Hystrix断路器在微服务网关中的应用（Spring Cloud Gateway）

{
    "timestamp": "2018-10-11T13:07:07.790+0000",
    "path": "/user/body",
    "status": 500,
    "error": "Internal Server Error",
    "message": "fallbackcmd failed and fallback failed."
}

com.netflix.hystrix.exception.HystrixRuntimeException: fallbackcmd failed and fallback failed.
	at com.netflix.hystrix.AbstractCommand$22.call(AbstractCommand.java:825) ~[hystrix-core-1.5.12.jar:1.5.12]
	at com.netflix.hystrix.AbstractCommand$22.call(AbstractCommand.java:804) ~[hystrix-core-1.5.12.jar:1.5.12]
	at rx.internal.operators.OperatorOnErrorResumeNextViaFunction$4.onError(OperatorOnErrorResumeNextViaFunction.java:140) ~[rxjava-1.3.8.jar:1.3.8]
	at rx.internal.operators.OnSubscribeDoOnEach$DoOnEachSubscriber.onError(OnSubscribeDoOnEach.java:87) ~[rxjava-1.3.8.jar:1.3.8]
	at rx.internal.operators.OnSubscribeDoOnEach$DoOnEachSubscriber.onError(OnSubscribeDoOnEach.java:87) ~[rxjava-1.3.8.jar:1.3.8]
	at com.netflix.hystrix.AbstractCommand$DeprecatedOnFallbackHookApplication$1.onError(AbstractCommand.java:1472) ~[hystrix-core-1.5.12.jar:1.5.12]
	at com.netflix.hystrix.AbstractCommand$FallbackHookApplication$1.onError(AbstractCommand.java:1397) ~[hystrix-core-1.5.12.jar:1.5.12]
	at rx.internal.operators.OnSubscribeDoOnEach$DoOnEachSubscriber.onError(OnSubscribeDoOnEach.java:87) ~[rxjava-1.3.8.jar:1.3.8]
	at rx.internal.reactivestreams.SubscriberAdapter.onError(SubscriberAdapter.java:59) ~[rxjava-reactive-streams-1.2.1.jar:1.2.1]

routes:
- id: hytstrix_route
  uri: lb://user
  order: 6000
  predicates:
  - Path=/user/**
  filters:
  - StripPrefix=1
  - name: Hystrix
    args:
      name: fallbackcmd
      fallbackUri: forward:/fallbackcontroller?a=123

AbstractCommand$22.call[821] : HystrixCommand execution COMMAND_EXCEPTION and fallback failed.

java.lang.IllegalArgumentException: Actual request host must not be null
at org.springframework.util.Assert.notNull(Assert.java:193)
at org.springframework.web.cors.reactive.CorsUtils.isSameOrigin(CorsUtils.java:74)
at org.springframework.web.cors.reactive.DefaultCorsProcessor.process(DefaultCorsProcessor.java:70)
at org.springframework.web.reactive.handler.AbstractHandlerMapping.lambda$getHandler$1(AbstractHandlerMapping.java:152)
at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:107)
at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:1640)
at

public boolean processRequest(@Nullable CorsConfiguration config, HttpServletRequest request,
			HttpServletResponse response) throws IOException {
		//是否为CORS请求（包含Origin头部）
		if (!CorsUtils.isCorsRequest(request)) {
			return true; //不是则直接返回
		}

		ServletServerHttpResponse serverResponse = new ServletServerHttpResponse(response);
		//根据serverResponse响应判断Access-Control-Allow-Origin
		if (responseHasCors(serverResponse)) {
			logger.debug("Skip CORS processing: response already contains \"Access-Control-Allow-Origin\" header");
			return true;
		}

		ServletServerHttpRequest serverRequest = new ServletServerHttpRequest(request);
		if (WebUtils.isSameOrigin(serverRequest)) {
			logger.debug("Skip CORS processing: request is from same origin");
			return true;
		}

		boolean preFlightRequest = CorsUtils.isPreFlightRequest(request);
		if (config == null) {
			if (preFlightRequest) {
				rejectRequest(serverResponse);
				return false;
			}
			else {
				return true;
			}
		}

		return handleInternal(serverRequest, serverResponse, config, preFlightRequest);
	}

routes:
- id: hytstrix_route
  uri: lb://user
  order: 6000
  predicates:
  - Path=/user/**
  filters:
  - StripPrefix=1
  - RemoveRequestHeader=Origin
  - name: Hystrix
    args:
      name: fallbackcmd
      fallbackUri: forward:/fallbackcontroller?a=123

@Bean
    public WebFilter corsFilter() {
        return (ServerWebExchange ctx, WebFilterChain chain) -> {
            ServerHttpRequest request = ctx.getRequest();
            if (CorsUtils.isCorsRequest(request)) {
                ServerHttpResponse response = ctx.getResponse();
                HttpHeaders headers = response.getHeaders();
                headers.add("Access-Control-Allow-Origin", ALLOWED_ORIGIN);
                headers.add("Access-Control-Allow-Methods", ALLOWED_METHODS);
                headers.add("Access-Control-Max-Age", MAX_AGE);
                headers.add("Access-Control-Allow-Headers",ALLOWED_HEADERS);
                if (request.getMethod() == HttpMethod.OPTIONS) {
                    response.setStatusCode(HttpStatus.OK);
                    return Mono.empty();
                }
            }
            return chain.filter(ctx);
        };
    }

spring:
  cloud:
    gateway:
      globalcors:
        corsConfigurations:
          '[/**]':
            allowedOrigins: "*"
            allowedMethods: "*"