I'm working on a project that has several event-driven microservices and also using Kubernetes for load balancing. All the services are both publishers and listeners. When a microservice publishes an event, all the listeners are catching the event (if it listens that specific event) and doing their job. There was no problem with this flow until this:

Let's say I have a microservice responsible for sending e-mails. And this service is duplicated 2 times by the load balancer due to high load. Now we have 3 instances of e-mail service. When a "sendMail" event is published, all the 3 instances are catching the event and sending an e-mail for their own. At the end of the day 3 e-mail are being sent.

My question is, can I configure a cloud bus that allows me to publish events for both scenarios. I want to say to an event "when a single listener catches you, disappear" or "go to every listener waiting out there".

For example;

Microservices: A, B, C

Duplicated by load balancer: A1, A2, A3, B1...

Case 1: I want to publish an event for all the services' instances.

Case 2: I want to publish an event for service A instances.

Case 3: I want to publish an event for a single instance of A (don't care which).

I have tried; Giving destinations to events, but all the instances have same bus name since they are duplicated as same. If I give/know a single instance bus name, I wouldn't use it because that pod might die.

Event publishing;

applicationContext().publishEvent(
        new customEvent(
                this,  // Source
                busProperties().getId(),  // Origin Service
                null  // Destination Service (null: all)
        )
);

Event listener;

@Component
public class Listener implements ApplicationListener<CustomEvent> {
    @Override
    public void onApplicationEvent(CustomEvent event) {
        Foo();
    }
}