add start metrics server

weed/server/volume_server.go

@@ -46,6 +46,7 @@ func NewVolumeServer(adminMux, publicMux *http.ServeMux, ip string,
 	readRedirect bool,
 	compactionMBPerSecond int,
 	fileSizeLimitMB int,
+	metricsHttpPort int,
 ) *VolumeServer {
 
 	v := util.GetViper()
@@ -97,6 +98,7 @@ func NewVolumeServer(adminMux, publicMux *http.ServeMux, ip string,
 	}
 
 	go vs.heartbeat()
+	go stats.StartMetricsServer(stats.VolumeServerGather, metricsHttpPort)
 	go stats.LoopPushingMetric("volumeServer", fmt.Sprintf("%s:%d", ip, port), stats.VolumeServerGather, vs.metricsAddress, vs.metricsIntervalSec)
 
 	return vs