unify leader election entrypoint across components that need it

Author: cheesesashimi

cmd/common/helpers.go

@@ -19,6 +19,7 @@ import (
 	"github.com/openshift/library-go/pkg/config/clusterstatus"
 	"github.com/openshift/library-go/pkg/config/leaderelection"
 	"k8s.io/client-go/rest"
+	k8sleaderelection "k8s.io/client-go/tools/leaderelection"
 )
 
 // CreateResourceLock returns an interface for the resource lock.
@@ -58,6 +59,38 @@ func CreateResourceLock(cb *clients.Builder, componentNamespace, componentName s
 	return lock
 }
 
+type RunOpts struct {
+	Namespace     string
+	ComponentName string
+	Builder       *clients.Builder
+	OnStart       func(context.Context)
+	OnStop        func()
+}
+
+func DoLeaderElectionAndRunOrDie(ctx context.Context, o *RunOpts) {
+	onStop := func() {
+		if o.OnStop != nil {
+			o.OnStop()
+		}
+
+		klog.Infof("Stopped leading, terminating %s", o.ComponentName)
+	}
+
+	cfg := GetLeaderElectionConfig(o.Builder.GetBuilderConfig())
+
+	k8sleaderelection.RunOrDie(ctx, k8sleaderelection.LeaderElectionConfig{
+		Lock:            CreateResourceLock(o.Builder, o.Namespace, o.ComponentName),
+		ReleaseOnCancel: true,
+		LeaseDuration:   cfg.LeaseDuration.Duration,
+		RenewDeadline:   cfg.RenewDeadline.Duration,
+		RetryPeriod:     cfg.RetryPeriod.Duration,
+		Callbacks: k8sleaderelection.LeaderCallbacks{
+			OnStartedLeading: o.OnStart,
+			OnStoppedLeading: onStop,
+		},
+	})
+}
+
 // GetLeaderElectionConfig returns leader election configs defaults based on the cluster topology
 func GetLeaderElectionConfig(restcfg *rest.Config) configv1.LeaderElection {
 

cmd/machine-config-controller/start.go

@@ -21,7 +21,6 @@ import (
 	"github.com/openshift/machine-config-operator/pkg/version"
 	"github.com/spf13/cobra"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
-	"k8s.io/client-go/tools/leaderelection"
 	"k8s.io/klog/v2"
 )
 
@@ -156,20 +155,11 @@ func runStartCmd(_ *cobra.Command, _ []string) {
 		<-ctx.Done()
 	}
 
-	leaderElectionCfg := common.GetLeaderElectionConfig(cb.GetBuilderConfig())
-
-	leaderelection.RunOrDie(runContext, leaderelection.LeaderElectionConfig{
-		Lock:            common.CreateResourceLock(cb, startOpts.resourceLockNamespace, componentName),
-		ReleaseOnCancel: true,
-		LeaseDuration:   leaderElectionCfg.LeaseDuration.Duration,
-		RenewDeadline:   leaderElectionCfg.RenewDeadline.Duration,
-		RetryPeriod:     leaderElectionCfg.RetryPeriod.Duration,
-		Callbacks: leaderelection.LeaderCallbacks{
-			OnStartedLeading: run,
-			OnStoppedLeading: func() {
-				klog.Infof("Stopped leading. Terminating.")
-			},
-		},
+	common.DoLeaderElectionAndRunOrDie(ctx, &common.RunOpts{
+		Namespace:     startOpts.resourceLockNamespace,
+		ComponentName: componentName,
+		Builder:       cb,
+		OnStart:       run,
 	})
 }
 

cmd/machine-config-operator/start.go

@@ -11,7 +11,6 @@ import (
 	"github.com/openshift/machine-config-operator/pkg/operator"
 	"github.com/openshift/machine-config-operator/pkg/version"
 	"github.com/spf13/cobra"
-	"k8s.io/client-go/tools/leaderelection"
 	"k8s.io/klog/v2"
 )
 
@@ -132,19 +131,10 @@ func runStartCmd(_ *cobra.Command, _ []string) {
 		<-ctx.Done()
 	}
 
-	leaderElectionCfg := common.GetLeaderElectionConfig(cb.GetBuilderConfig())
-
-	leaderelection.RunOrDie(runContext, leaderelection.LeaderElectionConfig{
-		Lock:            common.CreateResourceLock(cb, ctrlcommon.MCONamespace, componentName),
-		ReleaseOnCancel: true,
-		LeaseDuration:   leaderElectionCfg.LeaseDuration.Duration,
-		RenewDeadline:   leaderElectionCfg.RenewDeadline.Duration,
-		RetryPeriod:     leaderElectionCfg.RetryPeriod.Duration,
-		Callbacks: leaderelection.LeaderCallbacks{
-			OnStartedLeading: run,
-			OnStoppedLeading: func() {
-				klog.Info("Stopped leading. Terminating.")
-			},
-		},
+	common.DoLeaderElectionAndRunOrDie(runContext, &common.RunOpts{
+		Namespace:     ctrlcommon.MCONamespace,
+		ComponentName: componentName,
+		Builder:       cb,
+		OnStart:       run,
 	})
 }

cmd/machine-os-builder/start.go

@@ -8,7 +8,6 @@ import (
 	"github.com/openshift/machine-config-operator/internal/clients"
 	"github.com/openshift/machine-config-operator/pkg/controller/build"
 	ctrlcommon "github.com/openshift/machine-config-operator/pkg/controller/common"
-	"k8s.io/client-go/tools/leaderelection"
 
 	"github.com/openshift/machine-config-operator/pkg/version"
 	"github.com/spf13/cobra"
@@ -71,23 +70,16 @@ func runStartCmd(_ *cobra.Command, _ []string) {
 		ctrl.Run(ctx, 3)
 	}
 
-	leaderElectionCfg := common.GetLeaderElectionConfig(cb.GetBuilderConfig())
-
-	leaderelection.RunOrDie(ctx, leaderelection.LeaderElectionConfig{
-		Lock:            common.CreateResourceLock(cb, ctrlcommon.MCONamespace, componentName),
-		ReleaseOnCancel: true,
-		LeaseDuration:   leaderElectionCfg.LeaseDuration.Duration,
-		RenewDeadline:   leaderElectionCfg.RenewDeadline.Duration,
-		RetryPeriod:     leaderElectionCfg.RetryPeriod.Duration,
-		Callbacks: leaderelection.LeaderCallbacks{
-			OnStartedLeading: run,
-			OnStoppedLeading: func() {
-				// Block this function until the controller shutdown is complete to
-				// ensure that the controller both has enough time to finish its
-				// cleanup as well as to terminate its lease.
-				<-shutdownChan
-				klog.Infof("Stopped leading; machine-os-builder terminating.")
-			},
+	common.DoLeaderElectionAndRunOrDie(ctx, &common.RunOpts{
+		Namespace:     ctrlcommon.MCONamespace,
+		ComponentName: componentName,
+		Builder:       cb,
+		OnStart:       run,
+		OnStop: func() {
+			// Block this function until the controller shutdown is complete to
+			// ensure that the controller both has enough time to finish its
+			// cleanup as well as to terminate its lease.
+			<-shutdownChan
 		},
 	})
 }