Use consistent region during login

This change makes it so that the auth_url you have configured will
be the primary region used during initial login. This will help make
multi region keystone / horizon deployments more reliable and predictable.
Also, it may perform better if horizon is configured to point to the nearest
auth_url in multi region setups.

Change-Id: I99d40ed580a25f3694fbbd8e54d0b6416907f31b
Closes-bug: #1531003

openstack_auth/backend.py

@@ -217,12 +217,24 @@ class KeystoneBackend(object):
         # Check expiry for our new scoped token.
         self.check_auth_expiry(scoped_auth_ref)
 
+        # We want to try to use the same region we just logged into
+        # which may or may not be the default depending upon the order
+        # keystone uses
+        region_name = None
+        id_endpoints = scoped_auth_ref.service_catalog.\
+            get_endpoints(service_type='identity')
+        for id_endpoint in [cat for cat in id_endpoints['identity']]:
+            if auth_url in id_endpoint.values():
+                region_name = id_endpoint['region']
+                break
+
         interface = getattr(settings, 'OPENSTACK_ENDPOINT_TYPE', 'public')
 
         endpoint = utils.fix_auth_url_version(
             scoped_auth_ref.service_catalog.url_for(
                 service_type='identity',
-                interface=interface))
+                interface=interface,
+                region_name=region_name))
 
         # If we made it here we succeeded. Create our User!
         unscoped_token = unscoped_auth_ref.auth_token
@@ -230,7 +242,8 @@ class KeystoneBackend(object):
         user = auth_user.create_user_from_token(
             request,
             auth_user.Token(scoped_auth_ref, unscoped_token=unscoped_token),
-            endpoint)
+            endpoint,
+            services_region=region_name)
 
         if request is not None:
             request.session['unscoped_token'] = unscoped_token