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You said something about main?

But first, remember how we said we’d come back to main.go again? Let’s take a look and see what’s changed, and what we need to add.

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package main

import (

	clientgoscheme ""
	_ ""
	ctrl ""

	batchv1 ""
	// +kubebuilder:scaffold:imports

The first difference to notice is that kubebuilder has added the new API group’s package (batchv1) to our scheme. This means that we can use those objects in our controller.

If we would be using any other CRD we would have to add their scheme the same way. Builtin types such as Job have their scheme added by clientgoscheme.

var (
	scheme   = runtime.NewScheme()
	setupLog = ctrl.Log.WithName("setup")

func init() {
	_ = clientgoscheme.AddToScheme(scheme)

	_ = batchv1.AddToScheme(scheme)
	// +kubebuilder:scaffold:scheme

The other thing that’s changed is that kubebuilder has added a block calling our CronJob controller’s SetupWithManager method.

func main() {
old stuff
	var metricsAddr string
	var enableLeaderElection bool
	flag.StringVar(&metricsAddr, "metrics-addr", ":8080", "The address the metric endpoint binds to.")
	flag.BoolVar(&enableLeaderElection, "enable-leader-election", false,
		"Enable leader election for controller manager. Enabling this will ensure there is only one active controller manager.")


	mgr, err := ctrl.NewManager(ctrl.GetConfigOrDie(), ctrl.Options{
		Scheme:             scheme,
		MetricsBindAddress: metricsAddr,
		LeaderElection:     enableLeaderElection,
		Port:               9443,
	if err != nil {
		setupLog.Error(err, "unable to start manager")
	if err = (&controllers.CronJobReconciler{
		Client: mgr.GetClient(),
		Log:    ctrl.Log.WithName("controllers").WithName("Captain"),
		Scheme: mgr.GetScheme(),
	}).SetupWithManager(mgr); err != nil {
		setupLog.Error(err, "unable to create controller", "controller", "Captain")

We’ll also set up webhooks for our type, which we’ll talk about next. We just need to add them to the manager. Since we might want to run the webhooks separately, or not run them when testing our controller locally, we’ll put them behind an environment variable.

We’ll just make sure to set ENABLE_WEBHOOKS=false when we run locally.

	if os.Getenv("ENABLE_WEBHOOKS") != "false" {
		if err = (&batchv1.CronJob{}).SetupWebhookWithManager(mgr); err != nil {
			setupLog.Error(err, "unable to create webhook", "webhook", "Captain")
	// +kubebuilder:scaffold:builder
old stuff
	setupLog.Info("starting manager")
	if err := mgr.Start(ctrl.SetupSignalHandler()); err != nil {
		setupLog.Error(err, "problem running manager")

Now we can implement our controller.