Gunicorn Documentation

Gunicorn Documentation

Release 19.7.1

Benoit Chesneau

Sep 18, 2017

Contents

1 Features

3

2 Contents

2.1

Installation

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.2

Running Gunicorn

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

7

2.3

Configuration Overview

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

9

5

5

2.4

Settings

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

10

2.5

Instrumentation

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

28

2.6

Deploying Gunicorn

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

29

2.7

Signal Handling

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

35

2.8

Custom Application

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

37

2.9

Design

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

38

2.10 FAQ

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

40

2.11 Community

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

43

2.12 Changelog

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

44

i

ii

Gunicorn Documentation, Release 19.7.1

Website http://gunicorn.org

Source code https://github.com/benoitc/gunicorn

Issue tracker https://github.com/benoitc/gunicorn/issues

IRC #gunicorn on Freenode

Mail list http://lists.gunicorn.org/user/

Gunicorn ‘Green Unicorn’ is a Python WSGI HTTP Server for UNIX. It’s a pre-fork worker model ported from Ruby’s

Unicorn project. The Gunicorn server is broadly compatible with various web frameworks, simply implemented, light on server resources, and fairly speedy.

Contents 1


2 Contents

• Natively supports WSGI, Django, and Paster

• Automatic worker process management

• Simple Python configuration

• Multiple worker configurations

• Various server hooks for extensibility

• Compatible with Python 2.x >= 2.6 or 3.x >= 3.2

CHAPTER

1

Features

3


4 Chapter 1. Features

CHAPTER

2

Contents

Installation

Requirements Python 2.x >= 2.6 or Python 3.x >= 3.2

To install the latest released version of Gunicorn:

$ pip install gunicorn

From Source

You can install Gunicorn from source just as you would install any other Python package:

$ pip install git+https://github.com/benoitc/gunicorn.git

This will allow you to keep up to date with development on GitHub:

$ pip install -U git+https://github.com/benoitc/gunicorn.git

Async Workers

You may also want to install Eventlet or Gevent if you expect that your application code may need to pause for extended periods of time during request processing. Check out the design docs for more information on when you’ll want to consider one of the alternate worker types.

$ pip install greenlet # Required for both

$ pip install eventlet # For eventlet workers

$ pip install gevent # For gevent workers

Note: If installing greenlet fails you probably need to install the Python headers. These headers are available in most package managers. On Ubuntu the package name for apt-get is python-dev.

5


Gevent also requires that libevent 1.4.x or 2.0.4 is installed. This could be a more recent version than what is available in your package manager. If Gevent fails to build even with libevent installed, this is the most likely reason.

Debian GNU/Linux

If you are using Debian GNU/Linux and it is recommended that you use system packages to install Gunicorn except maybe when you want to use different versions of Gunicorn with virtualenv. This has a number of advantages:

• Zero-effort installation: Automatically starts multiple Gunicorn instances based on configurations defined in

/etc/gunicorn.d

.

• Sensible default locations for logs (/var/log/gunicorn). Logs can be automatically rotated and compressed using logrotate.

• Improved security: Can easily run each Gunicorn instance with a dedicated UNIX user/group.

• Sensible upgrade path: Upgrades to newer versions result in less downtime, handle conflicting changes in configuration options, and can be quickly rolled back in case of incompatibility. The package can also be purged entirely from the system in seconds.

stable (“stretch”)

The version of Gunicorn in the Debian “stable” distribution is 19.6.0 (June 2017). You can install it using:

$ sudo apt-get install gunicorn

You can also use the most recent version by using Debian Backports . First, copy the following line to your /etc/ apt/sources.list

: deb http://ftp.debian.org/debian stretch-backports main

Then, update your local package lists:

$ sudo apt-get update

You can then install the latest version using:

$ sudo apt-get -t stretch-backports install gunicorn

oldstable (“jessie”)

The version of Gunicorn in the Debian “oldstable” distribution is 19.0 (June 2014). you can install it using:


You can also use the most recent version by using Debian Backports . First, copy the following line to your /etc/ apt/sources.list

: deb http://ftp.debian.org/debian jessie-backports main

Then, update your local package lists:


6 Chapter 2. Contents

You can then install the latest version using:

$ sudo apt-get -t jessie-backports install gunicorn


Testing (“buster”) / Unstable (“sid”)

“buster” and “sid” contain the latest released version of Gunicorn. You can install it in the usual way:


Ubuntu

Ubuntu 12.04 (trusty) or later contains Gunicorn package by default so that you can install it in the usual way:



Running Gunicorn

You can run Gunicorn by using commands or integrate with Django or Paster. For deploying Gunicorn in production see

Deploying Gunicorn

.

Commands

After installing Gunicorn you will have access to the command line script gunicorn.

gunicorn

Basic usage:

$ gunicorn [ OPTIONS ] APP_MODULE

Where APP_MODULE is of the pattern $(MODULE_NAME):$(VARIABLE_NAME). The module name can be a full dotted path. The variable name refers to a WSGI callable that should be found in the specified module.

Example with the test app:

def

app (environ, start_response):

"""Simplest possible application object""" data = 'Hello, World!\n' status = '200 OK' response_headers = [

( 'Content-type' , 'text/plain' ),

( 'Content-Length' , str ( len (data)))

] start_response(status, response_headers)

return

iter ([data])

You can now run the app with the following command:

2.2. Running Gunicorn 7


$ gunicorn --workers = 2 test:app

Commonly Used Arguments

• -c CONFIG, --config=CONFIG - Specify a config file in the form $(PATH), file:$(PATH), or python:$(MODULE_NAME)

.

• -b BIND, --bind=BIND - Specify a server socket to bind. Server sockets can be any of $(HOST),

$(HOST):$(PORT)

, or unix:$(PATH). An IP is a valid $(HOST).

• -w WORKERS, --workers=WORKERS - The number of worker processes. This number should generally be between 2-4 workers per core in the server. Check the

FAQ

for ideas on tuning this parameter.

• -k WORKERCLASS, --worker-class=WORKERCLASS - The type of worker process to run. You’ll definitely want to read the production page for the implications of this parameter. You can set this to $(NAME) where $(NAME) is one of sync, eventlet, gevent, or tornado, gthread, gaiohttp. sync is the default.

• -n APP_NAME, --name=APP_NAME - If setproctitle is installed you can adjust the name of Gunicorn process as they appear in the process system table (which affects tools like ps and top).

Settings can be specified by using environment variable

GUNICORN_CMD_ARGS

.

See

Configuration Overview

and

Settings

for detailed usage.

Integration

We also provide integration for both Django and Paster applications.

Django

Gunicorn will look for a WSGI callable named application if not specified. So for a typical Django project, invoking Gunicorn would look like:

$ gunicorn myproject.wsgi

Note: This requires that your project be on the Python path; the simplest way to ensure that is to run this command from the same directory as your manage.py file.

You can use the –env option to set the path to load the settings. In case you need it you can also add your application path to PYTHONPATH using the –pythonpath option:

$ gunicorn --env DJANGO_SETTINGS_MODULE = myproject.settings myproject.wsgi

Paste

If you are a user/developer of a paste-compatible framework/app (as Pyramid, Pylons and Turbogears) you can use the

–paste option to run your application.

For example:



$ gunicorn --paste development.ini -b :8080 --chdir /path/to/project

Or use a different application:

$ gunicorn --paste development.ini#admin -b :8080 --chdir /path/to/project

It is all here. No configuration files nor additional Python modules to write!

Configuration Overview

Gunicorn pulls configuration information from three distinct places.

The first place that Gunicorn will read configuration from is the framework specific configuration file. Currently this only affects Paster applications.

The second source of configuration information is a configuration file that is optionally specified on the command line.

Anything specified in the Gunicorn config file will override any framework specific settings.

Lastly, the command line arguments used to invoke Gunicorn are the final place considered for configuration settings.

If an option is specified on the command line, this is the value that will be used.

Once again, in order of least to most authoritative:

1. Framework Settings

2. Configuration File

3. Command Line

Note: To check your configuration when using the command line or the configuration file you can run the following command:

$ gunicorn --check-config APP_MODULE

It also allows you to know if your application can be launched.

Command Line

If an option is specified on the command line, it overrides all other values that may have been specified in the app specific settings, or in the optional configuration file. Not all Gunicorn settings are available to be set from the command line. To see the full list of command line settings you can do the usual:

$ gunicorn -h

There is also a --version flag available to the command line scripts that isn’t mentioned in the list of

settings

.

Configuration File

The configuration file should be a valid Python source file. It only needs to be readable from the file system. More specifically, it does not need to be importable. Any Python is valid. Just consider that this will be run every time you start Gunicorn (including when you signal Gunicorn to reload).

2.3. Configuration Overview 9


To set a parameter, just assign to it. There’s no special syntax. The values you provide will be used for the configuration values.

For instance:

import multiprocessing

bind = "127.0.0.1:8000" workers = multiprocessing .

cpu_count()

*

2 + 1

All the settings are mentioned in the

settings

list.

Framework Settings

Currently, only Paster applications have access to framework specific settings. If you have ideas for providing settings to WSGI applications or pulling information from Django’s settings.py feel free to open an issue to let us know.

Paster Applications

In your INI file, you can specify to use Gunicorn as the server like such:

[server:main]

use = egg:gunicorn#main host = 192.168.0.1

port = 80 workers = 2 proc_name = brim

Any parameters that Gunicorn knows about will automatically be inserted into the base configuration. Remember that these will be overridden by the config file and/or the command line.

Settings

This is an exhaustive list of settings for Gunicorn. Some settings are only able to be set from a configuration file.

The setting name is what should be used in the configuration file. The command line arguments are listed as well for reference on setting at the command line.

Note: Settings can be specified by using environment variable GUNICORN_CMD_ARGS. All available command line arguments can be used. For example, to specify the bind address and number of workers:

$ GUNICORN_CMD_ARGS="--bind=127.0.0.1 --workers=3" gunicorn app:app

New in version 19.7.

Config File

config

• -c CONFIG, --config CONFIG

• None



The Gunicorn config file.

A string of the form PATH, file:PATH, or python:MODULE_NAME.

Only has an effect when specified on the command line or as part of an application specific configuration.

Changed in version 19.4: Loading the config from a Python module requires the python: prefix.

Server Socket

bind

• -b ADDRESS, --bind ADDRESS

• ['127.0.0.1:8000']

The socket to bind.

A string of the form: HOST, HOST:PORT, unix:PATH. An IP is a valid HOST.

Multiple addresses can be bound. ex.:

$ gunicorn -b 127.0.0.1:8000 -b [::1]:8000 test:app will bind the test:app application on localhost both on ipv6 and ipv4 interfaces.

backlog

• --backlog INT

• 2048

The maximum number of pending connections.

This refers to the number of clients that can be waiting to be served. Exceeding this number results in the client getting an error when attempting to connect. It should only affect servers under significant load.

Must be a positive integer. Generally set in the 64-2048 range.

Worker Processes

workers

• -w INT, --workers INT

• 1

The number of worker processes for handling requests.

A positive integer generally in the 2-4 x $(NUM_CORES) range. You’ll want to vary this a bit to find the best for your particular application’s work load.

By default, the value of the WEB_CONCURRENCY environment variable. If it is not defined, the default is 1.

2.4. Settings 11


worker_class

• -k STRING, --worker-class STRING

• sync

The type of workers to use.

The default class (sync) should handle most “normal” types of workloads. You’ll want to read

Design

for information on when you might want to choose one of the other worker classes.

A string referring to one of the following bundled classes:

• sync

• eventlet - Requires eventlet >= 0.9.7

• gevent - Requires gevent >= 0.13

• tornado - Requires tornado >= 0.2

• gthread - Python 2 requires the futures package to be installed

• gaiohttp - Requires Python 3.4 and aiohttp >= 0.21.5

Optionally, you can provide your own worker by giving Gunicorn a Python path to a subclass of gunicorn.

workers.base.Worker

. This alternative syntax will load the gevent class: gunicorn.workers.ggevent.

GeventWorker

.

threads

• --threads INT

• 1

The number of worker threads for handling requests.

Run each worker with the specified number of threads.

A positive integer generally in the 2-4 x $(NUM_CORES) range. You’ll want to vary this a bit to find the best for your particular application’s work load.

If it is not defined, the default is 1.

This setting only affects the Gthread worker type.

Note: If you try to use the sync worker type and set the threads setting to more than 1, the gthread worker type will be used instead.

worker_connections

• --worker-connections INT

• 1000

The maximum number of simultaneous clients.

This setting only affects the Eventlet and Gevent worker types.



max_requests

• --max-requests INT

• 0

The maximum number of requests a worker will process before restarting.

Any value greater than zero will limit the number of requests a work will process before automatically restarting. This is a simple method to help limit the damage of memory leaks.

If this is set to zero (the default) then the automatic worker restarts are disabled.

max_requests_jitter

• --max-requests-jitter INT

• 0

The maximum jitter to add to the max_requests setting.

The jitter causes the restart per worker to be randomized by randint(0, max_requests_jitter). This is intended to stagger worker restarts to avoid all workers restarting at the same time.


timeout

• -t INT, --timeout INT

• 30

Workers silent for more than this many seconds are killed and restarted.

Generally set to thirty seconds. Only set this noticeably higher if you’re sure of the repercussions for sync workers.

For the non sync workers it just means that the worker process is still communicating and is not tied to the length of time required to handle a single request.

graceful_timeout

• --graceful-timeout INT

• 30

Timeout for graceful workers restart.

After receiving a restart signal, workers have this much time to finish serving requests. Workers still alive after the timeout (starting from the receipt of the restart signal) are force killed.

keepalive

• --keep-alive INT

• 2

The number of seconds to wait for requests on a Keep-Alive connection.

Generally set in the 1-5 seconds range for servers with direct connection to the client (e.g. when you don’t have separate load balancer). When Gunicorn is deployed behind a load balancer, it often makes sense to set this to a higher value.



Note: sync worker does not support persistent connections and will ignore this option.

Security

limit_request_line

• --limit-request-line INT

• 4094

The maximum size of HTTP request line in bytes.

This parameter is used to limit the allowed size of a client’s HTTP request-line. Since the request-line consists of the

HTTP method, URI, and protocol version, this directive places a restriction on the length of a request-URI allowed for a request on the server. A server needs this value to be large enough to hold any of its resource names, including any information that might be passed in the query part of a GET request. Value is a number from 0 (unlimited) to 8190.

This parameter can be used to prevent any DDOS attack.

limit_request_fields

• --limit-request-fields INT

• 100

Limit the number of HTTP headers fields in a request.

This parameter is used to limit the number of headers in a request to prevent DDOS attack.

Used with the limit_request_field_size it allows more safety. By default this value is 100 and can’t be larger than 32768.

limit_request_field_size

• --limit-request-field_size INT

• 8190

Limit the allowed size of an HTTP request header field.

Value is a positive number or 0. Setting it to 0 will allow unlimited header field sizes.

Warning: Setting this parameter to a very high or unlimited value can open up for DDOS attacks.

Debugging

reload

• --reload

• False



Restart workers when code changes.

This setting is intended for development. It will cause workers to be restarted whenever application code changes.

The reloader is incompatible with application preloading. When using a paste configuration be sure that the server block does not import any application code or the reload will not work as designed.

The default behavior is to attempt inotify with a fallback to file system polling. Generally, inotify should be preferred if available because it consumes less system resources.

Note: In order to use the inotify reloader, you must have the inotify package installed.

reload_engine

• --reload-engine STRING

• auto

The implementation that should be used to power

reload

.

Valid engines are:

• ‘auto’

• ‘poll’

• ‘inotify’ (requires inotify)


reload_extra_files

• --reload-extra-file FILES

• []

Extends

reload

option to also watch and reload on additional files (e.g., templates, configurations, specifications, etc.).


spew

• --spew

• False

Install a trace function that spews every line executed by the server.

This is the nuclear option.

check_config

• --check-config

• False

Check the configuration.



Server Mechanics

preload_app

• --preload

• False

Load application code before the worker processes are forked.

By preloading an application you can save some RAM resources as well as speed up server boot times. Although, if you defer application loading to each worker process, you can reload your application code easily by restarting workers.

sendfile

• --no-sendfile

• None

Disables the use of sendfile().

If not set, the value of the SENDFILE environment variable is used to enable or disable its usage.


Changed in version 19.4: Swapped --sendfile with --no-sendfile to actually allow disabling.

Changed in version 19.6: added support for the SENDFILE environment variable

chdir

• --chdir

• /home/docs/checkouts/readthedocs.org/user_builds/gunicorn-docs/checkouts/ latest/docs/source

Chdir to specified directory before apps loading.

daemon

• -D, --daemon

• False

Daemonize the Gunicorn process.

Detaches the server from the controlling terminal and enters the background.

raw_env

• -e ENV, --env ENV

• []

Set environment variable (key=value).

Pass variables to the execution environment. Ex.:



$ gunicorn -b 127.0.0.1:8000 --env FOO=1 test:app and test for the foo variable environment in your application.

pidfile

• -p FILE, --pid FILE

• None

A filename to use for the PID file.

If not set, no PID file will be written.

worker_tmp_dir

• --worker-tmp-dir DIR

• None

A directory to use for the worker heartbeat temporary file.

If not set, the default temporary directory will be used.

Note: The current heartbeat system involves calling os.fchmod on temporary file handlers and may block a worker for arbitrary time if the directory is on a disk-backed filesystem.

See

How do I avoid Gunicorn excessively blocking in os.fchmod?

for more detailed information and a solution for avoiding this problem.

user

• -u USER, --user USER

• 1005

Switch worker processes to run as this user.

A valid user id (as an integer) or the name of a user that can be retrieved with a call to pwd.getpwnam(value) or

None to not change the worker process user.

group

• -g GROUP, --group GROUP

• 205

Switch worker process to run as this group.

A valid group id (as an integer) or the name of a user that can be retrieved with a call to pwd.getgrnam(value) or None to not change the worker processes group.



umask

• -m INT, --umask INT

• 0

A bit mask for the file mode on files written by Gunicorn.

Note that this affects unix socket permissions.

A valid value for the os.umask(mode) call or a string compatible with int(value, 0) (0 means Python guesses the base, so values like 0, 0xFF, 0022 are valid for decimal, hex, and octal representations)

initgroups

• --initgroups

• False

If true, set the worker process’s group access list with all of the groups of which the specified username is a member, plus the specified group id.


tmp_upload_dir

• None

Directory to store temporary request data as they are read.

This may disappear in the near future.

This path should be writable by the process permissions set for Gunicorn workers. If not specified, Gunicorn will choose a system generated temporary directory.

secure_scheme_headers

• {'X-FORWARDED-PROTOCOL': 'ssl', 'X-FORWARDED-PROTO': 'https',

'X-FORWARDED-SSL': 'on'}

A dictionary containing headers and values that the front-end proxy uses to indicate HTTPS requests. These tell

Gunicorn to set wsgi.url_scheme to https, so your application can tell that the request is secure.

The dictionary should map upper-case header names to exact string values. The value comparisons are case-sensitive, unlike the header names, so make sure they’re exactly what your front-end proxy sends when handling HTTPS requests.

It is important that your front-end proxy configuration ensures that the headers defined here can not be passed directly from the client.

forwarded_allow_ips

• --forwarded-allow-ips STRING

• 127.0.0.1



Front-end’s IPs from which allowed to handle set secure headers. (comma separate).

Set to * to disable checking of Front-end IPs (useful for setups where you don’t know in advance the IP address of

Front-end, but you still trust the environment).

By default, the value of the FORWARDED_ALLOW_IPS environment variable. If it is not defined, the default is

"127.0.0.1"

.

Logging

accesslog

• --access-logfile FILE

• None

The Access log file to write to.

'-' means log to stdout.

disable_redirect_access_to_syslog

• --disable-redirect-access-to-syslog

• False

Disable redirect access logs to syslog.


access_log_format

• --access-logformat STRING

• %(h)s %(l)s %(u)s %(t)s "%(r)s" %(s)s %(b)s "%(f)s" "%(a)s"

The access log format.



f a

B b

T

U q

H s t u r m l

Identifier h

Description remote address

'-' user name date of the request status line (e.g. GET / HTTP/1.1) request method

URL path without query string query string protocol status response length response length or '-' (CLF format) referer user agent request time in seconds

D

L p

{Header}i request time in microseconds request time in decimal seconds process ID request header

{Header}o response header

{Variable}e environment variable

errorlog

• --error-logfile FILE, --log-file FILE

• -

The Error log file to write to.

Using '-' for FILE makes gunicorn log to stderr.

Changed in version 19.2: Log to stderr by default.

loglevel

• --log-level LEVEL

• info

The granularity of Error log outputs.

Valid level names are:

• debug

• info

• warning

• error

• critical



capture_output

• --capture-output

• False

Redirect stdout/stderr to Error log.


logger_class

• --logger-class STRING

• gunicorn.glogging.Logger

The logger you want to use to log events in Gunicorn.

The default class (gunicorn.glogging.Logger) handle most of normal usages in logging. It provides error and access logging.

You can provide your own logger by giving Gunicorn a Python path to a subclass like gunicorn.glogging.

Logger

.

logconfig

• --log-config FILE

• None

The log config file to use. Gunicorn uses the standard Python logging module’s Configuration file format.

syslog_addr

• --log-syslog-to SYSLOG_ADDR

• udp://localhost:514

Address to send syslog messages.

Address is a string of the form:

• unix://PATH#TYPE : for unix domain socket. TYPE can be stream for the stream driver or dgram for the dgram driver. stream is the default.

• udp://HOST:PORT : for UDP sockets

• tcp://HOST:PORT : for TCP sockets

syslog

• --log-syslog

• False

Send Gunicorn logs to syslog.

Changed in version 19.8: You can now disable sending access logs by using the

disable_redirect_access_to_syslog

setting.



syslog_prefix

• --log-syslog-prefix SYSLOG_PREFIX

• None

Makes Gunicorn use the parameter as program-name in the syslog entries.

All entries will be prefixed by gunicorn.<prefix>. By default the program name is the name of the process.

syslog_facility

• --log-syslog-facility SYSLOG_FACILITY

• user

Syslog facility name

enable_stdio_inheritance

• -R, --enable-stdio-inheritance

• False

Enable stdio inheritance.

Enable inheritance for stdio file descriptors in daemon mode.

Note: To disable the Python stdout buffering, you can to set the user environment variable PYTHONUNBUFFERED .

statsd_host

• --statsd-host STATSD_ADDR

• None host:port of the statsd server to log to.


statsd_prefix

• --statsd-prefix STATSD_PREFIX

• (empty string)

Prefix to use when emitting statsd metrics (a trailing . is added, if not provided).


Process Naming

proc_name

• -n STRING, --name STRING

• None



A base to use with setproctitle for process naming.

This affects things like ps and top. If you’re going to be running more than one instance of Gunicorn you’ll probably want to set a name to tell them apart. This requires that you install the setproctitle module.

If not set, the default_proc_name setting will be used.

default_proc_name

• gunicorn

Internal setting that is adjusted for each type of application.


pythonpath

• --pythonpath STRING

• None

A comma-separated list of directories to add to the Python path.

e.g. '/home/djangoprojects/myproject,/home/python/mylibrary'.

paste

• --paste STRING, --paster STRING

• None

Load a PasteDeploy config file. The argument may contain a # symbol followed by the name of an app section from the config file, e.g. production.ini#admin.

At this time, using alternate server blocks is not supported. Use the command line arguments to control server configuration instead.

Server Hooks

on_starting

•

def

on_starting (server):

pass

Called just before the master process is initialized.

The callable needs to accept a single instance variable for the Arbiter.

on_reload

•

def

on_reload (server):

pass



Called to recycle workers during a reload via SIGHUP.


when_ready

•

def

when_ready (server):

pass

Called just after the server is started.


pre_fork

•

def

pre_fork (server, worker):

pass

Called just before a worker is forked.

The callable needs to accept two instance variables for the Arbiter and new Worker.

post_fork

•

def

post_fork (server, worker):

pass

Called just after a worker has been forked.

The callable needs to accept two instance variables for the Arbiter and new Worker.

post_worker_init

•

def

post_worker_init (worker):

pass

Called just after a worker has initialized the application.

The callable needs to accept one instance variable for the initialized Worker.

worker_int

•

def

worker_int (worker):

pass

Called just after a worker exited on SIGINT or SIGQUIT.




worker_abort

•

def

worker_abort (worker):

pass

Called when a worker received the SIGABRT signal.

This call generally happens on timeout.


pre_exec

•

def

pre_exec (server):

pass

Called just before a new master process is forked.


pre_request

•

def

pre_request (worker, req): worker .

log .

debug( " %s %s " % (req .

method, req .

path))

Called just before a worker processes the request.

The callable needs to accept two instance variables for the Worker and the Request.

post_request

•

def

post_request (worker, req, environ, resp):

pass

Called after a worker processes the request.

The callable needs to accept two instance variables for the Worker and the Request.

child_exit

•

def

child_exit (server, worker):

pass

Called just after a worker has been exited, in the master process.

The callable needs to accept two instance variables for the Arbiter and the just-exited Worker.




worker_exit

•

def

worker_exit (server, worker):

pass

Called just after a worker has been exited, in the worker process.

The callable needs to accept two instance variables for the Arbiter and the just-exited Worker.

nworkers_changed

•

def

nworkers_changed (server, new_value, old_value):

pass

Called just after num_workers has been changed.

The callable needs to accept an instance variable of the Arbiter and two integers of number of workers after and before change.

If the number of workers is set for the first time, old_value would be None.

on_exit

•

def

on_exit (server):

pass

Called just before exiting Gunicorn.



proxy_protocol

• --proxy-protocol

• False

Enable detect PROXY protocol (PROXY mode).

Allow using HTTP and Proxy together. It may be useful for work with stunnel as HTTPS frontend and Gunicorn as

HTTP server.

PROXY protocol: http://haproxy.1wt.eu/download/1.5/doc/proxy-protocol.txt

Example for stunnel config:

[https] protocol = proxy accept = 443 connect = 80 cert = / etc / ssl / certs / stunnel .

pem key = / etc / ssl / certs / stunnel .

key



proxy_allow_ips

• --proxy-allow-from

• 127.0.0.1

Front-end’s IPs from which allowed accept proxy requests (comma separate).

Set to * to disable checking of Front-end IPs (useful for setups where you don’t know in advance the IP address of

Front-end, but you still trust the environment)

SSL

keyfile

• --keyfile FILE

• None

SSL key file

certfile

• --certfile FILE

• None

SSL certificate file

ssl_version

• --ssl-version

• 2

SSL version to use (see stdlib ssl module’s)

Changed in version 19.7: The default value has been changed from ssl.PROTOCOL_TLSv1 to ssl.

PROTOCOL_SSLv23

.

cert_reqs

• --cert-reqs

• 0

Whether client certificate is required (see stdlib ssl module’s)

ca_certs

• --ca-certs FILE

• None

CA certificates file



suppress_ragged_eofs

• --suppress-ragged-eofs

• True

Suppress ragged EOFs (see stdlib ssl module’s)

do_handshake_on_connect

• --do-handshake-on-connect

• False

Whether to perform SSL handshake on socket connect (see stdlib ssl module’s)

ciphers

• --ciphers

• TLSv1

Ciphers to use (see stdlib ssl module’s)


raw_paste_global_conf

• --paste-global CONF

• []

Set a PasteDeploy global config variable in key=value form.

The option can be specified multiple times.

The variables are passed to the the PasteDeploy entrypoint. Example:

$ gunicorn -b 127.0.0.1:8000 --paste development.ini --paste-global FOO=1 --paste-

˓→ global BAR=2


Instrumentation


Gunicorn provides an optional instrumentation of the arbiter and workers using the statsD protocol over UDP. Thanks to the gunicorn.instrument.statsd module, Gunicorn becomes a statsD client. The use of UDP cleanly isolates Gunicorn from the receiving end of the statsD metrics so that instrumentation does not cause Gunicorn to be held up by a slow statsD consumer.

To use statsD, just tell Gunicorn where the statsD server is:

$ gunicorn --statsd-host = localhost:8125 ...



The Statsd logger overrides gunicorn.glogging.Logger to track all requests. The following metrics are generated:

• gunicorn.requests: request rate per second

• gunicorn.request.duration: histogram of request duration (in millisecond)

• gunicorn.workers: number of workers managed by the arbiter (gauge)

• gunicorn.log.critical: rate of critical log messages

• gunicorn.log.error: rate of error log messages

• gunicorn.log.warning: rate of warning log messages

• gunicorn.log.exception: rate of exceptional log messages

Deploying Gunicorn

We strongly recommend to use Gunicorn behind a proxy server.

Nginx Configuration

Although there are many HTTP proxies available, we strongly advise that you use Nginx . If you choose another proxy server you need to make sure that it buffers slow clients when you use default Gunicorn workers. Without this buffering Gunicorn will be easily susceptible to denial-of-service attacks. You can use Hey to check if your proxy is behaving properly.

An example configuration file for fast clients with Nginx :

worker_processes

1 ;

user

nobody nogroup ;

# 'user nobody nobody;' for systems with 'nobody' as a group instead

pid

/tmp/nginx.pid

;

error_log

/tmp/nginx.error.log

;

events

{

worker_connections

1024 ; # increase if you have lots of clients

accept_mutex

off ; # set to 'on' if nginx worker_processes > 1

# 'use epoll;' to enable for Linux 2.6+

# 'use kqueue;' to enable for FreeBSD, OSX

}

http

{

include

mime.types

;

# fallback in case we can't determine a type

default_type

application/octet-stream ;

access_log

/tmp/nginx.access.log combined ;

sendfile

on ;

upstream

app_server {

# fail_timeout=0 means we always retry an upstream even if it failed

# to return a good HTTP response

# for UNIX domain socket setups

server

unix:/tmp/gunicorn.sock fail_timeout=0 ;

2.6. Deploying Gunicorn 29


}

# for a TCP configuration

# server 192.168.0.7:8000 fail_timeout=0;

server

{

# if no Host match, close the connection to prevent host spoofing

listen

80 default_server ;

return

444 ;

}

server

{

# use 'listen 80 deferred;' for Linux

# use 'listen 80 accept_filter=httpready;' for FreeBSD

listen

80 ;

client_max_body_size

4G ;

# set the correct host(s) for your site

server_name

example.com www.example.com

;

keepalive_timeout

5 ;

# path for static files

root

/path/to/app/current/public ;

location

/ {

# checks for static file, if not found proxy to app

try_files

$uri @proxy_to_app ;

}

location

@proxy_to_app {

proxy_set_header

X-Forwarded-For $proxy_add_x_forwarded_for ;

# enable this if and only if you use HTTPS

# proxy_set_header X-Forwarded-Proto https;

proxy_set_header

Host $http_host ;

# we don't want nginx trying to do something clever with

# redirects, we set the Host: header above already.

proxy_redirect

off ;

proxy_pass

http://app_server ;

}

}

}

error_page

500 502 503 504 /500.html

;

location

= /500.html

{

root

/path/to/app/current/public ;

}

If you want to be able to handle streaming request/responses or other fancy features like Comet, Long polling, or Web sockets, you need to turn off the proxy buffering. When you do this you must run with one of the async worker classes.

To turn off buffering, you only need to add proxy_buffering off; to your location block:

...

location @proxy_to_app { proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_set_header Host $http_host; proxy_redirect off;



proxy_buffering off;

}

...

proxy_pass http://app_server;

When Nginx is handling SSL it is helpful to pass the protocol information to Gunicorn. Many web frameworks use this information to generate URLs. Without this information, the application may mistakenly generate ‘http’ URLs in

‘https’ responses, leading to mixed content warnings or broken applications. In this case, configure Nginx to pass an appropriate header:

...

proxy_set_header X-Forwarded-Proto $scheme;

...

If you are running Nginx on a different host than Gunicorn you need to tell Gunicorn to trust the X-Forwarded-* headers sent by Nginx. By default, Gunicorn will only trust these headers if the connection comes from localhost.

This is to prevent a malicious client from forging these headers:

$ gunicorn -w 3 --forwarded-allow-ips="10.170.3.217,10.170.3.220" test:app

When the Gunicorn host is completely firewalled from the external network such that all connections come from a trusted proxy (e.g. Heroku) this value can be set to ‘*’. Using this value is potentially dangerous if connections to

Gunicorn may come from untrusted proxies or directly from clients since the application may be tricked into serving

SSL-only content over an insecure connection.

Gunicorn 19 introduced a breaking change concerning how REMOTE_ADDR is handled. Previous to Gunicorn 19 this was set to the value of X-Forwarded-For if received from a trusted proxy. However, this was not in compliance with RFC 3875 which is why the REMOTE_ADDR is now the IP address of the proxy and not the actual user. You should instead configure Nginx to send the user’s IP address through the X-Forwarded-For header like this:

...

proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

...

It is also worth noting that the REMOTE_ADDR will be completely empty if you bind Gunicorn to a UNIX socket and not a TCP host:port tuple.

Using Virtualenv

To serve an app from a Virtualenv it is generally easiest to just install Gunicorn directly into the Virtualenv. This will create a set of Gunicorn scripts for that Virtualenv which can be used to run applications normally.

If you have Virtualenv installed, you should be able to do something like this:

$ mkdir ~/venvs/

$ virtualenv ~/venvs/webapp

$ source ~/venvs/webapp/bin/activate

$ pip install gunicorn

$ deactivate

Then you just need to use one of the three Gunicorn scripts that was installed into ~/venvs/webapp/bin.

Note: You can force the installation of Gunicorn in your Virtualenv by passing -I or --ignore-installed option to pip:



$ source ~/venvs/webapp/bin/activate

$ pip install -I gunicorn

Monitoring

Note: Make sure that when using either of these service monitors you do not enable the Gunicorn’s daemon mode.

These monitors expect that the process they launch will be the process they need to monitor. Daemonizing will forkexec which creates an unmonitored process and generally just confuses the monitor services.

Gaffer

Using Gafferd and gaffer

Gaffer can be used to monitor Gunicorn. A simple configuration is:

[process:gunicorn] cmd = gunicorn w 3 test:app cwd = / path / to / project

Then you can easily manage Gunicorn using Gaffer .

Using a Procfile

Create a Procfile in your project: gunicorn = gunicorn w 3 test:app

You can launch any other applications that should be launched at the same time.

Then you can start your Gunicorn application using Gaffer : gaffer start

If gafferd is launched you can also load your Procfile in it directly: gaffer load

All your applications will be then supervised by gafferd.

Runit

A popular method for deploying Gunicorn is to have it monitored by runit . Here is an example service definition:

#!/bin/sh

GUNICORN=/usr/local/bin/gunicorn

ROOT=/path/to/project

PID=/var/run/gunicorn.pid

APP=main:application



if [ -f $PID ]; then rm $PID; fi cd $ROOT exec $GUNICORN -c $ROOT/gunicorn.conf.py --pid=$PID $APP

Save this as /etc/sv/[app_name]/run, and make it executable (chmod u+x /etc/sv/[app_name]/ run

). Then run ln -s /etc/sv/[app_name] /etc/service/[app_name]. If runit is installed, Gunicorn should start running automatically as soon as you create the symlink.

If it doesn’t start automatically, run the script directly to troubleshoot.

Supervisor

Another useful tool to monitor and control Gunicorn is Supervisor . A simple configuration is:

[program:gunicorn] command =/ path / to / gunicorn main:application c / path / to / gunicorn .

conf .

py directory =/ path / to / project user = nobody autostart = true autorestart = true redirect_stderr = true

Upstart

Using Gunicorn with upstart is simple. In this example we will run the app “myapp” from a virtualenv. All errors will go to /var/log/upstart/myapp.log.

/etc/init/myapp.conf: description "myapp" start on (filesystem) stop on runlevel [ 016 ] respawn setuid nobody setgid nogroup chdir / path / to / app / directory exec / path / to / virtualenv / bin / gunicorn myapp:app

Systemd

A tool that is starting to be common on linux systems is Systemd . Below are configurations files and instructions for using systemd to create a unix socket for incoming Gunicorn requests. Systemd will listen on this socket and start gunicorn automatically in response to traffic. Later in this section are instructions for configuring Nginx to forward web traffic to the newly created unix socket:

/etc/systemd/system/gunicorn.service:



[Unit]

Description=gunicorn daemon

Requires=gunicorn.socket

After=network.target

[Service]

PIDFile=/run/gunicorn/pid

User=someuser

Group=someuser

RuntimeDirectory=gunicorn

WorkingDirectory=/home/someuser/applicationroot

ExecStart=/usr/bin/gunicorn --pid /run/gunicorn/pid \

--bind unix:/run/gunicorn/socket applicationname.wsgi

ExecReload=/bin/kill -s HUP $MAINPID

ExecStop=/bin/kill -s TERM $MAINPID

PrivateTmp=true

[Install]

WantedBy=multi-user.target

/etc/systemd/system/gunicorn.socket:

[Unit]

Description = gunicorn socket

[Socket]

ListenStream =/ run / gunicorn / socket

[Install]

WantedBy = sockets .

target

/etc/tmpfiles.d/gunicorn.conf: d / run / gunicorn 0755 someuser somegroup -

Next enable the socket so it autostarts at boot: systemctl enable gunicorn .

socket

Either reboot, or start the services manually: systemctl start gunicorn .

socket

After running curl --unix-socket /run/gunicorn/socket http, Gunicorn should start and you should see some HTML from your server in the terminal.

You must now configure your web proxy to send traffic to the new Gunicorn socket. Edit your nginx.conf to include the following:

/etc/nginx/nginx.conf:

...

http { server { listen server_name

8000 ;

127.0

.

0.1

; location / { proxy_pass http: // unix: / run / gunicorn / socket;



}

...

}

}

Note: The listen and server_name used here are configured for a local machine. In a production server you will most likely listen on port 80, and use your URL as the server_name.

Now make sure you enable the nginx service so it automatically starts at boot: systemctl enable nginx .

service

Either reboot, or start Nginx with the following command: systemctl start nginx

Now you should be able to test Nginx with Gunicorn by visiting http://127.0.0.1:8000/ in any web browser. Systemd is now set up.

Logging

Logging can be configured by using various flags detailed in the configuration documentation or by creating a logging configuration file . Send the USR1 signal to rotate logs if you are using the logrotate utility: kill -USR1 $(cat /var/run/gunicorn.pid)

Note: Overriding the LOGGING dictionary requires to set disable_existing_loggers:

False to not interfere with the Gunicorn logging.

Warning: Gunicorn error log is here to log errors from Gunicorn, not from another application.

Signal Handling

A brief description of the signals handled by Gunicorn. We also document the signals used internally by Gunicorn to communicate with the workers.

Master process

• QUIT, INT: Quick shutdown

• TERM: Graceful shutdown. Waits for workers to finish their current requests up to the

graceful_timeout

.

• HUP: Reload the configuration, start the new worker processes with a new configuration and gracefully shutdown older workers. If the application is not preloaded (using the

preload_app

option), Gunicorn will also load the new version of it.

• TTIN: Increment the number of processes by one

2.7. Signal Handling 35


• TTOU: Decrement the number of processes by one

• USR1: Reopen the log files

• USR2: Upgrade Gunicorn on the fly. A separate TERM signal should be used to kill the old master process. This signal can also be used to use the new versions of pre-loaded applications. See

Upgrading to a new binary on the fly

for more information.

• WINCH: Gracefully shutdown the worker processes when Gunicorn is daemonized.

Worker process

Sending signals directly to the worker processes should not normally be needed. If the master process is running, any exited worker will be automatically respawned.

• QUIT, INT: Quick shutdown

• TERM: Graceful shutdown

• USR1: Reopen the log files

Reload the configuration

The HUP signal can be used to reload the Gunicorn configuration on the fly.

2013 06 29 06 : 26 : 55 [ 20682 ] [INFO] Handling signal: hup

2013 06 29 06 : 26 : 55 [ 20682 ] [INFO] Hang up: Master

2013 06 29 06 : 26 : 55 [ 20703 ] [INFO] Booting worker

with

pid: 20703


with

pid: 20702

2013 06 29 06 : 26 : 55 [ 20688 ] [INFO] Worker exiting (pid: 20688 )




with

pid: 20704

Sending a HUP signal will reload the configuration, start the new worker processes with a new configuration and gracefully shutdown older workers. If the application is not preloaded (using the

preload_app

option), Gunicorn will also load the new version of it.

Upgrading to a new binary on the fly

Changed in version 19.6.0: PID file naming format has been changed from <name>.pid.oldbin to <name>.

pid.2

.

If you need to replace the Gunicorn binary with a new one (when upgrading to a new version or adding/removing server modules), you can do it without any service downtime - no incoming requests will be lost. Preloaded applications will also be reloaded.

First, replace the old binary with a new one, then send a USR2 signal to the current master process. It executes a new binary whose PID file is postfixed with .2 (e.g. /var/run/gunicorn.pid.2), which in turn starts a new master process and new worker processes:

PID USER

20844 benoitc

˓→

[test:app]

20849 benoitc

˓→

[test:app]

20850 benoitc

˓→

[test:app]

PR NI VIRT RES SHR S % CPU % MEM

20 0 54808 11 m 3352 S 0.0

0.1

20 0 54808 9.9

m 1500 S 0.0

0.1

20 0 54808 9.9

m 1500 S 0.0

0.1

TIME + COMMAND

0 : 00.36

gunicorn: master

0 : 00.02

gunicorn: worker

0 : 00.01

gunicorn: worker



20851 benoitc

˓→

[test:app]

20854 benoitc

˓→

[test:app]

20859 benoitc

˓→

[test:app]

20860 benoitc

˓→

[test:app]

20861 benoitc

˓→

[test:app]

20 0 54808 9.9

m 1500 S 0.0

0.1

20 0 55748 12 m 3348 S 0.0

0.2

20 0 55748 11 m 1500 S 0.0

0.1

20 0 55748 11 m 1500 S 0.0

0.1

20 0 55748 11 m 1500 S 0.0

0.1

0 : 00.01

gunicorn: worker

0 : 00.35

gunicorn: master

0 : 00.01

gunicorn: worker

0 : 00.00

gunicorn: worker

0 : 00.01

gunicorn: worker

At this point, two instances of Gunicorn are running, handling the incoming requests together. To phase the old instance out, you have to send a WINCH signal to the old master process, and its worker processes will start to gracefully shut down.

At this point you can still revert to the old process since it hasn’t closed its listen sockets yet, by following these steps:

• Send a HUP signal to the old master process - it will start the worker processes without reloading a configuration file

• Send a TERM signal to the new master process to gracefully shut down its worker processes

• Send a QUIT signal to the new master process to force it quit

If for some reason the new worker processes do not quit, send a KILL signal to them after the new master process quits, and everything will back to exactly as before the upgrade attempt.

If the update is successful and you want to keep the new master process, send a TERM signal to the old master process to leave only the new server running:

PID USER

20854 benoitc

˓→

[test:app]

20859 benoitc

˓→

[test:app]

20860 benoitc

˓→

[test:app]

20861 benoitc

˓→

[test:app]

PR NI VIRT RES SHR S % CPU % MEM

20 0 55748 12 m 3348 S 0.0

0.2

20 0 55748 11 m 1500 S 0.0

0.1

20 0 55748 11 m 1500 S 0.0

0.1

20 0 55748 11 m 1500 S 0.0

0.1

TIME + COMMAND

0 : 00.45

gunicorn: master

0 : 00.02

gunicorn: worker

0 : 00.02

gunicorn: worker

0 : 00.01

gunicorn: worker

Custom Application


Sometimes, you want to integrate Gunicorn with your WSGI application.

In this case, you can inherit from gunicorn.app.base.BaseApplication

.

Here is a small example where we create a very small WSGI app and load it with a custom Application:

from __future__ import

unicode_literals

import multiprocessing import gunicorn.app.base

from gunicorn.six

import

iteritems

2.8. Custom Application 37


def

number_of_workers ():

return

(multiprocessing .

cpu_count()

*

2 ) + 1

def

handler_app (environ, start_response): response_body = b'Works fine' status = '200 OK' response_headers = [

( 'Content-Type' , 'text/plain' ),

] start_response(status, response_headers)

return

[response_body]

class StandaloneApplication

(gunicorn .

app .

base .

BaseApplication):

def

__init__ ( self , app, options =

None

): self .

options = options

or

{} self .

application = app super (StandaloneApplication, self ) .

__init__ ()

def

load_config ( self ): config = dict ([(key, value)

for

key, value

in

iteritems( self .

options)

if

key

in

self .

cfg .

settings

and

value

is not None

])

for

key, value

in

iteritems(config): self .

cfg .

set(key .

lower(), value)

def

load ( self ):

return

self .

application

if

__name__ == '__main__' : options = {

'bind' : ' %s : %s ' % ( '127.0.0.1' , '8080' ),

'workers' : number_of_workers(),

}

StandaloneApplication(handler_app, options) .

run()

Design

A brief description of the architecture of Gunicorn.

Server Model

Gunicorn is based on the pre-fork worker model. This means that there is a central master process that manages a set of worker processes. The master never knows anything about individual clients. All requests and responses are handled completely by worker processes.



Master

The master process is a simple loop that listens for various process signals and reacts accordingly. It manages the list of running workers by listening for signals like TTIN, TTOU, and CHLD. TTIN and TTOU tell the master to increase or decrease the number of running workers. CHLD indicates that a child process has terminated, in this case the master process automatically restarts the failed worker.

Sync Workers

The most basic and the default worker type is a synchronous worker class that handles a single request at a time. This model is the simplest to reason about as any errors will affect at most a single request. Though as we describe below only processing a single request at a time requires some assumptions about how applications are programmed.

sync worker does not support persistent connections - each connection is closed after response has been sent (even if you manually add Keep-Alive or Connection: keep-alive header in your application).

Async Workers

The asynchronous workers available are based on Greenlets (via Eventlet and Gevent ). Greenlets are an implementation of cooperative multi-threading for Python. In general, an application should be able to make use of these worker classes with no changes.

Tornado Workers

There’s also a Tornado worker class. It can be used to write applications using the Tornado framework. Although the

Tornado workers are capable of serving a WSGI application, this is not a recommended configuration.

AsyncIO Workers

These workers are compatible with python3. You have two kind of workers.

The worker gthread is a threaded worker. It accepts connections in the main loop, accepted connections are added to the thread pool as a connection job. On keepalive connections are put back in the loop waiting for an event. If no event happen after the keep alive timeout, the connection is closed.

The worker gaiohttp is a full asyncio worker using aiohttp .

Choosing a Worker Type

The default synchronous workers assume that your application is resource-bound in terms of CPU and network bandwidth. Generally this means that your application shouldn’t do anything that takes an undefined amount of time. An example of something that takes an undefined amount of time is a request to the internet. At some point the external network will fail in such a way that clients will pile up on your servers. So, in this sense, any web application which makes outgoing requests to APIs will benefit from an asynchronous worker.

This resource bound assumption is why we require a buffering proxy in front of a default configuration Gunicorn. If you exposed synchronous workers to the internet, a DOS attack would be trivial by creating a load that trickles data to the servers. For the curious, Hey is an example of this type of load.

Some examples of behavior requiring asynchronous workers:

• Applications making long blocking calls (Ie, external web services)

• Serving requests directly to the internet

2.9. Design 39


• Streaming requests and responses

• Long polling

• Web sockets

• Comet

How Many Workers?

DO NOT scale the number of workers to the number of clients you expect to have. Gunicorn should only need 4-12 worker processes to handle hundreds or thousands of requests per second.

Gunicorn relies on the operating system to provide all of the load balancing when handling requests. Generally we recommend (2 x $num_cores) + 1 as the number of workers to start off with. While not overly scientific, the formula is based on the assumption that for a given core, one worker will be reading or writing from the socket while the other worker is processing a request.

Obviously, your particular hardware and application are going to affect the optimal number of workers. Our recommendation is to start with the above guess and tune using TTIN and TTOU signals while the application is under load.

Always remember, there is such a thing as too many workers. After a point your worker processes will start thrashing system resources decreasing the throughput of the entire system.

How Many Threads?

Since Gunicorn 19, a threads option can be used to process requests in multiple threads. Using threads assumes use of the gthread worker. One benefit from threads is that requests can take longer than the worker timeout while notifying the master process that it is not frozen and should not be killed. Depending on the system, using multiple threads, multiple worker processes, or some mixture, may yield the best results. For example, CPython may not perform as well as Jython when using threads, as threading is implemented differently by each. Using threads instead of processes is a good way to reduce the memory footprint of Gunicorn, while still allowing for application upgrades using the reload signal, as the application code will be shared among workers but loaded only in the worker processes (unlike when using the preload setting, which loads the code in the master process).

Note: Under Python 2.x, you need to install the ‘futures’ package to use this feature.

FAQ

WSGI Bits

How do I set SCRIPT_NAME?

By default SCRIPT_NAME is an empty string. The value could be set by setting SCRIPT_NAME in the environment or as an HTTP header.

Server Stuff



How do I reload my application in Gunicorn?

You can gracefully reload by sending HUP signal to gunicorn:

$ kill -HUP masterpid

How might I test a proxy configuration?

The Hey program is a great way to test that your proxy is correctly buffering responses for the synchronous workers:

$ hey -n 10000 -c 100 http://127.0.0.1:5000/

This runs a benchmark of 10000 requests with 100 running concurrently.

How can I name processes?

If you install the Python package setproctitle Gunicorn will set the process names to something a bit more meaningful.

This will affect the output you see in tools like ps and top. This helps for distinguishing the master process as well as between masters when running more than one app on a single machine. See the proc_name setting for more information.

Why is there no HTTP Keep-Alive?

The default Sync workers are designed to run behind Nginx which only uses HTTP/1.0 with its upstream servers. If you want to deploy Gunicorn to handle unbuffered requests (ie, serving requests directly from the internet) you should use one of the async workers.

Worker Processes

How do I know which type of worker to use?

Read the

Design

page for help on the various worker types.

What types of workers are there?

Check out the configuration docs for worker_class.

How can I figure out the best number of worker processes?

Here is our recommendation for tuning the number of workers.

How can I change the number of workers dynamically?

TTIN and TTOU signals can be sent to the master to increase or decrease the number of workers.

To increase the worker count by one:

$ kill -TTIN $masterpid

2.10. FAQ 41


To decrease the worker count by one:

$ kill -TTOU $masterpid

Does Gunicorn suffer from the thundering herd problem?

The thundering herd problem occurs when many sleeping request handlers, which may be either threads or processes, wake up at the same time to handle a new request. Since only one handler will receive the request, the others will have been awakened for no reason, wasting CPU cycles. At this time, Gunicorn does not implement any IPC solution for coordinating between worker processes. You may experience high load due to this problem when using many workers or threads. However a work has been started to remove this issue.

Why I don’t see any logs in the console?

In version R19, Gunicorn doesn’t log by default in the console. To watch the logs in the console you need to use the option --log-file=-. In version R20, Gunicorn logs to the console by default again.

Kernel Parameters

When dealing with large numbers of concurrent connections there are a handful of kernel parameters that you might need to adjust. Generally these should only affect sites with a very large concurrent load. These parameters are not specific to Gunicorn, they would apply to any sort of network server you may be running.

These commands are for Linux. Your particular OS may have slightly different parameters.

How can I increase the maximum number of file descriptors?

One of the first settings that usually needs to be bumped is the maximum number of open file descriptors for a given process. For the confused out there, remember that Unices treat sockets as files.

$ sudo ulimit -n 2048

How can I increase the maximum socket backlog?

Listening sockets have an associated queue of incoming connections that are waiting to be accepted. If you happen to have a stampede of clients that fill up this queue new connections will eventually start getting dropped.

$ sudo sysctl -w net.core.somaxconn="2048"

How can I disable the use of sendfile()

Disabling the use sendfile() can be done by using the --no-sendfile setting or by setting the environment variable SENDFILE to 0.



Troubleshooting

How do I fix Django reporting an ImproperlyConfigured error?

With asynchronous workers, creating URLs with the reverse function of django.core.urlresolvers may fail. Use reverse_lazy instead.

How do I avoid Gunicorn excessively blocking in os.fchmod?

The current heartbeat system involves calling os.fchmod on temporary file handlers and may block a worker for arbitrary time if the directory is on a disk-backed filesystem. For example, by default /tmp is not mounted as tmpfs in Ubuntu; in AWS an EBS root instance volume may sometimes hang for half a minute and during this time Gunicorn workers may completely block in os.fchmod. os.fchmod may introduce extra delays if the disk gets full. Also

Gunicon may refuse to start if it can’t create the files when the disk is full.

Currently to avoid these problems you can create a tmpfs mount (for a new directory or for /tmp) and pass its path to --worker-tmp-dir. First, check whether your /tmp is disk-backed or RAM-backed:

$ df /tmp

Filesystem

/dev/xvda1

1K-blocks

...

Used Available Use% Mounted on

...

...

... /

No luck. Let’s create a new tmpfs mount: sudo cp / etc / fstab / etc / fstab .

orig sudo mkdir / mem echo 'tmpfs /mem tmpfs defaults,size=64m,mode=1777,noatime,comment=for-gunicorn

˓→

0 0' | sudo tee a / etc / fstab sudo mount / mem

Check the result:

$ df /mem

Filesystem tmpfs

1K-blocks Used Available Use% Mounted on

65536 0 65536 0% /mem

Now you can set --worker-tmp-dir /mem.

Community

Use these channels to communicate about the project.

Project Management & Discussions

Gunicorn uses GitHub for the project management . GitHub issues are used for 3 different purposes:

• Bug tracker : to check latest bug

• Forum : Stackoverflow-style questions about Gunicorn usage

• Mailing list : Discussion of Gunicorn development, new features and project management.

Project maintainance guidelines are avaible on the wiki .

2.11. Community 43


IRC

The Gunicorn channel is on the Freenode IRC network. You can chat with other on #gunicorn channel .

Issue Tracking

Bug reports, enhancement requests and tasks generally go in the Github issue tracker .

Security Issues

The security mailing list is a place to report security issues. Only developers are subscribed to it. To post a message to the list use the address to [email protected]

.

Changelog

19.7.1 / 2017/03/21

• fix: continue if SO_REUSEPORT seems to be available but fails ( issue 1480 )

• fix: support non-decimal values for the umask command line option ( issue 1325 )

19.7.0 / 2017/03/01

• The previously deprecated gunicorn_django command has been removed. Use the

gunicorn

command-line interface instead.

• The previously deprecated django_settings setting has been removed. Use the

raw_env

setting instead.

• The default value of

ssl_version

has been changed from ssl.PROTOCOL_TLSv1

to ssl.

PROTOCOL_SSLv23

.

• fix: initialize the group access list when initgroups is set ( issue 1297 )

• add environment variables to gunicorn access log format ( issue 1291 )

• add –paste-global-conf option ( issue 1304 )

• fix: print access logs to STDOUT ( issue 1184 )

• remove upper limit on max header size config ( issue 1313 )

• fix: print original exception on AppImportError ( issue 1334 )

• use SO_REUSEPORT if available ( issue 1344 )

• fix leak of duplicate file descriptor for bound sockets.

• add –reload-engine option, support inotify and other backends ( issue 1368 , issue 1459 )

• fix: reject request with invalid HTTP versions

• add child_exit callback ( issue 1394 )

• add support for eventlets _AlreadyHandled object ( issue 1406 )

• format boot tracebacks properly with reloader ( issue 1408 )

• refactor socket activation and fd inheritance for better support of SystemD ( issue 1310 )



• fix: o fds are given by default in gunicorn ( issue 1423 )

• add ability to pass settings to GUNICORN_CMD_ARGS environnement variable which helps in container world ( issue 1385 )

• fix: catch access denied to pid file ( issue 1091 )

• many additions and improvements to the documentation

Breaking Change

• Python 2.6.0 is the last supported version

History

Changelog - 2017

Note: Please see

Changelog

for the latest changes

19.7.1 / 2017/03/21

• fix: continue if SO_REUSEPORT seems to be available but fails ( issue 1480 )

• fix: support non-decimal values for the umask command line option ( issue 1325 )

19.7.0 / 2017/03/01

• The previously deprecated gunicorn_django command has been removed. Use the

gunicorn

command-line interface instead.

• The previously deprecated django_settings setting has been removed. Use the

raw_env

setting instead.

• The default value of

ssl_version

has been changed from ssl.PROTOCOL_TLSv1

to ssl.

PROTOCOL_SSLv23

.

• fix: initialize the group access list when initgroups is set ( issue 1297 )

• add environment variables to gunicorn access log format ( issue 1291 )

• add –paste-global-conf option ( issue 1304 )

• fix: print access logs to STDOUT ( issue 1184 )

• remove upper limit on max header size config ( issue 1313 )

• fix: print original exception on AppImportError ( issue 1334 )

• use SO_REUSEPORT if available ( issue 1344 )

• fix leak of duplicate file descriptor for bound sockets.

• add –reload-engine option, support inotify and other backends ( issue 1368 , issue 1459 )

• fix: reject request with invalid HTTP versions

• add child_exit callback ( issue 1394 )

2.12. Changelog 45


• add support for eventlets _AlreadyHandled object ( issue 1406 )

• format boot tracebacks properly with reloader ( issue 1408 )

• refactor socket activation and fd inheritance for better support of SystemD ( issue 1310 )

• fix: o fds are given by default in gunicorn ( issue 1423 )

• add ability to pass settings to GUNICORN_CMD_ARGS environment variable which helps in container world

( issue 1385 )

• fix: catch access denied to pid file ( issue 1091 )

• many additions and improvements to the documentation

Breaking Change

• Python 2.6.0 is the last supported version


Note: Please see

Changelog

for the latest changes

19.6.0 / 2016/05/21

Core & Logging

• improvement of the binary upgrade behaviour using USR2: remove file locking ( issue 1270 )

• add the --capture-output setting to capture stdout/stderr tot the log file ( issue 1271 )

• Allow disabling sendfile() via the SENDFILE environment variable ( issue 1252 )

• fix reload under pycharm ( issue 1129 )

Workers

• fix: make sure to remove the signal from the worker pipe ( issue 1269 )

• fix: gthread worker, handle removed socket in the select loop ( issue 1258 )

19.5.0 / 2016/05/10

Core

• fix: Ensure response to HEAD request won’t have message body

• fix: lock domain socket and remove on last arbiter exit ( issue 1220 )

• improvement: use EnvironmentError instead of socket.error ( issue 939 )

• add: new FORWARDDED_ALLOW_IPS environment variable ( issue 1205 )

• fix: infinite recursion when destroying sockets ( issue 1219 )



• fix: close sockets on shutdown ( issue 922 )

• fix: clean up sys.exc_info calls to drop circular refs ( issue 1228 )

• fix: do post_worker_init after load_wsgi ( issue 1248 )

Workers

• fix access logging in gaiohttp worker ( issue 1193 )

• eventlet: handle QUIT in a new coroutine ( issue 1217 )

• gevent: remove obsolete exception clauses in run ( issue 1218 )

• tornado: fix extra “Server” response header ( issue 1246 )

• fix: unblock the wait loop under python 3.5 in sync worker ( issue 1256 )

Logging

• fix: log message for listener reloading ( issue 1181 )

• Let logging module handle traceback printing ( issue 1201 )

• improvement: Allow configuring logger_class with statsd_host ( issue 1188 )

• fix: traceback formatting ( issue 1235 )

• fix: print error logs on stderr and access logs on stdout ( issue 1184 )

Documentation

• Simplify installation instructions in gunicorn.org ( issue 1072 )

• Fix URL and default worker type in example_config ( issue 1209 )

• update django doc url to 1.8 lts ( issue 1213 )

• fix: miscellaneous wording corrections ( issue 1216 )

• Add PSF License Agreement of selectors.py to NOTICE (:issue: 1226)

• document LOGGING overriding ( issue 1051 )

• put a note that error logs are only errors from Gunicorn ( issue 1124 )

• add a note about the requirements of the threads workers under python 2.x ( issue 1200 )

• add access_log_format to config example ( issue 1251 )

Tests

• Use more pytest.raises() in test_http.py

19.4.5 / 2016/01/05

• fix: NameError fileno in gunicorn.http.wsgi ( issue 1178 )



19.4.4 / 2016/01/04

• fix: check if a fileobject can be used with sendfile(2) ( issue 1174 )

• doc: be more descriptive in errorlog option ( issue 1173 )


Note: Please see

Changelog

for the latest changes.

19.4.3 / 2015/12/30

• fix: don’t check if a file is writable using os.stat with SELINUX ( issue 1171 )

19.4.2 / 2015/12/29

Core

• improvement: handle HaltServer in manage_workers ( issue 1095 )

• fix: Do not rely on sendfile sending requested count ( issue 1155 )

• fix: claridy –no-sendfile default ( issue 1156 )

• fix: LoggingCatch sendfile failure from no file descriptor ( issue 1160 )

Logging

• fix: Always send access log to syslog if syslog is on

• fix: check auth before trying to own a file ( issue 1157 )

Documentation

• fix: Fix Slowloris broken link. ( issue 1142 )

• Tweak markup in faq.rst

Testing

• fix: gaiohttp test ( issue 1164 )

19.4.1 / 2015/11/25

• fix tornado worker ( issue 1154 )



19.4.0 / 2015/11/20

Core

• fix: make sure that a user is able to access to the logs after dropping a privilege ( issue 1116 )

• improvement: inherit the Exception class where it needs to be ( issue 997 )

• fix: make sure headers are always encoded as latin1 RFC 2616 ( issue 1102 )

• improvement: reduce arbiter noise ( issue 1078 )

• fix: don’t close the unix socket when the worker exit ( issue 1088 )

• improvement: Make last logged worker count an explicit instance var ( issue 1078 )

• improvement: prefix config file with its type ( issue 836 )

• improvement: pidfile handing ( issue 1042 )

• fix: catch OSError as well as ValueError on race condition ( issue 1052 )

• improve support of ipv6 by backporting urlparse.urlsplit from Python 2.7 to Python 2.6.

• fix: raise InvalidRequestLine when the line contains malicious data ( issue 1023 )

• fix: fix argument to disable sendfile

• fix: add gthread to the list of supported workers ( issue 1011 )

• improvement: retry socket binding up to five times upon EADDRNOTAVAIL ( issue 1004 )

• breaking change: only honor headers that can be encoded in ascii to comply to the RFC 7230 (See issue 1151 ).

Logging

• add new parameters to access log ( issue 1132 )

• fix: make sure that files handles are correctly reopened on HUP ( issue 627 )

• include request URL in error message ( issue 1071 )

• get username in access logs ( issue 1069 )

• fix statsd logging support on Python 3 ( issue 1010 )

Testing

• use last version of mock.

• many fixes in Travis CI support

• miscellaneous improvements in tests

Thread worker

• fix: Fix self.nr usage in ThreadedWorker so that auto restart works as expected ( issue 1031 )



Gevent worker

• fix quit signal handling ( issue 1128 )

• add support for Python 3 ( issue 1066 )

• fix: make graceful shutdown thread-safe ( issue 1032 )

Tornado worker

• fix ssl options ( issue 1146 , issue 1135 )

• don’t check timeout when stopping gracefully ( issue 1106 )

AIOHttp worker

• add SSL support ( issue 1105 )

Documentation

• fix link to proc name setting ( issue 1144 )

• fix worker class documentation ( issue 1141 , issue 1104 )

• clarify graceful timeout documentation ( issue 1137 )

• don’t duplicate NGINX config files examples ( issue 1050 , issue 1048 )

• add web.py framework example ( issue 1117 )

• update Debian/Ubuntu installations instructions ( issue 1112 )

• clarify pythonpath setting description ( issue 1080 )

• tweak some example for python3

• clarify sendfile documentation

• miscellaneous typos in source code comments (thanks!)

• clarify why REMOTE_ADD may not be the user’s IP address ( issue 1037 )

Misc

• fix: reloader should survive SyntaxError ( issue 994 )

• fix: expose the reloader class to the worker.

19.3.0 / 2015/03/06

Core

• fix: issue 978 make sure a listener is inheritable

• add check_config class method to workers



• fix: issue 983 fix select timeout in sync worker with multiple connections

• allows workers to access to the reloader. close issue 984

• raise TypeError instead of AssertionError

Logging

• make Logger.loglevel a class attribute

Documentation

• fix: issue 988 fix syntax errors in examples/gunicorn_rc

19.2.1 / 2015/02/4

Logging

• expose loglevel in the Logger class

AsyncIO worker (gaiohttp)

• fix issue 977 fix initial crash

Documentation

• document security mailing-list in the contributing page.

19.2 / 2015/01/30

Core

• optimize the sync workers when listening on a single interface

• add –sendfile settings to enable/disable sendfile. fix issue 856 .

• add the selectors module to the code base.

issue 886

• add –max-requests-jitter setting to set the maximum jitter to add to the max-requests setting.

• fix issue 899 propagate proxy_protocol_info to keep-alive requests

• fix issue 863 worker timeout: dynamic timeout has been removed

• fix: Avoid world writable file



Logging

• fix issue 941 set logconfig default to paster more trivially

• add statsd-prefix config setting: set the prefix to use when emitting statsd metrics

• issue 832 log to console by default

Thread Worker

• fix issue 908 make sure the worker can continue to accept requests

Eventlet Worker

• fix issue 867 Fix eventlet shutdown to actively shut down the workers.

Documentation

Many improvements and fixes have been done, see the detailed changelog for more information.


Note: Please see

Changelog

for the latest changes.

19.1.1 / 2014-08-16

Changes

Core

• fix issue 835 : display correct pid of already running instance

• fix pull request 833 : fix PyTest class in setup.py.

Logging

• fix issue 838 : statsd logger, send statsd timing metrics in milliseconds

• fix issue 839 : statsd logger, allows for empty log message while pushing metrics and restore worker number in

DEBUG logs

• fix issue 850 : add timezone to logging

• fix issue 853 : Respect logger_class setting unless statsd is on



AioHttp worker

• fix issue 830 make sure gaiohttp worker is shipped with gunicorn.

19.1 / 2014-07-26

Changes

Core

• fix issue 785 : handle binary type address given to a client socket address

• fix graceful shutdown. make sure QUIT and TERMS signals are switched everywhere.

• issue 799 : fix support loading config from module

• issue 805 : fix check for file-like objects

• fix issue 815 : args validation in WSGIApplication.init

• fix issue 787 : check if we load a pyc file or not.

Tornado worker

• fix issue 771 : support tornado 4.0

• fix issue 783 : x_headers error.

The x-forwarded-headers option has been removed in c4873681299212d6082cd9902740eef18c2f14f1 . The discussion is available on pull request 633 .

AioHttp worker

• fix: fetch all body in input. fix issue 803

• fix: don’t install the worker if python < 3.3

• fix issue 822 : Support UNIX sockets in gaiohttp worker

Async worker

• fix issue 790 : StopIteration shouldn’t be catched at this level.

Logging

• add statsd logging handler fix issue 748

Paster

• fix issue 809 : Set global logging configuration from a Paste config.



Extra

• fix RuntimeError in gunicorn.reloader ( issue 807 )

Documentation

• update faq: put a note on how watch logs in the console since many people asked for it.

19.0 / 2014-06-12

Gunicorn 19.0 is a major release with new features and fixes. This version improve a lot the usage of Gunicorn with python 3 by adding two new workers to it: gthread a fully threaded async worker using futures and gaiohttp a worker using asyncio.

Breaking Changes

Switch QUIT and TERM signals

With this change, when gunicorn receives a QUIT all the workers are killed immediately and exit and TERM is used for the graceful shutdown.

Note: the old behaviour was based on the NGINX but the new one is more correct according the following doc: https://www.gnu.org/software/libc/manual/html_node/Termination-Signals.html

also it is complying with the way the signals are sent by heroku: https://devcenter.heroku.com/articles/python-faq#what-constraints-exist-when-developing-applications-on-heroku

Deprecations

run_gunicorn

, gunicorn_django and gunicorn_paster are now completely deprecated and will be removed in the next release. Use the gunicorn command instead.

Changes core

• add aiohttp worker named gaiohttp using asyncio. Full async worker on python 3.

• fix HTTP-violating excess whitespace in write_error output

• fix: try to log what happened in the worker after a timeout, add a worker_abort hook on SIGABRT signal.

• fix: save listener socket name in workers so we can handle buffered keep-alive requests after the listener has closed.

• add on_exit hook called just before exiting gunicorn.

• add support for python 3.4

• fix: do not swallow unexpected errors when reaping



• fix: remove incompatible SSL option with python 2.6

• add new async gthread worker and –threads options allows to set multiple threads to listen on connection

• deprecate gunicorn_django and gunicorn_paster

• switch QUIT and TERM signal

• reap workers in SIGCHLD handler

• add universal wheel support

• use email.utils.formatdate in gunicorn.util.http_date

• deprecate the –debug option

• fix: log exceptions that occur after response start . . .

• allows loading of applications from .pyc files (#693)

• fix: issue #691, raw_env config file parsing

• use a dynamic timeout to wait for the optimal time. (Reduce power usage)

• fix python3 support when notifying the arbiter

• add: honor $WEB_CONCURRENCY environment variable. Useful for heroku setups.

• add: include tz offset in access log

• add: include access logs in the syslog handler.

• add –reload option for code reloading

• add the capability to load gunicorn.base.Application without the loading of the arguments of the command line.

It allows you to

embed gunicorn in your own application

.

• improve: set wsgi.multithread to True for async workers

• fix logging: make sure to redirect wsgi.errors when needed

• add: syslog logging can now be done to a unix socket

• fix logging: don’t try to redirect stdout/stderr to the logfile.

• fix logging: don’t propagate log

• improve logging: file option can be overriden by the gunicorn options –error-logfile and –access-logfile if they are given.

• fix: don’t override SERVER_* by the Host header

• fix: handle_error

• add more option to configure SSL

• fix: sendfile with SSL

• add: worker_int callback (to react on SIGTERM)

• fix: don’t depend on entry point for internal classes, now absolute modules path can be given.

• fix: Error messages are now encoded in latin1

• fix: request line length check

• improvement: proxy_allow_ips: Allow proxy protocol if “*” specified

• fix: run worker’s setup method before setting num_workers

• fix: FileWrapper inherit from object now



• fix: Error messages are now encoded in latin1

• fix: don’t spam the console on SIGWINCH.

• fix: logging -don’t stringify T and D logging atoms (#621)

• add support for the latest django version

• deprecate run_gunicorn django option

• fix: sys imported twice

gevent worker

• fix: make sure to stop all listeners

• fix: monkey patching is now done in the worker

• fix: “global name ‘hub’ is not defined”

• fix: reinit hub on old versions of gevent

• support gevent 1.0

• fix: add subprocess in monkey patching

• fix: add support for multiple listener

eventlet worker

• fix: merge duplicate EventletWorker.init_process method (fixes #657)

• fix: missing errno import for eventlet sendfile patch

• fix: add support for multiple listener

tornado worker

• add graceful stop support


18.0 / 2013-08-26

• new: add -e/--env command line argument to pass an environment variables to gunicorn

• new: add --chdir command line argument to specified directory before apps loading.

- new: add wsgi.file_wrapper support in async workers

• new: add --paste command line argument to set the paster config file

• deprecated: the command gunicorn_django is now deprecated. You should now run your application with the WSGI interface installed with your project (see https://docs.djangoproject.com/en/1.4/howto/deployment/ wsgi/gunicorn/ ) for more infos.

• deprecated: the command gunicorn_paste is deprecated. You now should use the new --paste argument to set the configuration file of your paster application.

• fix: Removes unmatched leading quote from the beginning of the default access log format string



• fix: null timeout

• fix: gevent worker

• fix: don’t reload the paster app when using pserve

• fix: after closing for error do not keep alive the connection

• fix: responses 1xx, 204 and 304 should not force the connection to be closed

17.5 / 2013-07-03

• new: add signals documentation

• new: add post_worker_init hook for workers

• new: try to use gunicorn.conf.py in current folder as the default config file.

• fix graceful timeout with the Eventlet worker

• fix: don’t raise an error when closing the socket if already closed

• fix: fix –settings parameter for django application and try to find the django settings when using the gunicorn command.

• fix: give the initial global_conf to paster application

• fix: fix ‘Expect: 100-continue’ support on Python 3

New versionning:

With this release, the versionning of Gunicorn is changing. Gunicorn is stable since a long time and there is no point to release a “1.0” now. It should have been done since a long time. 0.17 really meant it was the 17th stable version.

From the beginning we have only 2 kind of releases: major release: releases with major changes or huge features added services releases: fixes and minor features added So from now we will apply the following versionning <major>.<service>. For example 17.5 is a service release.

0.17.4 / 2013-04-24

• fix unix socket address parsing

0.17.3 / 2013-04-23

• add systemd sockets support

• add python -m gunicorn.app.wsgiapp support

• improve logger class inheritance

• exit when the config file isn’t found

• add the -R option to enable stdio inheritance in daemon mode

• don’t close file descriptors > 3 in daemon mode

• improve STDOUT/STDERR logging

• fix pythonpath option



• fix pidfile creation on Python 3

• fix gevent worker exit

• fix ipv6 detection when the platform isn’t supporting it

0.17.2 / 2013-01-07

• optimize readline

• make imports errors more visible when loading an app or a logging class

• fix tornado worker: don’t pass ssl options if there are none

• fix PEP3333: accept only bytetrings in the response body

• fix support on CYGWIN platforms

0.17.1 / 2013-01-05

• add syslog facility name setting

• fix --version command line argument

• fix wsgi url_scheme for https


0.17.0 / 2012-12-25

• allows gunicorn to bind to multiple address

• add SSL support

• add syslog support

• add nworkers_changed hook

• add response arg for post_request hook

• parse command line with argparse (replace deprecated optparse)

• fix PWD detection in arbiter

• miscellaneous PEP8 fixes

0.16.1 / 2012-11-19

• Fix packaging

0.16.0 / 2012-11-19

• Added support for Python 3.2 & 3.3

• Expose –pythonpath command to all gunicorn commands

• Honor $PORT environment variable, useful for deployment on heroku



• Removed support for Python 2.5

• Make sure we reopen the logs on the console

• Fix django settings module detection from path

• Reverted timeout for client socket. Fix issue on blocking issues.

• Fixed gevent worker

0.15.0 / 2012-10-18

• new documentation site on http://docs.gunicorn.org

• new website on http://gunicorn.org

• add haproxy PROXY protocol support

• add ForwardedAllowIPS option: allows to filter Front-end’s IPs allowed to handle X-Forwarded-* headers.

• add callable hooks for paster config

• add x-forwarded-proto as secure scheme default (Heroku is using this)

• allows gunicorn to load a pre-compiled application

• support file reopening & reexec for all loggers

• initialize the logging config file with defaults.

• set timeout for client socket (slow client DoS).

• NoMoreData, ChunkMissingTerminator, InvalidChunkSize are now IOError exceptions

• fix graceful shutdown in gevent

• fix limit request line check

0.14.6 / 2012-07-26

• fix gevent & subproces

• fix request line length check

• fix keepalive = 0

• fix tornado worker

0.14.5 / 2012-06-24

• fix logging during daemonisation

0.14.4 / 2012-06-24

• new –graceful-timeout option

• fix multiple issues with request limit

• more fixes in django settings resolutions

• fix gevent.core import



• fix keepalive=0 in eventlet worker

• fix handle_error display with the unix worker

• fix tornado.wsgi.WSGIApplication calling error

• breaking change: take the control on graceful reload back. graceful can’t be overrided anymore using the on_reload function.

0.14.3 / 2012-05-15

• improvement: performance of http.body.Body.readline()

• improvement: log HTTP errors in access log like Apache

• improvement: display traceback when the worker fails to boot

• improvement: makes gunicorn work with gevent 1.0

• examples: websocket example now supports hybi13

• fix: reopen log files after initialization

• fix: websockets support

• fix: django1.4 support

• fix: only load the paster application 1 time

0.14.2 / 2012-03-16

• add validate_class validator: allows to use a class or a method to initialize the app during in-code configuration

• add support for max_requests in tornado worker

• add support for disabling x_forwarded_for_header in tornado worker

• gevent_wsgi is now an alias of gevent_pywsgi

• Fix gevent_pywsgi worker

0.14.1 / 2012-03-02

• fixing source archive, reducing its size

0.14.0 / 2012-02-27

• check if Request line is too large: You can now pass the parameter --limit-request-line or set the limit_request_line in your configuration file to set the max size of the request line in bytes.

Add --limit-request-field and • limit the number of headers fields and their size.

limit-request-field-size settings

• add p variable to the log access format to log pidfile

• add {HeaderName}o variable to the logo access format to log the response header HeaderName

• request header is now logged with the variable {HeaderName}i in the access log file

• improve error logging



• support logging.configFile

• support django 1.4 in both gunicorn_django & run_gunicorn command

• improve reload in django run_gunicorn command (should just work now)

• allows people to set the X-Forwarded-For header key and disable it by setting an empty string.

• fix support of Tornado

• many other fixes.


0.13.4 / 2011-09-23

• fix util.closerange function used to prevent leaking fds on python 2.5 (typo)

0.13.3 / 2011-09-19

• refactor gevent worker

• prevent leaking fds on reexec

• fix inverted request_time computation

0.13.2 / 2011-09-17

• Add support for Tornado 2.0 in tornado worker

• Improve access logs: allows customisation of the log format & add request time

• Logger module is now pluggable

• Improve graceful shutdown in Python versions >= 2.6

• Fix post_request root arity for compatibility

• Fix sendfile support

• Fix Django reloading

0.13.1 / 2011-08-22

• Fix unix socket. log argument was missing.

0.13.0 / 2011-08-22

• Improve logging: allows file-reopening and add access log file compatible with the apache combined log format

• Add the possibility to set custom SSL headers. X-Forwarded-Protocol and X-Forwarded-SSL are still the default

• New on_reload hook to customize how gunicorn spawn new workers on SIGHUP

• Handle projects with relative path in django_gunicorn command

• Preserve path parameters in PATH_INFO



• post_request hook now accepts the environ as argument.

• When stopping the arbiter, close the listener asap.

• Fix Django command run_gunicorn in settings reloading

• Fix Tornado worker exiting

• Fix the use of sendfile in wsgi.file_wrapper

0.12.2 / 2011-05-18

• Add wsgi.file_wrapper optimised for FreeBSD, Linux & MacOSX (use sendfile if available)

• Fix django run_gunicorn command. Make sure we reload the application code.

• Fix django localisation

• Compatible with gevent 0.14dev

0.12.1 / 2011-03-23

• Add “on_starting” hook. This hook can be used to set anything before the arbiter really start

• Support bdist_rpm in setup

• Improve content-length handling (pep 3333)

• Improve Django support

• Fix daemonizing (#142)

• Fix ipv6 handling


0.12.0 / 2010-12-22

• Add support for logging configuration using a ini file. It uses the standard Python logging’s module Configuration file format and allows anyone to use his custom file handler

• Add IPV6 support

• Add multidomain application example

• Improve gunicorn_django command when importing settings module using DJANGO_SETTINGS_MODULE environment variable

• Send appropriate error status on http parsing

• Fix pidfile, set permissions so other user can read it and use it.

• Fix temporary file leaking

• Fix setpgrp issue, can now be launched via ubuntu upstart

• Set the number of workers to zero on WINCH



0.11.2 / 2010-10-30

• Add SERVER_SOFTWARE to the os.environ

• Add support for django settings environment variable

• Add support for logging configuration in Paster ini-files

• Improve arbiter notification in asynchronous workers

• Display the right error when a worker can’t be used

• Fix Django support

• Fix HUP with Paster applications

• Fix readline in wsgi.input

0.11.1 / 2010-09-02

• Implement max-requests feature to prevent memory leaks.

• Added ‘worker_exit’ server hook.

• Reseed the random number generator after fork().

• Improve Eventlet worker.

• Fix Django command run_gunicorn.

• Fix the default proc name internal setting.

• Workaround to prevent Gevent worker to segfault on MacOSX.

0.11.0 / 2010-08-12

• Improve dramatically performances of Gevent and Eventlet workers

• Optimize HTTP parsing

• Drop Server and Date headers in start_response when provided.

• Fix latency issue in async workers

0.10.1 / 2010-08-06

• Improve gevent’s workers.

Add “egg:gunicorn#gevent_wsgi” worker using gevent.wsgi

and

“egg:gunicorn#gevent_pywsgi” worker using gevent.pywsgi

.

“egg:gunicorn#gevent” using our own

HTTP parser is still here and is recommended for normal uses. Use the “gevent.wsgi” parser if you need really fast connections and don’t need streaming, keepalive or ssl.

• Add pre/post request hooks

• Exit more quietly

• Fix gevent dns issue



0.10.0 / 2010-07-08

• New HTTP parser.

• New HUP behaviour. Re-reads the configuration and then reloads all worker processes without changing the master process id. Helpful for code reloading and monitoring applications like supervisord and runit.

• Added a preload configuration parameter. By default, application code is now loaded after a worker forks. This couple with the new HUP handling can be used for dev servers to do hot code reloading. Using the preload flag can help a bit in small memory VM’s.

• Allow people to pass command line arguments to WSGI applications. See: examples/alt_spec.py

• Added an example gevent reloader configuration: examples/example_gevent_reloader.py

.

• New gevent worker “egg:gunicorn#gevent2”, working with gevent.wsgi.

• Internal refactoring and various bug fixes.

• New documentation website.

0.9.1 / 2010-05-26

• Support https via X-Forwarded-Protocol or X-Forwarded-Ssl headers

• Fix configuration

• Remove -d options which was used instead of -D for daemon.

• Fix umask in unix socket

0.9.0 / 2010-05-24

• Added when_ready hook. Called just after the server is started

• Added preload setting. Load application code before the worker processes are forked.

• Refactored Config

• Fix pidfile

• Fix QUIT/HUP in async workers

• Fix reexec

• Documentation improvements

0.8.1 / 2010-04-29

• Fix builtins import in config

• Fix installation with pip

• Fix Tornado WSGI support

• Delay application loading until after processing all configuration



0.8.0 / 2010-04-22

• Refactored Worker management for better async support. Now use the -k option to set the type of request processing to use

• Added support for Tornado

0.7.2 / 2010-04-15

• Added –spew option to help debugging (installs a system trace hook)

• Some fixes in async arbiters

• Fix a bug in start_response on error

0.7.1 / 2010-04-01

• Fix bug when responses have no body.

0.7.0 / 2010-03-26

• Added support for Eventlet and Gevent based workers.

• Added Websockets support

• Fix Chunked Encoding

• Fix SIGWINCH on OpenBSD

• Fix PEP 333 compliance for the write callable.

0.6.5 / 2010-03-11

• Fix pidfile handling

• Fix Exception Error

0.6.4 / 2010-03-08

• Use cStringIO for performance when possible.

• Fix worker freeze when a remote connection closes unexpectedly.

0.6.3 / 2010-03-07

• Make HTTP parsing faster.

• Various bug fixes



0.6.2 / 2010-03-01

• Added support for chunked response.

• Added proc_name option to the config file.

• Improved the HTTP parser. It now uses buffers instead of strings to store temporary data.

• Improved performance when sending responses.

• Workers are now murdered by age (the oldest is killed first).

0.6.1 / 2010-02-24

• Added gunicorn config file support for Django admin command

• Fix gunicorn config file. -c was broken.

• Removed TTIN/TTOU from workers which blocked other signals.

0.6.0 / 2010-02-22

• Added setproctitle support

• Change privilege switch behavior. We now work like NGINX, master keeps the permissions, new uid/gid permissions are only set for workers.

0.5.1 / 2010-02-22

• Fix umask

• Added Debian packaging

0.5.0 / 2010-02-20

• Added configuration file handler.

• Added support for pre/post fork hooks

• Added support for before_exec hook

• Added support for unix sockets

• Added launch of workers processes under different user/group

• Added umask option

• Added SCRIPT_NAME support

• Better support of some exotic settings for Django projects

• Better support of Paste-compatible applications

• Some refactoring to make the code easier to hack

• Allow multiple keys in request and response headers


R

RFC

RFC 3875,

31

Index

67

Gunicorn Documentation

Gunicorn Documentation

Release 19.7.1

Benoit Chesneau

Contents

CHAPTER

Features

CHAPTER

Contents

Installation

From Source

Async Workers

Debian GNU/Linux

Ubuntu

Running Gunicorn

Commands

Integration

Configuration Overview

Command Line

Configuration File

Framework Settings

Settings

Config File

Server Socket

Worker Processes

Security

Debugging

Server Mechanics

Logging

Process Naming

Server Mechanics

Server Hooks

Server Mechanics

SSL

Server Mechanics

Instrumentation

Deploying Gunicorn

Nginx Configuration

Using Virtualenv

Monitoring

Logging

Signal Handling

Master process

Worker process

Reload the configuration

Upgrading to a new binary on the fly

Custom Application

Design

Server Model

Choosing a Worker Type

How Many Workers?

How Many Threads?

FAQ

WSGI Bits

Server Stuff

Worker Processes

Kernel Parameters

Troubleshooting

Community

Project Management & Discussions

IRC

Issue Tracking

Security Issues

Changelog

19.7.1 / 2017/03/21

19.7.0 / 2017/03/01

History

R

Index

Table of contents