Add revert_snapshot_based_resize conductor RPC method

This adds the conductor ComputeTaskManager method
revert_snapshot_based_resize along with the related conductor
RPC API client method which will be an RPC cast from the API
for a revertResize server action.

Part of blueprint cross-cell-resize

Change-Id: Ia6b6b25238963a5f60349267da6d07cb740982f4

nova/conductor/api.py

@@ -180,3 +180,8 @@ class ComputeTaskAPI(object):
             self, ctxt, instance, migration, do_cast=True):
         self.conductor_compute_rpcapi.confirm_snapshot_based_resize(
             ctxt, instance, migration, do_cast=do_cast)
+
+    def revert_snapshot_based_resize(
+            self, ctxt, instance, migration):
+        self.conductor_compute_rpcapi.revert_snapshot_based_resize(
+            ctxt, instance, migration)

nova/conductor/manager.py

@@ -233,7 +233,7 @@ class ComputeTaskManager(base.Base):
     may involve coordinating activities on multiple compute nodes.
     """
 
-    target = messaging.Target(namespace='compute_task', version='1.22')
+    target = messaging.Target(namespace='compute_task', version='1.23')
 
     def __init__(self):
         super(ComputeTaskManager, self).__init__()
@@ -1875,3 +1875,22 @@ class ComputeTaskManager(base.Base):
         task = cross_cell_migrate.ConfirmResizeTask(
             context, instance, migration, self.notifier, self.compute_rpcapi)
         task.execute()
+
+    @targets_cell
+    # FIXME(mriedem): Upon successful completion of RevertResizeTask the
+    # instance is hard-deleted, along with its instance action record(s), from
+    # the target cell database so wrap_instance_event hits
+    # InstanceActionNotFound on __exit__.
+    @wrap_instance_event(prefix='conductor')
+    def revert_snapshot_based_resize(self, context, instance, migration):
+        """Executes the RevertResizeTask
+
+        :param context: nova auth request context targeted at the target cell
+        :param instance: Instance object in "resized" status from the target
+            cell
+        :param migration: Migration object from the target cell for the resize
+            operation expected to have status "reverting"
+        """
+        task = cross_cell_migrate.RevertResizeTask(
+            context, instance, migration, self.notifier, self.compute_rpcapi)
+        task.execute()

nova/conductor/rpcapi.py

@@ -285,6 +285,7 @@ class ComputeTaskAPI(object):
            potential alternate hosts for retries within a cell.
     1.21 - Added cache_images()
     1.22 - Added confirm_snapshot_based_resize()
+    1.23 - Added revert_snapshot_based_resize()
     """
 
     def __init__(self):
@@ -465,3 +466,11 @@ class ComputeTaskAPI(object):
         if do_cast:
             return cctxt.cast(ctxt, 'confirm_snapshot_based_resize', **kw)
         return cctxt.call(ctxt, 'confirm_snapshot_based_resize', **kw)
+
+    def revert_snapshot_based_resize(self, ctxt, instance, migration):
+        version = '1.23'
+        if not self.client.can_send_version(version):
+            raise exception.ServiceTooOld(_('nova-conductor too old'))
+        kw = {'instance': instance, 'migration': migration}
+        cctxt = self.client.prepare(version=version)
+        return cctxt.cast(ctxt, 'revert_snapshot_based_resize', **kw)

nova/tests/unit/conductor/test_conductor.py

@@ -1783,6 +1783,18 @@ class _BaseTaskTestCase(object):
             self.context, instance=instance, migration=migration)
         mock_execute.assert_called_once_with()
 
+    @mock.patch(
+        'nova.conductor.tasks.cross_cell_migrate.RevertResizeTask.execute')
+    def test_revert_snapshot_based_resize(self, mock_execute):
+        instance = self._create_fake_instance_obj(ctxt=self.context)
+        migration = objects.Migration(
+            context=self.context, source_compute=instance.host,
+            source_node=instance.node, instance_uuid=instance.uuid,
+            status='reverting', migration_type='migration')
+        self.conductor_manager.revert_snapshot_based_resize(
+            self.context, instance=instance, migration=migration)
+        mock_execute.assert_called_once_with()
+
 
 class ConductorTaskTestCase(_BaseTaskTestCase, test_compute.BaseTestCase):
     """ComputeTaskManager Tests."""
@@ -3843,6 +3855,17 @@ class ConductorTaskRPCAPITestCase(_BaseTaskTestCase,
                               self.context, mock.sentinel.instance,
                               mock.sentinel.migration)
 
+    def test_revert_snapshot_based_resize_old_service(self):
+        """Tests revert_snapshot_based_resize when the service is too old."""
+        with mock.patch.object(
+                self.conductor.client, 'can_send_version',
+                return_value=False) as can_send_version:
+            self.assertRaises(exc.ServiceTooOld,
+                              self.conductor.revert_snapshot_based_resize,
+                              self.context, mock.sentinel.instance,
+                              mock.sentinel.migration)
+        can_send_version.assert_called_once_with('1.23')
+
 
 class ConductorTaskAPITestCase(_BaseTaskTestCase, test_compute.BaseTestCase):
     """Compute task API Tests."""