improvment: added prometheus metrics for the number of groups in a room

back/src/Services/GaugeManager.ts

@@ -0,0 +1,54 @@
+import {Counter, Gauge} from "prom-client";
+
+//this class should manage all the custom metrics used by prometheus
+class GaugeManager {
+    private nbClientsGauge: Gauge<string>;
+    private nbClientsPerRoomGauge: Gauge<string>;
+    private nbGroupsPerRoomGauge: Gauge<string>;
+    private nbGroupsPerRoomCounter: Counter<string>;
+
+    constructor() {
+        this.nbClientsGauge = new Gauge({
+            name: 'workadventure_nb_sockets',
+            help: 'Number of connected sockets',
+            labelNames: [ ]
+        });
+        this.nbClientsPerRoomGauge = new Gauge({
+            name: 'workadventure_nb_clients_per_room',
+            help: 'Number of clients per room',
+            labelNames: [ 'room' ]
+        });
+
+        this.nbGroupsPerRoomCounter = new Counter({
+            name: 'workadventure_counter_groups_per_room',
+            help: 'Counter of groups per room',
+            labelNames: [ 'room' ]
+        });
+        this.nbGroupsPerRoomGauge = new Gauge({
+            name: 'workadventure_nb_groups_per_room',
+            help: 'Number of groups per room',
+            labelNames: [ 'room' ]
+        });
+    }
+
+    incNbClientPerRoomGauge(roomId: string): void {
+        this.nbClientsGauge.inc();
+        this.nbClientsPerRoomGauge.inc({ room: roomId });
+    }
+
+    decNbClientPerRoomGauge(roomId: string): void {
+        this.nbClientsGauge.dec();
+        this.nbClientsPerRoomGauge.dec({ room: roomId });
+    }
+
+    incNbGroupsPerRoomGauge(roomId: string): void {
+        this.nbGroupsPerRoomCounter.inc({ room: roomId })
+        this.nbGroupsPerRoomGauge.inc({ room: roomId })
+    }
+    
+    decNbGroupsPerRoomGauge(roomId: string): void {
+        this.nbGroupsPerRoomGauge.dec({ room: roomId })
+    }
+}
+
+export const gaugeManager = new GaugeManager();