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.

Config File

config

  • -c FILE, --config FILE
  • None

The path to a Gunicorn config file, or python module.

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

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 process 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.

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 http://docs.gunicorn.org/en/latest/design.html 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

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. Alternatively the syntax can also load the gevent class with egg:gunicorn#gevent

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.

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.

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.

Generally set to thirty seconds. How max time worker can handle request after got restart signal. If the time is up worker will be 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.

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 number from 0 (unlimited) to 8190. to set the limit on the allowed size of an HTTP request header field.

Debugging

debug

  • --debug
  • False

Turn on debugging in the server.

DEPRECATED: This no functionality was removed after v18.0. This option is now a no-op.

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.

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.

chdir

  • --chdir
  • /var/build/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.

user

  • -u USER, --user USER
  • 1001

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
  • 1001

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)

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)

Logging

accesslog

  • --access-logfile FILE
  • None

The Access log file to write to.

“-” means log to stderr.

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.

Identifier Description
h remote address
l ‘-‘
u currently ‘-‘, may be user name in future releases
t date of the request
r status line (e.g. GET / HTTP/1.1)
s status
b response length or ‘-‘
f referer
a user agent
T request time in seconds
D request time in microseconds
L request time in decimal seconds
p process ID
{Header}i request header
{Header}o response header

errorlog

  • --error-logfile FILE, --log-file FILE
  • None

The Error log file to write to.

“-” means log to stderr.

loglevel

  • --log-level LEVEL
  • info

The granularity of Error log outputs.

Valid level names are:

  • debug
  • info
  • warning
  • error
  • critical

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 worker by giving gunicorn a python path to a subclass like gunicorn.glogging.Logger. Alternatively the syntax can also load the Logger class with egg:gunicorn#simple

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.

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 .

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.

It defaults to ‘gunicorn’.

default_proc_name

  • gunicorn

Internal setting that is adjusted for each type of application.

Django

django_settings

  • --settings STRING
  • None

The Python path to a Django settings module. (deprecated)

e.g. ‘myproject.settings.main’. If this isn’t provided, the DJANGO_SETTINGS_MODULE environment variable will be used.

DEPRECATED: use the –env argument instead.

Server Mechanics

pythonpath

  • --pythonpath STRING
  • None

A directory to add to the Python path.

e.g. ‘/home/djangoprojects/myproject’.

paste

  • --paste STRING, --paster STRING
  • None

Load a paste.deploy 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.

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

when_ready

  • def when_ready(server):
        pass
    

Called just after the server is started.

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

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.

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

worker_abort

  • def worker_abort(worker):
        pass
    

Called when a worker received the SIGABRT signal.

This call generally happen on timeout.

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

pre_exec

  • def pre_exec(server):
        pass
    

Called just before a new master process is forked.

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

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.

worker_exit

  • def worker_exit(server, worker):
        pass
    

Called just after a worker has been exited.

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.

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

Server Mechanics

proxy_protocol

  • --proxy-protocol
  • False

Enable detect PROXY protocol (PROXY mode).

Allow using Http and Proxy together. It’s may be useful for work with stunnel as https frondend 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
  • 3

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

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)

Logging

statsd_host

  • --statsd-host STATSD_ADDR
  • None

host:port of the statsd server to log to