Spring Cloud Gateway 500实例停机

Question

我有一个使用Spring Cloud Load Balancer (Spring Cloud version: Hoxton.SR6)的Spring Cloud Gateway (eureka client)应用程序，我还有一个spring boot应用程序的实例(spring boot 2.3，支持优雅关机) (eureka client)。

当我关闭spring启动服务并通过网关执行请求时，网关会抛出500错误(连接被拒绝)，而不是503。503在1-2分钟后出现。

有人能澄清这是否是一种预期的行为吗？

问题似乎来自于eureka-client (在我的例子中是1.9.21版本) AtomicReference<Applications> localRegionApps不经常更新

谢谢!

更新:我决定更深入地检查这个500错误。结果是，如果端口未被使用，我的系统(ubuntu)会给出这个错误：

curl -v localhost:9722
 Rebuilt URL to: localhost:9722/
   Trying 127.0.0.1...
 TCP_NODELAY set
 connect to 127.0.0.1 port 9722 failed: Connection refused
 Failed to connect to localhost port 9722: Connection refused
 Closing connection 0

所以我输入了我的application.yml：

spring:
  cloud:
    gateway:
      routes:
        - id: my_route
          uri: http://localhost:9722/

然后，当我的请求被路由到my_route，并且没有应用程序使用9722时，我会得到一个错误：

io.netty.channel.AbstractChannel$AnnotatedConnectException: finishConnect(..) failed: Connection refused: localhost/127.0.0.1:9722
    Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException: 
Error has been observed at the following site(s):
    |_ checkpoint ⇢ org.springframework.cloud.gateway.filter.WeightCalculatorWebFilter [DefaultWebFilterChain]
    |_ checkpoint ⇢ org.springframework.boot.actuate.metrics.web.reactive.server.MetricsWebFilter [DefaultWebFilterChain]
    |_ checkpoint ⇢ HTTP GET "/internal/mail/internal/health-check" [ExceptionHandlingWebHandler]
Stack trace:
Caused by: java.net.ConnectException: finishConnect(..) failed: Connection refused
    at io.netty.channel.unix.Errors.throwConnectException(Errors.java:124)
    at io.netty.channel.unix.Socket.finishConnect(Socket.java:251)
    at io.netty.channel.epoll.AbstractEpollChannel$AbstractEpollUnsafe.doFinishConnect(AbstractEpollChannel.java:672)
    at io.netty.channel.epoll.AbstractEpollChannel$AbstractEpollUnsafe.finishConnect(AbstractEpollChannel.java:649)
    at io.netty.channel.epoll.AbstractEpollChannel$AbstractEpollUnsafe.epollOutReady(AbstractEpollChannel.java:529)
    at io.netty.channel.epoll.EpollEventLoop.processReady(EpollEventLoop.java:465)
    at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:378)
    at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)
    at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
    at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
    at java.base/java.lang.Thread.run(Thread.java:834)

这似乎是一个意想不到的异常，因为它不可能使用断路器或任何网关过滤器来处理它。

是否有可能正确处理此错误？在这种情况下，我想返回503。

Answer 1

将特定异常映射到特定HTTP状态代码的最简单方法之一是提供org.springframework.boot.web.reactive.error.ErrorAttributes类型的自定义bean。下面是一个示例：

@Bean
public ErrorAttributes errorAttributes() {
    return new CustomErrorAttributes(httpStatusExceptionTypeMapper);
}

public class CustomErrorAttributes extends DefaultErrorAttributes {
    @Override
    public Map<String, Object> getErrorAttributes(ServerRequest request, ErrorAttributeOptions options) {
        Map<String, Object> attributes = super.getErrorAttributes(request, options);
        Throwable error = getError(request);
        MergedAnnotation<ResponseStatus> responseStatusAnnotation = MergedAnnotations
            .from(error.getClass(), MergedAnnotations.SearchStrategy.TYPE_HIERARCHY).get(ResponseStatus.class);
        HttpStatus errorStatus = determineHttpStatus(error, responseStatusAnnotation);
        attributes.put("status", errorStatus.value());
        return attributes;
    }

    private HttpStatus determineHttpStatus(Throwable error, MergedAnnotation<ResponseStatus> responseStatusAnnotation) {
        if (error instanceof ResponseStatusException) {
            return ((ResponseStatusException) error).getStatus();
        }
        return responseStatusAnnotation.getValue("code", HttpStatus.class).orElseGet(() -> {
           if (error instanceof java.net.ConnectException) {
               return HttpStatus.SERVICE_UNAVAILABLE;
           }
           return HttpStatus.INTERNAL_SERVER_ERROR;
        }
    }
}

Answer 2

请尝试定义您的自定义ErrorWebExceptionHandler。请参阅：org.springframework.boot.web.reactive.error.ErrorWebExceptionHandler org.springframework.boot.autoconfigure.web.reactive.error.DefaultErrorWebExceptionHandler

Answer 3

您应该使用Cloud Circuit Breaker。

要做到这一点：

1. 在您的pom中声明相应的starter：

org.springframework.cloud spring-cloud-starter-circuitbreaker-reactor-resilience4j

1. 在application.yaml中声明断路器

forward:/inCaseOfFailureUseThis：cloud: gateway: routes：- id: my_route uri：http://localhost:9722/过滤器：- name: CircuitBreaker args: name: myCircuitBreaker fallbackUri: spring

1. 声明在出现故障(例如，连接错误)时将调用的端点

@ Mono.just(ResponseEntity.status(HttpStatus.SERVICE_UNAVAILABLE).body("body (“/inCaseOfFailureUseThis”)公共Mono inCaseOfFailureUseThis() {返回服务失败案例的映射“)；}