add serializer for vtn viewset
diff --git a/xos/core/xoslib/methods/vtn.py b/xos/core/xoslib/methods/vtn.py
index 1a2af53..5c8b1b4 100644
--- a/xos/core/xoslib/methods/vtn.py
+++ b/xos/core/xoslib/methods/vtn.py
@@ -16,6 +16,9 @@
 import json
 import subprocess
 
+class VTNSerializer(PlusModelSerializer):
+        id = ReadOnlyField()
+
 class VTNViewSet(XOSViewSet):
     base_name = "vtn"
     method_name = "rs/vtn"
@@ -26,6 +29,8 @@
     queryset = Service.objects.none() # CordSubscriber.get_tenant_objects().select_related().all()
     model = Service
 
+    serializer_class = VTNSerializer
+
     @classmethod
     def get_urlpatterns(self):
         patterns = []