Add desired number of rooms metrics

internal/core/operations/healthcontroller/executor.go

@@ -93,6 +93,8 @@ func (ex *Executor) Execute(ctx context.Context, op *operation.Operation, defini
 	}
 
 	availableRooms, expiredRooms := ex.findAvailableAndExpiredRooms(ctx, op, existentGameRoomsInstancesMap)
+	reportCurrentNumberOfRooms(scheduler.Game, scheduler.Name, len(availableRooms))
+
 	if len(expiredRooms) > 0 {
 		logger.Sugar().Infof("found %v expired rooms to be deleted", len(expiredRooms))
 		err = ex.enqueueRemoveExpiredRooms(ctx, op, logger, expiredRooms)
@@ -107,6 +109,7 @@ func (ex *Executor) Execute(ctx context.Context, op *operation.Operation, defini
 		logger.Error("error getting the desired number of rooms", zap.Error(err))
 		return err
 	}
+	reportDesiredNumberOfRooms(scheduler.Game, scheduler.Name, desiredNumberOfRooms)
 
 	err = ex.ensureDesiredAmountOfInstances(ctx, op, def, logger, len(availableRooms), desiredNumberOfRooms)
 	if err != nil {

internal/core/operations/healthcontroller/metrics.go

@@ -0,0 +1,35 @@
+package healthcontroller
+
+import "github.com/topfreegames/maestro/internal/core/monitoring"
+
+var (
+	desiredNumberOfRoomsMetric = monitoring.CreateGaugeMetric(&monitoring.MetricOpts{
+		Namespace: monitoring.Namespace,
+		Subsystem: monitoring.SubsystemWorker,
+		Name:      "desired_rooms",
+		Help:      "Desired number of rooms for a scheduler, based on the autoscaling policy",
+		Labels: []string{
+			monitoring.LabelGame,
+			monitoring.LabelScheduler,
+		},
+	})
+
+	currentNumberOfRoomsMetric = monitoring.CreateGaugeMetric(&monitoring.MetricOpts{
+		Namespace: monitoring.Namespace,
+		Subsystem: monitoring.SubsystemWorker,
+		Name:      "current_rooms",
+		Help:      "Current number of rooms for a scheduler",
+		Labels: []string{
+			monitoring.LabelGame,
+			monitoring.LabelScheduler,
+		},
+	})
+)
+
+func reportDesiredNumberOfRooms(game, scheduler string, desired int) {
+	desiredNumberOfRoomsMetric.WithLabelValues(game, scheduler).Set(float64(desired))
+}
+
+func reportCurrentNumberOfRooms(game, scheduler string, current int) {
+	currentNumberOfRoomsMetric.WithLabelValues(game, scheduler).Set(float64(current))
+}