fix: do not register storage metric collectors if it is not enabled

If discovery service storage is not enabled, we were still wrongly registering it as prometheus metrics collector, because the nil check was done against the interface. It had to be done on the concrete type instead.

Signed-off-by: Utku Ozdemir <[email protected]>

pkg/service/service.go

@@ -181,7 +181,7 @@ func Run(ctx context.Context, options Options, logger *zap.Logger) error {
 		return fmt.Errorf("failed to configure server: %w", err)
 	}
 
-	if options.SnapshotsEnabled {
+	if stateStorage != nil {
 		eg.Go(func() error {
 			return stateStorage.Start(ctx, clockwork.NewRealClock(), options.SnapshotInterval)
 		})
@@ -295,7 +295,11 @@ func Run(ctx context.Context, options Options, logger *zap.Logger) error {
 	}
 
 	if options.MetricsRegisterer != nil {
-		collectors := []prom.Collector{state, srv, metrics, stateStorage}
+		collectors := []prom.Collector{state, srv, metrics}
+
+		if stateStorage != nil {
+			collectors = append(collectors, stateStorage)
+		}
 
 		defer unregisterCollectors(options.MetricsRegisterer, collectors...)
 
@@ -319,20 +323,12 @@ func recoveryHandler(logger *zap.Logger) grpc_recovery.RecoveryHandlerFunc {
 
 func unregisterCollectors(registerer prom.Registerer, collectors ...prom.Collector) {
 	for _, collector := range collectors {
-		if collector == nil {
-			continue
-		}
-
 		registerer.Unregister(collector)
 	}
 }
 
 func registerCollectors(registerer prom.Registerer, collectors ...prom.Collector) (err error) {
 	for _, collector := range collectors {
-		if collector == nil {
-			continue
-		}
-
 		if err = registerer.Register(collector); err != nil {
 			return fmt.Errorf("failed to register collector: %w", err)
 		}