Need a way to notify contoller-manager from each controller

[taoj-action]

I am trying the figure a way for doing health check (liveness and readiness) for controller manager created using either kubebuilder or operator-sdk. The health check result should be determined by health check result of each controller. Therefore, there should be a way to notify manager from controller by adding a function inside manager interface. (basically, Observer pattern)
https://github.com/kubernetes-sigs/controller-runtime/blob/master/pkg/manager/manager.go#L56
So, each controller can call mgr.Update() to notify manager.

The other approach is to use channel but currently only stop channel is available.
https://github.com/kubernetes-sigs/controller-runtime/blob/master/pkg/manager/internal.go#L227

[DirectXMan12]

/kind feature

We do have a bug to track health and liveness support, it was just not quite titled correctly. I'm going to close this as a duplicate. Please weigh in on the other bug: #297

[szykes]

@DirectXMan12 I ask this just to make sure. Does "Closed" status of this ticket mean the following code snippet will not respond, when any problems happen within the controller? Any problem can be a hanging reconciliation, an internal issue in kubebuilder framework, etc.

    if err := mgr.AddHealthzCheck("healthz", healthz.Ping); err != nil {
        setupLog.Error(err, "unable to set up health check")
        os.Exit(1)
    }