SpringCloud Gateway 소스 코드 추적 분석

1. 스프링클라우드 게이트웨이 

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

2. 핵심 구성 요소:

술부

GetewayFilter

전역 필터

3. 개략적인 개요

https://docs.spring.io/spring-cloud-gateway/docs/current/reference/html/images/spring_cloud_gateway_diagram.png

3. SpringMVC와의 수평적 비교

SpringMVC =====> 스프링 WebFlux

DispatchServlet =====> DispatchHandler

경로 일치:

핸들러 매핑 =====>핸들러 매핑

HanderAdaper ====> HanderAdaper

핸들러 =====> 웹핸더

4. 소스코드 추적

핵심 클래스: org.springframework.web.reactive.DispatcherHandler

public Mono<Void> handle(ServerWebExchange exchange) {
    return this.handlerMappings == null ? this.createNotFoundError() : Flux.fromIterable(this.handlerMappings).concatMap((mapping) -> {
        return mapping.getHandler(exchange);
    }).next().switchIfEmpty(this.createNotFoundError()).flatMap((handler) -> {
        return this.invokeHandler(exchange, handler);
    }).flatMap((result) -> {
        return this.handleResult(exchange, result);
    });
}

org.springframework.cloud.gateway.handler.RoutePredicateHandlerMapping#getHandler내부

LookupRoute에서 모든 Predicate 어설션을 실행합니다.

protected Mono<Route> lookupRoute(ServerWebExchange exchange) {
    return this.routeLocator.getRoutes().concatMap((route) -> {
        return Mono.just(route).filterWhen((r) -> {
            exchange.getAttributes().put(ServerWebExchangeUtils.GATEWAY_PREDICATE_ROUTE_ATTR, r.getId());
            return (Publisher)r.getPredicate().apply(exchange);
        }).doOnError((e) -> {
            this.logger.error("Error applying predicate for route: " + route.getId(), e);
        }).onErrorResume((e) -> {
            return Mono.empty();
        });
    }).next().map((route) -> {
        if (this.logger.isDebugEnabled()) {
            this.logger.debug("Route matched: " + route.getId());
        }

        this.validateRoute(route, exchange);
        return route;
    });
}

 org.springframework.cloud.gateway.handler.FilteringWebHandler#handle

모든 GlobalFilters를 필터로 변환하고 필터 체인에 추가합니다.

public Mono<Void> handle(ServerWebExchange exchange) {
    Route route = (Route)exchange.getRequiredAttribute(ServerWebExchangeUtils.GATEWAY_ROUTE_ATTR);
    List<GatewayFilter> gatewayFilters = route.getFilters();
    List<GatewayFilter> combined = new ArrayList(this.globalFilters);
    combined.addAll(gatewayFilters);
    AnnotationAwareOrderComparator.sort(combined);
    if (logger.isDebugEnabled()) {
        logger.debug("Sorted gatewayFilterFactories: " + combined);
    }

    return (new FilteringWebHandler.DefaultGatewayFilterChain(combined)).filter(exchange);
}

 모든 필터

핵심 클래스 org.springframework.cloud.gateway.filter.LoadBalancerClientFilter

리본은 serviceId를 기반으로 해당 서비스의 IP를 찾습니다.

public Mono<Void> handle(ServerWebExchange exchange) {
    Route route = (Route)exchange.getRequiredAttribute(ServerWebExchangeUtils.GATEWAY_ROUTE_ATTR);
    List<GatewayFilter> gatewayFilters = route.getFilters();
    List<GatewayFilter> combined = new ArrayList(this.globalFilters);
    combined.addAll(gatewayFilters);
    AnnotationAwareOrderComparator.sort(combined);
    if (logger.isDebugEnabled()) {
        logger.debug("Sorted gatewayFilterFactories: " + combined);
    }

    return (new FilteringWebHandler.DefaultGatewayFilterChain(combined)).filter(exchange);
}