Add active connections gauge

metrics/metrics.go

@@ -16,3 +16,9 @@ var Votes = promauto.NewCounter(prometheus.CounterOpts{
 	Name:      "votes",
 	Help:      "number of votes counted",
 })
+
+var ActiveConnections = promauto.NewGauge(prometheus.GaugeOpts{
+	Namespace: "matrix",
+	Name:      "active",
+	Help:      "number of votes counted",
+})

web/socket.go

@@ -30,6 +30,8 @@ func broadcast(start bool) {
 var socketsByTeams = make(map[string][]sockjs.Session)
 
 func socketHandler(session sockjs.Session) {
+	go metrics.ActiveConnections.Inc()
+	defer metrics.ActiveConnections.Dec()
 	connectedSockets = append(connectedSockets, session)
 
 	e := sendMsg(session, &resp{