🌱 Certwatcher: Don't require leaderelection

Controller-Runtime starts the certwatcher in the webhook server, which
means it always runs regardless of the current replica being leader or
not.

It turns out that kubebuilder adds it to the manager and as a result, it
only runs on leader replicas. Make it a `LeaderElectionRunnable` and
don't require leader election so that it will work correctly even if
other projects use it in ways that were not originally anticipated.

Author: alvaroaleman

pkg/certwatcher/certwatcher.go

@@ -240,3 +240,7 @@ func (cw *CertWatcher) handleEvent(event fsnotify.Event) {
 		log.Error(err, "error re-reading certificate")
 	}
 }
+
+func (cw *CertWatcher) NeedLeaderElection() bool {
+	return false
+}

pkg/certwatcher/certwatcher_test.go

@@ -37,6 +37,7 @@ import (
 
 	"sigs.k8s.io/controller-runtime/pkg/certwatcher"
 	"sigs.k8s.io/controller-runtime/pkg/certwatcher/metrics"
+	"sigs.k8s.io/controller-runtime/pkg/manager"
 )
 
 var _ = Describe("CertWatcher", func() {
@@ -92,6 +93,12 @@ var _ = Describe("CertWatcher", func() {
 			}
 		})
 
+		It("should not require LeaderElection", func() {
+			leaderElectionRunnable, isLeaderElectionRunnable := any(watcher).(manager.LeaderElectionRunnable)
+			Expect(isLeaderElectionRunnable).To(BeTrue())
+			Expect(leaderElectionRunnable.NeedLeaderElection()).To(BeFalse())
+		})
+
 		It("should read the initial cert/key", func() {
 			// This test verifies the initial read succeeded. So interval doesn't matter.
 			doneCh := startWatcher(10 * time.Second)