Merge pull request #9606 from jpbetz/automated-cherry-pick-of-#9587-release-3.1

Automated cherry pick of #9587

Author: gyuho

etcdserver/metrics.go

@@ -28,6 +28,12 @@ var (
 		Name:      "has_leader",
 		Help:      "Whether or not a leader exists. 1 is existence, 0 is not.",
 	})
+	isLeader = prometheus.NewGauge(prometheus.GaugeOpts{
+		Namespace: "etcd",
+		Subsystem: "server",
+		Name:      "is_leader",
+		Help:      "Whether or not this member is a leader. 1 if is, 0 otherwise.",
+	})
 	leaderChanges = prometheus.NewCounter(prometheus.CounterOpts{
 		Namespace: "etcd",
 		Subsystem: "server",
@@ -62,6 +68,7 @@ var (
 
 func init() {
 	prometheus.MustRegister(hasLeader)
+	prometheus.MustRegister(isLeader)
 	prometheus.MustRegister(leaderChanges)
 	prometheus.MustRegister(proposalsCommitted)
 	prometheus.MustRegister(proposalsApplied)

etcdserver/raft.go

@@ -171,6 +171,11 @@ func (r *raftNode) start(rh *raftReadyHandler) {
 
 					atomic.StoreUint64(&r.lead, rd.SoftState.Lead)
 					islead = rd.RaftState == raft.StateLeader
+					if islead {
+						isLeader.Set(1)
+					} else {
+						isLeader.Set(0)
+					}
 					rh.updateLeadership()
 				}