Add Inner Ring code

pkg/network/peers/metrics.go

@@ -0,0 +1,45 @@
+package peers
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+	"google.golang.org/grpc/connectivity"
+)
+
+const stateLabel = "state"
+
+var grpcConnections = prometheus.NewGaugeVec(
+	prometheus.GaugeOpts{
+		Help:      "gRPC connections",
+		Name:      "grpc_connections",
+		Namespace: "neofs",
+	},
+	[]string{stateLabel},
+)
+
+var conStates = []connectivity.State{
+	connectivity.Idle,
+	connectivity.Connecting,
+	connectivity.Ready,
+	connectivity.TransientFailure,
+	connectivity.Shutdown,
+}
+
+func updateMetrics(items map[connectivity.State]float64) {
+	for _, state := range conStates {
+		grpcConnections.With(prometheus.Labels{
+			stateLabel: state.String(),
+		}).Set(items[state])
+	}
+}
+
+func init() {
+	prometheus.MustRegister(
+		grpcConnections,
+	)
+
+	for _, state := range conStates {
+		grpcConnections.With(prometheus.Labels{
+			stateLabel: state.String(),
+		}).Set(0)
+	}
+}