[SpringCloud] API Gateway Service

API Gateway Service

• 인증 및 권한 부여
• 서비스 검색 통합
• 응답 캐싱
• 정책, 회로 차단기 및 Qos
• 속도 제한
• 부하 분산
• 로깅, 추적, 상관관계
• 헤더, 쿼리 문자열 및 청구 변환
• IP 허용 목록에 추가

 

SpringCloud에서의 MSA간 통신

• RestTemplate

RestTemplate restTemplate = new RestTemplate();
restTemplate.getForObject("http://localhost:8080/", User.class, 200);

• Feign Client
• FeignClient라는 마이크로서비스 이름가지고 호출이 가능함.

@FeignClient("stores")
public interface StoreClient {
	@RequestMapping(method = RequestMethod.GET, value="/stores")
    List<Store> getStores();
}

 

Ribbon

• Client side Load Balancer 
• SpringBoot 2.4에서 Maintenance 상태임
• 서비스 이름으로 호출
• Health Check

Netflix Zuul

 

1. 테스트용 프로젝트 생성하기

 

FirstService 프로젝트

package com.example.firstserivce;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/")
public class FirstServiceController {
    @GetMapping("/welcome")
    public String welcome() {
        return "Welcome to the First Service";
    }
}

application.yml

server:
  port: 8081

spring:
  application:
    name: my-first-service

eureka:
  client:
    fetch-registry: false
    register-with-eureka: false

 

SecondService

package com.example.secondservice;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/")
public class SecondServiceController {
    @GetMapping("/welcome")
    public String welcome() {
        return "Welcome to the Second Service";
    }
}

application.yml

server:
  port: 8082

spring:
  application:
    name: my-second-service

eureka:
  client:
    fetch-registry: false
    register-with-eureka: false

 

Zuul 프로젝트 생성

SpringCloundRouting - Zuul을 사용하려면 스프링부트 2.4이하 버전을 사용해야한다.

@EnableZuulProxy를 사용한다.

@SpringBootApplication
@EnableZuulProxy
public class ZuulServiceApplication {

    public static void main(String[] args) {
        SpringApplication.run(ZuulServiceApplication.class, args);
    }

}

server:
  port: 8000

spring:
  application:
    name: my-zuul-service

zuul:
  routes:
    first-service:
      path: /first-service/**
      url: http://localhost:8081

    second-service:
      path: /second-service/**
      url: http://localhost:8082

같은 url로 서비스를 라우팅 해준다.

요청이 들어오기전에 filter를 구현하여 Log출력을 해볼 수도 있다!

package com.example.zuulservice.filter;

import com.netflix.zuul.ZuulFilter;
import com.netflix.zuul.context.RequestContext;
import com.netflix.zuul.exception.ZuulException;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;

import javax.servlet.http.HttpServletRequest;

@Slf4j // Logger객체를 바로 사용할 수 있다.
@Component
public class ZuulLoggingFilter extends ZuulFilter {

    @Override
    public String filterType() {
        return "pre";
    }

    @Override
    public int filterOrder() {
        return 1;
    }

    @Override
    public boolean shouldFilter() {
        return true;
    }

    @Override
    public Object run() throws ZuulException {
        log.info("*********************** printing logs: ");

        RequestContext ctx = RequestContext.getCurrentContext();
        HttpServletRequest request = ctx.getRequest();
        log.info("*********************** : " + request.getRequestURI());
        return null;
    }
}

---

Spring Cloud Gateway

비동기 처리가 가능하다.

해당 gateway를 어디로 routing시켜줄지 설정시켜줄 수 있다.

 

1. Client 요청이 오면 header추가

2.  Predicate 

3. Pre Filter

4. Post Filter

5. Client한테 response할때 header값 추가함

 

= > header값 추가하는 작업을 SpringCloud가 대신해준다.

server:
  port: 8011

eureka:
  client:
    register-with-eureka: false
    fetch-registry: true
    service-url:
      defaultZone: http://localhost:8761/eureka

spring:
  application:
    name: apigateway-service
  cloud:
    gateway:
      routes:
        - id: first-service
          uri: http://localhost:8081
          predicates:
            - Path=/first-service/**
        - id: second-service
          uri: http://localhost:8081
          predicates:
            - Path=/second-service/**

application.yml에 저장해두었던 부분을 java code로도 작성할 수 있다! Lambda를 이용해서!

 

Filter/FilterConfig.java

앞의 addRequestHeader, addResponseHeader를 통해서 header를 추가할 수 있다.

package com.example.apigatewayservice.config;

import org.springframework.cloud.gateway.route.RouteLocator;
import org.springframework.cloud.gateway.route.builder.RouteLocatorBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class FilterConfig {
    @Bean
    public RouteLocator gatewayRoutes(RouteLocatorBuilder builder) {
        return builder.routes()
                .route(r -> r.path("/first-service/**")
                        .filters(f -> f.addRequestHeader("first-request","first-request-header")
                                .addResponseHeader("first-response","first-response-header"))
                        .uri("http://localhost:8081"))
                .route(r -> r.path("/second-service/**")
                        .filters(f -> f.addRequestHeader("second-request","second-request-header")
                                .addResponseHeader("second-response","second-response-header"))
                        .uri("http://localhost:8082"))
                .build();
    }
}

FirstService 프로젝트에 FirstServiceController.java에 해당 message 엔드포인트 추가한다

    @GetMapping("/message")
    public String message(@RequestHeader("first-request") String header) {
        log.info(header);
        return "Welcome to the First Service";
    }

SecondService프로젝트에도 추가함

    @GetMapping("/message")
    public String message(@RequestHeader("second-request") String header) {
        log.info(header);
        return "Welcome to the Second Service";
    }

application.yml 파일에 filter를 추가할 수도 있다.

spring:
  application:
    name: apigateway-service
  cloud:
    gateway:
      routes:
        - id: first-service
          uri: http://localhost:8081 # 이동될 주소
          predicates:
            - Path=/first-service/**
          filters:
            - AddRequestHeader=first-request, first-requests-header2
            - AddResponseHeader=first-response, first-response-header2
        - id: second-service
          uri: http://localhost:8081
          predicates:
            - Path=/second-service/**
          filters:
            - AddRequestHeader=second-request, second-requests-header2
            - AddResponseHeader=second-response, second-response-header2

Postman으로 추가하면 header로 해당 정보를 확인할 수 있다.

---

CustomFilter

Custom Filter.java

package com.example.apigatewayservice.filter;

import lombok.extern.slf4j.Slf4j;
import org.springframework.cloud.gateway.filter.GatewayFilter;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.cloud.gateway.filter.factory.AbstractGatewayFilterFactory;
import org.springframework.stereotype.Component;
import reactor.core.publisher.Mono;

@Component
@Slf4j
public class CustomFilter extends AbstractGatewayFilterFactory<CustomFilter.Config> {
    public CustomFilter() {
        super(Config.class);
    }

    @Override
    public GatewayFilter apply(Config config) {
        return ((exchange, chain) -> {
            ServerHttpRequest request = exchange.getRequest();
            ServerHttpResponse response = exchange.getResponse();

            log.info("Custom PRE filter: request id -> {}", request.getId());

            // Custom Post Filter
            return chain.filter(exchange).then(Mono.fromRunnable(() -> {
                log.info("Custom POST filter: response code -> {}", response.getStatusCode());
            }));
        });
    }

    public static class Config {

    }
}

 

GlobalFilter

- 공통으로 다 쓸 수 있는 filter

spring:
  application:
    name: apigateway-service
  cloud:
    gateway:
      default-filters:
        - name:
            args:
              baseMessage: SpringCloud Gateway Global Filter
              preLogger: true
              postLogger: true

package com.example.apigatewayservice.filter;

import lombok.Data;
import lombok.extern.slf4j.Slf4j;
import org.springframework.cloud.gateway.filter.GatewayFilter;
import org.springframework.cloud.gateway.filter.factory.AbstractGatewayFilterFactory;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.stereotype.Component;
import reactor.core.publisher.Mono;

@Component
@Slf4j
public class GlobalFilter extends AbstractGatewayFilterFactory<GlobalFilter.Config> {
    public GlobalFilter() {
        super(Config.class);
    }

    @Override
    public GatewayFilter apply(Config config) {
        return ((exchange, chain) -> {
            ServerHttpRequest request = exchange.getRequest();
            ServerHttpResponse response = exchange.getResponse();

            log.info("Global Filter baseMessage: {}", config.getBaseMessage());

            if(config.isPreLogger()) {
                log.info("Global Filter start: request id -> {}", request.getId());
            }
            // Custom Post Filter
            return chain.filter(exchange).then(Mono.fromRunnable(() -> {
                if(config.isPostLogger()) {
                    log.info("Global Filter end: request id -> {}", response.getStatusCode());
                }
            }));
        });
    }

    @Data
    public static class Config {
        private String baseMessage;
        private boolean preLogger;
        private boolean postLogger;
    }
}

 

---

LoggingFilter

package com.example.apigatewayservice.filter;

import lombok.Data;
import lombok.extern.slf4j.Slf4j;
import org.springframework.cloud.gateway.filter.GatewayFilter;
import org.springframework.cloud.gateway.filter.OrderedGatewayFilter;
import org.springframework.cloud.gateway.filter.factory.AbstractGatewayFilterFactory;
import org.springframework.core.Ordered;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.stereotype.Component;
import reactor.core.publisher.Mono;

@Component
@Slf4j
public class LoggingFilter extends AbstractGatewayFilterFactory<LoggingFilter.Config> {
    public LoggingFilter() {
        super(Config.class);
    }

    @Override
    public GatewayFilter apply(Config config) {
        GatewayFilter filter = new OrderedGatewayFilter((exchange, chain) -> {
            ServerHttpRequest request = exchange.getRequest();
            ServerHttpResponse response = exchange.getResponse();

            log.info("Logging Filter baseMessage: {}", config.getBaseMessage());
            if (config.isPreLogger()) {
                log.info("Logging PRE Filter: request id -> {}", request.getId());
            }
            return chain.filter(exchange).then(Mono.fromRunnable(()->{
                if (config.isPostLogger()) {
                    log.info("Logging POST Filter: response code -> {}", response.getStatusCode());
                }
            }));
        }, Ordered.LOWEST_PRECEDENCE);
        return filter;
    }

    @Data
    public static class Config {
        private String baseMessage;
        private boolean preLogger;
        private boolean postLogger;
    }
}

application.yml 

spring:
  application:
    name: apigateway-service
  cloud:
    gateway:
      default-filters:
        - name:
            args:
              baseMessage: SpringCloud Gateway Global Filter
              preLogger: true
              postLogger: true
      routes:
        - id: first-service
          uri: lb://MY-FIRST-SERVICE
          predicates:
            - Path=/first-service/**
          filters:
            - AddRequestHeader=first-request, first-request-header2
            - AddResponseHeader=first-response, first-response-header2
        #            - CustomFilter
        - id: second-service
          uri: lb://MY-SECOND-SERVICE
          predicates:
            - Path=/second-service/**
          filters:
            - AddRequestHeader=second-request, second-request-header2
            - AddResponseHeader=second-response, second-response-header2
            #            - name: CustomFilter
            - name: LoggingFilter
              args:
                baseMessage: Hi, there.
                preLogger: true
                postLogger: true

---

Eureka 연동

 

Eureka에 위치가 어디 저장되었는지 물어보고 -> forwarding 해준다.

Eureka 서버를 실행시켜주고, http://localhost:8761 접속하면 기동이 된다.