Is it Possible to Subscribe to the CircuitBreaker Opening Event in Hystrix?

Question

For unit testing I would like to be able to subscribe to Hystrix events, particularly should there be an event when a circuit breaker opens or closes. I looked around for examples and it appears that the work around is to tap into the metrics stream and monitor the circuit breaker flags.

Since Hystrix is build on RxJava I thought there should be a subscription interface for events somewhere. Is there an easy way to subscribe to these type of events in Hystrix?

Thank you!

Answer 1

You need to write Custom event notifier and registered it in HystrixPlugins. have look on below code.

public class CircuitBreakerHystrixEventNotifier extends HystrixEventNotifier{

    public CircuitBreakerHystrixEventNotifier(){

    }

   public void markEvent(HystrixEventType eventType, HystrixCommandKey key) {
        //here write code based on eventTypes.
    }
}

You need to registered this CircuitBreakerHystrixEventNotifier in hystrix, see below

HystrixPlugins.getInstance().registerEventNotifier(getCircuitBreakerHystrixEventNotifier());