app: add beacon node peer_id metric

app/metrics.go

@@ -89,6 +89,13 @@ var (
 		Help:      "Constant gauge with label set to the node version of the upstream beacon node",
 	}, []string{"version"})
 
+	beaconNodePeerIDGauge = promauto.NewResetGaugeVec(prometheus.GaugeOpts{
+		Namespace: "app",
+		Subsystem: "beacon_node",
+		Name:      "peer_id",
+		Help:      "Constant gauge with label set to the peer_id of the upstream beacon node",
+	}, []string{"peer_id"})
+
 	thresholdGauge = promauto.NewGauge(prometheus.GaugeOpts{
 		Namespace: "cluster",
 		Name:      "threshold",

app/monitoringapi.go

@@ -286,6 +286,19 @@ func beaconNodeVersionMetric(ctx context.Context, eth2Cl eth2wrap.Client, clock
 		eth2wrap.CheckBeaconNodeVersion(ctx, version)
 	}
 
+	setNodePeerID := func() {
+		response, err := eth2Cl.NodeIdentity(ctx, &eth2api.NodeIdentityOpts{})
+		if err != nil {
+			log.Error(ctx, "Failed to fetch beacon node identity. Check beacon node connectivity and API availability", err)
+			return
+		}
+
+		peerID := response.Data.PeerID
+
+		beaconNodePeerIDGauge.Reset()
+		beaconNodePeerIDGauge.WithLabelValues(peerID).Set(1)
+	}
+
 	go func() {
 		onStartup := make(chan struct{}, 1)
 		onStartup <- struct{}{}
@@ -294,8 +307,10 @@ func beaconNodeVersionMetric(ctx context.Context, eth2Cl eth2wrap.Client, clock
 			select {
 			case <-onStartup:
 				setNodeVersion()
+				setNodePeerID()
 			case <-nodeVersionTicker.Chan():
 				setNodeVersion()
+				setNodePeerID()
 			case <-ctx.Done():
 				return
 			}