Java/Spring: How to find what error opened the Resilence4J circuit breaker?

Question

I am using the Resilence4j circuit breaker with Spring Boot as shown below:

import io.github.resilience4j.circuitbreaker.annotation.CircuitBreaker;

@Component
@CircuitBreaker(name = "ExternalService")
public class ExternalServiceClient implements APIClient {
     //....
}

I haven't specified any additional configs in my application.yml so the circuit breaker is operating with the default values. Whenever the breaker opens, I see errors like:

Failure to call external service  for entity id 12343
   stack_trace: io.github.resilience4j.circuitbreaker.CallNotPermittedException: CircuitBreaker 'ExternalService' is OPEN and does not permit further calls
    at io.github.resilience4j.circuitbreaker.CallNotPermittedException.createCallNotPermittedException(CallNotPermittedException.java:37) ~[resilience4j-circuitbreaker-1.1.0.jar!/:1.1.0]
    at io.github.resilience4j.circuitbreaker.internal.CircuitBreakerStateMachine$HalfOpenState.acquirePermission(CircuitBreakerStateMachine.java:685)
    at io.github.resilience4j.circuitbreaker.internal.CircuitBreakerStateMachine.acquirePermission(CircuitBreakerStateMachine.java:146)
    at io.github.resilience4j.circuitbreaker.CircuitBreaker.lambda$decorateCheckedSupplier$82a9021a$1(CircuitBreaker.java:599)
    at io.github.resilience4j.circuitbreaker.CircuitBreaker.executeCheckedSupplier(CircuitBreaker.java:340)
    at io.github.resilience4j.circuitbreaker.configure.CircuitBreakerAspect.defaultHandling(CircuitBreakerAspect.java:155) ~[resilience4j-spring-0.16.0.jar!/:0.16.0]
    at io.github.resilience4j.circuitbreaker.configure.CircuitBreakerAspect.proceed(CircuitBreakerAspect.java:115)
    at io.github.resilience4j.circuitbreaker.configure.CircuitBreakerAspect.circuitBreakerAroundAdvice(CircuitBreakerAspect.java:98)
    at jdk.internal.reflect.GeneratedMethodAccessor238.invoke(Unknown Source) ~[na:na]
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:566)
    at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:644) ~[spring-aop-5.2.5.RELEASE.jar!/:5.2.5.RELEASE]
    at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:633)
    at org.springframework.aop.aspectj.AspectJAroundAdvice.invoke(AspectJAroundAdvice.java:70)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:175)
    at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:749)
    at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:95)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:749)
    at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:691)

This is telling me the breaker opened due to some error condition(and as a result no more calls are permitted) but doesn't specify what the original error was. Is there a way to figure out the original error? Is there specific text I should look for in the logs or is there some setting I need to turn on so this error also tells me the original reason for breaker opening?

Answer 1

CallNotPermittedException and the underlying stack trace occur within the state machine logic after the breaker is opened, this is not the right place to look.

The events consumer buffer exposed through the actuator endpoint /actuator/circuitbreakerevents would list all the events within the breaker, what are errors, and the corresponding message.

https://resilience4j.readme.io/docs/getting-started-3#events-endpoint