Kafka Consumer with Circuit Breaker, Retry Patterns using Resilience4j

Question

I need some help in understanding how I can come up with a solution using Spring boot, Kafka, Resilence4J to achieve a microservice call from my Kafka Consumer. Let's say if the Microservice is down then I need to notify my Kafka consumer using a circuit breaker pattern to stop fetching the messages/events until the Microservice is up and running.

Answer 1

If you are using Spring Kafka, you could maybe use the pause and resume methods of the ConcurrentMessageListenerContainer class. You can attach an EventListener to the CircuitBreaker which listens on state transitions and pauses or resumes processing of events. Inject the CircuitBreakerRegistry into you bean:

circuitBreakerRegistry.circuitBreaker("yourCBName").getEventPublisher().onStateTransition(
                        event -> {
                            switch (event.getStateTransition()) {
                                case CLOSED_TO_OPEN:
                                    container.pause();
                                case OPEN_TO_HALF_OPEN:
                                    container.resume();
                                case HALF_OPEN_TO_CLOSED:
                                    container.resume();
                                case HALF_OPEN_TO_OPEN:
                                    container.pause();
                                case CLOSED_TO_FORCED_OPEN:
                                    container.pause();
                                case FORCED_OPEN_TO_CLOSED:
                                    container.resume();
                                case FORCED_OPEN_TO_HALF_OPEN:
                                    container.resume();
                                default:
                            }
                        }
                );