func main()

in cmd/hubagent/main.go [91:198]
91 lines of code
13 McCabe index (conditional complexity)

func main() {
	// The wait group for synchronizing the steps (esp. the exit) of the controller manager and the scheduler.
	var wg sync.WaitGroup

	opts := options.NewOptions()
	opts.AddFlags(flag.CommandLine)

	flag.Parse()
	defer handleExitFunc()

	flag.VisitAll(func(f *flag.Flag) {
		klog.InfoS("flag:", "name", f.Name, "value", f.Value)
	})
	if errs := opts.Validate(); len(errs) != 0 {
		klog.ErrorS(errs.ToAggregate(), "invalid parameter")
		exitWithErrorFunc()
	}
	config := ctrl.GetConfigOrDie()
	config.QPS, config.Burst = float32(opts.HubQPS), opts.HubBurst

	mgr, err := ctrl.NewManager(config, ctrl.Options{
		Scheme: scheme,
		Cache: cache.Options{
			SyncPeriod: &opts.ResyncPeriod.Duration,
		},
		LeaderElection:             opts.LeaderElection.LeaderElect,
		LeaderElectionID:           opts.LeaderElection.ResourceName,
		LeaderElectionNamespace:    opts.LeaderElection.ResourceNamespace,
		LeaderElectionResourceLock: opts.LeaderElection.ResourceLock,
		HealthProbeBindAddress:     opts.HealthProbeAddress,
		Metrics: metricsserver.Options{
			BindAddress: opts.MetricsBindAddress,
		},
		WebhookServer: ctrlwebhook.NewServer(ctrlwebhook.Options{
			Port:    FleetWebhookPort,
			CertDir: FleetWebhookCertDir,
		}),
	})
	if err != nil {
		klog.ErrorS(err, "unable to start controller manager.")
		exitWithErrorFunc()
	}

	klog.V(2).InfoS("starting hubagent")
	if opts.EnableV1Alpha1APIs {
		klog.Info("Setting up memberCluster v1alpha1 controller")
		if err = (&mcv1alpha1.Reconciler{
			Client:                  mgr.GetClient(),
			NetworkingAgentsEnabled: opts.NetworkingAgentsEnabled,
		}).SetupWithManager(mgr, "memberclusterv1alpha1-controller"); err != nil {
			klog.ErrorS(err, "unable to create v1alpha1 controller", "controller", "MemberCluster")
			exitWithErrorFunc()
		}
	}
	if opts.EnableV1Beta1APIs {
		klog.Info("Setting up memberCluster v1beta1 controller")
		if err = (&mcv1beta1.Reconciler{
			Client:                  mgr.GetClient(),
			NetworkingAgentsEnabled: opts.NetworkingAgentsEnabled,
			MaxConcurrentReconciles: int(math.Ceil(float64(opts.MaxFleetSizeSupported) / 100)), //one member cluster reconciler routine per 100 member clusters
			ForceDeleteWaitTime:     opts.ForceDeleteWaitTime.Duration,
		}).SetupWithManager(mgr, "membercluster-controller"); err != nil {
			klog.ErrorS(err, "unable to create v1beta1 controller", "controller", "MemberCluster")
			exitWithErrorFunc()
		}
	}

	if err := mgr.AddHealthzCheck("healthz", healthz.Ping); err != nil {
		klog.ErrorS(err, "unable to set up health check")
		exitWithErrorFunc()
	}
	if err := mgr.AddReadyzCheck("readyz", healthz.Ping); err != nil {
		klog.ErrorS(err, "unable to set up ready check")
		exitWithErrorFunc()
	}

	if opts.EnableWebhook {
		whiteListedUsers := strings.Split(opts.WhiteListedUsers, ",")
		if err := SetupWebhook(mgr, options.WebhookClientConnectionType(opts.WebhookClientConnectionType), opts.WebhookServiceName, whiteListedUsers, opts.EnableGuardRail, opts.EnableV1Beta1APIs); err != nil {
			klog.ErrorS(err, "unable to set up webhook")
			exitWithErrorFunc()
		}
	}

	ctx := ctrl.SetupSignalHandler()
	if err := workload.SetupControllers(ctx, &wg, mgr, config, opts); err != nil {
		klog.ErrorS(err, "unable to set up ready check")
		exitWithErrorFunc()
	}

	// +kubebuilder:scaffold:builder

	wg.Add(1)
	go func() {
		defer wg.Done()

		// Start() is a blocking call and it is set to exit on context cancellation.
		if err := mgr.Start(ctx); err != nil {
			klog.ErrorS(err, "problem starting manager")
			exitWithErrorFunc()
		}

		klog.InfoS("The controller manager has exited")
	}()

	// Wait for the controller manager and the scheduler to exit.
	wg.Wait()
}