Spring Cloud Feign FallbackFactory가 동작하지 않는다

공식문서를 살펴보자

If Spring Cloud CircuitBreaker is on the classpath and spring.cloud.openfeign.circuitbreaker.enabled=true, Feign will wrap all methods with a circuit breaker.

CircuitBeaker가 classpath에 존재하고, spring.cloud.openfeign.circuitbraker.enabled=true가 되어있으면 circuit braker로 모든 feign 메서드를 래핑 한다.

 

기본옵션은 false

 

Fallback Factory 구현

import org.springframework.cloud.openfeign.FallbackFactory
import org.springframework.cloud.openfeign.FeignClient
import org.springframework.http.ResponseEntity
import org.springframework.stereotype.Component
import org.springframework.web.bind.annotation.GetMapping


@FeignClient(
    name = "test",
    url = "localhost:8081",
    fallbackFactory = TestClient.TestFallbackFactory::class

)

interface TestClient {
    @GetMapping("/test")
    fun get(): ResponseEntity<WrongFeignDataClass>

    @Component
    class TestFallbackFactory : FallbackFactory<FallbackWithFactory> {
        override fun create(cause: Throwable): FallbackWithFactory {
            println(cause.message)
            return FallbackWithFactory()
        }
    }

    class FallbackWithFactory : TestClient {

        override fun get(): ResponseEntity<WrongFeignDataClass> {
            println("fallback start")
            return ResponseEntity.notFound().build()
        }
    }
}

data class WrongFeignDataClass(
    val notExistProperty: String,
)

의도적으로 WrongFeignDataClass로 이상한 클래스를 넣어 파싱에러가 나도록 하였습니다.

 

 

application.yml에 옵션

spring:
  cloud:
    openfeign:
      circuitbreaker:
        enabled: true
        alphanumeric-ids:
          enabled: true
  client:
    config:
      default:
        connectTimeout: 5000
        readTimeout: 5000
        loggerLevel: basic

 

하지만 동작하지 않는다 : CircuitBreakerPresentFeignBuilderConfiguration

@Configuration(proxyBeanMethods = false)
	@ConditionalOnClass(CircuitBreaker.class)
	@ConditionalOnProperty("spring.cloud.openfeign.circuitbreaker.enabled")
	protected static class CircuitBreakerPresentFeignBuilderConfiguration {

		@Bean
		@Scope("prototype")
		@ConditionalOnMissingBean({ Feign.Builder.class, CircuitBreakerFactory.class })
		public Feign.Builder defaultFeignBuilder(Retryer retryer) {
			return Feign.builder().retryer(retryer);
		}

		@Bean
		@Scope("prototype")
		@ConditionalOnMissingBean
		@ConditionalOnBean(CircuitBreakerFactory.class)
		public Feign.Builder circuitBreakerFeignBuilder() {
			return FeignCircuitBreaker.builder();
		}

	}

찾아보다 보니 CircuitBreakerPresentFeignBuilderConfiguration클래스를 발견했으며 해당 클래스에서 Property 옵션이 true인 경우에 적용되는 것을 볼 수 있습니다.

그리고 디버깅으로 쫓아가보니 FeignCircuitBreaker가 등록되어야 할 것 같은데 Fenign.builder()가 호출되고 있었습니다.

그러면 여기서 조건인 CircuitBrakerFactory 클래스가 존재해야 한다는 것이 마음에 걸립니다.

위의 문서에서 간과했던 것이 CircuitBeaker가 classpath에 존재해야 한다는 것이었습니다.

 

Dependencies 추가

dependencies {
	implementation("org.springframework.boot:spring-boot-starter-web")
	implementation("org.springframework:spring-webmvc")
	implementation(enforcedPlatform("org.springframework.cloud:spring-cloud-dependencies:${springCloudVersion}"))
	implementation("org.springframework.cloud:spring-cloud-starter-openfeign")
	implementation("io.github.openfeign:feign-okhttp")
	implementation("org.springframework.cloud:spring-cloud-starter-circuitbreaker-resilience4j:1.0.2.RELEASE")
}

맨 하단의 circuitbraker를 추가해주고 나니 이제 정상적으로 동작합니다.

Spring 문서에서는 서킷브레이커의 의존성을 명시해주지 않아서 조금 아쉬웠습니다.

 

Fallback이 드디어 동작한다

Error while extracting response for type [class com.example.client.feign.WrongFeignDataClass] and content type [application/json]
fallback start

 

 

 

 

참고자료

https://stackoverflow.com/questions/70855000/manually-creating-a-circuit-breaker-wrapped-feign-client

Manually creating a circuit-breaker-wrapped feign client

https://docs.spring.io/spring-cloud-openfeign/docs/current/reference/html/appendix.html

Common application properties

https://docs.spring.io/spring-cloud-openfeign/docs/current/reference/html/#spring-cloud-feign-circuitbreaker

Spring Cloud OpenFeign

https://spring.io/projects/spring-cloud-circuitbreaker

Spring Cloud Circuit Breaker