django-rest-framework/docs/api-guide/authentication.md

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 schemes out of the box, and also allows you to implement custom schemes.

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.

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Note: Don't forget that authentication by itself won't allow or disallow an incoming request, it simply identifies the credentials that the request was made with. For information on how to setup the permission polices for your API please see the permissions documentation.

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How authentication is determined

The authentication schemes are 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 scheme

The default authentication schemes 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 scheme on a per-view basis, using the APIView class based views.

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

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

Unauthorized and Forbidden responses

When an unauthenticated request is denied permission there are two different error codes that may be appropriate.

• HTTP 401 Unauthorized
• HTTP 403 Permission Denied

The kind of response that will be used depends on the type of authentication scheme in use, and the ordering of the authentication classes.

Although multiple authentication schemes may be in use, only one scheme may be used to determine the type of response. The first authentication class set on the view is given priority when determining the type of response.

Note that when a successfully authenticated request is denied permission, a 403 Permission Denied response will always be used, regardless of the authentication scheme.

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API Reference

BasicAuthentication

This authentication scheme 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.

Unauthenticated responses that are denied permission will result in an HTTP 401 Unauthenticated response with an appropriate WWW-Authenticate header. For example:

WWW-Authenticate: Basic realm="api"

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 authentication scheme 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 scheme, 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.

Unauthenticated responses that are denied permission will result in an HTTP 401 Unauthenticated response with an appropriate WWW-Authenticate header. For example:

WWW-Authenticate: Token

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

OAuth2Authentication

This authentication scheme 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, OAuth2Authentication 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.

TODO: Note type of response (401 vs 403)

TODO: Implement OAuth2Authentication, using django-oauth2-provider.

SessionAuthentication

This authentication scheme 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.

Unauthenticated responses that are denied permission will result in an HTTP 403 Forbidden response.

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Custom authentication

To implement a custom authentication scheme, 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.

In some circumstances instead of returning None, you may want to raise an Unauthenticated exception from the .authenticate() method.

Typically the approach you should take is:

• If authentication is not attempted, return None. Any other authentication schemes also in use will still be checked.
• If authentication is attempted but fails, raise an Unauthenticated exception. An error response will be returned immediately, without checking any other authentication schemes.

You may also override the .authentication_header(self, request) method. If implemented, it should return a string that will be used as the value of the WWW-Authenticate header in a HTTP 401 Unauthenticated response.

If the .authentication_header() method is not overridden, the authentication scheme will return HTTP 403 Forbidden responses when an unauthenticated request is denied access.