.. _deploying-uwsgi:

uWSGI
=====

uWSGI is a deployment option on servers like `nginx`_, `lighttpd`_, and
`cherokee`_; see :doc:`fastcgi` and :doc:`wsgi-standalone` for other options.
To use your WSGI application with uWSGI protocol you will need a uWSGI server
first. uWSGI is both a protocol and an application server; the application
server can serve uWSGI, FastCGI, and HTTP protocols.

The most popular uWSGI server is `uwsgi`_, which we will use for this
guide. Make sure to have it installed to follow along.

.. admonition:: Watch Out

   Please make sure in advance that any ``app.run()`` calls you might
   have in your application file are inside an ``if __name__ ==
   '__main__':`` block or moved to a separate file.  Just make sure it's
   not called because this will always start a local WSGI server which
   we do not want if we deploy that application to uWSGI.

Starting your app with uwsgi
----------------------------

`uwsgi` is designed to operate on WSGI callables found in python modules.

Given a flask application in myapp.py, use the following command:

.. sourcecode:: text

    $ uwsgi -s /tmp/yourapplication.sock --manage-script-name --mount /yourapplication=myapp:app

The ``--manage-script-name`` will move the handling of ``SCRIPT_NAME`` to uwsgi,
since it is smarter about that. It is used together with the ``--mount``
directive which will make requests to ``/yourapplication`` be directed to
``myapp:app``. If your application is accessible at root level, you can use a
single ``/`` instead of ``/yourapplication``. ``myapp`` refers to the name of
the file of your flask application (without extension) or the module which
provides ``app``. ``app`` is the callable inside of your application (usually
the line reads ``app = Flask(__name__)``.

If you want to deploy your flask application inside of a virtual environment,
you need to also add ``--virtualenv /path/to/virtual/environment``. You might
also need to add ``--plugin python`` or ``--plugin python3`` depending on which
python version you use for your project.

Configuring nginx
-----------------

A basic flask nginx configuration looks like this::

    location = /yourapplication { rewrite ^ /yourapplication/; }
    location /yourapplication { try_files $uri @yourapplication; }
    location @yourapplication {
      include uwsgi_params;
      uwsgi_pass unix:/tmp/yourapplication.sock;
    }

This configuration binds the application to ``/yourapplication``.  If you want
to have it in the URL root its a bit simpler::

    location / { try_files $uri @yourapplication; }
    location @yourapplication {
        include uwsgi_params;
        uwsgi_pass unix:/tmp/yourapplication.sock;
    }

.. _nginx: https://nginx.org/
.. _lighttpd: https://www.lighttpd.net/
.. _cherokee: http://cherokee-project.com/
.. _uwsgi: https://uwsgi-docs.readthedocs.io/