vm: migration with zero downtime

circle/vm/models/instance.py

@@ -822,7 +822,8 @@ class Instance(AclBase, VirtualMachineDescModel, StatusModel, OperatedMixin,
     def migrate_vm(self, to_node, timeout=120):
         queue_name = self.get_remote_queue_name('vm', 'slow')
         return vm_tasks.migrate.apply_async(args=[self.vm_name,
-                                                  to_node.host.hostname],
+                                                  to_node.host.hostname,
+                                                  True],
                                             queue=queue_name
                                             ).get(timeout=timeout)
 

circle/vm/operations.py

@@ -250,10 +250,6 @@ class MigrateOperation(InstanceOperation):
                 to_node = self.instance.select_node()
                 sa.result = to_node
 
-        # Shutdown networks
-        with activity.sub_activity('shutdown_net'):
-            self.instance.shutdown_net()
-
         try:
             with activity.sub_activity('migrate_vm'):
                 self.instance.migrate_vm(to_node=to_node, timeout=timeout)
@@ -262,6 +258,10 @@ class MigrateOperation(InstanceOperation):
                 self.rollback(activity)
             raise
 
+        # Shutdown networks
+        with activity.sub_activity('shutdown_net'):
+            self.instance.shutdown_net()
+
         # Refresh node information
         self.instance.node = to_node
         self.instance.save()