workaround for RAX repose configuration

The RAX Repose environment is blocking access to the API version
information by local policy, returning a 401 before we even get to
Nova itself. While this in clearly incorrect behavior, it is behavior
in the field, and we should not break all our users on that cloud.

This catches the 401 and translates that so that it's the equivalent
of only supporting v2.0. We will be taking these API calls to defcore,
and intend to remove this work around once that is done.

Change-Id: I2072095c24b41efcfd58d6f25205bcc94f1174da
Related-Bug: #1491579

novaclient/tests/unit/test_api_versions.py

@@ -357,3 +357,15 @@ class DiscoverVersionTestCase(utils.TestCase):
             api_versions.discover_version(
                 fake_client,
                 api_versions.APIVersion('2.latest')).get_string())
+
+    def test_server_without_microversion_rax_workaround(self):
+        fake_client = mock.MagicMock()
+        fake_client.versions.get_current.return_value = None
+        novaclient.API_MAX_VERSION = api_versions.APIVersion("2.11")
+        novaclient.API_MIN_VERSION = api_versions.APIVersion("2.1")
+
+        self.assertEqual(
+            "2.0",
+            api_versions.discover_version(
+                fake_client,
+                api_versions.APIVersion('2.latest')).get_string())

novaclient/tests/unit/v2/test_versions.py

@@ -14,6 +14,7 @@
 
 import mock
 
+from novaclient import exceptions as exc
 from novaclient.tests.unit import utils
 from novaclient.tests.unit.v2 import fakes
 from novaclient.v2 import versions
@@ -64,3 +65,11 @@ class VersionsTest(utils.TestCase):
         self.cs.callback = []
         self.cs.versions.get_current()
         self.cs.assert_called('GET', 'http://nova-api:8774/v2.1/')
+
+    @mock.patch.object(versions.VersionManager, '_is_session_client',
+                       return_value=True)
+    @mock.patch.object(versions.VersionManager, '_get',
+                       side_effect=exc.Unauthorized("401 RAX"))
+    def test_get_current_with_rax_workaround(self, session, get):
+        self.cs.callback = []
+        self.assertIsNone(self.cs.versions.get_current())

novaclient/v2/versions.py

@@ -20,6 +20,7 @@ from six.moves import urllib
 
 from novaclient import base
 from novaclient import client
+from novaclient import exceptions as exc
 
 
 class Version(base.Resource):
@@ -45,7 +46,15 @@ class VersionManager(base.ManagerWithFind):
             # that's actually a 300 redirect to /v2/... because of how
             # paste works. So adding the end slash is really important.
             url = "%s/" % url
-            return self._get(url, "version")
+            try:
+                return self._get(url, "version")
+            except exc.Unauthorized:
+                # NOTE(sdague): RAX's repose configuration blocks
+                # access to the versioned endpoint, which is
+                # definitely non-compliant behavior. However, there is
+                # no defcore test for this yet. Remove this code block
+                # once we land things in defcore.
+                return None
         else:
             # NOTE(andreykurilin): HTTPClient doesn't have ability to send get
             # request without token in the url, so `self._get` doesn't work.