Merge "Don't attempt to lazy-load tags on a deleted instance"

nova/objects/instance.py

@@ -980,6 +980,11 @@ class Instance(base.NovaPersistentObject, base.NovaObject,
             # filters on instances.deleted == 0, so if the instance is deleted
             # don't attempt to even load services since we'll fail.
             self.services = objects.ServiceList(self._context)
+        elif attrname == 'tags' and self.deleted:
+            # NOTE(mriedem): Same story as services, the DB API query
+            # in instance_tag_get_by_instance_uuid will fail if the instance
+            # has been deleted so just return an empty tag list here.
+            self.tags = objects.TagList(self._context)
         else:
             # FIXME(comstud): This should be optimized to only load the attr.
             self._load_generic(attrname)

nova/tests/unit/objects/test_instance.py

@@ -208,6 +208,13 @@ class _TestInstanceObject(object):
                                     deleted=True)
         self.assertEqual(0, len(instance.services))
 
+    def test_lazy_load_tags_on_deleted_instance(self):
+        # We should avoid trying to hit the database to reload the instance
+        # and just set the tags attribute to an empty list.
+        instance = objects.Instance(self.context, uuid=uuids.instance,
+                                    deleted=True)
+        self.assertEqual(0, len(instance.tags))
+
     @mock.patch.object(db, 'instance_get')
     def test_get_by_id(self, mock_get):
         mock_get.return_value = self.fake_instance