that a client
used to connect to your server.Your server access logs contain only the protocol used between the server
and the load balancer; they contain no information about the protocol used between the client and the
load balancer. To determine the protocol used between the client and the load balancer, use the
X-Forwarded-Proto request header. Elastic Load Balancing stores the protocol used between the
client and the load balancer in the X-Forwarded-Proto request header and passes the header along
to your server.
Your application or website can use the protocol stored in the X-Forwarded-Proto request header to
render a response that redirects to the appropriate URL.
The X-Forwarded-Proto request header takes the following form:
X-Forwarded-Proto: originatingProtocol
The following example contains an X-Forwarded-Proto request header for a request that originated
from the client as an HTTPS request:
X-Forwarded-Proto: https
X-Forwarded-Port
The X-Forwarded-Port request header helps you identify the port that an HTTP or HTTPS load balancer
uses to connect to the client.
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Configure the Idle Timeout
Configure Your Load Balancer
Contents
• Configure the Idle Connection Timeout for Your Load Balancer (p. 82)
• Configure Cross-Zone Load Balancing for Your Load Balancer (p. 83)
• Configure Connection Draining for Your Load Balancer (p. 86)
• Configure Proxy Protocol Support for Your Load Balancer (p. 88)
• Configure Sticky Sessions for Your Load Balancer (p. 92)
• Tag Your Load Balancer (p. 96)
• Configure a Custom Domain Name for Your Load Balancer (p. 98)
Configure the Idle Connection Timeout for Your
Load Balancer
For each request that a client makes through a load balancer, the load balancer maintains two connections.
One connection is with the client and the other connection is to the back-end instance. For each connection,
the load balancer manages an idle timeout that is triggered when no data is sent over the connection for
a specified time period. After the idle timeout period has elapsed, if no data has been sent or received,
the load balancer closes the connection.
By default, Elastic Load Balancing sets the idle timeout to 60 seconds for both connections. If an HTTP
request doesn't complete within the idle timeout period, the load balancer closes the connection, even if
data is still being transferred. You can change the idle timeout setting for the connections to ensure that
lengthy operations, such as file uploads, have time to complete.
If you use HTTP and HTTPS listeners, we recommend that you enable the keep-alive option for your
EC2 instances. You can enable keep-alive in your web server settings or in the kernel settings for your
EC2 instances. Keep-alive, when enabled, enables the load balancer to re-use connections to your
back-end instance, which reduces the CPU utilization. To ensure that the load balancer is responsible
for closing the connections to your back-end instance, make sure that the value you set for the keep-alive
time is greater than the idle timeout setting on your load balancer.
Contents
• Configure the Idle Timeout Using the Console (p. 83)
• Configure the Idle Timeout Using the AWS CLI (p. 83)
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Configure the Idle Timeout Using the Console
Configure the Idle Timeout Using the Console
Use the following procedure to set the idle timeout for your load balancer.
To configure the idle timeout setting for your load balancer
1.
2.
3.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
Select your load balancer.
4.
5.
In the bottom pane, select the Description tab.
Find Connection Settings, and then click (Edit).
6.
In the Configure Connection Settings dialog box, enter a value for Idle Timeout. The range for
the idle timeout is 1 to 3,600 seconds.
Click Save.
7.
Configure the Idle Timeout Using the AWS CLI
Use the following modify-load-balancer-attributes command to set the idle timeout for your load balancer:
aws elb modify-load-balancer-attributes --load-balancer-name my-loadbalancer -load-balancer-attributes "{\"ConnectionSettings\":{\"IdleTimeout\":30}}"
The following is an example response:
{
"LoadBalancerAttributes": {
"ConnectionSettings": {
"IdleTimeout": 30
}
},
"LoadBalancerName": "my-loadbalancer"
}
Configure Cross-Zone Load Balancing for Your
Load Balancer
By default, your load balancer distributes incoming requests evenly across its enabled Availability Zones.
To ensure that your load balancer distributes incoming requests evenly across all back-end instances in
its enabled Availability Zones, enable cross-zone load balancing. Cross-zone load balancing reduces the
need to maintain equivalent numbers of back-end instances in each enabled Availability Zone, and
improves your application's ability to handle the loss of one or more back-end instances. However, we
still recommend that you maintain approximately equivalent numbers of back-end instances in each
enabled Availability Zone for higher fault tolerance.
Note
When you enable cross-zone load balancing, you are not charged for data transfer between the
load balancer nodes and back-end instances.
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Enable Cross-Zone Load Balancing
For environments where clients cache DNS lookups, incoming requests might favor one of the Availability
Zones. Using cross-zone load balancing, this imbalance in the request load is spread across all available
back-end instances in the region, reducing the impact of misbehaving clients.
Contents
• Enable Cross-Zone Load Balancing (p. 84)
• Disable Cross-Zone Load Balancing (p. 85)
Enable Cross-Zone Load Balancing
You can enable cross-zone load balancing for your load balancer at any time.
To enable cross-zone load balancing using the console
1.
2.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
3.
4.
5.
6.
Select your load balancer.
In the bottom pane, click (Edit) in the Cross-Zone Load Balancing: Disabled row.
In the Configure Cross-Zone Load Balancing dialog box, select Enable.
Click Save.
To enable cross-zone load balancing, set the CrossZoneLoadBalancing attribute of your load balancer
to true.
To enable cross-zone load balancing using the AWS CLI
1.
Use the following modify-load-balancer-attributes command:
aws elb modify-load-balancer-attributes --load-balancer-name my-loadbalancer
--load-balancer-attributes "{\"CrossZoneLoadBalancing\":{\"Enabled\":true}}"
The following is an example response:
{
"LoadBalancerAttributes": {
"CrossZoneLoadBalancing": {
"Enabled": true
}
},
"LoadBalancerName": "my-loadbalancer"
}
2.
(Optional) Use the following describe-load-balancer-attributes command to verify that cross-zone
load balancing is enabled for your load balancer:
aws elb describe-load-balancer-attributes --load-balancer-name my-loadbalancer
The following is an example response:
{
"LoadBalancerAttributes": {
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Elastic Load Balancing Developer Guide
Disable Cross-Zone Load Balancing
"ConnectionDraining": {
"Enabled": false,
"Timeout": 300
},
"CrossZoneLoadBalancing": {
"Enabled": true
},
"ConnectionSettings": {
"IdleTimeout": 60
},
"AccessLog": {
"Enabled": false
}
}
}
Disable Cross-Zone Load Balancing
You can disable the cross-zone load balancing option for your load balancer at any time.
To disable cross-zone load balancing using the console
1.
2.
3.
4.
5.
6.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
Select your load balancer.
In the bottom pane, click (Edit) in the Cross-Zone Load Balancing: Enabled row.
In the Configure Cross-Zone Load Balancing dialog box, select Disable.
Click Save.
To disable cross-zone load balancing, set the CrossZoneLoadBalancing attribute of your load balancer
to false.
To disable cross-zone load balancing using the AWS CLI
1.
Use the following modify-load-balancer-attributes command:
aws elb modify-load-balancer-attributes --load-balancer-name my-loadbalancer
--load-balancer-attributes "{\"CrossZoneLoadBalancing\":{\"Enabled\":false}}"
The following is an example response:
{
"LoadBalancerAttributes": {
"CrossZoneLoadBalancing": {
"Enabled": false
}
},
"LoadBalancerName": "my-loadbalancer"
}
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Configure Connection Draining
2.
(Optional) Use the following describe-load-balancer-attributes command to verify that cross-zone
load balancing is disabled for your load balancer:
aws elb describe-load-balancer-attributes --load-balancer-name my-loadbalancer
The following is an example response:
{
"LoadBalancerAttributes": {
"ConnectionDraining": {
"Enabled": false,
"Timeout": 300
},
"CrossZoneLoadBalancing": {
"Enabled": false
},
"ConnectionSettings": {
"IdleTimeout": 60
},
"AccessLog": {
"Enabled": false
}
}
}
Configure Connection Draining for Your Load
Balancer
To ensure that the load balancer stops sending requests to instances that are de-registering or unhealthy,
while keeping the existing connections open, use connection draining. This enables the load balancer to
complete in-flight requests made to instances that are de-registering or unhealthy.
When you enable connection draining, you can specify a maximum time for the load balancer to keep
connections alive before reporting the instance as de-registered. The maximum timeout value can be set
between 1 and 3,600 seconds (the default is 300 seconds). When the maximum time limit is reached,
the load balancer forcibly closes connections to the de-registering instance.
While in-flight requests are being served, the load balancer reports the state of a de-registering instance
as InService: Instance deregistration currently in progress. When the de-registering
instance is finished serving all in-flight requests, or when the maximum timeout limit is reached, the load
balancer reports the instance state as OutOfService: Instance is not currently registered
with the LoadBalancer.
If an instance becomes unhealthy, the load balancer reports the instance state as OutOfService. If
there are in-flight requests made to the unhealthy instance, they are completed. The maximum timeout
limit does not apply to connections to unhealthy instances.
If your instances are part of an Auto Scaling group and connection draining is enabled for your load
balancer, Auto Scaling waits for the in-flight requests to complete, or for the maximum timeout to expire,
before terminating instances due to a scaling event or health check replacement.
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Enable Connection Draining
You can disable connection draining if you want your load balancer to immediately close connections to
the instances that are de-registering or have become unhealthy. When connection draining is disabled,
any in-flight requests made to instances that are de-registering or unhealthy are not completed.
Contents
• Enable Connection Draining (p. 87)
• Disable Connection Draining (p. 87)
Enable Connection Draining
You can enable connection draining for your load balancer at any time.
To enable connection draining using the console
1.
2.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
3.
4.
5.
6.
7.
Select your load balancer.
In the bottom pane, select the Instances tab.
Click (Edit) next to Connection Draining.
In the Configure Connection Draining dialog box, select Enable Connection Draining.
(Optional) In the Timeout field, enter the maximum time limit. This is a value between 1 and 3,600
seconds.
Click Save.
8.
To enable connection draining using the AWS CLI
Use the following modify-load-balancer-attributes command:
aws elb modify-load-balancer-attributes --load-balancer-name my-loadbalancer -load-balancer-attributes "{\"ConnectionDraining\":{\"En
abled\":true,\"Timeout\":300}}"
The following is an example response:
{
"LoadBalancerAttributes": {
"ConnectionDraining": {
"Enabled": true,
"Timeout": 300
}
},
"LoadBalancerName": "my-loadbalancer"
}
Disable Connection Draining
You can disable connection draining for your load balancer at any time.
To disable connection draining using the console
1.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
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Elastic Load Balancing Developer Guide
Configure Proxy Protocol
2.
3.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
Select your load balancer.
4.
5.
6.
In the bottom pane, select the Instances tab.
Click (Edit) next to Connection Draining.
In the Configure Connection Draining dialog box, deselect Enable Connection Draining.
7.
Click Save.
To disable connection draining using the AWS CLI
Use the following modify-load-balancer-attributes command:
aws elb modify-load-balancer-attributes --load-balancer-name my-loadbalancer -load-balancer-attributes "{\"ConnectionDraining\":{\"Enabled\":false}}"
The following is an example response:
{
"LoadBalancerAttributes": {
"ConnectionDraining": {
"Enabled": false,
"Timeout": 300
}
},
"LoadBalancerName": "my-loadbalancer"
}
Configure Proxy Protocol Support for Your Load
Balancer
Proxy Protocol is an Internet protocol used to carry connection information from the source requesting
the connection to the destination for which the connection was requested. Elastic Load Balancing uses
Proxy Protocol version 1, which uses a human-readable header format.
By default, when you use Transmission Control Protocol (TCP) for both the front-end and back-end
connections, your load balancer forwards requests to the back-end instances without modifying the request
headers. If you enable Proxy Protocol, a human-readable header is added to the request header with
connection information such as the source IP address, destination IP address, and port numbers. The
header is then sent to the back-end instance as part of the request.
Note
The AWS Management Console does not support enabling Proxy Protocol.
Contents
• Proxy Protocol Header (p. 89)
• Prerequisites for Enabling Proxy Protocol (p. 89)
• Enable Proxy Protocol Using the AWS CLI (p. 89)
• Disable Proxy Protocol Using the AWS CLI (p. 91)
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Proxy Protocol Header
Proxy Protocol Header
The Proxy Protocol header helps you identify the IP address of a client when you use a load balancer
configured for TCP connections. Because load balancers intercept traffic between clients and your
back-end instances, the access logs from your back-end instance contain the IP address of the load
balancer instead of the originating client.You can parse the first line of the request to retrieve your client's
IP address and the port number.
The address of the proxy in the header for IPv6 is the public IPv6 address of your load balancer. This
IPv6 address matches the IP address that is resolved from your load balancer's DNS name, which begins
with either ipv6 or dualstack. If the client connects with IPv4, the address of the proxy in the header
is the private IPv4 address of the load balancer, which is not resolvable through a DNS lookup outside
of the EC2-Classic network.
The Proxy Protocol line is a single line that ends with a carriage return and line feed ("\r\n"), and has
the following form:
PROXY_STRING + single space + INET_PROTOCOL + single space + CLIENT_IP + single
space + PROXY_IP + single space + CLIENT_PORT + single space + PROXY_PORT +
"\r\n"
Example: IPv4
The following is an example of the Proxy Protocol line for IPv4.
PROXY TCP4 198.51.100.22 203.0.113.7 35646 80\r\n
Example: IPv6 (EC2-Classic only)
The following is an example of the IPv6 Proxy Protocol line for IPv6.
PROXY TCP6 2001:DB8::21f:5bff:febf:ce22:8a2e 2001:DB8::12f:8baa:eafc:ce29:6b2e
35646 80\r\n
Prerequisites for Enabling Proxy Protocol
Before you begin, do the following:
• Confirm that your load balancer is not behind a proxy server with Proxy Protocol enabled. If Proxy
Protocol is enabled on both the proxy server and the load balancer, the load balancer adds another
header to the request, which already has a header from the proxy server. Depending on how your
back-end instance is configured, this duplication might result in errors.
• Confirm that your back-end instances can process the Proxy Protocol information.
Enable Proxy Protocol Using the AWS CLI
To enable Proxy Protocol, you need to create a policy of type ProxyProtocolPolicyType and then
enable the policy on the back-end instance port.
Use the following procedure to create a new policy for your load balancer of type
ProxyProtocolPolicyType, set the newly created policy to the back-end instance on port 80, and
verify that the policy is enabled.
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Enable Proxy Protocol Using the AWS CLI
To enable proxy protocol for your load balancer
1.
(Optional) Use the following describe-load-balancer-policy-types command to list the policies supported
by Elastic Load Balancing:
aws elb describe-load-balancer-policy-types
The response includes the names and descriptions of the supported policy types. The following
shows the output for the ProxyProtocolPolicyType type:
{
"PolicyTypeDescriptions": [
...
{
"PolicyAttributeTypeDescriptions": [
{
"Cardinality": "ONE",
"AttributeName": "ProxyProtocol",
"AttributeType": "Boolean"
}
],
"PolicyTypeName": "ProxyProtocolPolicyType",
"Description": "Policy that controls whether to include the IP
address and port of the originating
request for TCP messages. This policy operates on TCP/SSL listeners only"
},
...
]
}
2.
Use the following create-load-balancer-policy command to create a policy that enables Proxy Protocol:
aws elb create-load-balancer-policy --load-balancer-name my-loadbalancer -policy-name my-ProxyProtocol-policy --policy-type-name ProxyProtocolPoli
cyType --policy-attributes AttributeName=ProxyProtocol,AttributeValue=true
3.
Use the following set-load-balancer-policies-for-backend-server command to enable the newly created
policy on the specified port. Note that this command replaces the current set of enabled policies.
Therefore, the --policy-names option must specify both the policy that you are adding to the list
(for example, my-ProxyProtocol-policy) and any policies that are currently enabled (for example,
my-existing-policy).
aws elb set-load-balancer-policies-for-backend-server --load-balancer-name
my-loadbalancer --instance-port 80 --policy-names my-ProxyProtocol-policy
my-existing-policy
4.
(Optional) Use the following describe-load-balancers command to verify that Proxy Protocol is enabled:
aws elb describe-load-balancers --load-balancer-name my-loadbalancer
The response includes the following information, which shows that the my-ProxyProtocol-policy
policy is associated with port 80.
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Disable Proxy Protocol Using the AWS CLI
{
"LoadBalancerDescriptions": [
{
...
"BackendServerDescriptions": [
{
"InstancePort": 80,
"PolicyNames": [
"my-ProxyProtocol-policy"
]
}
],
...
}
]
}
Disable Proxy Protocol Using the AWS CLI
You can disable the policies associated with your back-end instance and then enable them at a later time.
To disable the Proxy Protocol policy
1.
Use the following set-load-balancer-policies-for-backend-server command to disable the Proxy
Protocol policy by omitting it from the --policy-names option, but including the other policies that
should remain enabled (for example, my-existing-policy).
aws elb set-lb-policies-for-backend-server my-loadbalancer --instance-port
80 --policy-names my-existing-policy
If there are no other policies to enable, specify an empty string with --policy-names option as
follows:
aws elb set-load-balancer-policies-for-backend-server --load-balancer-name
my-loadbalancer --instance-port 80 --policy-names "[]"
2.
(Optional) Use the following describe-load-balancers command to verify that the policy is disabled:
aws elb describe-load-balancers --load-balancer-name my-loadbalancer
The response includes the following information, which shows that no ports are associated with a
policy.
{
"LoadBalancerDescriptions": [
{
...
"BackendServerDescriptions": [],
...
}
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Configure Sticky Sessions
]
}
Configure Sticky Sessions for Your Load
Balancer
By default, a load balancer routes each request independently to the registered instance with the smallest
load. However, you can use the sticky session feature (also known as session affinity), which enables
the load balancer to bind a user's session to a specific instance. This ensures that all requests from the
user during the session are sent to the same instance.
The key to managing sticky sessions is to determine how long your load balancer should consistently
route the user's request to the same instance. If your application has its own session cookie, then you
can configure Elastic Load Balancing so that the session cookie follows the duration specified by the
application's session cookie. If your application does not have its own session cookie, then you can
configure Elastic Load Balancing to create a session cookie by specifying your own stickiness duration.
Elastic Load Balancing creates a cookie, named AWSELB, that is used to map the session to the instance.
Requirements
• An HTTP/HTTPS load balancer.
• At least one healthy instance in each Availability Zone.
Compatibility
• The RFC for the path property of a cookie allows underscores. However, Elastic Load Balancing URI
encodes underscore characters as %5F because some browsers, such as Internet Explorer 7, expect
underscores to be URI encoded as %5F. Because of the potential to impact browsers that are currently
working, Elastic Load Balancing continues to URI encode underscore characters. For example, if the
cookie has the property path=/my_path, Elastic Load Balancing changes this property in the forwarded
request to path=/my%5Fpath.
• You can't set the secure or HttpOnly flags on your session stickiness cookies. However, these
cookies contain no sensitive data.
Contents
• Duration-Based Session Stickiness (p. 92)
• Application-Controlled Session Stickiness (p. 94)
Duration-Based Session Stickiness
The load balancer uses a special cookie to track the instance for each request to each listener. When
the load balancer receives a request, it first checks to see if this cookie is present in the request. If so,
the request is sent to the instance specified in the cookie. If there is no cookie, the load balancer chooses
an instance based on the existing load balancing algorithm. A cookie is inserted into the response for
binding subsequent requests from the same user to that instance. The stickiness policy configuration
defines a cookie expiration, which establishes the duration of validity for each cookie. The cookie is
automatically updated after its duration expires.
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Duration-Based Session Stickiness
If an instance fails or becomes unhealthy, the load balancer stops routing requests to that instance, and
chooses a new healthy instance based on the existing load balancing algorithm. The request is routed
to the new instance as if there is no cookie and the session is no longer sticky.
If a client switches to a different listener, stickiness is lost.
To enable duration-based sticky sessions for a load balancer using the console
1.
2.
3.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
Select your load balancer.
4.
5.
In the Description tab, find Port Configuration, and then click (Edit), which is next to the port.
In the Edit stickiness dialog box, click Enable Load Balancer Generated Cookie Stickiness.
6.
(Optional) In Expiration Period, enter the cookie expiration period, in seconds. After this period, the
cookie is considered stale. If you do not specify an expiration period, the sticky session lasts for the
duration of the browser session.
7.
Click Save.
To enable duration-based sticky sessions for a load balancer using the AWS CLI
1.
Use the following create-lb-cookie-stickiness-policy command to create a load balancer-generated
cookie stickiness policy with a cookie expiration period of 60 seconds:
aws elb create-lb-cookie-stickiness-policy --load-balancer-name my-loadbal
ancer --policy-name my-duration-cookie-policy --cookie-expiration-period 60
2.
Use the following set-load-balancer-policies-of-listener command to enable session stickiness for
the specified load balancer:
aws elb set-load-balancer-policies-of-listener --load-balancer-name myloadbalancer --load-balancer-port 443 --policy-names my-duration-cookiepolicy
Note
The set-load-balancer-policies-of-listener command replaces the current set
of policies associated with the specified load balancer port. Every time you use this command,
specify the --policy-names option to list all policies to enable.
3.
(Optional) Use the following describe-load-balancers command to verify that the policy is enabled:
aws elb describe-load-balancers --load-balancer-name my-loadbalancer
The response includes the following information, which shows that the policy is enabled for the listener
on the specified port:
{
"LoadBalancerDescriptions": [
{
...
"ListenerDescriptions": [
{
"Listener": {
"InstancePort": 443,
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Application-Controlled Session Stickiness
"SSLCertificateId":
"arn:aws:iam::123456789012:server-certificate/my-server-certificate",
"LoadBalancerPort": 443,
"Protocol": "HTTPS",
"InstanceProtocol": "HTTPS"
},
"PolicyNames": [
"my-duration-cookie-policy",
"ELBSecurityPolicy-2015-05"
]
},
...
],
...
"Policies": {
"LBCookieStickinessPolicies": [
{
"PolicyName": "my-duration-cookie-policy",
"CookieExpirationPeriod": 60
}
],
"AppCookieStickinessPolicies": [],
"OtherPolicies": [
"ELBSecurityPolicy-2015-05"
]
},
...
}
]
}
Application-Controlled Session Stickiness
The load balancer uses a special cookie to associate the session with the instance that handled the initial
request, but follows the lifetime of the application cookie specified in the policy configuration. The load
balancer only inserts a new stickiness cookie if the application response includes a new application cookie.
The load balancer stickiness cookie does not update with each request. If the application cookie is explicitly
removed or expires, the session stops being sticky until a new application cookie is issued.
If an instance fails or becomes unhealthy, the load balancer stops routing requests to that instance, and
chooses a new healthy instance based on the existing load balancing algorithm. The load balancer treats
the session as now "stuck" to the new healthy instance, and continues routing requests to that instance
even if the failed instance comes back.
To enable application-controlled session stickiness using the console
1.
2.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
3.
4.
5.
Select your load balancer.
In the Description tab, find Port Configuration, and then click (Edit), which is next to the port.
In the Edit stickiness dialog box, click Enable Application Generated Cookie Stickiness.
6.
7.
In Cookie Name, enter the name of your application cookie.
Click Save.
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Application-Controlled Session Stickiness
To enable application-controlled session stickiness using the AWS CLI
1.
Use the following create-app-cookie-stickiness-policy command to create an application-generated
cookie stickiness policy:
aws elb create-app-cookie-stickiness-policy --load-balancer-name my-loadbal
ancer --policy-name my-app-cookie-policy --cookie-name my-app-cookie
2.
Use the following set-load-balancer-policies-of-listener command to enable session stickiness for a
load balancer:
aws elb set-load-balancer-policies-of-listener --load-balancer-name myloadbalancer --load-balancer-port 443 --policy-names my-app-cookie-policy
Note
The set-load-balancer-policies-of-listener command replaces the current set
of policies associated with the specified load balancer port. Every time you use this command,
specify the --policy-names option to list all policies to enable.
3.
(Optional) Use the following describe-load-balancers command to verify that the sticky policy is
enabled:
aws elb describe-load-balancers --load-balancer-name my-loadbalancer
4.
The response includes the following information, which shows that the policy is enabled for the listener
on the specified port:
{
"LoadBalancerDescriptions": [
{
...
"ListenerDescriptions": [
{
"Listener": {
"InstancePort": 443,
"SSLCertificateId":
"arn:aws:iam::123456789012:server-certificate/my-server-certificate",
"LoadBalancerPort": 443,
"Protocol": "HTTPS",
"InstanceProtocol": "HTTPS"
},
"PolicyNames": [
"my-app-cookie-policy",
"ELBSecurityPolicy-2015-05"
]
},
{
"Listener": {
"InstancePort": 80,
"LoadBalancerPort": 80,
"Protocol": "TCP",
"InstanceProtocol": "TCP"
},
"PolicyNames": []
}
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Tag Your Load Balancer
],
...
"Policies": {
"LBCookieStickinessPolicies": [],
"AppCookieStickinessPolicies": [
{
"PolicyName": "my-app-cookie-policy",
"CookieName": "my-app-cookie"
}
],
"OtherPolicies": [
"ELBSecurityPolicy-2015-05"
]
},
...
}
]
}
Tag Your Load Balancer
Tags help you to categorize your load balancers in different ways, for example, by purpose, owner, or
environment.
You can add up to ten tags to each load balancer. Tag keys must be unique for each load balancer. If
you add a tag with a key that is already associated with the load balancer, it updates the value of that
tag.
When you are finished with a tag, you can remove it from your load balancer.
Contents
• Tag Restrictions (p. 96)
• Add a Tag (p. 97)
• Remove a Tag (p. 97)
Tag Restrictions
The following basic restrictions apply to tags:
• Maximum number of tags per resource—10
• Maximum key length—127 Unicode characters
• Maximum value length—255 Unicode characters
• Tag keys and values are case sensitive. Allowed characters are letters, spaces, and numbers
representable in UTF-8, plus the following special characters: + - = . _ : / @. Do not use leading or
trailing spaces.
• Do not use the aws: prefix in your tag names or values because it is reserved for AWS use. You can't
edit or delete tag names or values with this prefix. Tags with this prefix do not count against your tags
per resource limit.
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Add a Tag
Add a Tag
You can add tags to your load balancer at any time.
To add a tag using the console
1.
2.
3.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
Select your load balancer.
4.
5.
In the bottom pane, select the Tags tab.
Click Add/Edit Tags.
6.
In the Add/Edit Tags dialog box, click Create Tag and specify a key and a value for each tag.
7.
After you are done adding tags, click Save.
To add a tag using the AWS CLI
Use the following add-tags command to add the specified tag:
aws elb add-tags --load-balancer-name my-loadbalancer --tag Key=pro
ject,Value=lima
Remove a Tag
You can remove tags from your load balancer whenever you are finished with them.
To remove a tag using the console
1.
2.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
3.
4.
5.
Select your load balancer.
In the bottom pane, select the Tags tab.
Click Add/Edit Tags.
6.
In the Add/Edit Tags dialog box, click the remove icon of the tag you want to remove.
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Configure the Domain Name
7.
After you are done removing the tags, click Save.
To remove a tag using the AWS CLI
Use the following remove-tags command to remove the tag with the specified key:
aws elb remove-tags --load-balancer-name my-loadbalancer --tag project
Configure a Custom Domain Name for Your Load
Balancer
Each load balancer receives a default Domain Name System (DNS) name. This DNS name includes the
name of the AWS region in which the load balancer is created. For example, if you create a load balancer
named my-loadbalancer in the US West (Oregon) region, your load balancer receives a DNS name
such as my-loadbalancer-1234567890.us-west-2.elb.amazonaws.com. To access the website
on your back-end instances, you paste this DNS name into the address field of a web browser. However,
this DNS name is not easy for your customers to remember and use.
If you'd prefer to use a friendly DNS name for your load balancer, such as www.example.com, instead
of the default DNS name, you can create a custom domain name and associate it with the DNS name
for your load balancer. When a client makes a request using this custom domain name, the DNS server
resolves it to the DNS name for your load balancer.
Contents
• Associating Your Custom Domain Name with Your Load Balancer Name (p. 98)
• Configure DNS Failover for Your Load Balancer (p. 99)
• Disassociating Your Custom Domain Name from Your Load Balancer (p. 100)
Associating Your Custom Domain Name with Your
Load Balancer Name
First, if you haven't already done so, register your domain name. The Internet Corporation for Assigned
Names and Numbers (ICANN) manages domain names on the Internet. You register a domain name
using a domain name registrar, an ICANN-accredited organization that manages the registry of domain
names.The website for your registrar will provide detailed instructions and pricing information for registering
your domain name. For more information, see the following resources:
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Configure DNS Failover for Your Load Balancer
• To use Amazon Route 53 to register a domain name, see Registering Domain Names Using Amazon
Route 53 in the Amazon Route 53 Developer Guide.
• For a list of accredited registrars, see the Accredited Registrar Directory.
Next, use your DNS service, such as your domain registrar, to create a CNAME record to route queries
to your load balancer. For more information, see the documentation for your DNS service.
Alternatively, you can use Amazon Route 53 as your DNS service. You create a hosted zone, which
contains information about how to route traffic on the Internet for your domain, and an alias resource
record set, which routes queries for your domain name to your load balancer. Amazon Route 53 doesn't
charge for DNS queries for alias record sets, and you can use alias record sets to route DNS queries to
your load balancer for the zone apex of your domain (for example, example.com). For information about
transferring DNS services for existing domains to Amazon Route 53, see Configuring Amazon Route 53
as Your DNS Service in the Amazon Route 53 Developer Guide.
To create a hosted zone and an alias record set for your domain using Amazon Route 53
1.
2.
3.
4.
Open the Amazon Route 53 console at https://console.aws.amazon.com/route53/.
If you are new to Amazon Route 53, you see a welcome page; click Get Started Now under DNS
Management. Otherwise, click Hosted Zones in the navigation pane.
Click Create Hosted Zone.
Under Create Hosted Zone, do the following:
a.
b.
c.
5.
6.
7.
8.
In Domain Name, enter your domain name.
Leave the default type, Public Hosted Zone, and optionally enter a comment.
Click Create.
Select the hosted zone that you just created for your domain.
Click Go to Record Sets.
Click Create Record Set.
Under Create Record Set, do the following:
a.
b.
c.
d.
Leave the default name, which is the name of your domain.
From Type, select A — IPv4 address.
For Alias, click Yes. An alias enables Amazon Route 53 to associate your domain name with
an AWS resource, such as a load balancer.
Click Alias Target. Select your load balancer from the list. The console adds the dualstack
prefix.
e.
f.
From Routing Policy, select Simple.
Leave Evaluate Target Health set to No.
g.
Click Create.
Configure DNS Failover for Your Load Balancer
If you use Amazon Route 53 to route DNS queries to your load balancer, you can also configure DNS
failover for your load balancer using Amazon Route 53. In a failover configuration, Amazon Route 53
checks the health of the registered EC2 instances for the load balancer to determine whether they are
available. If there are no healthy EC2 instances registered with the load balancer, or if the load balancer
itself is unhealthy, Amazon Route 53 routes traffic to another available resource, such as a healthy load
balancer or a static website in Amazon S3.
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Disassociating Your Custom Domain Name from Your
Load Balancer
For example, suppose that you have a web application for www.example.com, and you want redundant
instances running behind two load balancers residing in different regions. You want the traffic to be
primarily routed to the load balancer in one region, and you want to use the load balancer in the other
region as a backup during failures. If you configure DNS failover, you can specify your primary and
secondary (backup) load balancers. Amazon Route 53 directs traffic to the primary load balancer if it is
available, or to the secondary load balancer otherwise.
To configure DNS failover for two load balancers using Amazon Route 53
1.
2.
3.
Open the Amazon Route 53 console at https://console.aws.amazon.com/route53/.
In the navigation pane, click Hosted Zones.
Select your hosted zone.
4.
5.
Click Go to Record Sets.
Click Create Record Set.
6.
In Name, the default value is the name of your domain (for example, example.com). To route DNS
queries for a subdomain (for example, www.example.com) to your load balancer, specify the name
of the subdomain.
7.
8.
9.
From Type, select A - IPv4 address.
For Alias, click Yes
Click Alias Target. Select your primary load balancer from the list. The console adds the dualstack
prefix.
10.
11.
12.
13.
14.
15.
16.
Note that the value of Alias Hosted Zone ID is based on the load balancer that you selected.
For Routing Policy, select Failover.
For Failover Record Type, select Primary.
For Set ID, enter an ID for the record set or use the default value.
For Evaluate Target Health, select Yes.
For Associate with Health Check, select No.
Click Create.
Repeat the same steps to create an alias record set for your secondary load balancer, with the
following exceptions:
• In Alias Target, select your secondary load balancer.
• For Failover Record Type, select Secondary.
• For Evaluate Target Health, select Yes to evaluate the health of the secondary load balancer. If
the secondary load balancer is unhealthy, Amazon Route 53 routes traffic to the primary load
balancer. If you select No, Amazon Route 53 assumes that the secondary load balancer is healthy
and routes traffic to it whenever the primary load balancer is unhealthy.
For information about setting up advanced DNS failover configurations, see Configuring Amazon Route 53
Active-Active and Active-Passive Failover in the Amazon Route 53 Developer Guide.
Disassociating Your Custom Domain Name from
Your Load Balancer
You can disassociate your custom domain name from a load balancer instance by first deleting the
resource record sets in your hosted zone and then deleting the hosted zone. For more information, see
Creating, Changing, and Deleting Resource Record Sets and Deleting a Hosted Zone in the Amazon
Route 53 Developer Guide.
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Monitor CloudWatch Metrics
Monitor Your Load Balancer
You can use the following features to monitor your load balancers, analyze traffic patterns, and troubleshoot
issues with your load balancers and back-end instances.
CloudWatch metrics
Elastic Load Balancing publishes data points to Amazon CloudWatch about your load balancers and
back-end instances. CloudWatch enables you to retrieve statistics about those data points as an
ordered set of time-series data, known as metrics. You can use these metrics to verify that your
system is performing as expected. For more information, see Monitor Your Load Balancer Using
Amazon CloudWatch (p. 101).
Elastic Load Balancing access logs
The access logs for Elastic Load Balancing capture detailed information for all requests made to your
load balancer and stores them as log files in the Amazon S3 bucket that you specify. Each log contains
details such as the time a request was received, the client's IP address, latencies, request path, and
server responses.You can use these access logs to analyze traffic patterns and to troubleshoot your
back-end applications. For more information, see Monitor Your Load Balancer Using Elastic Load
Balancing Access Logs (p. 107).
CloudTrail logs
AWS CloudTrail enables you to keep track of the calls made to the Elastic Load Balancing API by
or on behalf of your AWS account. CloudTrail stores the information in log files in the Amazon S3
bucket that you specify. You can use these log files to monitor activity of your load balancers by
determining which requests were made, the source IP addresses where the requests came from,
who made the request, when the request was made, and so on. For more information, see Log Elastic
Load Balancing API Calls Using AWS CloudTrail (p. 116).
Monitor Your Load Balancer Using Amazon
CloudWatch
Elastic Load Balancing publishes data points to Amazon CloudWatch for your load balancers and your
back-end instances. CloudWatch enables you to retrieve statistics about those data points as an ordered
set of time-series data, known as metrics. Think of a metric as a variable to monitor, and the data points
as the values of that variable over time. For example, you can monitor the total number of healthy EC2
instances for a load balancer over a specified time period. Each data point has an associated time stamp
and an optional unit of measurement.
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Elastic Load Balancing Metrics
You can use metrics to verify that your system is performing as expected. For example, you can create
a CloudWatch alarm to monitor a specified metric and initiate an action (such as sending a notification
to an email address) if the metric goes outside what you consider an acceptable range.
For more information about Amazon CloudWatch, see the Amazon CloudWatch Developer Guide.
Contents
• Elastic Load Balancing Metrics (p. 102)
• Statistics for Elastic Load Balancing Metrics (p. 105)
• Dimensions for Elastic Load Balancing Metrics (p. 105)
• View CloudWatch Metrics for Your Load Balancer (p. 106)
• Create CloudWatch Alarms for Your Load Balancer (p. 106)
Elastic Load Balancing Metrics
Elastic Load Balancing reports metrics to CloudWatch only when requests are flowing through the load
balancer. If there are requests flowing through the load balancer, Elastic Load Balancing measures and
sends its metrics in 60-second intervals. If there are no requests flowing through the load balancer or no
data for a metric, the metric is not reported.
Note that not every statistic available through CloudWatch applies to every metric for Elastic Load
Balancing, though they are all available. For each metric, be aware of the statistics that provide the most
useful information.
Elastic Load Balancing provides the following CloudWatch metrics.
Metric
Description
HealthyHostCount,
The number of healthy and unhealthy instances registered with your load
UnHealthyHostCount balancer. A newly registered instance is considered healthy after it passes
the first health check. An instance is considered unhealthy after it exceeds
the unhealthy threshold configured for health checks. An unhealthy instance
is considered healthy again after it meets the healthy threshold configured
for health checks. If cross-zone load balancing is enabled, the number of
healthy instances for the LoadBalancerName dimension is calculated across
all Availability Zones.
Reporting criteria: There are registered instances
Statistics: The most useful statistics are average, min, and max. These
statistics are determined by the load balancer nodes. Note that some load
balancer nodes might determine that an instance is unhealthy for a brief
period while other nodes determine that it is healthy.
Example: Suppose that your load balancer has 2 instances in us-west-2a
and 2 instances in us-west-2b, us-west-2a has 1 unhealthy instance, and uswest-2b has no unhealthy instances.With the AvailabilityZone dimension,
there is an average of 1 healthy and 1 unhealthy instance in us-west-2a, and
an average of 2 healthy and 0 unhealthy instances in us-west-2b.
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Elastic Load Balancing Metrics
Metric
Description
RequestCount
The number of requests completed or connections made during the specified
interval (1 or 5 minutes).
[HTTP listener] The number of requests received and routed, including HTTP
error responses from the registered instances.
[TCP listener] The number of connections made to the registered instances.
Reporting criteria: There is a nonzero value
Statistics: The most useful statistic is sum. Note that min, max, and average
are always 1.
Example: Suppose that your load balancer has 2 instances in us-west-2a
and 2 instances in us-west-2b, and that 100 requests are sent to the load
balancer. There are 60 requests sent to us-west-2a, with each instance receiving 30 requests, and 40 requests sent to us-west-2b, with each instance
receiving 20 requests. With the AvailabilityZone dimension, there is a
sum of 60 requests in us-west-2a and 40 requests in us-west-2b. With the
LoadBalancerName dimension, there is a sum of 100 requests.
Latency
[HTTP listener] The time elapsed, in seconds, after the request leaves the
load balancer until the headers of the response are received.
[TCP listener] The time elapsed, in seconds, for the load balancer to successfully establish a connection to a registered instance. This measurement does
not generally reflect the performance of the application running on the instance.
Reporting criteria: There is a nonzero value
Statistics: The most useful statistic is average. Use max to determine
whether some requests are taking substantially longer than the average. Note
that min is typically not useful.
Example: Suppose that your load balancer has 2 instances in us-west-2a
and 2 instances in us-west-2b, and that requests sent to 1 instance in uswest-2a have a higher latency. The average for us-west-2a has a higher value
than the average for us-west-2b.
SurgeQueueLength
The total number of requests that are pending routing. The load balancer
queues a request if it is unable to establish a connection with a healthy instance in order to route the request. For TCP/SSL listeners, all requests go
through the surge queue, so it is common to have pending requests in the
queue.
The maximum size of the queue is 1,024. Additional requests are rejected
when the queue is full. For more information, see SpilloverCount.
Reporting criteria: There is a nonzero value.
Statistics: The most useful statistic is max, because it represents the peak
of queued requests. The average statistic can be useful in combination with
min and max to determine the range of queued requests. Note that sum is
not useful.
Example: Suppose that your load balancer has us-west-2a and us-west-2b
enabled, and that instances in us-west-2a are experiencing high latency and
are slow to respond to requests. As a result, the surge queue for the load
balancer nodes in us-west-2a fills, with clients likely experiencing increased
response times. If this continues, the load balancer will likely have spillovers
(see the SpilloverCount metric). If us-west-2b continues to respond normally, the max for the load balancer will be the same as the max for us-west2a.
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Elastic Load Balancing Metrics
Metric
Description
SpilloverCount
The total number of requests that were rejected because the surge queue is
full.
[HTTP listener] The load balancer returns an HTTP 503 error code.
[TCP listener] The load balancer closes the connection.
Reporting criteria: There is a nonzero value
Statistics: The most useful statistic is sum. Note that average, min, and
max are reported per load balancer node and are not typically useful.
Example: Suppose that your load balancer has us-west-2a and us-west-2b
enabled, and that instances in us-west-2a are experiencing high latency and
are slow to respond to requests. As a result, the surge queue for the load
balancer node in us-west-2a fills, resulting in spillover. If us-west-2b continues
to respond normally, the sum for the load balancer will be the same as the
sum for us-west-2a.
HTTPCode_ELB_4XX
[HTTP listener] The number of HTTP 4XX client error codes generated by
the load balancer. Client errors are generated when a request is malformed
or incomplete.
Reporting criteria: There is a nonzero value
Statistics: The most useful statistic is sum. Note that min and max are always
0 and average is always 1.
Example: Suppose that your load balancer has us-west-2a and us-west-2b
enabled, and that client requests include a malformed request URL. As a
result, client errors would likely increase in all Availability Zones. The sum
for the load balancer is the sum of the values for the Availability Zones.
HTTPCode_ELB_5XX
[HTTP listener] The number of HTTP 5XX server error codes generated by
the load balancer. This count does not include any response codes generated
by the registered instances. The metric is reported if there are no healthy instances registered to the load balancer, or if the request rate exceeds the
capacity of the instances (spillover) or the load balancer.
Reporting criteria: There is a nonzero value
Statistics: The most useful statistic is sum. Note that min and max are always
0 and average is always 1.
Example: Suppose that your load balancer has us-west-2a and us-west-2b
enabled, and that instances in us-west-2a are experiencing high latency and
are slow to respond to requests. As a result, the surge queue for the load
balancer nodes in us-west-2a fills and clients receive a 503 error. If us-west2b continues to respond normally, the sum for the load balancer equals the
sum for us-west-2a.
HTTPCode_Backend_2XX,
HTTPCode_Backend_3XX,
HTTPCode_Backend_4XX,
HTTPCode_Backend_5XX
[HTTP listener] The number of HTTP response codes generated by registered
instances. This count does not include any response codes generated by the
load balancer.
Reporting criteria: There is a nonzero value
Statistics: The most useful statistic is sum. Note that min and max are always
0 and average is always 1.
Example: Suppose that your load balancer has 2 instances in us-west-2a
and 2 instances in us-west-2b, and that requests sent to 1 instance in uswest-2a result in HTTP 500 responses. The sum for us-west-2a includes
these error responses, while the sum for us-west-2b does not include them.
Therefore, the sum for the load balancer equals the sum for us-west-2a.
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Statistics for Elastic Load Balancing Metrics
Metric
Description
BackendConnection- The number of connections that were not successfully established between
the load balancer and the registered instances. Because the load balancer
Errors
retries the connection when there are errors, this count can exceed the request
rate. Note that this count also includes any connection errors related to health
checks.
Reporting criteria: There is a nonzero value
Statistics: The most useful statistic is sum. Note that average, min, and
max are reported per load balancer node and are not typically useful. However,
the difference between the minimum and maximum (or peak to average or
average to trough) might be useful to determine whether a load balancer
node is an outlier.
Example: Suppose that your load balancer has 2 instances in us-west-2a
and 2 instances in us-west-2b, and that attempts to connect to 1 instance in
us-west-2a result in back-end connection errors. The sum for us-west-2a includes these connection errors, while the sum for us-west-2b does not include
them. Therefore, the sum for the load balancer equals the sum for us-west2a.
Statistics for Elastic Load Balancing Metrics
CloudWatch provides statistics based on the metric data points published by Elastic Load Balancing.
Statistics are metric data aggregations over specified period of time. When you request statistics, the
returned data stream is identified by the metric name and dimension. A dimension is a name/value pair
that uniquely identifies a metric. For example, you can request statistics for all the healthy EC2 instances
behind a load balancer launched in a specific Availability Zone.
The min and max statistics reflect the minimum and maximum reported by the individual load balancer
nodes. For example, suppose there are 2 load balancer nodes. One node has HealthyHostCount with
a min of 2, a max of 10, and an average of 6, while the other node has HealthyHostCount with a min
of 1, a max of 5, and an average of 3. Therefore, the load balancer has a min of 1, a max of 10, and an
average of about 4.
The sum statistic is the aggregate value across all load balancer nodes. Because metrics include multiple
reports per period, sum is only applicable to metrics that are aggregated across all load balancer nodes,
such as RequestCount, HTTPCode_ELB_4XX, HTTPCode_ELB_5XX, HTTPCode_Backend_XXX,
BackendConnectionErrors, and SpilloverCount.
The count statistic is the number of samples measured. Because metrics are gathered based on sampling
intervals and events, count is typically not useful. For example, with HealthyHostCount, count is
based on the number of samples that each load balancer node reports, not the number of healthy hosts.
Dimensions for Elastic Load Balancing Metrics
To filter the metrics for Elastic Load Balancing, you can use the following dimensions.
Dimension
Description
LoadBalancerName
Filter the metric data by the specified load balancer.
AvailabilityZone
Filter the metric data by the specified Availability Zone.
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View CloudWatch Metrics for Your Load Balancer
View CloudWatch Metrics for Your Load Balancer
You can view the CloudWatch metrics for your load balancers using the Amazon EC2 console. These
metrics are displayed as monitoring graphs. The monitoring graphs show data points if the load balancer
is active and receiving requests.
Note
Alternatively, you can view metrics for your load balancer using the CloudWatch console. For
more information, see Viewing Your AWS Metrics with Amazon CloudWatch in the Amazon
CloudWatch Developer Guide.
To view the metrics from your load balancer
1.
2.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
3.
4.
Select your load balancer.
In the bottom pane, click the Monitoring tab.
5.
6.
To filter the results by time, select a time range from Showing data for.
Select an individual graph to get a larger view of the individual metric. The following metrics are
available:
•
•
•
•
•
•
•
•
•
•
•
•
Sum HTTP 2XXs
Sum HTTP 4XXs
Sum HTTP 5XXs
Sum ELB HTTP 4XXs
Sum ELB HTTP 5XXs
Healthy Hosts
Unhealthy Hosts
Average Latency
Sum Requests
Backend Connection Errors
Surge Queue Length
Spillover Count
Create CloudWatch Alarms for Your Load Balancer
An alarm watches a single metric over the time period that you specify. Depending on the value of the
metric relative to a threshold that you define, the alarm can send one or more notifications using Amazon
SNS, a service that enables applications, end users, and devices to instantly send and receive notifications.
For more information, see Get Started with Amazon SNS.
An alarm sends notifications to Amazon SNS when the specified metric reaches the defined range and
remains in that range for a specified period of time. An alarm has three possible states:
• OK—The value of the metric is within the range you've specified.
• ALARM—The value of the metric is outside the range that you've specified for the specified period of
time.
• INSUFFICIENT_DATA—Either the metric is not yet available or there is not enough data is available
for the metric to determine the alarm state.
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Whenever the state of an alarm changes, CloudWatch uses Amazon SNS to send a notification to the
email addresses that you specified.
Use the following procedure to create an alarm for your load balancer using the Amazon EC2 console.
The alarm sends notifications to an SNS topic whenever the load balancer's latency is above 120 seconds
for 1 consecutive period of 5 minutes. Note that a short period creates a more sensitive alarm, while a
longer period can mitigate brief spikes in a metric.
Note
Alternately, you can create an alarm for your load balancer using the CloudWatch console. For
more information, see Send Email Based on Load Balancer Alarm in the Amazon CloudWatch
Developer Guide.
To create an alarm for your load balancer
1.
2.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
3.
4.
5.
Select your load balancer.
From the Monitoring tab, click Create Alarm.
If you have an SNS topic that you want to use, select it from Send a notification to. Otherwise,
create an SNS topic as follows:
a.
b.
c.
Click create topic.
In Send a notification to, enter a name for your topic.
In With these recipients, enter the email addresses of the recipients to notify, separated by
commas.You can enter up to 10 email addresses. Each recipient receives an email from Amazon
SNS with a link to subscribe to the SNS topic in order to receive notifications.
6.
Define the threshold for your alarm as follows. For Whenever, select Average and Average Latency.
For Is, select > and enter 120. For For at least, specify 1 consecutive period of 5 minutes.
7.
In Name of alarm, a name is automatically generated for you. If you prefer, you can specify a different
name.
Click Create Alarm.
8.
Monitor Your Load Balancer Using Elastic Load
Balancing Access Logs
Elastic Load Balancing provides access logs that capture detailed information about requests sent to
your load balancer. Each log contains information such as the time the request was received, the client's
IP address, latencies, request paths, and server responses. You can use these access logs to analyze
traffic patterns and to troubleshoot issues.
Access logging is an optional feature of Elastic Load Balancing that is disabled by default. After you
enable access logging for your load balancer, Elastic Load Balancing captures the logs and stores them
in the Amazon S3 bucket that you specify. You can disable access logging at any time.
There is no additional charge for access logs. You will be charged storage costs for Amazon S3, but will
not be charged for the bandwidth used by Elastic Load Balancing to send log files to Amazon S3. For
more information about storage costs, see Amazon S3 Pricing.
Contents
• Access Log Files (p. 108)
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Access Log Files
• Access Log Entries (p. 109)
• Processing Access Logs (p. 111)
• Enable Access Logs for Your Load Balancer (p. 111)
• Disable Access Logs for Your Load Balancer (p. 115)
Access Log Files
Elastic Load Balancing publishes a log file for each load balancer node at the interval you specify. You
can specify a publishing interval of either 5 minutes or 60 minutes when you enable the access log for
your load balancer. By default, Elastic Load Balancing publishes logs at a 60-minute interval. If the interval
is set for 5 minutes, the logs are published at 1:05, 1:10, 1:15, and so on. The start of log delivery is
delayed up to 5 minutes if the interval is set to 5 minutes, and up to 15 minutes if the interval is set to 60
minutes. You can modify the publishing interval at any time.
The load balancer can deliver multiple logs for the same period. This usually happens if the site has high
traffic, multiple load balancer nodes, and a short log publishing interval.
The file names of the access logs use the following format:
bucket[/prefix]/AWSLogs/aws-account-id/elasticloadbalancing/re
gion/yyyy/mm/dd/aws-account-id_elasticloadbalancing_region_load-balancername_end-time_ip-address_random-string.log
bucket
The name of the S3 bucket.
prefix
The prefix (logical hierarchy) in the bucket. If you don't specify a prefix, the logs are placed at the
root level of the bucket.
aws-account-id
The AWS account ID of the owner.
region
The region for your load balancer and S3 bucket.
yyyy/mm/dd
The date that the log was delivered.
load-balancer-name
The name of the load balancer.
end-time
The date and time that the logging interval ended. For example, an end time of 20140215T2340Z
contains entries for requests made between 23:35 and 23:40 if the publishing interval is 5 minutes.
ip-address
The IP address of the load balancer node that handled the request. For an internal load balancer,
this is a private IP address.
random-string
A system-generated random string.
The following is an example log file name:
s3://my-loadbalancer-logs/my-app/AWSLogs/123456789012/elasticloadbalancing/uswest-2/2014/02/15/123456789012_elasticloadbalancing_us-west-2_my-loadbalan
cer_20140215T2340Z_172.160.001.192_20sg8hgm.log
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Access Log Entries
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. For more information, see Object Lifecycle
Management in the Amazon Simple Storage Service Developer Guide.
Access Log Entries
Elastic Load Balancing logs requests sent to the load balancer, including requests that never made it to
the back-end instances. For example, if a client sends a malformed request, or there are no healthy
instances to respond, the requests are still logged.
Syntax
Each log entry contains the details of a single request made to the load balancer. All fields in the log entry
are delimited by spaces. Each entry in the log file has the following format:
timestamp elb client:port backend:port request_processing_time backend_pro
cessing_time response_processing_time elb_status_code backend_status_code re
ceived_bytes sent_bytes "request" "user_agent" ssl_cipher ssl_protocol
The following table describes the fields of an access log entry.
Field
Description
timestamp
The time when the load balancer received the request from the client, in ISO
8601 format.
elb
The name of the load balancer
client:port
The IP address and port of the requesting client.
backend:port
The IP address and port of the registered instance that processed this request.
If the client didn't send a full request, the load balancer can't dispatch the request to a registered instance, and this value is set to -.
request_processing_time
[HTTP listener] The total time elapsed, in seconds, from the time the load
balancer received the request and sent it to a registered instance.
[TCP listener] The total time elapsed, in seconds, from the time the load balancer accepted a TCP/SSL connection from a client to the time the load balancer sends the first byte of data to a registered instance.
This value is set to -1 if the load balancer can't dispatch the request to a registered instance. This can happen if the registered instance closes the connection before the idle timeout or if the client sends a malformed request.
Additionally, for TCP listeners, this can happen if the client establishes a
connection with the load balancer but does not send any data.
backend_processing_time
[HTTP listener] The total time elapsed, in seconds, from the time the load
balancer sent the request to a registered instance until the instance started
to send the response headers.
[TCP listener] The total time elapsed, in seconds, for the load balancer to
successfully establish a connection to a registered instance.
This value is set to -1 if the load balancer can't dispatch the request to a registered instance. This can happen if the registered instance closes the connection before the idle timeout or if the client sends a malformed request.
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Field
Description
response_processing_time
[HTTP listener] The total time elapsed (in seconds) from the time the load
balancer received the response header from the registered instance until it
started to send the response to the client. This includes both the queuing
time at the load balancer and the connection acquisition time from the load
balancer to the back end.
[TCP listener] The total time elapsed, in seconds, from the time the load balancer received the first byte from the registered instance until it started to
send the response to the client.
This value is set to -1 if the load balancer can't dispatch the request to a registered instance. This can happen if the registered instance closes the connection before the idle timeout or if the client sends a malformed request.
elb_status_code
[HTTP listener] The status code of the response from the load balancer.
backend_status_code
[HTTP listener] The status code of the response from the registered instance.
received_bytes
The size of the request, in bytes, received from the client (requester).
[HTTP listener] The value includes the request body but not the headers.
[TCP listener] The value includes the request body and the headers.
sent_bytes
The size of the response, in bytes, sent to the client (requester).
[HTTP listener] The value includes the response body but not the headers.
[TCP listener] The value includes the request body and the headers.
request
The request line from the client enclosed in double quotes and logged in the
following format: HTTP Method + Protocol://Host header:port + Path + HTTP
version.
[TCP listener] The URL is three dashes, each separated by a space, and
ending with a space ("- - - ").
user_agent
[HTTP/HTTPS listener] A User-Agent string that identifies the client that originated the request. The string consists of one or more product identifiers,
product[/version]. If the string is longer than 8 KB, it is truncated.
ssl_cipher
[HTTPS/SSL listener] The SSL cipher. This value is recorded only if the incoming SSL/TLS connection was established after a successful negotiation.
Otherwise, the value is set to -.
ssl_protocol
[HTTPS/SSL listener] The SSL protocol. This value is recorded only if the
incoming SSL/TLS connection was established after a successful negotiation.
Otherwise, the value is set to -.
Example HTTP Entry
The following is an example log entry for an HTTP listener (port 80 to port 80):
2015-05-13T23:39:43.945958Z my-loadbalancer 192.168.131.39:2817 10.0.0.1:80
0.000073 0.001048 0.000057 200 200 0 29 "GET http://www.example.com:80/ HTTP/1.1"
"curl/7.38.0" - -
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Example HTTPS Entry
The following is an example log entry for an HTTPS listener (port 443 to port 80):
2015-05-13T23:39:43.945958Z my-loadbalancer 192.168.131.39:2817 10.0.0.1:80
0.000086 0.001048 0.001337 200 200 0 57 "GET https://www.example.com:443/ HT
TP/1.1" "curl/7.38.0" DHE-RSA-AES128-SHA TLSv1.2
Example TCP Entry
The following is an example log entry for an TCP listener (port 8080 to port 80):
2015-05-13T23:39:43.945958Z my-loadbalancer 192.168.131.39:2817 10.0.0.1:80
0.001069 0.000028 0.000041 - - 82 305 "- - - " "-" - -
Example SSL Entry
The following is an example log entry for an SSL listener (port 8443 to port 80):
2015-05-13T23:39:43.945958Z my-loadbalancer 192.168.131.39:2817 10.0.0.1:80
0.001065 0.000015 0.000023 - - 57 502 "- - - " "-" ECDHE-ECDSA-AES128-GCM-SHA256
TLSv1.2
Processing Access Logs
If there is a lot of demand on your website, your load balancer can generate log files with gigabytes of
data.You might not be able to process such a large amount of data using line-by-line processing.Therefore,
you might have to use analytical tools that provide parallel processing solutions. For example, you can
use the following analytical tools to analyze and process access logs:
• Amazon EMR enables you to quickly and efficiently process vast amounts of data. For more information,
see the Amazon Elastic MapReduce Developer Guide.
• Splunk
• Sumo Logic
Enable Access Logs for Your Load Balancer
To enable access logs for your load balancer, you must specify the name of the Amazon S3 bucket where
the load balancer will store the logs.You must also attach a bucket policy to this bucket that grants Elastic
Load Balancing permission to write to the bucket.
Important
The bucket and your load balancer must be in the same region. The bucket can be owned by a
different account than the account that owns the load balancer.
Tasks
• Step 1: Create an S3 Bucket (p. 112)
• Step 2: Attach a Policy to Your S3 Bucket (p. 112)
• Step 3: Enable Access Logs (p. 114)
• Step 4: Verify that the Load Balancer Created a Test File in the S3 Bucket (p. 115)
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Step 1: Create an S3 Bucket
You can create an S3 bucket using the Amazon S3 console. If you already have a bucket and want to
use it to store the access logs, skip this step and go to Step 2: Attach a Policy to Your S3 Bucket (p. 112)
to grant Elastic Load Balancing permission to write logs to your bucket.
Tip
If you will use the console to enable access logs, you can skip this step and have Elastic Load
Balancing create a bucket with the required permissions for you. If you will use the AWS CLI to
enable access logs, you must create the bucket and grant the required permissions yourself.
To create an Amazon S3 bucket
1.
Open the Amazon S3 console at https://console.aws.amazon.com/s3/.
2.
3.
Click Create Bucket.
In the Create a Bucket dialog box, do the following:
a.
b.
c.
In the Bucket Name box, enter a name for your bucket (for example, my-loadbalancer-logs).
This name must be unique across all existing bucket names in Amazon S3. In some regions,
there might be additional restrictions on bucket names. For more information, see Bucket
Restrictions and Limitations in the Amazon Simple Storage Service Developer Guide.
In Region, select the region where you created your load balancer.
Click Create.
Step 2: Attach a Policy to Your S3 Bucket
After you've created or identified your S3 bucket, you must attach a policy to the bucket. Bucket policies
are a collection of JSON statements written in the access policy language to define access permissions
for your bucket. Each statement includes information about a single permission and contains a series of
elements.
If your bucket already has an attached policy, you can add the statements for the Elastic Load Balancing
access log to the policy. If you do so, we recommend that you evaluate the resulting set of permissions
to ensure that they are appropriate for the users that need access to the bucket for access logs.
Tip
If you will use the console to enable access logs, you can skip this step and have Elastic Load
Balancing create a bucket with the required permissions for you.
To attach a policy statement to your bucket
1.
2.
Open the Amazon S3 console at https://console.aws.amazon.com/s3/.
Select the bucket, and then click Properties.
3.
Under Permissions, click Add bucket policy.
4.
5.
On the Bucket Policy Editor page, click AWS Policy Generator.
On the AWS Policy Generator page, do the following:
a.
b.
c.
For Select Type of Policy, select S3 Bucket Policy.
For Effect, select Allow to allow access to the S3 bucket.
In Principal, specify the account ID for Elastic Load Balancing to grant Elastic Load Balancing
access to the S3 bucket. Select the account ID that corresponds to the region for your load
balancer and bucket.
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Region
Region Name
Elastic Load Balancing Account ID
us-east-1
US East (N. Virginia)
127311923021
us-west-2
US West (Oregon)
797873946194
us-west-1
US West (N. California)
027434742980
eu-west-1
EU (Ireland)
156460612806
eu-central-1
EU (Frankfurt)
054676820928
ap-southeast-1
Asia Pacific (Singapore)
114774131450
ap-northeast-1
Asia Pacific (Tokyo)
582318560864
ap-southeast-2
Asia Pacific (Sydney)
783225319266
ap-northeast-2
Asia Pacific (Seoul)
600734575887
sa-east-1
South America (São
Paulo)
507241528517
us-gov-west-1*
AWS GovCloud (US)
048591011584
cn-north-1**
China (Beijing)
638102146993
* This region requires a separate account. For more information, see AWS GovCloud (US).
d.
** This region requires a separate account. For more information, see China (Beijing).
For Actions, select PutObject to allow Elastic Load Balancing to store objects in the S3 bucket.
e.
For Amazon Resource Name (ARN), enter the ARN of the S3 bucket in the following format:
arn:aws:s3:::bucket/prefix/AWSLogs/aws-account-id/*
You must specify the ID of the AWS account that owns the load balancer, and you should not
include the hyphens. For example:
arn:aws:s3:::my-loadbalancer-logs/my-app/AWSLogs/123456789012/*
f.
g.
Note that if you are using us-gov-west-1 region, use arn:aws-us-gov: instead of arn:aws:
in the ARN.
Click Add Statement, and then click Generate Policy.
Copy the policy that is displayed in the Policy JSON Document page, and then click Close.
The policy document should look similar to the following:
{
"Id": "Policy1429136655940",
"Version": "2012-10-17",
"Statement": [
{
"Sid": "Stmt1429136633762",
"Action": [
"s3:PutObject"
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],
"Effect": "Allow",
"Resource": "arn:aws:s3:::my-loadbalancer-logs/my-app/AWS
Logs/123456789012/*",
"Principal": {
"AWS": [
"797873946194"
]
}
}
]
}
6.
Go back to the Bucket Policy Editor page and paste the policy into the text area.
7.
8.
Click Save to save the policy. If Save is not enabled, press Enter.
Under Permissions, click Save to attach the policy to your bucket.
Step 3: Enable Access Logs
You can enable access logs using the AWS Management Console or the AWS CLI. Note that when you
enable access logs using the console, you can have Elastic Load Balancing create the bucket for you
with necessary permissions for the load balancer to write to your bucket.
Use the following example to capture and deliver logs to your S3 bucket every 60 minutes (the default
interval).
To enable access logs for your load balancer using the console
1.
2.
3.
4.
5.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
Select your load balancer.
In the Description tab, find Access Logs, and then click (Edit).
In the Configure Access Logs dialog box, do the following:
a.
Select Enable Access Logs.
b.
Leave Interval set to the default setting, 60 minutes.
c.
In S3 Location, enter the name of your S3 bucket, including the prefix (for example,
my-loadbalancer-logs/my-app).
Tip
If you want Elastic Load Balancing to create the bucket, you must specify a name that
is unique across all existing bucket names in Amazon S3. In some regions, there might
be additional restrictions on bucket names. For more information, see Bucket Restrictions
and Limitations in the Amazon Simple Storage Service Developer Guide.
d.
e.
(Optional) If you want Elastic Load Balancing to create the bucket, select Create the location
for me.
Click Save.
To enable access logs for your load balancer using the AWS CLI
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First, create a .json file that enables Elastic Load Balancing to capture and deliver logs every 60 minutes
to the S3 bucket that you created for the logs:
{
"AccessLog": {
"Enabled": true,
"S3BucketName": "my-loadbalancer-logs",
"EmitInterval": 60,
"S3BucketPrefix": "my-app"
}
}
To enable access logs, specify the .json file in the modify-load-balancer-attributes command as follows:
aws elb modify-load-balancer-attributes --load-balancer-name my-loadbalancer -load-balancer-attributes file://my-json-file.json
The following is an example response:
{
"LoadBalancerAttributes": {
"AccessLog": {
"Enabled": true,
"EmitInterval": 60,
"S3BucketName": "my-loadbalancer-logs",
"S3BucketPrefix": "my-app"
}
},
"LoadBalancerName": "my-loadbalancer"
}
Step 4: Verify that the Load Balancer Created a Test File in
the S3 Bucket
After the access log is enabled for your load balancer, Elastic Load Balancing validates the S3 bucket
and creates a test file. You can use the S3 console to verify that the test file was created.
To verify that Elastic Load Balancing created a test file in your S3 bucket
1.
Open the Amazon S3 console at https://console.aws.amazon.com/s3/.
2.
From the All Buckets list, select your S3 bucket.
3.
Navigate to the test log file. The path should be as follows:
my-bucket/prefix/AWSLogs/123456789012/ELBAccessLogTestFile
Disable Access Logs for Your Load Balancer
You can disable access logs for your load balancer at any time. After you disable access logging, your
access logs remain in your Amazon S3 until you delete the them. For information about managing your
S3 bucket, see Working with Buckets in the Amazon Simple Storage Service Console User Guide.
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Log API Calls
To disable access logging using the console
1.
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
2.
3.
In the navigation pane, under LOAD BALANCING, click Load Balancers.
Select your load balancer.
4.
5.
6.
In the Description tab, find Access Logs, and then click (Edit).
In the Configure Access Logs dialog box, select Disable Access Logs.
Click Save.
To disable access logging using the AWS CLI
Use the following modify-load-balancer-attributes command to disable access logging:
aws elb modify-load-balancer-attributes --load-balancer-name my-loadbalancer -load-balancer-attributes "{\"AccessLog\":{\"Enabled\":false}}"
The following is an example response:
{
"LoadBalancerName": "my-loadbalancer",
"LoadBalancerAttributes": {
"AccessLog": {
"S3BucketName": "my-loadbalancer-logs",
"EmitInterval": 60,
"Enabled": false,
"S3BucketPrefix": "my-app"
}
}
}
Log Elastic Load Balancing API Calls Using AWS
CloudTrail
You can use AWS CloudTrail to capture all calls to the Elastic Load Balancing API made by or on behalf
of your AWS account. CloudTrail stores the information as log files in an Amazon S3 bucket that you
specify. CloudTrail logs all calls to the Elastic Load Balancing API, whenever you use the Elastic Load
Balancing API directly, or indirectly through the AWS Management Console or AWS CLI. You can use
the logs collected by CloudTrail to monitor the activity of your load balancers and determine what API
call was made, what source IP address was used, who made the call, when it was made, and so on. For
the complete list of Elastic Load Balancing API actions, see the Elastic Load Balancing API Reference.
AWS CloudTrail only logs calls to the API. To monitor other actions for your load balancer, such as when
a client makes a request to your load balancer, use access logs. For more information, see Monitor Your
Load Balancer Using Elastic Load Balancing Access Logs (p. 107).
Contents
• Configure CloudTrail Event Logging (p. 117)
• Elastic Load Balancing Event Entries in CloudTrail Log Files (p. 117)
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Configure CloudTrail Event Logging
Configure CloudTrail Event Logging
CloudTrail creates log entries in each supported region separately and stores them in the Amazon S3
bucket for that region. For information about the regions supported by CloudTrail, see Regions and
Endpoints – CloudTrail in the Amazon Web Services General Reference.
When you enable CloudTrail logging, the CloudTrail service can create an Amazon S3 bucket for you to
store your log files. If you prefer one log file for all supported regions, you can aggregate the logs created
across the regions to a single bucket.
For more information, see Creating and Updating Your Trail and Aggregating CloudTrail Log Files to a
Single Amazon S3 Bucket in the AWS CloudTrail User Guide.
You can optionally configure CloudTrail to use Amazon SNS to notify you when a log file is created.
CloudTrail can send notifications to you frequently, so we recommend that you use Amazon SNS with
an Amazon SQS queue and handle the notifications programmatically.
There is no cost to use CloudTrail. However, the standard rates for Amazon S3 apply, as well as the
standard rates for Amazon SNS and Amazon SQS, if you use them.
Elastic Load Balancing Event Entries in CloudTrail
Log Files
The log files from CloudTrail contain event information in JSON format. An event record represents a
single AWS API call and includes information about the requested action, such as the user that requested
the action, and the date and the time of the request. The log files include events for all AWS API calls for
your AWS account, not just Elastic Load Balancing API calls. However, you can read the log files and
scan for calls to the Elastic Load Balancing API using the eventSource element with the value
elasticloadbalancing.amazonaws.com. To view information about a specific ELB API, such as
CreateLoadBalancer, scan for the API name in the eventName element.
The following example shows a CloudTrail log file for a user who created a load balancer and then deleted
that load balancer using the ELB CLI. The CLI is identified by the userAgent element. The requested
API calls (CreateLoadBalancer and DeleteLoadBalancer) are found in the eventName element for each
record. Information about the user (Alice) can be found in the userIdentity element. For more
information about the different elements and values in CloudTrail log files, see CloudTrail Event Reference
in the AWS CloudTrail User Guide.
{
Records: [
eventVersion: "1.01",
userIdentity:
{
type: "IAMUser",
principalId: "60505EXAMPLE",
arn: "arn:aws:iam::123456789012:user/Alice",
accountId: "123456789012",
accessKeyId: "AKIAIOSFODNN7EXAMPLE"
},
eventTime: "2014-04-01T15:31:48Z",
eventSource: "elasticloadbalancing.amazonaws.com",
eventName: "CreateLoadBalancer",
awsRegion: "us-west-2",
sourceIPAddress: "127.0.0.01",
userAgent: "Amazon CLI/ElasticLoadBalancing API 2012-06-01",
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Elastic Load Balancing Event Entries in CloudTrail Log
Files
requestParameters:
{
loadBalancerName: "my-loadbalancer",
listeners:
[
{
loadBalancerPort: 80,
protocol: "http",
instanceProtocol: "http",
instancePort: 80
}
],
availabilityZones:
[
"us-west-2a"
]
},
responseElements:
{
dNSName: "my-loadbalancer-1234567890.elb.amazonaws.com"
},
requestID: "b9960276-b9b2-11e3-8a13-f1ef1EXAMPLE",
eventID: "6f4ab5bd-2daa-4d00-be14-d92efEXAMPLE"
}
]
{
eventVersion: "1.01",
userIdentity:
{
type: "IAMUser",
principalId: "60505EXAMPLE",
arn: "arn:aws:iam::123456789012:user/Alice",
accountId: "123456789012",
accessKeyId: "AKIAIOSFODNN7EXAMPLE"
},
eventTime: "2014-04-01T16:30:30Z",
eventSource: "elasticloadbalancing.amazonaws.com",
eventName: "DeleteLoadBalancer",
awsRegion: "us-west-2",
sourceIPAddress: "127.0.0.02",
userAgent: "Amazon CLI/ElasticLoadBalancing API 2012-06-01",
requestParameters: {
loadBalancerName: "my-loadbalancer"
},
responseElements: null,
requestID: "f0f17bb6-b9ba-11e3-9b20-999fdEXAMPLE",
eventID: "4f99f0e8-5cf8-4c30-b6da-3b69fEXAMPLE"
},
. . .
]
}
You can also use one of the Amazon partner solutions that integrate with CloudTrail to read and analyze
your CloudTrail log files. For more information, see the AWS partners page.
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Using an IAM Policy to Grant Permissions
Control Access to Your Load
Balancer
AWS uses security credentials to identify you and to grant you access to your AWS resources. You can
use features of AWS Identity and Access Management (IAM) to allow other users, services, and applications
to use your AWS resources without sharing your security credentials. You can choose to allow full use
or limited use of your AWS resources.
By default, IAM users don't have permission to create, view, or modify AWS resources. To allow an IAM
user to access resources, such as a load balancer, and perform tasks, you must create an IAM policy
that grants the IAM user permission to use the specific resources and API actions they'll need, then attach
the policy to the IAM user or the group the IAM user belongs to. When you attach a policy to a user or
group of users, it allows or denies the users permission to perform the specified tasks on the specified
resources.
For example, you can use IAM to create users and groups under your AWS account (an IAM user can
be a person, a system, or an application). Then you grant permissions to the users and groups to perform
specific actions on the specified resources using an IAM policy.
Contents
• Using an IAM Policy to Grant Permissions (p. 119)
• Actions for Elastic Load Balancing (p. 120)
• Resource-Level Permissions for Elastic Load Balancing (p. 121)
• Condition Keys for Elastic Load Balancing (p. 122)
• Example IAM Policies for Elastic Load Balancing (p. 122)
Using an IAM Policy to Grant Permissions
When you attach a policy to a user or group of users, it allows or denies the users permission to perform
the specified tasks on the specified resources.
An IAM policy is a JSON document that consists of one or more statements. Each statement is structured
as follows:
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Actions for Elastic Load Balancing
{
"Version": "2012-10-17",
"Statement":[{
"Effect": "effect",
"Action": "action",
"Resource": "resource-arn",
"Condition": {
"condition": {
"key":"value"
}
}
}]
}
• Effect— The effect can be Allow or Deny. By default, IAM users don't have permission to use resources
and API actions, so all requests are denied. An explicit allow overrides the default. An explicit deny
overrides any allows.
• Action— The action is the specific API action for which you are granting or denying permission. To
learn about specifying action, see Actions for Elastic Load Balancing (p. 120).
• Resource— The resource that's affected by the action. With many Elastic Load Balancing API actions,
you can restrict the permissions granted or denied to a specific load balancer by specifying its Amazon
Resource Name (ARN) in this statement. Otherwise, you can use the * wildcard to specify all of your
load balancers. For more information, see Resource-Level Permissions for Elastic Load Balancing (p. 121).
• Condition— You can optionally use conditions to control when your policy is in effect. For more
information, see Condition Keys for Elastic Load Balancing (p. 122).
For general information about IAM, see What is IAM?. For information about creating and managing users
and groups, see IAM Users and Groups.
Actions for Elastic Load Balancing
In the Action element of your IAM policy statement, you can specify any API action that Elastic Load
Balancing offers. You must prefix the action name with the lowercase string elasticloadbalancing:,
as shown in the following example:
"Action": "elasticloadbalancing:DescribeLoadBalancers"
To specify multiple actions in a single statement, enclose them in square brackets and separate them
with a comma as follows:
"Action": ["elasticloadbalancing:action1","elasticloadbalancing:action2"]
You can also specify multiple actions using the * wildcard. The following example specifies all API action
names for Elastic Load Balancing that start with Create:
"Action": "elasticloadbalancing:Create*"
To specify all API actions for Elastic Load Balancing, use the * wildcard as in the following example:
"Action": "elasticloadbalancing:*"
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Resource-Level Permissions for Elastic Load Balancing
For the complete list of the API actions for Elastic Load Balancing, see Actions in the Elastic Load Balancing
API Reference.
Resource-Level Permissions for Elastic Load
Balancing
Resource-level permissions refers to the ability to specify which resources users are allowed to perform
actions on. Elastic Load Balancing has partial support for resource-level permissions. For API actions
that support resource-level permissions, you can control the load balancers that users are allowed to use
with the action.
To specify a load balancer in a policy statement, you must use its Amazon Resource Name (ARN).
Otherwise, you must use the * wildcard.
API Actions with No Support for Resource-Level Permissions
You can't specify the ARN for a specific load balancer with the following API actions:
• DescribeInstanceHealth
• DescribeLoadBalancerAttributes
• DescribeLoadBalancerPolicyTypes
• DescribeLoadBalancers
• DescribeLoadBalancerPolicies
• DescribeTags
For API actions that don't support resource-level permissions, you must specify the following resource
statement:
"Resource": "*"
ARN Syntax
The ARN for a load balancer has the following syntax:
arn:aws:elasticloadbalancing:region:my-account-id:loadbalancer/load-balancername
region
The region for the load balancer. For list of regions supported by Elastic Load Balancing, see Regions
and Endpoints in the Amazon Web Services General Reference.
account-id
Your AWS account ID, with no hyphens (for example, 0123456789012).
load-balancer-name
The name of your load balancer.
ARN Example
The following is an example ARN for a load balancer:
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Condition Keys for Elastic Load Balancing
"Resource": "arn:aws:elasticloadbalancing:us-west-2:123456789012:loadbalancer/myload-balancer"
Condition Keys for Elastic Load Balancing
In an IAM policy statement, you have the option to specify conditions that control when it is in effect. Each
condition contains one or more key-value pairs. AWS has defined the following keys you can use to
specify conditions under which your IAM users and groups can use the load balancers.
Note
Key names are case sensitive.
• aws:CurrentTime— Use with date/time conditions to restrict access based on request time (see Date
Conditions).
• aws:EpochTime— Use with date/time conditions to specify a date in epoch or UNIX time (see Date
Conditions).
• aws:MultiFactorAuthPresent— Use to check whether the IAM user making the API request was
authenticated using a multi-factor authentication (MFA) device.
• aws:MultiFactorAuthAge— Use to check how long ago (in seconds) the Multi-Factor Authentication
(MFA) validated security credentials making the request were issued using multi-factor authentication
(MFA). Unlike other keys, if MFA is not used, this key is not present (see Existence of Condition Keys,
Numeric Conditions and Using Multi-Factor Authentication (MFA) Devices with AWS).
• aws:SecureTransport— Use to check whether the request was sent using SSL (see Boolean
Conditions).
• aws:SourceIp— Use to check the requester's IP address (see IP Address). Note that if you use
aws:SourceIp, and the request comes from an EC2 instance, the public IP address of the instance
is evaluated.
• aws:Referer— Use to check the user making the HTTP request.
• aws:UserAgent— Use with string conditions to check the client application that made the request
(see String Conditions).
• aws:userid— Use to check the user ID of the requester (see String Conditions).
• aws:username—Use to check the user name of the requester, if available (see String Conditions).
After you have decided how you want to control access to your load balancers, open the https://
console.aws.amazon.com/iam/ and follow the directions in Managing IAM Policies to create an IAM policy
for Elastic Load Balancing. For information about testing your IAM policies, see Testing IAM Policies.
Example IAM Policies for Elastic Load Balancing
The following examples show policy statements that you can use to control the permissions that IAM
users have to access your load balancer.
• Example 1: Allow users to use specific API actions with a specific load balancer (p. 122)
• Example 2: Allow users to use specific API actions with two specific load balancers (p. 123)
• Example 3: Allow users to use API actions with a specific load balancer using SSL (p. 124)
Example 1: Allow users to use specific API actions with a specific load balancer
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Example IAM Policies for Elastic Load Balancing
The following policy includes two statements. The first statement grants users permission to use all
Describe APIs for Elastic Load Balancing with all load balancers, and to use the Amazon EC2 APIs
required to register or de-register instances using the console. The second statement grants users
permission to use the specified APIs with the specified load balancer.
{
"Version": "2012-10-17",
"Statement": [{
"Effect": "Allow",
"Action": [
"elasticloadbalancing:Describe*",
"ec2:DescribeInstances",
"ec2:DescribeAvailabilityZones",
"ec2:DescribeSubnets"
],
"Resource": "*"
},
{
"Effect": "Allow",
"Action": [
"elasticloadbalancing:ApplySecurityGroupsToLoadBalancer",
"elasticloadbalancing:AttachLoadBalancerToSubnets",
"elasticloadbalancing:ConfigureHealthCheck",
"elasticloadbalancing:Create*",
"elasticloadbalancing:Delete*",
"elasticloadbalancing:DeregisterInstancesFromLoadBalancer",
"elasticloadbalancing:DetachLoadBalancerFromSubnets",
"elasticloadbalancing:DisableAvailabilityZonesForLoadBalancer",
"elasticloadbalancing:EnableAvailabilityZonesForLoadBalancer",
"elasticloadbalancing:ModifyLoadBalancerAttributes",
"elasticloadbalancing:RegisterInstancesWithLoadBalancer",
"elasticloadbalancing:Set*"
],
"Resource": "arn:aws:elasticloadbalancing:us-west-2:123456789012:loadbal
ancer/my-load-balancer"
}]
}
Example 2: Allow users to use specific API actions with two specific load balancers
The following policy grants users permission to use all Describe APIs with all load balancers associated
with the AWS account, and to use the specified APIs with the specified load balancers:
{
"Version": "2012-10-17",
"Statement": [{
"Effect": "Allow",
"Action": [
"elasticloadbalancing:Describe*",
"ec2:DescribeInstances",
"ec2:DescribeAvailabilityZones",
"ec2:DescribeSubnets"
],
"Resource": "*"
},
{
"Effect": "Allow",
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Example IAM Policies for Elastic Load Balancing
"Action": [
"elasticloadbalancing:ApplySecurityGroupsToLoadBalancer",
"elasticloadbalancing:AttachLoadBalancerToSubnets",
"elasticloadbalancing:ConfigureHealthCheck",
"elasticloadbalancing:Create*",
"elasticloadbalancing:Delete*",
"elasticloadbalancing:DeregisterInstancesFromLoadBalancer",
"elasticloadbalancing:DetachLoadBalancerFromSubnets",
"elasticloadbalancing:DisableAvailabilityZonesForLoadBalancer",
"elasticloadbalancing:EnableAvailabilityZonesForLoadBalancer",
"elasticloadbalancing:ModifyLoadBalancerAttributes",
"elasticloadbalancing:RegisterInstancesWithLoadBalancer",
"elasticloadbalancing:Set*"
],
"Resource": [
"arn:aws:elasticloadbalancing:us-west-2:123456789012:loadbalancer/myload-balancer-1",
"arn:aws:elasticloadbalancing:us-west-2:123456789012:loadbalancer/myload-balancer-2"
]
}]
}
Example 3: Allow users to use API actions with a specific load balancer using SSL
The following policy grants users permission to use the specified APIs with the specified load balancer
using an SSL request.
{
"Version": "2012-10-17",
"Statement": [{
"Effect": "Allow",
"Action": "elasticloadbalancing:*",
"Condition": {"Bool":{"aws:SecureTransport":"true"}},
"Resource": "arn:aws:elasticloadbalancing:us-west-2:123456789012:loadbal
ancer/my-load-balancer"
}]
}
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Troubleshoot Your Load Balancer
The following tables list the troubleshooting resources that you'll find useful as you work with Elastic Load
Balancing.
API Errors
Error
CertificateNotFound: undefined (p. 126)
OutofService: A Transient Error Occurred (p. 127)
HTTP Errors
Error
HTTP 400: BAD_REQUEST (p. 127)
HTTP 405: METHOD_NOT_ALLOWED (p. 127)
HTTP 408: Request Timeout (p. 128)
HTTP 502: Bad Gateway (p. 128)
HTTP 503: Service Unavailable (p. 128)
HTTP 504: Gateway Timeout (p. 128)
Response Code Metrics
Response Code Metric
HTTPCode_ELB_4XX (p. 129)
HTTPCode_ELB_5XX (p. 129)
HTTPCode_Backend_2XX (p. 129)
HTTPCode_Backend_3XX (p. 130)
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API Errors
Response Code Metric
HTTPCode_Backend_4XX (p. 130)
HTTPCode_Backend_5XX (p. 130)
Health Check Issues
Issue
Connection to the instances has timed out (p. 131)
Health check target page error (p. 132)
Public key authentication is failing (p. 132)
Instance is not receiving traffic from the load balancer (p. 132)
Ports on instance are not open (p. 132)
Instances in an Auto Scaling group are failing the ELB health check (p. 133)
Instance Registration Issues
Issue
Taking too long to register an EC2 instance (p. 133)
Unable to register an instance launched from a paid AMI (p. 134)
Troubleshooting Elastic Load Balancing: API
Errors
The following are error messages returned by Elastic Load Balancing API, the potential causes, and the
steps you can take to resolve the issues.
Error Messages
• CertificateNotFound: undefined (p. 126)
• OutofService: A Transient Error Occurred (p. 127)
CertificateNotFound: undefined
Cause 1: There is a delay in propagating the certificate to all regions when it is created using the AWS
Management Console. When this delay occurs, the error message is shown in the last step in the process
of creating the load balancer.
Solution 1: Wait approximately 15 minutes and then try again. If the problem persists, go to the AWS
Support Center for assistance.
Cause 2: If you are using the AWS CLI or API directly, you can receive this error if you provide an Amazon
Resource Name (ARN) for a certificate that does not exist.
Solution 2: Use the Identity and Access Management (IAM) action GetServerCertificate to get the
certificate ARN and verify that you provided the correct value for the ARN.
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OutofService: A Transient Error Occurred
OutofService: A Transient Error Occurred
Cause: There is a transient internal problem within the Elastic Load Balancing service or the underlying
network. This temporary issue might also occur when Elastic Load Balancing queries the health of the
load balancer and its registered instances.
Solution: Retry the API call. If the problem persists, go to the AWS Support Center for assistance.
Troubleshooting Elastic Load Balancing: HTTP
Errors
The HTTP method (also called the verb) specifies the action to be performed on the resource receiving
an HTTP request. The standard methods for HTTP requests are defined in RFC 2616, Hypertext Transfer
Protocol-HTTP/1.1. The standard methods include GET, POST, PUT, HEAD, and OPTIONS. Some web
applications require (and sometimes introduce) methods that are extensions of HTTP/1.1 methods.
Common examples of HTTP extended methods include PATCH, REPORT, MKCOL, PROPFIND, MOVE,
and LOCK. Elastic Load Balancing accepts all standard and non-standard HTTP methods.
When a load balancer receives an HTTP request, it checks for malformed requests and for the length of
the method. The total method length in an HTTP request to a load balancer must not exceed 127
characters. If the HTTP request passes both checks, the load balancer sends the request to the EC2
instance. If the method field in the request is malformed, the load balancer responds with an HTTP 400:
BAD_REQUEST (p. 127) error. If the length of the method in the request exceeds 127 characters, the
load balancer responds with an HTTP 405: METHOD_NOT_ALLOWED (p. 127) error.
The EC2 instance processes a valid request by implementing the method in the request and sending a
response back to the client.Your instances must be configured to handle both supported and unsupported
methods.
The following are error messages returned by your load balancer, the potential causes, and the steps
you can take to resolve the issues.
Error Messages
• HTTP 400: BAD_REQUEST (p. 127)
• HTTP 405: METHOD_NOT_ALLOWED (p. 127)
• HTTP 408: Request Timeout (p. 128)
• HTTP 502: Bad Gateway (p. 128)
• HTTP 503: Service Unavailable (p. 128)
• HTTP 504: Gateway Timeout (p. 128)
HTTP 400: BAD_REQUEST
Description: Indicates that the client sent a bad request.
Cause: The client sent a malformed request that does not meet HTTP specifications. For example, a
request can't have spaces in the URL.
Solution: Connect directly to your instance and capture the details of the client request. Review the
headers and the URL for malformed requests. Verify that the request meets HTTP specifications.
HTTP 405: METHOD_NOT_ALLOWED
Description: Indicates that the method length is not valid.
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HTTP 408: Request Timeout
Cause: The length of the method in the request header exceeds 127 characters.
Solution: Check the length of the method.
HTTP 408: Request Timeout
Description: Indicates that the client cancelled the request or failed to send a full request.
Cause 1: A network interruption or a bad request construction, such as partially formed headers; specified
content size doesn't match the actual content size transmitted; and so on.
Solution 1: Inspect the code that is making the request and try sending it directly to your registered
instances (or a development / test environment) where you have more control over inspecting the actual
request.
Cause 2: Connection to the client is closed (load balancer could not send a response)
Solution 2: Verify that the client is not closing the connection before a response is sent by using a packet
sniffer on the machine making the request.
HTTP 502: Bad Gateway
Description: Indicates that the load balancer was unable to parse the response sent from a registered
instance.
Cause: Malformed response from the instance or potentially an issue with the load balancer.
Solution: Verify that the response being sent from the instance conforms to HTTP specifications. Go to
the AWS Support Center for assistance.
HTTP 503: Service Unavailable
Description: Indicates that either the load balancer or the registered instances are causing the error.
Cause 1: Insufficient capacity in the load balancer to handle the request.
Solution 1: This should be a transient issue and should not last more than a few minutes. If it persists,
go to the AWS Support Center for assistance.
Cause 2: No registered instances.
Solution 2: Register at least one instance in every Availability Zone that your load balancer is configured
to respond in. Verify this by looking at the HealthyHostCount metrics in CloudWatch. If you can't ensure
that an instance is registered in each Availability Zone, we recommend enabling cross-zone load balancing.
For more information, see Configure Cross-Zone Load Balancing for Your Load Balancer (p. 83).
Cause 3: No healthy instances.
Solution 3: Ensure that you have healthy instances in every Availability Zone that your load balancer is
configured to respond in. Verify this by looking at the HealthyHostCount in CloudWatch.
HTTP 504: Gateway Timeout
Description: Indicates that the load balancer closed a connection because a request did not complete
within the idle timeout period.
Cause 1: The application takes longer to respond than the configured idle timeout.
Solution 1: Monitor the HTTPCode_ELB_5XX and Latency metrics. If there is an increase in these
metrics, it could be due to the application not responding within the idle timeout period. For details about
the requests that are timing out, enable access logs on the load balancer and review the 504 response
codes in the logs that are generated by Elastic Load Balancing. If necessary, you can increase your
capacity or increase the configured idle timeout so that lengthy operations (such as uploading a large
file) can complete.
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Response Code Metrics
Cause 2: Registered instances closing the connection to Elastic Load Balancing.
Solution 2: Enable keep-alive settings on your EC2 instances and set the keep-alive timeout to greater
than or equal to the idle timeout settings of your load balancer.
Troubleshooting Elastic Load Balancing:
Response Code Metrics
Your load balancer sends metrics to Amazon CloudWatch for the HTTP response codes sent to clients,
identifying the source of the errors as either the load balancer or the registered instances. You can use
the metrics returned by CloudWatch for your load balancer to troubleshoot issues. For more information,
see Monitor Your Load Balancer Using Amazon CloudWatch (p. 101).
The following are response code metrics returned by CloudWatch for your load balancer, the potential
causes, and the steps you can take to resolve the issues.
Response Code Metrics
• HTTPCode_ELB_4XX (p. 129)
• HTTPCode_ELB_5XX (p. 129)
• HTTPCode_Backend_2XX (p. 129)
• HTTPCode_Backend_3XX (p. 130)
• HTTPCode_Backend_4XX (p. 130)
• HTTPCode_Backend_5XX (p. 130)
HTTPCode_ELB_4XX
Cause: A malformed or canceled request from the client.
Solutions
• See HTTP 400: BAD_REQUEST (p. 127).
• See HTTP 405: METHOD_NOT_ALLOWED (p. 127).
• See HTTP 408: Request Timeout (p. 128).
HTTPCode_ELB_5XX
Cause: Either the load balancer or the registered instance is causing the error or the load balancer is
unable to parse the response.
Solutions
• See HTTP 502: Bad Gateway (p. 128).
• See HTTP 503: Service Unavailable (p. 128).
• See HTTP 504: Gateway Timeout (p. 128).
HTTPCode_Backend_2XX
Cause: A normal, successful response from the registered instances.
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HTTPCode_Backend_3XX
Solution: None.
HTTPCode_Backend_3XX
Cause: A redirect response sent from the registered instances.
Solution: View the access logs or the error logs on your instance to determine the cause. Send requests
directly to the instance (bypassing the load balancer) to view the responses.
HTTPCode_Backend_4XX
Cause: A client error response sent from the registered instances.
Solution: View the access or error logs on your instances to determine the cause. Send requests directly
to the instance (bypass the load balancer) to view the responses.
Note
If the client cancels an HTTP request that was initiated with a Transfer-Encoding: chunked
header, there is a known issue where the load balancer forwards the request to the instance
even though the client canceled the request. This can cause backend errors.
HTTPCode_Backend_5XX
Cause: A server error response sent from the registered instances.
Solution: View the access logs or the error logs on your instances to determine the cause. Send requests
directly to the instance (bypass the load balancer) to view the responses.
Note
If the client cancels an HTTP request that was initiated with a Transfer-Encoding: chunked
header, there is a known issue where the load balancer forwards the request to the instance
even though the client canceled the request. This can cause backend errors.
Troubleshooting Elastic Load Balancing: Health
Checks
Your load balancer checks the health of its registered instances using either the default health check
configuration provided by Elastic Load Balancing or a custom health check configuration that you specify.
The health check configuration contains information such as the protocol, ping port, ping path, response
timeout, and health check interval. For more information health checks and how to check the health status
of your registered EC2 instances, see Configure Health Checks (p. 59).
If the current state of some or all your instances is OutOfService and the description field displays the
message that the Instance has failed at least the Unhealthy Threshold number of
health checks consecutively, the instances have failed the load balancer health check. The
following are the issues to look for, the potential causes, and the steps you can take to resolve the issues.
Issues
• Connection to the instances has timed out (p. 131)
• Connection to your Internet-facing load balancer launched in a VPC has timed out (p. 131)
• Health check target page error (p. 132)
• Public key authentication is failing (p. 132)
• Instance is not receiving traffic from the load balancer (p. 132)
• Ports on instance are not open (p. 132)
• Instances in an Auto Scaling group are failing the ELB health check (p. 133)
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Connection to the instances has timed out
Connection to the instances has timed out
Problem: Health check requests from your load balancer to your EC2 instances are timing out or failing
intermittently.
First, verify the issue by connecting directly with the instance. We recommend that you connect to your
instance from within the network using the private IP address of the instance.
Use the following command for a TCP connection:
telnet private-IP-address-of-the-instance port
Use the following command for an HTTP or HTTPS connection:
curl –I private-IP-address-of-the-instance:port/health-check-target-page
If you are using an HTTP/HTTPS connection and getting a non-200 response, see Health check target
page error (p. 132). If you are able to connect directly to the instance, check for the following:
Cause 1: The instance is failing to respond within the configured response timeout period.
Solution 1: Adjust the response timeout settings in your load balancer health check configuration.
Cause 2: The instance is under significant load and is taking longer than your configured response timeout
period to respond.
Solution 2:
• Check the monitoring graph for over-utilization of CPU. For information, see Get Statistics for a Specific
EC2 Instance in the Amazon EC2 User Guide for Linux Instances.
• Check the utilization of other application resources, such as memory or limits, by connecting to your
EC2 instances.
• If necessary, add more instances or enable Auto Scaling. For more information, see What is Auto
Scaling? in the Auto Scaling Developer Guide.
Cause 3: If you are using an HTTP or an HTTPS connection and the health check is being performed on
a target page specified in the ping path field (for example, HTTP:80/index.html), the target page might
be taking longer to respond than your configured timeout.
Solution 3: Use a simpler health check target page or adjust the health check interval settings.
Connection to your Internet-facing load balancer
launched in a VPC has timed out
Problem: Health check requests are not reaching your instances launched in a VPC because the front-end
connection (client to load balancer) has timed out.
Cause: Your Internet-facing load balancer is attached to a private subnet.
Solution: Verify that the VPC has an Internet gateway and that the route table has a route to the Internet
Gateway.
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Health check target page error
Health check target page error
Problem: An HTTP GET request issued to the instance on the specified ping port and the ping path (for
example, HTTP:80/index.html) receives a non-200 response code. Or, some instances are failing the
health check and some instances are healthy.
Cause 1: No target page is configured on some or all the instances.
Solution 1: Create a target page (for example, index.html) on all the registered instances.
Cause 2: The value of the Content-Length header in the response is not set.
Solution 2: If the response includes a body, then either set the Content-Length header to a value greater
than or equal to zero, or set the Transfer-Encoding value to 'chunked'.
Cause 3: The application on the instances is not configured to receive request from the load balancer.
Solution 3: Check the application on your instance to investigate the cause for non-200 response.
Public key authentication is failing
Problem: A load balancer configured to use the HTTPS or SSL protocol with back-end authentication
enabled fails public key authentication.
Cause: The public key on the SSL certificate does not match the public key configured on the load
balancer. Use the s_client command to see the list of server certificates in the certificate chain. For
more information, see https://www.openssl.org/docs/apps/s_client.html.
Solution:Your might need to update your SSL certificate. If your SSL certificate is current, try re-installing
it on your load balancer. For more information, see Replace the SSL Certificate for Your Load
Balancer (p. 51).
Instance is not receiving traffic from the load
balancer
Problem: The security group for the instance is blocking the traffic from the load balancer.
Do a packet capture on the instance to verify the issue. Use the following command:
# tcpdump port health-check-port
Cause 1: The security group associated with the instance does not allow traffic from the load balancer.
Solution 1: Edit the instance security group to allow traffic from the load balancer. Add a rule to allow all
traffic from the load balancer security group.
Cause 2: The security group of your load balancer in a VPC does not allow traffic to the EC2 instances.
Solution 2: Edit the security group of your load balancer to allow traffic to the subnets and the EC2
instances.
For information about managing security groups for EC2-Classic, see Security Groups for Back-end
Instances in EC2-Classic (p. 66).
For information about managing security groups for a VPC, see Security Groups for Load Balancers in
a VPC (p. 62).
Ports on instance are not open
Problem: The health check sent to the EC2 instance by the load balancer is blocked by the port or a
firewall.
Verify the issue by using the following command:
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Instances in an Auto Scaling group are failing the ELB
health check
netstat –ant
Cause: The specified health port or the listener port (if configured differently) is not open. Both the port
specified for the health check and the listener port must be open and listening.
Solution: Open up the listener port and the port specified in your health check configuration (if configured
differently) on your instances to receive load balancer traffic.
Instances in an Auto Scaling group are failing the
ELB health check
Problem: Instances in your Auto Scaling group pass the default Auto Scaling health check but fail the
ELB health check.
Cause: Auto Scaling uses EC2 status checks to detect hardware and software issues with the instances,
but the load balancer performs health checks by sending a request to the instance and waiting for a 200
response code, or by establishing a TCP connection (for a TCP-based health check) with the instance.
An instance might fail the ELB health check because an application running on the instance has issues
that cause the load balancer to consider the instance out of service. This instance might pass the Auto
Scaling health check; it would not be replaced by the Auto Scaling policy because it is considered healthy
based on the EC2 status check.
Solution: Use the ELB health check for your Auto Scaling group. When you use the ELB health check,
Auto Scaling determines the health status of your instances by checking the results of both the instance
status check and the ELB health check. For more information, see Add an Elastic Load Balancing Health
Check to your Auto Scaling Group in the Auto Scaling Developer Guide.
Troubleshooting Elastic Load Balancing:
Instance Registration
When you register an instance with your load balancer, there are a number of steps that are taken before
the load balancer can begin to send requests to your instance.
The following are issues your load balancer might encounter when registering your EC2 instances, the
potential causes, and the steps you can take to resolve the issues.
Issues
• Taking too long to register an EC2 instance (p. 133)
• Unable to register an instance launched from a paid AMI (p. 134)
Taking too long to register an EC2 instance
Problem: Registered EC2 instances are taking longer than expected to be in the InService state.
Cause: Your instance might be failing the health check. After the initial instance registration steps are
completed (it can take up to approximately 30 seconds), the load balancer starts sending health check
requests. Your instance is not InService until one health check succeeds.
Solution: See Connection to the instances has timed out (p. 131).
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Elastic Load Balancing Developer Guide
Unable to register an instance launched from a paid AMI
Unable to register an instance launched from a
paid AMI
Problem: Elastic Load Balancing is not registering an instance launched using a paid AMI.
Cause: Your instances might have been launched using a paid AMI from Amazon DevPay.
Solution: Elastic Load Balancing does not support registering instances launched using paid AMIs from
Amazon DevPay. Note that you can use paid AMIs from AWS Marketplace. If you are already using a
paid AMI from AWS Marketplace and are unable to register an instance launched from that paid AMI, go
to the AWS Support Center for assistance.
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Elastic Load Balancing Developer Guide
Elastic Load Balancing Limits
Your AWS account comes with the following default limits for Elastic Load Balancing:
•
•
•
•
Load balancers per region: 20
Listeners per load balancer: 100
Security groups per load balancer: 5
Subnets per Availability Zone per load balancer: 1
For information about the limits for other services and how to request limit increases, see AWS Service
Limits in the Amazon Web Services General Reference.
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Elastic Load Balancing Developer Guide
Document History
The following table describes the releases and important changes for Elastic Load Balancing.
Feature
WSDL
Description
Release
Date
Support for AWS
Certificate Manager (ACM)
You can request an SSL/TLS certificate January 21,
from ACM and deploy it to your load
2016
balancer. For more information, see SSL
Certificates for Elastic Load Balancing (p. 22).
Support for additional ports
Load balancers in a VPC can listen on September
any port in the range 1-65535. For more 15, 2015
information, see Listeners for Your Load
Balancer (p. 76).
Additional fields for
access log entries
Added the user_agent, ssl_cipher, May 18,
and ssl_protocol fields. For more in- 2015
formation, see Access Log Files (p. 108).
Support for register- 2014-08-11 WSDL
ing linked EC2Classic instances
Added support for registering linked
EC2-Classic instances with your load
balancer.
136
January 19,
2015
Elastic Load Balancing Developer Guide
Feature
WSDL
Description
Support for tagging 2014-08-11 WSDL
your load balancer
Release
Date
You can use tags to organize and man- August 11,
age your load balancers.
2014
Starting with this release, Elastic Load
Balancing CLI (ELB CLI) has been replaced by AWS Command Line Interface
(AWS CLI), a unified tool to manage
multiple AWS services. New features
released after ELB CLI version 1.0.35.0
(dated 7/24/14) will be included in the
AWS CLI only. If you are currently using
the ELB CLI, we recommend that you
start using the AWS Command Line Interface (AWS CLI) instead. For more information, see Access Elastic Load Balancing Using the AWS CLI (p. 8).
idle connection
timeout
2014-07-24 WSDL
You can configure the idle connection
timeout for your load balancer.
July 24,
2014
Support for grant- 2014-03-20 WSDL
ing IAM users and
groups access to
specific load balancers or API actions
You can create an IAM policy to grant
May 12,
IAM users and groups access to specific 2014
load balancers or API actions. For more
information, see Control Access to Your
Load Balancer (p. 119).
Support for AWS
CloudTrail
2014-03-20 WSDL
You can use CloudTrail to capture API
April 04,
calls made by or on behalf of your AWS 2014
account using the ELB API, the AWS
Management Console, the ELB CLI, or
the AWS CLI. For more information, see
Log Elastic Load Balancing API Calls
Using AWS CloudTrail (p. 116).
connection draining
2014-03-20 WSDL
Added information about connection
March 20,
draining. With this support you can en- 2014
able your load balancer to stop sending
new requests to the registered instance
when the instance is de-registering or
when the instance becomes unhealthy,
while keeping the existing connections
open. For more information, see Configure Connection Draining for Your Load
Balancer (p. 86).
access logs
2014-03-06 WSDL
You can enable your load balancer to
March 06,
capture detailed information about the 2014
requests sent to your load balancer and
store it in an S3 bucket. For more information, see Monitor Your Load Balancer
Using Elastic Load Balancing Access
Logs (p. 107).
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Elastic Load Balancing Developer Guide
Feature
WSDL
Description
Release
Date
Support for
TLSv1.1-1.2
2013-11-06 WSDL
Added information about TLSv1.1-1.2
February 19,
protocol support for load balancers con- 2014
figured with HTTPS/SSL listeners. With
this support, Elastic Load Balancing also
updates the predefined SSL negotiation
configurations. For information about the
updated predefined SSL negotiation
configurations, see SSL Negotiation
Configurations for Elastic Load Balancing (p. 28). For information about updating your current SSL negotiation configuration, see Update the SSL Negotiation
Configuration of Your Load Balancer (p. 53).
cross-zone load
balancing
2013-11-06 WSDL
Added information about enabling cross- November
zone load balancing for your load balan- 06, 2013
cer. For information on cross-zone load
balancing, see Request Routing (p. 4).
For procedure on enabling or disabling
the cross-zone load balancing, see
Configure Cross-Zone Load Balancing
for Your Load Balancer (p. 83)
Additional CloudWatch Metrics
2012-06-01 WSDL
Added information about the additional October 28,
Cloudwatch metrics reported by Elastic 2013
Load Balancing. For more information,
see Monitor Your Load Balancer Using
Amazon CloudWatch (p. 101).
Support for Proxy
Protocol
2012-06-01 WSDL
Added information about Proxy Protocol July 30,
support for load balancers configured
2013
for TCP/SSL connections. For more information, see Proxy Protocol Header (p. 89).
Support for DNS
failover
2012-06-01 WSDL
Added information about configuring
June 03,
Route 53 DNS failover for load balan2013
cers. For more information, see Configure DNS Failover for Your Load Balancer (p. 99).
Console support
2012-06-01 WSDL
for viewing CloudWatch metrics and
creating alarms
Added information about viewing
March 28,
CloudWatch metrics and creating alarms 2013
for a specified load balancer using the
console. For more information, see
Monitor Your Load Balancer Using
Amazon CloudWatch (p. 101).
Support for register- 2012-06-01 WSDL
ing EC2 instances
in a default VPC
Added support for EC2 instances
launched in a default VPC.
138
March 11,
2013
Elastic Load Balancing Developer Guide
Feature
WSDL
Description
Release
Date
internal load balan- 2012-06-01 WSDL
cers
With this release, a load balancer in a
June 10,
virtual private cloud (VPC) can be made 2012
either internal or Internet-facing. An internal load balancer has a publicly
resolvable DNS name that resolves to
private IP addresses. An Internet-facing
load balancer has a publicly resolvable
DNS name that resolves to public IP
addresses. For more information, see
Create an Internal Load Balancer (p. 18).
Console support
for managing
listeners, cipher
settings, and SSL
certificates
For information, see Configure an HTMay 18,
TPS Listener for Your Load Balan2012
cer (p. 48) and Replace the SSL Certificate for Your Load Balancer (p. 51).
2011-11-15 WSDL
Support for Elastic 2011-11-15 WSDL
Load Balancing in
Amazon VPC
Added support for creating a load balan- November
cer in a virtual private cloud (VPC).
21, 2011
Amazon CloudWatch
2011-08-15 WSDL
You can monitor your load balancer us- October 17,
ing CloudWatch. For more information, 2011
see Monitor Your Load Balancer Using
Amazon CloudWatch (p. 101).
Additional security
features
2011-08-15 WSDL
You can configure SSL ciphers, backAugust 30,
end SSL, and back-end server authentic- 2011
ation. For more information, see Create
an HTTPS Load Balancer (p. 34).
zone apex domain
name
2011-04-05 WSDL
For more information, see Configure a
Custom Domain Name for Your Load
Balancer (p. 98).
May 24,
2011
instance lock-down 2011-04-05 WSDL
You can use the security group provided May 24,
by Elastic Load Balancing to lock down 2011
your back-end instance. For more information, see Security Groups for Back-end
Instances in EC2-Classic (p. 66).
Support for IPv6
You can use Internet Protocol version 6 May 24,
(IPv6) with your load balancer in EC2- 2011
Classic.
2011-04-05 WSDL
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Elastic Load Balancing Developer Guide
Feature
WSDL
Description
Support for X-Forwarded-Proto and
X-Forwarded-Port
headers
2010-07-01 WSDL
The X-Forwarded-Proto header indicates October 27,
the protocol of the originating request, 2010
and the X-Forwarded-Port header indicates the port of the originating request.
The addition of these headers to requests enables customers to determine
if an incoming request to their load balancer is encrypted, and the specific port
on the load balancer that the request
was received on. For more information,
see X-Forwarded Headers for Elastic
Load Balancing (p. 80).
Support for HTTPS 2010-07-01 WSDL
With this release, you can leverage the October 14,
SSL/TLS protocol for encrypting traffic 2010
and offload SSL processing from the
application instance to the load balancer.
This feature also provides centralized
management of SSL server certificates
at the load balancer, rather than managing certificates on individual application instances.
Support for AWS
2010-07-01 WSDL
Identity and Access Management
(IAM)
For more information, see Control Access to Your Load Balancer (p. 119).
September
02, 2010
sticky sessions
2009-11-25 WSDL
For more information, see Configure
Sticky Sessions for Your Load Balancer (p. 92).
April 07,
2010
AWS SDK for Java 2009-11-25 WSDL
Added support for the SDK for Java.
March 22,
2010
AWS SDK for .NET 2009-05-15 WSDL
Added support for the AWS SDK for
.NET.
November
11, 2009
New service
Initial public beta release of Elastic Load May 18,
Balancing.
2009
2009-05-15 WSDL
140
Release
Date
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