From 10c61daee45303501e333ff6b2f937e455c4acc9 Mon Sep 17 00:00:00 2001
From: stefanprodan <stefan.prodan@gmail.com>
Date: Sun, 7 Jul 2019 12:52:32 +0300
Subject: [PATCH] Exit when losing leadership

---
 Makefile                     | 9 ++++++++-
 cmd/flagger/main.go          | 8 +++++++-
 pkg/controller/controller.go | 9 ---------
 3 files changed, 15 insertions(+), 11 deletions(-)

diff --git a/Makefile b/Makefile
index fbca7d9c..eb575eb6 100644
--- a/Makefile
+++ b/Makefile
@@ -8,7 +8,14 @@ TS=$(shell date +%Y-%m-%d_%H-%M-%S)
 
 run:
 	GO111MODULE=on go run cmd/flagger/* -kubeconfig=$$HOME/.kube/config -log-level=info -mesh-provider=istio -namespace=test \
-	-metrics-server=https://prometheus.istio.weavedx.com
+	-metrics-server=https://prometheus.istio.weavedx.com \
+	-enable-leader-election=true
+
+run2:
+	GO111MODULE=on go run cmd/flagger/* -kubeconfig=$$HOME/.kube/config -log-level=info -mesh-provider=istio -namespace=test \
+	-metrics-server=https://prometheus.istio.weavedx.com \
+	-enable-leader-election=true \
+	-port=9092
 
 run-appmesh:
 	GO111MODULE=on go run cmd/flagger/* -kubeconfig=$$HOME/.kube/config -log-level=info -mesh-provider=appmesh \
diff --git a/cmd/flagger/main.go b/cmd/flagger/main.go
index 1aabb4a8..9a17aaba 100644
--- a/cmd/flagger/main.go
+++ b/cmd/flagger/main.go
@@ -203,22 +203,27 @@ func main() {
 		}
 	}
 
+	// leader election context
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 
+	// prevents new requests when leadership is lost
 	cfg.Wrap(transport.ContextCanceller(ctx, fmt.Errorf("the leader is shutting down")))
 
+	// cancel leader election context on shutdown signals
 	go func() {
 		<-stopCh
 		cancel()
 	}()
 
+	// wrap controller run
 	runController := func() {
 		if err := c.Run(threadiness, stopCh); err != nil {
 			logger.Fatalf("Error running controller: %v", err)
 		}
 	}
 
+	// run controller when this instance wins the leader election
 	if enableLeaderElection {
 		ns := leaderElectionNamespace
 		if namespace != "" {
@@ -265,7 +270,8 @@ func startLeaderElection(ctx context.Context, run func(), ns string, kubeClient
 				run()
 			},
 			OnStoppedLeading: func() {
-				logger.Infof("Leader election lost")
+				logger.Infof("Leadership lost")
+				os.Exit(1)
 			},
 			OnNewLeader: func(identity string) {
 				if identity != id {
diff --git a/pkg/controller/controller.go b/pkg/controller/controller.go
index 80dec4a8..16a0b8a3 100644
--- a/pkg/controller/controller.go
+++ b/pkg/controller/controller.go
@@ -216,15 +216,6 @@ func (c *Controller) syncHandler(key string) error {
 	}
 
 	c.canaries.Store(fmt.Sprintf("%s.%s", cd.Name, cd.Namespace), cd)
-
-	//if cd.Spec.TargetRef.Kind == "Deployment" {
-	//	err = c.bootstrapDeployment(cd)
-	//	if err != nil {
-	//		c.logger.Warnf("%s.%s bootstrap error %v", cd.Name, cd.Namespace, err)
-	//		return err
-	//	}
-	//}
-
 	c.logger.Infof("Synced %s", key)
 
 	return nil