Avoid stuck task_state on snapshot image failure

Fixes bug LP 1101136

Previously if the glance interaction failed prior to an
instance being snapshot'd or backed up, the task state
remained stuck at image_snapshot/backup.

The normal task state reversion logic did not kick in,
as this is limited to the compute layer, whereas the
intial glance interaction occurs within the API layer.

Now, we avoid this problem by delaying setting the task
state until the initial initial image creation/retrieval
has completed.

Change-Id: Id498ae6b3674306743013e4fe99837da8e2031b5

1 files changed, 10 insertions, 6 deletions

diff --git a/nova/compute/api.py b/nova/compute/api.py
index 4b15a3e27..9092a001a 100644
--- a/nova/compute/api.py
+++ b/nova/compute/api.py
@@ -1353,9 +1353,6 @@ class API(base.Base):
             None if rotation shouldn't be used (as in the case of snapshots)
         :param extra_properties: dict of extra image properties to include
         """
-        instance = self.update(context, instance,
-                               task_state=task_states.IMAGE_BACKUP,
-                               expected_task_state=None)
         if image_id:
             # The image entry has already been created, so just pull the
             # metadata.
@@ -1364,6 +1361,11 @@ class API(base.Base):
             image_meta = self._create_image(context, instance, name,
                     'backup', backup_type=backup_type,
                     rotation=rotation, extra_properties=extra_properties)
+
+        instance = self.update(context, instance,
+                               task_state=task_states.IMAGE_BACKUP,
+                               expected_task_state=None)
+
         self.compute_rpcapi.snapshot_instance(context, instance=instance,
                 image_id=image_meta['id'], image_type='backup',
                 backup_type=backup_type, rotation=rotation)
@@ -1381,9 +1383,6 @@ class API(base.Base):
 
         :returns: A dict containing image metadata
         """
-        instance = self.update(context, instance,
-                               task_state=task_states.IMAGE_SNAPSHOT,
-                               expected_task_state=None)
         if image_id:
             # The image entry has already been created, so just pull the
             # metadata.
@@ -1391,6 +1390,11 @@ class API(base.Base):
         else:
             image_meta = self._create_image(context, instance, name,
                     'snapshot', extra_properties=extra_properties)
+
+        instance = self.update(context, instance,
+                               task_state=task_states.IMAGE_SNAPSHOT,
+                               expected_task_state=None)
+
         self.compute_rpcapi.snapshot_instance(context, instance=instance,
                 image_id=image_meta['id'], image_type='snapshot')
         return image_meta