Spring Cloud Zuul 在实例关闭时重试并转发到其他可用实例

使用“Camden.SR5”作为 spring-cloud 依赖项，并使用 spring boot“1.5.2.RELEASE”。

在我当前的设置中，我有

• 尤里卡服务器
• 配置服务器（在随机端口上运行）
• zuul网关服务器
• 和 2 个服务实例（在随机端口上运行）

所有这些实例都已成功注册到 Eureka。

当所有服务都运行时，负载平衡通过zuul正确完成，没有任何问题。

当实例被杀死时，Zuul 仍在尝试使用已关闭的同一服务来满足请求。但是，如果在关闭实例后等到尤里卡注册表被获取，请求将由其他处于“UP”状态的实例完成。

    2017-03-07 19:57:41.409 DEBUG 26658 --- [nio-5555-exec-3] c.n.l.reactive.LoadBalancerCommand       : Got error org.apache.http.conn.HttpHostConnectException: Connect to 10.99.4.151:64381 [/10.99.4.151] failed: Connection refused when executed on server 10.99.4.151:64381
2017-03-07 19:57:41.420 DEBUG 26658 --- [nio-5555-exec-3] com.netflix.hystrix.AbstractCommand      : Error executing HystrixCommand.run(). Proceeding to fallback logic ...

com.netflix.client.ClientException: null
    at com.netflix.client.AbstractLoadBalancerAwareClient.executeWithLoadBalancer(AbstractLoadBalancerAwareClient.java:123) ~[ribbon-loadbalancer-2.2.0.jar:2.2.0]
    at com.netflix.client.AbstractLoadBalancerAwareClient.executeWithLoadBalancer(AbstractLoadBalancerAwareClient.java:81) ~[ribbon-loadbalancer-2.2.0.jar:2.2.0]
    at org.springframework.cloud.netflix.zuul.filters.route.support.AbstractRibbonCommand.run(AbstractRibbonCommand.java:96) ~[spring-cloud-netflix-core-1.2.5.RELEASE.jar:1.2.5.RELEASE]
    at org.springframework.cloud.netflix.zuul.filters.route.support.AbstractRibbonCommand.run(AbstractRibbonCommand.java:42) ~[spring-cloud-netflix-core-1.2.5.RELEASE.jar:1.2.5.RELEASE]

    at org.apache.http.conn.socket.PlainConnectionSocketFactory.connectSocket(PlainConnectionSocketFactory.java:75) ~[httpclient-4.5.3.jar:4.5.3]
    at org.apache.http.impl.conn.DefaultHttpClientConnectionOperator.connect(DefaultHttpClientConnectionOperator.java:142) ~[httpclient-4.5.3.jar:4.5.3]
    ... 162 common frames omitted

2017-03-07 19:57:41.425 DEBUG 26658 --- [nio-5555-exec-3] com.netflix.hystrix.AbstractCommand      : No fallback for HystrixCommand. 

java.lang.UnsupportedOperationException: No fallback available.
    at com.netflix.hystrix.HystrixCommand.getFallback(HystrixCommand.java:292) [hystrix-core-1.5.6.jar:1.5.6]
    at org.springframework.cloud.netflix.zuul.filters.route.support.AbstractRibbonCommand.getFallback(AbstractRibbonCommand.java:117) ~[spring-cloud-netflix-core-1.2.5.RELEASE.jar:1.2.5.RELEASE]
    at org.springframework.cloud.netflix.zuul.filters.route.support.AbstractRibbonCommand.getFallback(AbstractRibbonCommand.java:42) ~[spring-cloud-netflix-core-1.2.5.RELEASE.jar:1.2.5.RELEASE]

at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_66]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.5.11.jar:8.5.11]
    at java.lang.Thread.run(Thread.java:745) [na:1.8.0_66]

2017-03-07 19:57:41.428  WARN 26658 --- [nio-5555-exec-3] o.s.c.n.z.filters.post.SendErrorFilter   : Error during filtering

com.netflix.zuul.exception.ZuulException: Forwarding error
    at org.springframework.cloud.netflix.zuul.filters.route.RibbonRoutingFilter.handleException(RibbonRoutingFilter.java:170) ~[spring-cloud-netflix-core-1.2.5.RELEASE.jar:1.2.5.RELEASE]
    at org.springframework.cloud.netflix.zuul.filters.route.RibbonRoutingFilter.forward(RibbonRoutingFilter.java:145) ~[spring-cloud-netflix-core-1.2.5.RELEASE.jar:1.2.5.RELEASE]
    at org.springframework.cloud.netflix.zuul.filters.route.RibbonRoutingFilter.run(RibbonRoutingFilter.java:88) ~[spring-cloud-netflix-core-1.2.5.RELEASE.jar:1.2.5.RELEASE]

以下是与@EnableZuulProxy和@EnableEurekaClient一起使用的zuul配置

    server:
  port: 5555

spring:
  application:
    name: gateway-server
  cloud:
    config:
      discovery:
        enabled: true
        service-id: CONFIGSERVER
      fail-fast: true
      retry:
        multiplier:  1.1
        initial-interval: 1000
        max-attempts: 6
        max-interval: 2000

hystrix:
  command:
    default:
      execution:
        isolation:
          thread:
            timeoutInMilliseconds: 100000
        timeout:
          enabled: false

ribbon:
  ReadTimeout: 5000
  ConnectTimeout: 3000
  maxAutoRetries: 1
  MaxAutoRetriesNextServer: 2
  OkToRetryOnAllOperations: true


logging:
  level:
    ROOT: DEBUG

zuul:
  routes:
    security-service:
      retryable: true

2 个服务实例以唯一的实例 ID 运行

@EnableEurekaClient
@EnableHystrix
@SpringBootApplication
public class SecurityServer implements HealthIndicator{

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

    @Override
    public Health health() {
        return Health.up().withDetail("STATUS", "SUCCESS").build();
    }
}

instanceId: ${spring.cloud.client.hostname}:${spring.application.name}:${spring.application.instance_id:${random.uuid}}

您能否帮助我进行 zuul & 实例配置，以便当实例出现故障时，该请求会自动转发到其他可用实例。

在搜索更多内容并研究 spring-cloud-netflix 问题跟踪器后，之间进行了精彩的讨论威廉·特兰 https://github.com/william-tran and 瑞安巴克斯特 https://github.com/ryanjbaxter关于最佳实践。感谢你们俩。

https://github.com/spring-cloud/spring-cloud-netflix/issues/1290#issuecomment-242204614 https://github.com/spring-cloud/spring-cloud-netflix/issues/1290#issuecomment-242204614

https://github.com/spring-cloud/spring-cloud-netflix/issues/1295 https://github.com/spring-cloud/spring-cloud-netflix/issues/1295

总之，Camden 不使用 Ribbon HTTP 客户端（已弃用），因此所有ribbon.* 属性都无法帮助您控制重试逻辑。卡姆登使用 Apache HTTP 客户端。

因此，解决方案是使用以下配置在 camden 版本中使用 Ribbon HTTP Client

ribbon.restclient.enabled=true

or

移至 Camden.BUILD-SNAPSHOT 或 Dalston.BUILD-SNAPSHOT 以使用 spring-retry (https://github.com/spring-projects/spring-retry https://github.com/spring-projects/spring-retry)