LeaderCallbacks defines callbacks for events from LeaderElector It is guaranteed that each methods will be executed from the same goroutine, so only one method can be run at once.

Component defines a process that will be run in the application Component should be designed in such a way that it can be stopped by stop channel and started again (for example when instance is reelected for a leader).

GracefulComponent is a component that supports waiting until it's finished.