django22: Add 'request' as first argument to 'authenticate'

As noted in the Django 2.1 release notes [1]:

  The authenticate() method of authentication backends requires request
  as the first positional argument.

This can be seen here [2]. Simple enough, though it took me ages to
figure this out because Django gave me *zero* warning that a backend
because of this change. Heck, raising the TypeError would have helped :(

[1] https://docs.djangoproject.com/en/2.2/releases/2.1/#features-removed-in-2-1
[2] https://github.com/django/django/commit/5e31be1b96f

Change-Id: I0dd37d33c8e42a70c00a9f1460c1cec86c5b6006
Signed-off-by: Stephen Finucane <stephenfin@redhat.com>

openstack_auth/backend.py

@@ -33,6 +33,8 @@ LOG = logging.getLogger(__name__)
 KEYSTONE_CLIENT_ATTR = "_keystoneclient"
 
 
+# TODO(stephenfin): Subclass 'django.contrib.auth.backends.BaseBackend' once we
+# (only) support Django 3.0
 class KeystoneBackend(object):
     """Django authentication backend for use with ``django.contrib.auth``."""
 
@@ -99,7 +101,7 @@ class KeystoneBackend(object):
                         'configuration error that should be addressed.')
             raise exceptions.KeystoneAuthException(msg)
 
-    def authenticate(self, auth_url=None, **kwargs):
+    def authenticate(self, request, auth_url=None, **kwargs):
         """Authenticates a user via the Keystone Identity API."""
         LOG.debug('Beginning user authentication')
 
@@ -117,7 +119,6 @@ class KeystoneBackend(object):
 
         # the recent project id a user might have set in a cookie
         recent_project = None
-        request = kwargs.get('request')
         if request:
             # Grab recent_project found in the cookie, try to scope
             # to the last project used.

openstack_auth/views.py

@@ -161,7 +161,7 @@ def websso(request):
     auth_url = utils.clean_up_auth_url(referer)
     token = request.POST.get('token')
     try:
-        request.user = auth.authenticate(request=request, auth_url=auth_url,
+        request.user = auth.authenticate(request, auth_url=auth_url,
                                          token=token)
     except exceptions.KeystoneAuthException as exc:
         if utils.is_websso_default_redirect():
@@ -330,7 +330,7 @@ def switch_keystone_provider(request, keystone_provider=None,
     if unscoped_auth_ref:
         try:
             request.user = auth.authenticate(
-                request=request, auth_url=unscoped_auth.auth_url,
+                request, auth_url=unscoped_auth.auth_url,
                 token=unscoped_auth_ref.auth_token)
         except exceptions.KeystoneAuthException as exc:
             msg = 'Keystone provider switch failed: %s' % six.text_type(exc)