[#1614] metrics: Add health metrics

Also, rename metrics structure since it collects not only storage metrics
now.

Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>

cmd/neofs-node/config.go

@@ -105,7 +105,7 @@ type cfg struct {
 
 	cfgNotifications cfgNotifications
 
-	metricsCollector *metrics.StorageMetrics
+	metricsCollector *metrics.NodeMetrics
 
 	workers []worker
 
@@ -326,7 +326,7 @@ func initCfg(path string) *cfg {
 	user.IDFromKey(&c.ownerIDFromKey, key.PrivateKey.PublicKey)
 
 	if metricsconfig.Enabled(c.appCfg) {
-		c.metricsCollector = metrics.NewStorageMetrics()
+		c.metricsCollector = metrics.NewNodeMetrics()
 		netState.metrics = c.metricsCollector
 	}
 

cmd/neofs-node/netmap.go

@@ -31,7 +31,7 @@ type networkState struct {
 
 	nodeInfo atomic.Value // *netmapSDK.NodeInfo
 
-	metrics *metrics.StorageMetrics
+	metrics *metrics.NodeMetrics
 }
 
 func newNetworkState() *networkState {

pkg/metrics/metrics.go

@@ -4,19 +4,23 @@ import "github.com/prometheus/client_golang/prometheus"
 
 const namespace = "neofs_node"
 
-type StorageMetrics struct {
+type NodeMetrics struct {
 	objectServiceMetrics
 	engineMetrics
+	stateMetrics
 	epoch prometheus.Gauge
 }
 
-func NewStorageMetrics() *StorageMetrics {
+func NewNodeMetrics() *NodeMetrics {
 	objectService := newObjectServiceMetrics()
 	objectService.register()
 
 	engine := newEngineMetrics()
 	engine.register()
 
+	state := newStateMetrics()
+	state.register()
+
 	epoch := prometheus.NewGauge(prometheus.GaugeOpts{
 		Namespace: namespace,
 		Subsystem: innerRingSubsystem,
@@ -25,14 +29,15 @@ func NewStorageMetrics() *StorageMetrics {
 	})
 	prometheus.MustRegister(epoch)
 
-	return &StorageMetrics{
+	return &NodeMetrics{
 		objectServiceMetrics: objectService,
 		engineMetrics:        engine,
+		stateMetrics:         state,
 		epoch:                epoch,
 	}
 }
 
 // SetEpoch updates epoch metric.
-func (m *StorageMetrics) SetEpoch(epoch uint64) {
+func (m *NodeMetrics) SetEpoch(epoch uint64) {
 	m.epoch.Set(float64(epoch))
 }

pkg/metrics/state.go

@@ -0,0 +1,28 @@
+package metrics
+
+import "github.com/prometheus/client_golang/prometheus"
+
+const stateSubsystem = "state"
+
+type stateMetrics struct {
+	healthCheck prometheus.Gauge
+}
+
+func newStateMetrics() stateMetrics {
+	return stateMetrics{
+		healthCheck: prometheus.NewGauge(prometheus.GaugeOpts{
+			Namespace: namespace,
+			Subsystem: stateSubsystem,
+			Name:      "health",
+			Help:      "Current Node state",
+		}),
+	}
+}
+
+func (m stateMetrics) register() {
+	prometheus.MustRegister(m.healthCheck)
+}
+
+func (m stateMetrics) SetHealth(s int32) {
+	m.healthCheck.Set(float64(s))
+}