Fix for mixed metric types in server connection panel

Author: rokka

dashboard/nginx-vts-exporter.json

@@ -154,7 +154,7 @@
           "steppedLine": false,
           "targets": [
             {
-              "expr": "sum(irate(nginx_server_connections[5m])) by (status)",
+              "expr": "nginx_server_connections{status=~\"active|writing|reading|waiting\"}",
               "intervalFactor": 2,
               "legendFormat": "{{ status }}",
               "metric": "nginx_server_connections",
@@ -687,4 +687,4 @@
       "collapse": false
     }
   ]
-}
+}