How to deploy with WSGI

Django’s primary deployment platform is WSGI, the Python standard for webservers and applications.

Django’s startproject management command sets up a minimal defaultWSGI configuration for you, which you can tweak as needed for your project,and direct any WSGI-compliant application server to use.

Django includes getting-started documentation for the following WSGI servers:

• How to use Django with Gunicorn
• How to use Django with uWSGI
• How to use Django with Apache and mod_wsgi
• Authenticating against Django’s user database from Apache

The application object

The key concept of deploying with WSGI is the application callable whichthe application server uses to communicate with your code. It’s commonlyprovided as an object named application in a Python module accessible tothe server.

The startproject command creates a file<project_name>/wsgi.py that contains such an application callable.

It’s used both by Django’s development server and in production WSGIdeployments.

WSGI servers obtain the path to the application callable from theirconfiguration. Django’s built-in server, namely the runservercommand, reads it from the WSGI_APPLICATION setting. By default, it’sset to <project_name>.wsgi.application, which points to the applicationcallable in <project_name>/wsgi.py.

Configuring the settings module

When the WSGI server loads your application, Django needs to import thesettings module — that’s where your entire application is defined.

Django uses the DJANGO_SETTINGS_MODULE environment variable tolocate the appropriate settings module. It must contain the dotted path to thesettings module. You can use a different value for development and production;it all depends on how you organize your settings.

If this variable isn’t set, the default wsgi.py sets it tomysite.settings, where mysite is the name of your project. That’s howrunserver discovers the default settings file by default.

Note

Since environment variables are process-wide, this doesn’t work when yourun multiple Django sites in the same process. This happens with mod_wsgi.

To avoid this problem, use mod_wsgi’s daemon mode with each site in itsown daemon process, or override the value from the environment byenforcing os.environ["DJANGO_SETTINGS_MODULE"] = "mysite.settings" inyour wsgi.py.

Applying WSGI middleware

To apply WSGI middleware you can wrap the application object. For instanceyou could add these lines at the bottom of wsgi.py:

from helloworld.wsgi import HelloWorldApplication
application = HelloWorldApplication(application)

You could also replace the Django WSGI application with a custom WSGIapplication that later delegates to the Django WSGI application, if you wantto combine a Django application with a WSGI application of another framework.