Authentication

Auth needs to be pluggable.

— Jacob Kaplan-Moss, "REST worst practices"

Authentication is the mechanism of associating an incoming request with a set of identifying credentials, such as the user the request came from, or the token that it was signed with. The permission and throttling policies can then use those credentials to determine if the request should be permitted.

REST framework provides a number of authentication policies out of the box, and also allows you to implement custom policies.

Authentication will run the first time either the request.user or request.auth properties are accessed, and determines how those properties are initialized.

The request.user property will typically be set to an instance of the contrib.auth package's User class.

The request.auth property is used for any additional authentication information, for example, it may be used to represent an authentication token that the request was signed with.

How authentication is determined

The authentication policy is always defined as a list of classes. REST framework will attempt to authenticate with each class in the list, and will set request.user and request.auth using the return value of the first class that successfully authenticates.

If no class authenticates, request.user will be set to an instance of django.contrib.auth.models.AnonymousUser, and request.auth will be set to None.

The value of request.user and request.auth for unauthenticated requests can be modified using the UNAUTHENTICATED_USER and UNAUTHENTICATED_TOKEN settings.

Setting the authentication policy

The default authentication policy may be set globally, using the DEFAULT_AUTHENTICATION setting. For example.

REST_FRAMEWORK = {
    'DEFAULT_AUTHENTICATION': (
        'rest_framework.authentication.UserBasicAuthentication',
        'rest_framework.authentication.SessionAuthentication',
    )
}

You can also set the authentication policy on a per-view basis, using the APIView class based views.

class ExampleView(APIView):
    authentication_classes = (SessionAuthentication, UserBasicAuthentication)

    def get(self, request, format=None):
        content = {
            'user': unicode(request.user),  # `django.contrib.auth.User` instance.
            'auth': unicode(request.auth),  # None
        }
        return Response(content)

Or, if you're using the @api_view decorator with function based views.

@api_view(
    allowed=('GET',),
    authentication_classes=(SessionAuthentication, UserBasicAuthentication)
)
def example_view(request, format=None):
    content = {
        'user': unicode(request.user),  # `django.contrib.auth.User` instance.
        'auth': unicode(request.auth),  # None
    }
    return Response(content)

BasicAuthentication

This policy uses HTTP Basic Authentication, signed against a user's username and password. Basic authentication is generally only appropriate for testing.

If successfully authenticated, BasicAuthentication provides the following credentials.

request.user will be a django.contrib.auth.models.User instance.
request.auth will be None.

Note: If you use BasicAuthentication in production you must ensure that your API is only available over https only. You should also ensure that your API clients will always re-request the username and password at login, and will never store those details to persistent storage.

TokenAuthentication

This policy uses a simple token-based HTTP Authentication scheme. Token authentication is appropriate for client-server setups, such as native desktop and mobile clients.

To use the TokenAuthentication policy, include rest_framework.authtoken in your INSTALLED_APPS setting.

You'll also need to create tokens for your users.

from rest_framework.authtoken.models import Token

token = Token.objects.create(user=...)
print token.key

For clients to authenticate, the token key should be included in the Authorization HTTP header. The key should be prefixed by the string literal "Token", with whitespace seperating the two strings. For example:

Authorization: Token 9944b09199c62bcf9418ad846dd0e4bbdfc6ee4b

If successfully authenticated, TokenAuthentication provides the following credentials.

request.user will be a django.contrib.auth.models.User instance.
request.auth will be a rest_framework.tokenauth.models.BasicToken instance.

Note: If you use TokenAuthentication in production you must ensure that your API is only available over https only.

OAuthAuthentication

This policy uses the OAuth 2.0 protocol to authenticate requests. OAuth is appropriate for server-server setups, such as when you want to allow a third-party service to access your API on a user's behalf.

If successfully authenticated, OAuthAuthentication provides the following credentials.

request.user will be a django.contrib.auth.models.User instance.
request.auth will be a rest_framework.models.OAuthToken instance.

SessionAuthentication

This policy uses Django's default session backend for authentication. Session authentication is appropriate for AJAX clients that are running in the same session context as your website.

If successfully authenticated, SessionAuthentication provides the following credentials.

request.user will be a django.contrib.auth.models.User instance.
request.auth will be None.

Custom authentication policies

To implement a custom authentication policy, subclass BaseAuthentication and override the .authenticate(self, request) method. The method should return a two-tuple of (user, auth) if authentication succeeds, or None otherwise.

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