only wait for plugtime events in pre-live-migration

This change modifies _get_neutron_events_for_live_migration
to filter the event to just the subset that will be sent
at plug-time.

Currently neuton has a bug where by the dhcp agent
send a network-vif-plugged event during live migration after
we update the port profile with "migrating-to:"
this cause a network-vif-plugged event to be sent for
configuration where vif_plugging in nova/os-vif is a noop.

when that is corrected the current logic in nova cause the migration
to time out as its waiting for an event that will never arrive.

This change filters the set of events we wait for to just the plug
time events.

Related-Bug: #1815989
Closes-Bug: #1901707
Change-Id: Id2d8d72d30075200d2b07b847c4e5568599b0d3b

Author: SeanMooney

nova/compute/manager.py

@@ -8055,12 +8055,12 @@ def _neutron_failed_migration_callback(event_name, instance):
         LOG.error(msg, msg_args)
 
     @staticmethod
-    def _get_neutron_events_for_live_migration(instance):
+    def _get_neutron_events_for_live_migration(instance, migration):
         # We don't generate events if CONF.vif_plugging_timeout=0
         # meaning that the operator disabled using them.
         if CONF.vif_plugging_timeout:
-            return [('network-vif-plugged', vif['id'])
-                    for vif in instance.get_network_info()]
+            return (instance.get_network_info()
+                    .get_live_migration_plug_time_events())
         else:
             return []
 
@@ -8131,7 +8131,8 @@ class _BreakWaitForInstanceEvent(Exception):
             """
             pass
 
-        events = self._get_neutron_events_for_live_migration(instance)
+        events = self._get_neutron_events_for_live_migration(
+            instance, migration)
         try:
             if ('block_migration' in migrate_data and
                     migrate_data.block_migration):

nova/network/model.py

@@ -469,6 +469,14 @@ def has_bind_time_event(self, migration):
         return (self.is_hybrid_plug_enabled() and not
                 migration.is_same_host())
 
+    @property
+    def has_live_migration_plug_time_event(self):
+        """Returns whether this VIF's network-vif-plugged external event will
+        be sent by Neutron at "plugtime" - in other words, as soon as neutron
+        completes configuring the network backend.
+        """
+        return self.is_hybrid_plug_enabled()
+
     def is_hybrid_plug_enabled(self):
         return self['details'].get(VIF_DETAILS_OVS_HYBRID_PLUG, False)
 
@@ -530,15 +538,22 @@ def json(self):
         return jsonutils.dumps(self)
 
     def get_bind_time_events(self, migration):
-        """Returns whether any of our VIFs have "bind-time" events. See
-        has_bind_time_event() docstring for more details.
+        """Returns a list of external events for any VIFs that have
+        "bind-time" events during cold migration.
         """
         return [('network-vif-plugged', vif['id'])
                 for vif in self if vif.has_bind_time_event(migration)]
 
+    def get_live_migration_plug_time_events(self):
+        """Returns a list of external events for any VIFs that have
+        "plug-time" events during live migration.
+        """
+        return [('network-vif-plugged', vif['id'])
+                for vif in self if vif.has_live_migration_plug_time_event]
+
     def get_plug_time_events(self, migration):
-        """Complementary to get_bind_time_events(), any event that does not
-        fall in that category is a plug-time event.
+        """Returns a list of external events for any VIFs that have
+        "plug-time" events during cold migration.
         """
         return [('network-vif-plugged', vif['id'])
                 for vif in self if not vif.has_bind_time_event(migration)]

nova/tests/unit/compute/test_compute_mgr.py

@@ -9256,24 +9256,41 @@ def test_get_neutron_events_for_live_migration_empty(self):
         """Tests the various ways that _get_neutron_events_for_live_migration
         will return an empty list.
         """
+        migration = mock.Mock()
+        migration.is_same_host = lambda: False
+        self.assertFalse(migration.is_same_host())
+
         # 1. no timeout
         self.flags(vif_plugging_timeout=0)
 
         with mock.patch.object(self.instance, 'get_network_info') as nw_info:
             nw_info.return_value = network_model.NetworkInfo(
-                [network_model.VIF(uuids.port1)])
+                [network_model.VIF(uuids.port1, details={
+                        network_model.VIF_DETAILS_OVS_HYBRID_PLUG: True})])
+            self.assertTrue(nw_info.return_value[0].is_hybrid_plug_enabled())
             self.assertEqual(
                 [], self.compute._get_neutron_events_for_live_migration(
-                    self.instance))
+                    self.instance, migration))
 
         # 2. no VIFs
         self.flags(vif_plugging_timeout=300)
 
         with mock.patch.object(self.instance, 'get_network_info') as nw_info:
-            nw_info.return_value = []
+            nw_info.return_value = network_model.NetworkInfo([])
             self.assertEqual(
                 [], self.compute._get_neutron_events_for_live_migration(
-                    self.instance))
+                    self.instance, migration))
+
+        # 3. no plug time events
+        with mock.patch.object(self.instance, 'get_network_info') as nw_info:
+            nw_info.return_value = network_model.NetworkInfo(
+                [network_model.VIF(
+                    uuids.port1, details={
+                        network_model.VIF_DETAILS_OVS_HYBRID_PLUG: False})])
+            self.assertFalse(nw_info.return_value[0].is_hybrid_plug_enabled())
+            self.assertEqual(
+                [], self.compute._get_neutron_events_for_live_migration(
+                    self.instance, migration))
 
     @mock.patch('nova.compute.rpcapi.ComputeAPI.pre_live_migration')
     @mock.patch('nova.compute.manager.ComputeManager._post_live_migration')
@@ -9288,9 +9305,11 @@ def test_live_migration_wait_vif_plugged(
             wait_for_vif_plugged=True)
         mock_get_bdms.return_value = objects.BlockDeviceMappingList(objects=[])
         mock_pre_live_mig.return_value = migrate_data
+        details = {network_model.VIF_DETAILS_OVS_HYBRID_PLUG: True}
         self.instance.info_cache = objects.InstanceInfoCache(
             network_info=network_model.NetworkInfo([
-                network_model.VIF(uuids.port1), network_model.VIF(uuids.port2)
+                network_model.VIF(uuids.port1, details=details),
+                network_model.VIF(uuids.port2, details=details)
             ]))
         self.compute._waiting_live_migrations[self.instance.uuid] = (
             self.migration, mock.MagicMock()
@@ -9320,11 +9339,12 @@ def test_live_migration_wait_vif_plugged_old_dest_host(
         of not waiting.
         """
         migrate_data = objects.LibvirtLiveMigrateData()
+        details = {network_model.VIF_DETAILS_OVS_HYBRID_PLUG: True}
         mock_get_bdms.return_value = objects.BlockDeviceMappingList(objects=[])
         mock_pre_live_mig.return_value = migrate_data
         self.instance.info_cache = objects.InstanceInfoCache(
             network_info=network_model.NetworkInfo([
-                network_model.VIF(uuids.port1)]))
+                network_model.VIF(uuids.port1, details=details)]))
         self.compute._waiting_live_migrations[self.instance.uuid] = (
             self.migration, mock.MagicMock()
         )
@@ -9468,9 +9488,11 @@ def test_live_migration_aborted_before_running(self, mock_rpc,
         mock_get_bdms.return_value = source_bdms
         migrate_data = objects.LibvirtLiveMigrateData(
             wait_for_vif_plugged=True)
+        details = {network_model.VIF_DETAILS_OVS_HYBRID_PLUG: True}
         self.instance.info_cache = objects.InstanceInfoCache(
             network_info=network_model.NetworkInfo([
-                network_model.VIF(uuids.port1), network_model.VIF(uuids.port2)
+                network_model.VIF(uuids.port1, details=details),
+                network_model.VIF(uuids.port2, details=details)
             ]))
         self.compute._waiting_live_migrations = {}
         fake_migration = objects.Migration(