Springboot Cloud Openfeign

Openfeign의 ErrorDecoder를 이용해서 Exception을 처리한다.

1. pom.xml 설정

Springboot Version에 따라 spring-cloud.version을 맞춰야 한다.

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.4.2</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>

	<properties>
		<java.version>11</java.version>
		<spring-cloud.version>2020.0.1</spring-cloud.version>
	</properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
    </dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

(참조) Spring Cloud 와 Boot 의 Version 호환

아래 링크의 하단에 버전의 호환여부를 확인해야 한다.

Release Train	Boot Version
2021.0.x aka Jubilee	2.6.x, 2.7.x (Starting with 2021.0.3)
2020.0.x aka Ilford	2.4.x, 2.5.x (Starting with 2020.0.3)
Hoxton	2.2.x, 2.3.x (Starting with SR5)

2. Enable 설정

App 전체에 영향을 미치지 않도록 별도의 Configuration 클래스에 적용

@Configiration
@EnableFeignClients(basePackages = "me.kalpha.userservice.feign")
public class FeignConfiguration {
    ...
}

3. Remote API Interface 선언

@FeignClient의 속성 중 name은 app name을 입력한다. url로 host를 설정할 수도 있다.

@FeignClient(name = "order-service", url = "http://10.20.30.41:8080", configuration = {FeignConfiguration.class})
public interface OrderServiceClient {
    @GetMapping("/order-service/{userId}/orders")
    List<ResponseOrder> getOrders(@PathVariable("userId") String userId);
}

4. Remote API 호출

public class UserServiceImpl implements UserService {
    @Autowired
    private OrderServiceClient orderServiceClient;

    /* ErrorDecorder 이용*/
    public List<ResponseOrder> getOrders(userId) {
        List<ResponseOrder> orderList=orderServiceClient.getOrders(userId);
        return orderList;
    }
}

5. Logging

설정하는것 만으로 충분한 log를 확인할 수 있다.

public class FeignConfiguration {
    ...
        
    @Bean
    public Logger.Level getFeignLoggerLevel() {
        return Logger.Level.FULL;
    }
}

6. Exception 처리

FeginException을 직접사 용해서 try catch하는 것이 아니라, FeignErrorDecorder를 활용해서 에러처리.

@Component
public class FeignErrorDecoder implements ErrorDecoder {
    @Override
    public Exception decode(String methodKey, Response response) {
        switch (response.status()) {
            case 400:
                break;
            case 404:
                if (methodKey.contains("getOrders")) {
                    return new ResponseStatusException(HttpStatus.valueOf(response.status()),
                            "User's order is empty");
                }
                break;
            default:
                return new Exception(response.reason());
        }
        return null;
    }
}    

public class FeignConfiguration {
    ...
        
    @Bean
    public FeignErrorDecode getFeignErrorDecode() {
        return new FeignErrorDecode();
    }
}

기타 1. Url을 동적으로 받도록 수정하기

Url을 동적으로 받아서 호출시점에 할당할 수 있다 (어노테이션의 url파라미터는 의미 없음)

// FeignClient 선언
@FeignClient(name = "order-service", url = "dynamic-url", configuration = {FeignConfiguration.class})
public interface OrderServiceClient {
    @GetMapping("/order-service/{userId}/orders")
    List<ResponseOrder> getOrders(URI uri, @PathVariable("userId") String userId);
}

// FeignClient 호출
public class UserServiceImpl {}
    @Autowired
    private OrderServiceClient orderServiceClient;

    ...
    public List<ResponseOrder> getOrders(baseUrl, userId) {}
        URI uri = new URI(("http://"+baseUrl+":8080"));
        List<ResponseOrder> orderList=orderServiceClient.getOrders(uri, userId);
        return orderList;
    }
}

기타 2. Sprinboot 2.2 / 2.3에서 사용

spring.boot과 spring-cloud, openfeign의 version을 맞춰야 한다.

    <properties>
        <spring.boot.version>2.3.1.RELEASE</spring.boot.version>
        <spring-cloud.version>Hoxton.SR12</spring-cloud.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
            <version>2.2.9.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-cirbuitbreaker-resilience4j</artifactId>
            <version>1.0.6.RELEASE</version>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>