Handle API limit exception in nova_utils.refresh_server

novaclient raises an OverLimit exception when a 413 response code (API
limit) is returned from the Nova API.  Previously, this would cause the
stack action to fail.  Log a warning instead.

Change-Id: I52c9dc96b34d0645662d98aaeebb7dabe6956e25
Implements: blueprint improve-api-polling

heat/engine/resources/nova_utils.py

@@ -54,6 +54,12 @@ def refresh_server(server):
     '''
     try:
         server.get()
+    except clients.novaclient.exceptions.OverLimit as exc:
+        msg = _("Server %(name)s (%(id)s) received an OverLimit "
+                "response during server.get(): %(exception)s")
+        logger.warning(msg % {'name': server.name,
+                              'id': server.id,
+                              'exception': str(exc)})
     except clients.novaclient.exceptions.ClientException as exc:
         if exc.code == 500:
             msg = _('Server "%(name)s" (%(id)s) received the following '

heat/tests/test_nova_utils.py

@@ -14,6 +14,7 @@
 #    under the License.
 """Tests for :module:'heat.engine.resources.nova_utls'."""
 
+import mock
 import uuid
 
 from heat.common import exception
@@ -118,6 +119,12 @@ class NovaUtilsRefreshServerTests(HeatTestCase):
         self.assertIsNone(nova_utils.refresh_server(server))
         self.m.VerifyAll()
 
+    def test_overlimit_error(self):
+        server = mock.Mock()
+        server.get.side_effect = clients.novaclient.exceptions.OverLimit(
+            413, "limit reached")
+        self.assertIsNone(nova_utils.refresh_server(server))
+
     def test_500_error(self):
         server = self.m.CreateMockAnything()
         msg = ("ClientException: The server has either erred or is "