Allow to update vnic_type when port is not bound

Updating vnic type is legal procedure, and is used by Ironic. This patch
allows to update vnic type when port is not bound (doesn't have
references to VM or Vrouter)

Closes-Bug: 1719268

Change-Id: Ic7b6a7232316c698b2f8521a9b3d46fb755d4e3d

src/config/api-server/vnc_cfg_types.py

@@ -1190,6 +1190,19 @@ def _check_service_health_check_type(cls, obj_dict, db_dict, db_conn):
 
         return (True, '')
 
+    @classmethod
+    def _is_port_bound(cls, obj_dict):
+        """Check whatever port is bound.
+
+        We assume port is bound when it is linked to either VM or Vrouter.
+
+        :param obj_dict: Port dict to check
+        :returns: True if port is bound, False otherwise.
+        """
+
+        return (obj_dict.get('logical_router_back_refs') or
+                obj_dict.get('virtual_machine_refs'))
+
     @classmethod
     def pre_dbe_create(cls, tenant_name, obj_dict, db_conn):
         vn_dict = obj_dict['virtual_network_refs'][0]
@@ -1393,8 +1406,10 @@ def pre_dbe_update(cls, id, fq_name, obj_dict, db_conn,
         if kvps:
             kvp_dict = cls._kvp_to_dict(kvps)
             new_vnic_type = kvp_dict.get('vnic_type', old_vnic_type)
-            if (old_vnic_type  != new_vnic_type):
-                return (False, (409, "Vnic_type can not be modified"))
+            if (old_vnic_type != new_vnic_type):
+                if cls._is_port_bound(read_result):
+                    return (False, (409, "Vnic_type can not be modified when "
+                                    "port is linked to Vrouter or VM."))
 
         if old_vnic_type == cls.portbindings['VNIC_TYPE_DIRECT']:
             cls._check_vrouter_link(read_result, kvp_dict, obj_dict, db_conn)