How to deploy with ASGI

As well as WSGI, Django also supports deploying on ASGI, the emerging Pythonstandard for asynchronous web servers and applications.

Django’s startproject management command sets up a default ASGIconfiguration for you, which you can tweak as needed for your project, anddirect any ASGI-compliant application server to use.

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

The application object

Like WSGI, ASGI has you supply an 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>/asgi.py that contains such an application callable.

It’s not used by the development server (runserver), but can be used byany ASGI server either in development or in production.

ASGI servers usually take the path to the application callable as a string;for most Django projects, this will look like myproject.asgi:application.

Warning

While Django’s default ASGI handler will run all your code in a synchronousthread, if you choose to run your own async handler you must be aware ofasync-safety.

Do not call blocking synchronous functions or libraries in any async code.Django prevents you from doing this with the parts of Django that are notasync-safe, but the same may not be true of third-party apps or Pythonlibraries.

Configuring the settings module

When the ASGI 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 to locatethe 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 asgi.py sets it tomysite.settings, where mysite is the name of your project.

Applying ASGI middleware

To apply ASGI middleware, or to embed Django in another ASGI application, youcan wrap Django’s application object in the asgi.py file. For example:

  1. from some_asgi_library import AmazingMiddleware
  2. application = AmazingMiddleware(application)