Listener.md

Kyma Listener

Listener module that listens to events sent by the Kyma Watcher component.

Overview

Typically, we use the Listener module with operators built using Kubebuilder, but we can use it for other operators as well.

Use

1. For operators built using the Kubebuilder framework, leverage your SetupWithManager() method to initialize the Listener by calling RegisterListenerComponent().

2. Set up your controller to watch for changes sent through the source.Channel{} returned by the Listener module, and to react to them by calling the (blder *Builder) Watches() method and providing your handler.EventHandler implementation.

3. To start the Listener, add it as a runnable to your controller-manager: Call mgr.Add() and pass the Listener returned by RegisterListenerComponent().

Sample code

//register listener component
runnableListener, eventChannel := listener.RegisterListenerComponent(listenerAddr, strings.ToLower(v1alpha1.KymaKind))

//watch event channel
controllerBuilder.Watches(eventChannel, &handler.EnqueueRequestForObject{})

//start listener as a manager runnable
mgr.Add(runnableListener)