Soft delete virtual_interfaces when instance is destroyed

Like the other reference table entries for an instance,
we should soft_delete virtual_interfaces when destroying
an instance. Failing to do so can lead to archive issues
due to the referential constraint.

Change-Id: I04355bdec5477b4c144105fea130089fe1ae6772
Closes-Bug: #1823781

Author: mriedem

nova/db/sqlalchemy/api.py

@@ -1806,6 +1806,8 @@ def instance_destroy(context, instance_uuid, constraint=None):
     model_query(context, models.Migration).\
             filter_by(instance_uuid=instance_uuid).\
             soft_delete()
+    model_query(context, models.VirtualInterface).filter_by(
+        instance_uuid=instance_uuid).soft_delete()
     model_query(context, models.InstanceIdMapping).filter_by(
         uuid=instance_uuid).soft_delete()
     # NOTE(snikitin): We can't use model_query here, because there is no

nova/tests/unit/db/test_db_api.py

@@ -2574,6 +2574,21 @@ def test_delete_migrations_on_instance_destroy(self):
         self.assertTrue(instance.deleted)
         self.assertEqual(0, len(migrations))
 
+    def test_delete_virtual_interfaces_on_instance_destroy(self):
+        # Create the instance.
+        ctxt = context.get_admin_context()
+        uuid = uuidsentinel.uuid1
+        db.instance_create(ctxt, {'uuid': uuid})
+        # Create the VirtualInterface.
+        db.virtual_interface_create(ctxt, {'instance_uuid': uuid})
+        # Make sure the vif is tied to the instance.
+        vifs = db.virtual_interface_get_by_instance(ctxt, uuid)
+        self.assertEqual(1, len(vifs))
+        # Destroy the instance and verify the vif is gone as well.
+        db.instance_destroy(ctxt, uuid)
+        self.assertEqual(
+            0, len(db.virtual_interface_get_by_instance(ctxt, uuid)))
+
     def test_instance_update_and_get_original(self):
         instance = self.create_instance_with_args(vm_state='building')
         (old_ref, new_ref) = db.instance_update_and_get_original(self.ctxt,