add leader transitions to leader election record

pkg/client/leaderelection/leaderelection.go

@@ -150,6 +150,7 @@ type LeaderElectionRecord struct {
 	LeaseDurationSeconds int              `json:"leaseDurationSeconds"`
 	AcquireTime          unversioned.Time `json:"acquireTime"`
 	RenewTime            unversioned.Time `json:"renewTime"`
+	LeaderTransitions    int              `json:"leaderTransitions"`
 }
 
 // Run starts the leader election loop
@@ -242,8 +243,9 @@ func (le *LeaderElector) tryAcquireOrRenew() bool {
 		e.Annotations = make(map[string]string)
 	}
 
-	if oldLeaderElectionRecordBytes, found := e.Annotations[LeaderElectionRecordAnnotationKey]; found {
 	var oldLeaderElectionRecord LeaderElectionRecord
+
+	if oldLeaderElectionRecordBytes, found := e.Annotations[LeaderElectionRecordAnnotationKey]; found {
 		if err := json.Unmarshal([]byte(oldLeaderElectionRecordBytes), &oldLeaderElectionRecord); err != nil {
 			glog.Errorf("error unmarshaling leader election record: %v", err)
 			return false
@@ -252,9 +254,6 @@ func (le *LeaderElector) tryAcquireOrRenew() bool {
 			le.observedRecord = oldLeaderElectionRecord
 			le.observedTime = time.Now()
 		}
-		if oldLeaderElectionRecord.HolderIdentity == le.config.Identity {
-			leaderElectionRecord.AcquireTime = oldLeaderElectionRecord.AcquireTime
-		}
 		if le.observedTime.Add(le.config.LeaseDuration).After(now.Time) &&
 			oldLeaderElectionRecord.HolderIdentity != le.config.Identity {
 			glog.Infof("lock is held by %v and has not yet expired", oldLeaderElectionRecord.HolderIdentity)
@@ -262,6 +261,14 @@ func (le *LeaderElector) tryAcquireOrRenew() bool {
 		}
 	}
 
+	// We're going to try to update. The leaderElectionRecord is set to it's default
+	// here. Let's correct it before updating.
+	if oldLeaderElectionRecord.HolderIdentity == le.config.Identity {
+		leaderElectionRecord.AcquireTime = oldLeaderElectionRecord.AcquireTime
+	} else {
+		leaderElectionRecord.LeaderTransitions = oldLeaderElectionRecord.LeaderTransitions + 1
+	}
+
 	leaderElectionRecordBytes, err := json.Marshal(leaderElectionRecord)
 	if err != nil {
 		glog.Errorf("err marshaling leader election record: %v", err)

pkg/client/leaderelection/leaderelection_test.go

@@ -46,6 +46,7 @@ func TestTryAcquireOrRenew(t *testing.T) {
 		}
 
 		expectSuccess    bool
+		transitionLeader bool
 		outHolder        string
 	}{
 		// acquire from no endpoints
@@ -94,7 +95,9 @@ func TestTryAcquireOrRenew(t *testing.T) {
 					},
 				},
 			},
+
 			expectSuccess:    true,
+			transitionLeader: true,
 			outHolder:        "baz",
 		},
 		// acquire from led, unacked endpoints
@@ -128,6 +131,7 @@ func TestTryAcquireOrRenew(t *testing.T) {
 			observedTime:   past,
 
 			expectSuccess:    true,
+			transitionLeader: true,
 			outHolder:        "baz",
 		},
 		// don't acquire from led, acked endpoints
@@ -225,7 +229,13 @@ func TestTryAcquireOrRenew(t *testing.T) {
 			t.Errorf("[%v]expected holder:\n\t%+v\ngot:\n\t%+v", i, test.outHolder, le.observedRecord.HolderIdentity)
 		}
 		if len(test.reactors) != len(c.Actions()) {
-			t.Errorf("[%v]wrong number of api interactions")
+			t.Errorf("[%v]wrong number of api interactions", i)
+		}
+		if test.transitionLeader && le.observedRecord.LeaderTransitions != 1 {
+			t.Errorf("[%v]leader should have transitioned but did not", i)
+		}
+		if !test.transitionLeader && le.observedRecord.LeaderTransitions != 0 {
+			t.Errorf("[%v]leader should not have transitioned but did", i)
 		}
 	}
 }