Expose leader information

[goldmann]

JOSDK supports leader election where we can have multiple replicas running the operator and only one will be guaranteed to perform it's job and the other will be on stand-by: https://javaoperatorsdk.io/docs/documentation/features/#leader-election

It would be good to have a way to expose this information so that other parts of the service could make use of it. And by other parts I mean code that is not strictly related to the operator. For example our custom logic should be only run on the pod that is the current leader.

[metacosm]

What exactly would you get access to, and how?

[goldmann]

The only thing I wanted to get access to is a boolean flag that would indicate whether the current instance is a leader.

Something like? I'm making things up here.

@Inject
Operator operator;

void blah() {
  if (operator.isLeader()) {
    // Nice!
  }
}

A programmatic way would be welcome too!

[metacosm]

You can pass callbacks to the LeaderElectionConfiguration that should be injectable in the QuarkusConfigurationService that is used for your operator. So if you create a LeaderElectionConfiguration bean on which you define LeaderCallbacks which let you react to when an instance starts / stops leading or when a new leader is elected. Maybe that could be enough for your purpose?

[metacosm]

@goldmann would the solution provided above be good enough for you?