app: Add version metric

closes #87

Signed-off-by: Evgenii Baidakov <[email protected]>

cmd/neofs-rest-gw/config.go

@@ -467,6 +467,7 @@ func newNeofsAPI(ctx context.Context, logger *zap.Logger, v *viper.Viper) (*hand
 	apiPrm.PrometheusService = metrics.NewPrometheusService(logger, prometheusConfig)
 	if prometheusConfig.Enabled {
 		apiPrm.GateMetric = metrics.NewGateMetrics(poolStat)
+		apiPrm.GateMetric.SetGWVersion(Version)
 	}
 
 	apiPrm.ServiceShutdownTimeout = defaultShutdownTimeout

metrics/metrics.go

@@ -38,6 +38,7 @@ type GateMetrics struct {
 
 type stateMetrics struct {
 	healthCheck prometheus.Gauge
+	gwVersion   *prometheus.GaugeVec
 }
 
 type poolMetricsCollector struct {
@@ -71,11 +72,20 @@ func newStateMetrics() *stateMetrics {
 			Name:      "health",
 			Help:      "Current REST gateway state",
 		}),
+		gwVersion: prometheus.NewGaugeVec(
+			prometheus.GaugeOpts{
+				Help:      "Gateway version",
+				Name:      "version",
+				Namespace: namespace,
+			},
+			[]string{"version"},
+		),
 	}
 }
 
 func (m stateMetrics) register() {
 	prometheus.MustRegister(m.healthCheck)
+	prometheus.MustRegister(m.gwVersion)
 }
 
 func (m stateMetrics) SetHealth(s int32) {
@@ -224,3 +234,7 @@ func NewPrometheusService(log *zap.Logger, cfg Config) *Service {
 		log:         log.With(zap.String("service", "Prometheus")),
 	}
 }
+
+func (g *GateMetrics) SetGWVersion(ver string) {
+	g.gwVersion.WithLabelValues(ver).Add(1)
+}