Support discovery on the AUTH_INTERFACE

We need to allow get_endpoint(interface=auth.AUTH_INTERFACE, version=X)
to support the same version negotiation that the service catalog goes
through. This is required to support generic plugins where you often
provide an unversioned auth_url to the plugin but need a versioned URL
to query for available projects.

Change-Id: Id423a538c169264a81c5714e6a9eff9b33912a55
Closes-Bug: #1438013

keystoneclient/auth/identity/base.py

@@ -197,26 +197,29 @@ class BaseIdentityPlugin(base.BaseAuthPlugin):
         :rtype: string or None
         """
         # NOTE(jamielennox): if you specifically ask for requests to be sent to
-        # the auth url then we can ignore the rest of the checks. Typically if
-        # you are asking for the auth endpoint it means that there is no
-        # catalog to query anyway.
+        # the auth url then we can ignore many of the checks. Typically if you
+        # are asking for the auth endpoint it means that there is no catalog to
+        # query however we still need to support asking for a specific version
+        # of the auth_url for generic plugins.
         if interface is base.AUTH_INTERFACE:
-            return self.auth_url
+            url = self.auth_url
+            service_type = service_type or 'identity'
 
-        if not service_type:
-            LOG.warn(_LW('Plugin cannot return an endpoint without knowing '
-                         'the service type that is required. Add service_type '
-                         'to endpoint filtering data.'))
-            return None
+        else:
+            if not service_type:
+                LOG.warn(_LW('Plugin cannot return an endpoint without '
+                             'knowing the service type that is required. Add '
+                             'service_type to endpoint filtering data.'))
+                return None
 
-        if not interface:
-            interface = 'public'
+            if not interface:
+                interface = 'public'
 
-        service_catalog = self.get_access(session).service_catalog
-        url = service_catalog.url_for(service_type=service_type,
-                                      endpoint_type=interface,
-                                      region_name=region_name,
-                                      service_name=service_name)
+            service_catalog = self.get_access(session).service_catalog
+            url = service_catalog.url_for(service_type=service_type,
+                                          endpoint_type=interface,
+                                          region_name=region_name,
+                                          service_name=service_name)
 
         if not version:
             # NOTE(jamielennox): This may not be the best thing to default to

keystoneclient/tests/unit/auth/test_identity_common.py

@@ -368,6 +368,36 @@ class CatalogHackTests(utils.TestCase):
 
         self.assertEqual(self.V2_URL, endpoint)
 
+    def test_getting_endpoints_on_auth_interface(self):
+        disc = fixture.DiscoveryList(href=self.BASE_URL)
+        self.stub_url('GET',
+                      ['/'],
+                      base_url=self.BASE_URL,
+                      status_code=300,
+                      json=disc)
+
+        token = fixture.V2Token()
+        service = token.add_service(self.IDENTITY)
+        service.add_endpoint(public=self.V2_URL,
+                             admin=self.V2_URL,
+                             internal=self.V2_URL)
+
+        self.stub_url('POST',
+                      ['tokens'],
+                      base_url=self.V2_URL,
+                      json=token)
+
+        v2_auth = identity.V2Password(self.V2_URL,
+                                      username=uuid.uuid4().hex,
+                                      password=uuid.uuid4().hex)
+
+        sess = session.Session(auth=v2_auth)
+
+        endpoint = sess.get_endpoint(interface=base.AUTH_INTERFACE,
+                                     version=(3, 0))
+
+        self.assertEqual(self.V3_URL, endpoint)
+
 
 class GenericPlugin(base.BaseAuthPlugin):
 

keystoneclient/tests/unit/auth/test_identity_v3.py

@@ -114,9 +114,8 @@ class V3IdentityPlugin(utils.TestCase):
     def setUp(self):
         super(V3IdentityPlugin, self).setUp()
 
-        V3_URL = "%sv3" % self.TEST_URL
         self.TEST_DISCOVERY_RESPONSE = {
-            'versions': {'values': [fixture.V3Discovery(V3_URL)]}}
+            'versions': {'values': [fixture.V3Discovery(self.TEST_URL)]}}
 
         self.TEST_RESPONSE_DICT = {
             "token": {