fix: type

services/mqttaccess/main.go

@@ -7,7 +7,7 @@ import (
 )
 
 var deviceOnlineCount prometheus.Gauge
-var deviceMessageCount prometheus.CounterVec
+var deviceMessageCount *prometheus.CounterVec
 
 func main() {
 	// init server
@@ -52,7 +52,7 @@ func main() {
 
 	server.RegisterMetric(deviceOnlineMetric, recvMessageCount)
 	deviceOnlineCount = deviceOnlineMetric.MetricCollector.(prometheus.Gauge)
-	deviceMessageCount = recvMessageCount.MetricCollector.(prometheus.CounterVec)
+	deviceMessageCount = recvMessageCount.MetricCollector.(*prometheus.CounterVec)
 	// start to run
 	err = server.Run()
 	if err != nil {