core/scheduler: add validator balance (#1051)

Adds validator balance metric in scheduler.

category: misc
ticket: #981

app/app.go

@@ -575,8 +575,9 @@ func createMockValidators(pubkeys []eth2p0.BLSPubKey) beaconmock.ValidatorSet {
 		vIdx := eth2p0.ValidatorIndex(i)
 
 		resp[vIdx] = &eth2v1.Validator{
-			Index:  vIdx,
-			Status: eth2v1.ValidatorStateActiveOngoing,
+			Balance: eth2p0.Gwei(31300000000),
+			Index:   vIdx,
+			Status:  eth2v1.ValidatorStateActiveOngoing,
 			Validator: &eth2p0.Validator{
 				WithdrawalCredentials: []byte("12345678901234567890123456789012"),
 				PublicKey:             pubkey,

core/scheduler/metrics.go

@@ -16,6 +16,7 @@
 package scheduler
 
 import (
+	eth2p0 "github.com/attestantio/go-eth2-client/spec/phase0"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
 
@@ -50,6 +51,13 @@ var (
 		Name:      "validators_active",
 		Help:      "Number of active validators",
 	})
+
+	balanceGauge = promauto.NewGaugeVec(prometheus.GaugeOpts{
+		Namespace: "core",
+		Subsystem: "scheduler",
+		Name:      "validator_balance_gwei",
+		Help:      "Total balance of a validator by public key",
+	}, []string{"pubkey"})
 )
 
 // instrumentSlot sets the current slot and epoch metrics.
@@ -62,3 +70,8 @@ func instrumentSlot(slot core.Slot) {
 func instrumentDuty(duty core.Duty, defSet core.DutyDefinitionSet) {
 	dutyCounter.WithLabelValues(duty.Type.String()).Add(float64(len(defSet)))
 }
+
+// instrumentValidator sets the validator balance.
+func instrumentValidator(pubkey core.PubKey, totalBal eth2p0.Gwei) {
+	balanceGauge.WithLabelValues(pubkey.String()).Set(float64(totalBal))
+}

core/scheduler/scheduler.go

@@ -502,6 +502,8 @@ func resolveActiveValidators(ctx context.Context, eth2Cl eth2wrap.Client,
 			return nil, err
 		}
 
+		instrumentValidator(pubkey, val.Balance)
+
 		resp = append(resp, validator{
 			PubKey: pubkey,
 			VIdx:   index,