Refactor metric collection

router.go

@@ -60,8 +60,11 @@ func (rl *rushlink) metricsMiddleware(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		srw := statusResponseWriter{Inner: w}
 		next.ServeHTTP(&srw, r)
+
 		status := strconv.Itoa(srw.StatusCode)
-		metricRequestsTotalCounter.WithLabelValues(status, r.Method).Inc()
+		labels := map[string]string{"code": status, "method": r.Method}
+		// Update requests counter metric
+		metricRequestsTotalCounter.With(labels).Inc()
 	})
 }