==================
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 slowloris_ to check if your proxy is behaving properly.

An `example configuration`_ file for fast clients with Nginx_::

    worker_processes 1;

    user nobody nogroup;
    pid /tmp/nginx.pid;
    error_log /tmp/nginx.error.log;

    events {
        worker_connections 1024;
        accept_mutex off;
    }

    http {
        include mime.types;
        default_type application/octet-stream;
        access_log /tmp/nginx.access.log combined;
        sendfile on;

        upstream app_server {
            server unix:/tmp/gunicorn.sock fail_timeout=0;
            # For a TCP configuration:
            # server 192.168.0.7:8000 fail_timeout=0;
        }

        server {
            listen 80 default;
            client_max_body_size 4G;
            server_name _;

            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;
                proxy_set_header Host $http_host;
                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_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
      proxy_set_header Host $http_host;
      proxy_redirect off;
      proxy_buffering off;

      if (!-f $request_filename) {
          proxy_pass http://app_server;
          break;
      }
  }
  ...

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
    $ ~/venvs/webapp/bin/easy_install -U 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 fork-exec which creates an unmonitored process and generally just
    confuses the monitor services.

Gaffer
------

Using Gafferd and gafferctl
+++++++++++++++++++++++++++

`Gaffer <http://gaffer.readthedocs.org/en/latest/index.html>`_ 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 `gafferctl <http://gaffer.readthedocs.org/en/latest/gafferctl.html>`_.


Using a Procfile
++++++++++++++++

Create a ``Procfile`` in your project::

    gunicorn = gunicorn -w 3 test:app

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

Then you can start your gunicorn application using `gafferp <http://gaffer.readthedocs.org/en/latest/gafferp.html>`_.::

    gafferp start

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

    gafferp 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
    console log
    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_. Here
are configurations files to set the gunicorn launch in systemd and 
the interfaces on which gunicorn will listen. The sockets will be managed by
systemd:

**gunicorn.service**::

    [Unit]
    Description=gunicorn daemon

    [Service]
    User=urban
    WorkingDirectory=/home/urban/gunicorn/bin
    ExecStart=/home/urban/gunicorn/bin/gunicorn --debug --log-level debug test:app

    [Install]
    WantedBy=multi-user.target

**gunicorn.socket**::

    [Unit]
    Description=gunicorn socket

    [Socket]
    ListenStream=/run/unicorn.sock
    ListenStream=0.0.0.0:9000
    ListenStream=[::]:8000

    [Install]
    WantedBy=sockets.target

After running curl http://localhost:9000/ gunicorn should start and you
should see something like that in logs::

    2013-02-19 23:48:19 [31436] [DEBUG] Socket activation sockets: unix:/run/unicorn.sock,http://0.0.0.0:9000,http://[::]:8000

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)

.. _Nginx: http://www.nginx.org
.. _slowloris: http://ha.ckers.org/slowloris/
.. _`example configuration`: http://github.com/benoitc/gunicorn/blob/master/examples/nginx.conf
.. _runit: http://smarden.org/runit/
.. _`example service`: http://github.com/benoitc/gunicorn/blob/master/examples/gunicorn_rc
.. _Supervisor: http://supervisord.org
.. _`simple configuration`: http://github.com/benoitc/gunicorn/blob/master/examples/supervisor.conf
.. _`configuration documentation`: http://gunicorn.org/configure.html#logging
.. _`logging configuration file`: https://github.com/benoitc/gunicorn/blob/master/examples/logging.conf
.. _Virtualenv: http://pypi.python.org/pypi/virtualenv
.. _Systemd: http://www.freedesktop.org/wiki/Software/systemd