[VOL-2027] Included instanceId in log message

Change-Id: I83e54640169d9a010ea0a644e8e3ef8ed0663827
diff --git a/cmd/arouter/arouter.go b/cmd/arouter/arouter.go
index abea7b0..d3838ac 100644
--- a/cmd/arouter/arouter.go
+++ b/cmd/arouter/arouter.go
@@ -36,7 +36,7 @@
 	}
 
 	// Setup logging
-	if _, err := log.SetDefaultLogger(log.JSON, *conf.LogLevel, nil); err != nil {
+	if _, err := log.SetDefaultLogger(log.JSON, *conf.LogLevel, log.Fields{"instanceId": conf.InstanceID}); err != nil {
 		log.With(log.Fields{"error": err}).Fatal("Cannot setup logging")
 	}