+def _GetInstReasonFilename(instance_name):
+ """Path of the file containing the reason of the instance status change.
+
+ @type instance_name: string
+ @param instance_name: The name of the instance
+ @rtype: string
+ @return: The path of the file
+
+ """
+ return utils.PathJoin(pathutils.INSTANCE_REASON_DIR, instance_name)
+
+
+def _StoreInstReasonTrail(instance_name, trail):
+ """Serialize a reason trail related to an instance change of state to file.
+
+ The exact location of the file depends on the name of the instance and on
+ the configuration of the Ganeti cluster defined at deploy time.
+
+ @type instance_name: string
+ @param instance_name: The name of the instance
+ @rtype: None
+
+ """
+ json = serializer.DumpJson(trail)
+ filename = _GetInstReasonFilename(instance_name)
+ utils.WriteFile(filename, data=json)
+
+