Workaround missing RequestSpec.instance_group.uuid

It's clear that we could have a RequestSpec.instance_group
without a uuid field if the InstanceGroup is set from the
_populate_group_info method which should only be used for
legacy translation of request specs using legacy filter
properties dicts.

To workaround the issue, we look for the group scheduler hint
to get the group uuid before loading it from the DB.

The related functional regression recreate test is updated
to show this solves the issue.

Change-Id: I20981c987549eec40ad9762e74b0db16e54f4e63
Closes-Bug: #1830747

Author: mriedem

nova/objects/request_spec.py

@@ -242,6 +242,8 @@ def _populate_group_info(self, filter_properties):
             policies = list(filter_properties.get('group_policies'))
             hosts = list(filter_properties.get('group_hosts'))
             members = list(filter_properties.get('group_members'))
+            # TODO(mriedem): We could try to get the group uuid from the
+            # group hint in the filter_properties.
             self.instance_group = objects.InstanceGroup(policy=policies[0],
                                                         hosts=hosts,
                                                         members=members)
@@ -545,6 +547,12 @@ def _from_db_object(context, spec, db_spec):
         spec._context = context
 
         if 'instance_group' in spec and spec.instance_group:
+            # NOTE(mriedem): We could have a half-baked instance group with no
+            # uuid if some legacy translation was performed on this spec in the
+            # past. In that case, try to workaround the issue by getting the
+            # group uuid from the scheduler hint.
+            if 'uuid' not in spec.instance_group:
+                spec.instance_group.uuid = spec.get_scheduler_hint('group')
             # NOTE(danms): We don't store the full instance group in
             # the reqspec since it would be stale almost immediately.
             # Instead, load it by uuid here so it's up-to-date.

nova/tests/functional/regressions/test_bug_1830747.py

@@ -11,11 +11,9 @@
 # under the License.
 
 import mock
-import six
 
 from nova.conductor import api as conductor_api
 from nova import context as nova_context
-from nova import exception
 from nova import objects
 from nova.scheduler import weights
 from nova import test
@@ -142,17 +140,10 @@ def stub_resize_instance(_self, context, instance,
         with mock.patch.dict(host1_driver.capabilities,
                              supports_migrate_to_same_host=False):
             self.api.post_server_action(server['id'], {'migrate': None})
-            # FIXME(mriedem): Due to bug 1830747 we don't go to VERIFY_RESIZE
-            # because the reschedule fails and the instance is put into
-            # ERROR status. When the bug is fixed the status should be
-            # VERIFY_RESIZE and the server should be on host2.
             server = self._wait_for_state_change(
-                self.api, server, 'ERROR')
-            self.assertEqual('host1', server['OS-EXT-SRV-ATTR:host'])
-
-        # And the RequestSpec.instance_group.uuid should be missing which
-        # leads to us failing to load the RequestSpec.
-        ex = self.assertRaises(exception.ObjectActionError,
-                               objects.RequestSpec.get_by_instance_uuid,
-                               ctxt, server['id'])
-        self.assertIn('unable to load uuid', six.text_type(ex))
+                self.api, server, 'VERIFY_RESIZE')
+            self.assertEqual('host2', server['OS-EXT-SRV-ATTR:host'])
+
+        # The RequestSpec.instance_group.uuid should still be set.
+        reqspec = objects.RequestSpec.get_by_instance_uuid(ctxt, server['id'])
+        self.assertEqual(group_id, reqspec.instance_group.uuid)