当第一个尤里卡服务器关闭时，Spring Boot 应用程序不会启动

如何解决当第一个尤里卡服务器关闭时，Spring Boot 应用程序不会启动

我有多个服务器的 Eureka 集群：

#ENV 
EUREKA_URL=http://host1:8761/eureka/,http://host2:8761/eureka/,http://host3:8761/eureka/

#boostrap.yml
eureka:
 client:
  registryFetchIntervalSeconds: 5
  serviceUrl:
   defaultZone: ${EUREKA_URL:http://127.0.0.1:8761/eureka/}

万一，当 host1 关闭时，我的应用程序不会以异常启动：

13410 2021-01-14 11:28:34,994 ERROR [ main ] o.s.b.SpringApplication                                 | Application run Failed 
org.springframework.web.client.ResourceAccessException: I/O error on GET request for "http://host1:8761/eureka/apps/": Connection refused (Connection refused); nested exception is java.net.ConnectException: Connection refused (Connection refused)
    at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:748)
    at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:674)
    at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:583)
    at org.springframework.cloud.netflix.eureka.http.RestTemplateEurekaHttpClient.getApplicationsInternal(RestTemplateEurekaHttpClient.java:154)
    at org.springframework.cloud.netflix.eureka.http.RestTemplateEurekaHttpClient.getApplications(RestTemplateEurekaHttpClient.java:142)
    at org.springframework.cloud.netflix.eureka.config.EurekaconfigserverBootstrapConfiguration.lambda$eurekaconfigserverInstanceProvider$0(EurekaconfigserverBootstrapConfiguration.java:112)
    at org.springframework.cloud.config.client.configserverInstanceProvider.getconfigserverInstances(configserverInstanceProvider.java:50)
    at org.springframework.cloud.config.client.configserverInstanceProvider$$FastClassBySpringcglib$$facbf882.invoke(<generated>)
    at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218)
    at org.springframework.aop.framework.cglibAopProxy$cglibMethodInvocation.invokeJoinpoint(cglibAopProxy.java:771)
    at 

这对我来说很奇怪，因为我预计 eureka 会尝试连接到其他服务器，但事实并非如此。我在 spring-cloud-netflix-eureka-client-2.2.3.RELEASE.jar 中找到了它：

       // EurekaconfigserverBootstrapConfiguration.java
        private String getEurekaUrl(EurekaClientConfigBean config) {
            List<String> urls = EndpointUtils.getServiceUrlsFromConfig(config,EurekaClientConfigBean.DEFAULT_ZONE,true);
            return urls.get(0);
        }

和

    // DefaultEurekaClientConfig.java
    @Override
    public List<String> getEurekaServerServiceUrls(String myZone) {
        String serviceUrls = configInstance.getStringProperty(
                namespace + CONfig_EUREKA_SERVER_SERVICE_URL_PREFIX + "." + myZone,null).get();
        if (serviceUrls == null || serviceUrls.isEmpty()) {
            serviceUrls = configInstance.getStringProperty(
                    namespace + CONfig_EUREKA_SERVER_SERVICE_URL_PREFIX + ".default",null).get();

        }
        if (serviceUrls != null) {
            return Arrays.asList(serviceUrls.split(URL_SEParaTOR));
        }

        return new ArrayList<String>();
    }

最后：

    // RestTemplateEurekaHttpClient.java
    private EurekaHttpResponse<Applications> getApplicationsInternal(String urlPath,String[] regions) {
        String url = serviceUrl + urlPath;

        if (regions != null && regions.length > 0) {
            url = url + (urlPath.contains("?") ? "&" : "?") + "regions="
                    + StringUtil.join(regions);
        }

        // There is no exception handling here and above!
        ResponseEntity<EurekaApplications> response = restTemplate.exchange(url,HttpMethod.GET,null,EurekaApplications.class);

        return anEurekaHttpResponse(response.getStatusCodeValue(),response.getStatusCode().value() == HttpStatus.OK.value()
                        && response.hasBody() ? (Applications) response.getBody() : null)
                                .headers(headersOf(response)).build();
    }

我有 java11、springBootVersion = '2.3.4.RELEASE'、spring-cloud-netflix-eureka-client-2.2.3.RELEASE、eureka-client-1.9.21。

我怎样才能让尤里卡在第一台服务器注册失败的情况下继续在后面的服务器上尝试？有什么想法吗？

解决方法

我找到了解决方法。 我只是覆盖 bean：

@Slf4j
@Configuration
public class EurekaMultiClientBoostrapConfig {
    @Bean
    @Primary
    public RestTemplateEurekaHttpClient configDiscoveryRestTemplateEurekaHttpClient(EurekaClientConfigBean config) {
        List<String> urls = EndpointUtils.getServiceUrlsFromConfig(config,EurekaClientConfigBean.DEFAULT_ZONE,true);
        for (String url : urls) {
            try {
                RestTemplateEurekaHttpClient client = (RestTemplateEurekaHttpClient) new RestTemplateTransportClientFactory()
                        .newClient(new DefaultEndpoint(url));
                client.getApplications(config.getRegion());
                log.info("Registered on Eureka host '{}' is successful.",url);
                return client;
            } catch (Exception e) {
                log.warn("Eureka host '{}' is unavailable(reason: {})",url,e.getMessage());
            }
        }
        throw new IllegalStateException("Failed to register on any eureka host.");
    }

附言由于此配置属于 Bootstrap 配置，所以不要忘记在 resources/META-INF/spring.factories

中添加以下参数

org.springframework.cloud.bootstrap.BootstrapConfiguration=your.app.package.EurekaMultiClientBoostrapConfig