Filter
클라이언트가 Spring Cloud Gateway에 요청을 하게 되면 gateway 내부의 predicate에서 어떤 서비스로 갈지 판단 후 요청을 전달한다.
Filter는 작업 전에 수행되는 Pre Filter와 처리 이후 수행되는 Post Filter로 나누어진다.
Filter 적용
Filter 설정 역시 application.yml(properties 파일) 또는 Java 코드로 가능하다.
1. application.yml
server:
port: 8000
eureka:
client:
register-with-eureka: false
fetch-registry: false
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/**
filters:
- AddRequestHeader=first-request, first-request-header
- AddResponseHeader=first-response, first-response-header
- id: second-service
uri: http://localhost:8082/
predicates:
- Path=/second-service/**
filters:
- AddRequestHeader=second-request, second-request-header
- AddResponseHeader=second-response, second-response-header2. Java Code
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:8081"))
.build();
}
}Custom Filter 적용
별도의 Filter 클래스를 생성해서 Filter 동작을 정의하고 Custom Filter를 등록해보자.
Filter 클래스 작성
package com.example.apigatewayservice.filter;
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; // reactive 패키지 Webflux 지원(Spring 5~)
import org.springframework.http.server.reactive.ServerHttpResponse;
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) {
// Custom Pre Filter
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(() -> { // Mono : 비동기 방식의 서버에서 단일값을 전달할 때 사용
log.info("Custom POST filter : response code -> {}", response.getStatusCode());
}));
};
}
public static class Config {
// Put the configuration properties ...
}
}
- AbstractGatewayFilterFactory를 상속받아야 하고 apply 메소드를 오버라이딩하여 필터가 수행할 동작을 정의해주어야 한다.
- 비동기 서버 Netty에서는 동기 서버(ex:tomcat)와 다르게 request/response 객체를 선언할 때 Server~를 사용한다.
- ServletHttpRequest -> ServerHttpRequest
- ServletHttpResponse -> ServerHttpResponse
Filter 등록
server:
port: 8000
eureka:
client:
register-with-eureka: false
fetch-registry: false
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/**
filters:
- CustomFilter
- id: second-service
uri: http://localhost:8082/
predicates:
- Path=/second-service/**
filters:
- CustomFilterspring.cloud.gateway.routes 내 filters 항목에 필터의 빈 이름을 추가해준다.
Global Filter 적용
- CustomFilter와 생성하는 방법은 동일하지만, route 별로 적용하는 것이 아닌 공통적으로 실행되는 필터
- 모든 필터의 가장 첫번째로 실행이 되고 가장 마지막에 종료가 된다.
Filter 클래스 작성
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) {
// Global Pre Filter
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());
}
// Global Post Filter
return chain.filter(exchange).then(Mono.fromRunnable(() -> {
if(config.isPostLogger()) {
log.info("Global Filter End : response code -> {}", response.getStatusCode());
}
}));
};
}
@Data
public static class Config {
private String baseMessage;
private boolean preLogger;
private boolean postLogger;
}
}Filter 등록 및 Config 멤버 값 설정
server:
port: 8000
eureka:
client:
register-with-eureka: false
fetch-registry: false
service-url:
defaultZone: http://localhost:8761/eureka
spring:
application:
name: apigateway-service
cloud:
gateway:
default-filters:
- name: GlobalFilter
args:
baseMessage: Spring Cloud Gateway Global Filter
preLogger: true
postLogger: true
routes:
- id: first-service
uri: http://localhost:8081/
predicates:
- Path=/first-service/**
filters:
- CustomFilter
- id: second-service
uri: http://localhost:8082/
predicates:
- Path=/second-service/**
filters:
- CustomFilter
spring.cloud.gateway.default-filters에 Global Filter에 대한 정보를 등록한다.
name: Global Filter의 빈 이름args: Config 내부 클래스의 멤버 변수 값에 대한 정의
