Fixed instance deletion issue from Nova API.

When host Compute is down, Nova API deletes the resources associated with the
instance. However, since the instance is marked deleted first, the next query
to update the instance vm_state and task_state in DB fails. And instance
remains in state vm_state=ACTIVE, task_state=DELETING, deleted=True.

Fixes LP: #1074305

Change-Id: I0a4e64d180b4b2c5e398a21a62b29b7d59549a9f

2 files changed, 9 insertions, 6 deletions

diff --git a/nova/compute/api.py b/nova/compute/api.py
index 28c7068ba..0987b0549 100644
--- a/nova/compute/api.py
+++ b/nova/compute/api.py
@@ -954,7 +954,6 @@ class API(base.Base):
         elevated = context.elevated()
         self.network_api.deallocate_for_instance(elevated,
                 instance)
-        self.db.instance_destroy(context, instance_uuid)
         system_meta = self.db.instance_system_metadata_get(context,
                 instance_uuid)
 
@@ -979,6 +978,7 @@ class API(base.Base):
                                          vm_state=vm_states.DELETED,
                                          task_state=None,
                                          terminated_at=timeutils.utcnow())
+        self.db.instance_destroy(context, instance_uuid)
         compute_utils.notify_about_instance_usage(
             context, instance, "delete.end", system_metadata=system_meta)
 
diff --git a/nova/tests/compute/test_compute.py b/nova/tests/compute/test_compute.py
index d8bc34883..52b7c4401 100644
--- a/nova/tests/compute/test_compute.py
+++ b/nova/tests/compute/test_compute.py
@@ -3150,7 +3150,7 @@ class ComputeAPITestCase(BaseTestCase):
 
         def dummy(*args, **kwargs):
             self.network_api_called = True
-            pass
+
         self.stubs.Set(self.compute_api.network_api, 'deallocate_for_instance',
                        dummy)
 
@@ -3166,10 +3166,13 @@ class ComputeAPITestCase(BaseTestCase):
         self.assertEqual(instance['task_state'], None)
         self.assertTrue(self.network_api_called)
 
-        #local delete, so db should be clean
-        self.assertRaises(exception.InstanceNotFound, db.instance_destroy,
-                self.context,
-                instance['uuid'])
+        # fetch the instance state from db and verify deletion.
+        deleted_context = context.RequestContext('fake', 'fake',
+                                                 read_deleted='yes')
+        instance = db.instance_get_by_uuid(deleted_context, instance_uuid)
+        self.assertEqual(instance['vm_state'], vm_states.DELETED)
+        self.assertEqual(instance['task_state'], None)
+        self.assertTrue(instance['deleted'])
 
     def test_repeated_delete_quota(self):
         in_use = {'instances': 1}