前言
apollo是一个十分风行的开源的配置核心我的项目，这里就不多介绍了。接触过apollo和运行过apollo的人必定都遇到过启动configService时抛异样了，而且100%会抛一个异样。起因是，在apollo的架构中configService既作为config服务，同时也承载了metaService的性能，所以这个模块，既作为eureka的服务端也是eureka的客户端，这就造成了利用启动时，eurekaServer未齐全启动，eurekaClient拉取注册表信息时就抛异样了。不过这个拉取动作是在独立的线程中运行的，独立于启动利用的主线程，所以异样并不影响利用的启动，这个问题也就始终从开源到留到了当初。目前，这个问题已被博主解决，正在合并pr中。
本文pr地址：https://github.com/ctripcorp/...
触发起因剖析
首先看下异样的信息，异样的信息比拟多，如下：
2020-12-23 09:55:19.882 ERROR 7022 --- [ main] c.n.d.s.t.d.RedirectingEurekaHttpClient : Request execution errorcom.sun.jersey.api.client.ClientHandlerException: java.net.ConnectException: Connection refused (Connection refused) at com.sun.jersey.client.apache4.ApacheHttpClient4Handler.handle(ApacheHttpClient4Handler.java:187) at com.sun.jersey.api.client.filter.GZIPContentEncodingFilter.handle(GZIPContentEncodingFilter.java:123) at com.netflix.discovery.EurekaIdentityHeaderFilter.handle(EurekaIdentityHeaderFilter.java:27) at com.sun.jersey.api.client.Client.handle(Client.java:652) at com.sun.jersey.api.client.WebResource.handle(WebResource.java:682) at com.sun.jersey.api.client.WebResource.access$200(WebResource.java:74) at com.sun.jersey.api.client.WebResource$Builder.get(WebResource.java:509) at com.netflix.discovery.shared.transport.jersey.AbstractJerseyEurekaHttpClient.getApplicationsInternal(AbstractJerseyEurekaHttpClient.java:194) at com.netflix.discovery.shared.transport.jersey.AbstractJerseyEurekaHttpClient.getApplications(AbstractJerseyEurekaHttpClient.java:165) at com.netflix.discovery.shared.transport.decorator.EurekaHttpClientDecorator$6.execute(EurekaHttpClientDecorator.java:137) at com.netflix.discovery.shared.transport.decorator.MetricsCollectingEurekaHttpClient.execute(MetricsCollectingEurekaHttpClient.java:73) at com.netflix.discovery.shared.transport.decorator.EurekaHttpClientDecorator.getApplications(EurekaHttpClientDecorator.java:134) at com.netflix.discovery.shared.transport.decorator.EurekaHttpClientDecorator$6.execute(EurekaHttpClientDecorator.java:137) at com.netflix.discovery.shared.transport.decorator.RedirectingEurekaHttpClient.executeOnNewServer(RedirectingEurekaHttpClient.java:118) at com.netflix.discovery.shared.transport.decorator.RedirectingEurekaHttpClient.execute(RedirectingEurekaHttpClient.java:79) at com.netflix.discovery.shared.transport.decorator.EurekaHttpClientDecorator.getApplications(EurekaHttpClientDecorator.java:134) at com.netflix.discovery.shared.transport.decorator.EurekaHttpClientDecorator$6.execute(EurekaHttpClientDecorator.java:137) at com.netflix.discovery.shared.transport.decorator.RetryableEurekaHttpClient.execute(RetryableEurekaHttpClient.java:120) at com.netflix.discovery.shared.transport.decorator.EurekaHttpClientDecorator.getApplications(EurekaHttpClientDecorator.java:134) at com.netflix.discovery.shared.transport.decorator.EurekaHttpClientDecorator$6.execute(EurekaHttpClientDecorator.java:137) at com.netflix.discovery.shared.transport.decorator.SessionedEurekaHttpClient.execute(SessionedEurekaHttpClient.java:77) at com.netflix.discovery.shared.transport.decorator.EurekaHttpClientDecorator.getApplications(EurekaHttpClientDecorator.java:134) at com.netflix.discovery.DiscoveryClient.getAndStoreFullRegistry(DiscoveryClient.java:1051) at com.netflix.discovery.DiscoveryClient.fetchRegistry(DiscoveryClient.java:965) at com.netflix.discovery.DiscoveryClient.<init>(DiscoveryClient.java:414) at com.netflix.discovery.DiscoveryClient.<init>(DiscoveryClient.java:269) at org.springframework.cloud.netflix.eureka.CloudEurekaClient.<init>(CloudEurekaClient.java:63) at org.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration$RefreshableEurekaClientConfiguration.eurekaClient(EurekaClientAutoConfiguration.java:290) at org.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration$RefreshableEurekaClientConfiguration$$EnhancerBySpringCGLIB$$5cf7ced9.CGLIB$eurekaClient$2(<generated>) at org.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration$RefreshableEurekaClientConfiguration$$EnhancerBySpringCGLIB$$5cf7ced9$$FastClassBySpringCGLIB$$328872d8.invoke(<generated>) at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:228) at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:365) at org.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration$RefreshableEurekaClientConfiguration$$EnhancerBySpringCGLIB$$5cf7ced9.eurekaClient(<generated>) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:582) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1247) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1096) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:535) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:495) at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$1(AbstractBeanFactory.java:353) at org.springframework.cloud.context.scope.GenericScope$BeanLifecycleWrapper.getBean(GenericScope.java:390) at org.springframework.cloud.context.scope.GenericScope.get(GenericScope.java:184) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:350) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) at org.springframework.aop.target.SimpleBeanTargetSource.getTarget(SimpleBeanTargetSource.java:35) at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:193) at com.sun.proxy.$Proxy145.getApplications(Unknown Source) at org.springframework.cloud.netflix.eureka.server.EurekaServerAutoConfiguration.peerAwareInstanceRegistry(EurekaServerAutoConfiguration.java:164) at org.springframework.cloud.netflix.eureka.server.EurekaServerAutoConfiguration$$EnhancerBySpringCGLIB$$ef07d99b.CGLIB$peerAwareInstanceRegistry$5(<generated>) at org.springframework.cloud.netflix.eureka.server.EurekaServerAutoConfiguration$$EnhancerBySpringCGLIB$$ef07d99b$$FastClassBySpringCGLIB$$458f0ac6.invoke(<generated>) at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:228) at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:365) at org.springframework.cloud.netflix.eureka.server.EurekaServerAutoConfiguration$$EnhancerBySpringCGLIB$$ef07d99b.peerAwareInstanceRegistry(<generated>) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:582) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1247) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1096) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:535) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:495) at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:317) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:315) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:251) at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1135) at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1062) at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:818) at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:724) at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:474) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1247) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1096) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:535) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:495) at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:317) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:315) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:251) at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1135) at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1062) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:583) at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:90) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:372) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1341) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:572) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:495) at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:317) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:315) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:759) at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:869) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550) at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140) at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:780) at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:412) at org.springframework.boot.SpringApplication.run(SpringApplication.java:333) at org.springframework.boot.SpringApplication.run(SpringApplication.java:1277) at org.springframework.boot.SpringApplication.run(SpringApplication.java:1265) at com.ctrip.framework.apollo.configservice.ConfigServiceApplication.main(ConfigServiceApplication.java:33)Caused by: java.net.ConnectException: Connection refused (Connection refused) at java.net.PlainSocketImpl.socketConnect(Native Method) at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:476) at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:218) at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:200) at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:394) at java.net.Socket.connect(Socket.java:606) at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:121) at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:180) at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:144) at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:134) at org.apache.http.impl.client.DefaultRequestDirector.tryConnect(DefaultRequestDirector.java:610) at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:445) at org.apache.http.impl.client.AbstractHttpClient.doExecute(AbstractHttpClient.java:835) at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:118) at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:56) at com.sun.jersey.client.apache4.ApacheHttpClient4Handler.handle(ApacheHttpClient4Handler.java:173) ... 107 common frames omitted2020-12-23 09:55:19.883 WARN 7022 --- [ main] c.n.d.s.t.d.RetryableEurekaHttpClient : Request execution failed with message: java.net.ConnectException: Connection refused (Connection refused)2020-12-23 09:55:19.883 ERROR 7022 --- [ main] com.netflix.discovery.DiscoveryClient : DiscoveryClient_APOLLO-CONFIGSERVICE/172.26.203.178:apollo-configservice:8080 - was unable to refresh its cache! status = Cannot execute request on any known servercom.netflix.discovery.shared.transport.TransportException: Cannot execute request on any known server at com.netflix.discovery.shared.transport.decorator.RetryableEurekaHttpClient.execute(RetryableEurekaHttpClient.java:112) at com.netflix.discovery.shared.transport.decorator.EurekaHttpClientDecorator.getApplications(EurekaHttpClientDecorator.java:134) at com.netflix.discovery.shared.transport.decorator.EurekaHttpClientDecorator$6.execute(EurekaHttpClientDecorator.java:137) at com.netflix.discovery.shared.transport.decorator.SessionedEurekaHttpClient.execute(SessionedEurekaHttpClient.java:77) at com.netflix.discovery.shared.transport.decorator.EurekaHttpClientDecorator.getApplications(EurekaHttpClientDecorator.java:134) at com.netflix.discovery.DiscoveryClient.getAndStoreFullRegistry(DiscoveryClient.java:1051) at com.netflix.discovery.DiscoveryClient.fetchRegistry(DiscoveryClient.java:965) at com.netflix.discovery.DiscoveryClient.<init>(DiscoveryClient.java:414) at com.netflix.discovery.DiscoveryClient.<init>(DiscoveryClient.java:269) at org.springframework.cloud.netflix.eureka.CloudEurekaClient.<init>(CloudEurekaClient.java:63) at org.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration$RefreshableEurekaClientConfiguration.eurekaClient(EurekaClientAutoConfiguration.java:290) at org.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration$RefreshableEurekaClientConfiguration$$EnhancerBySpringCGLIB$$5cf7ced9.CGLIB$eurekaClient$2(<generated>) at org.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration$RefreshableEurekaClientConfiguration$$EnhancerBySpringCGLIB$$5cf7ced9$$FastClassBySpringCGLIB$$328872d8.invoke(<generated>) at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:228) at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:365) at org.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration$RefreshableEurekaClientConfiguration$$EnhancerBySpringCGLIB$$5cf7ced9.eurekaClient(<generated>) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:582) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1247) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1096) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:535) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:495) at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$1(AbstractBeanFactory.java:353) at org.springframework.cloud.context.scope.GenericScope$BeanLifecycleWrapper.getBean(GenericScope.java:390) at org.springframework.cloud.context.scope.GenericScope.get(GenericScope.java:184) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:350) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) at org.springframework.aop.target.SimpleBeanTargetSource.getTarget(SimpleBeanTargetSource.java:35) at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:193) at com.sun.proxy.$Proxy145.getApplications(Unknown Source) at org.springframework.cloud.netflix.eureka.server.EurekaServerAutoConfiguration.peerAwareInstanceRegistry(EurekaServerAutoConfiguration.java:164) at org.springframework.cloud.netflix.eureka.server.EurekaServerAutoConfiguration$$EnhancerBySpringCGLIB$$ef07d99b.CGLIB$peerAwareInstanceRegistry$5(<generated>) at org.springframework.cloud.netflix.eureka.server.EurekaServerAutoConfiguration$$EnhancerBySpringCGLIB$$ef07d99b$$FastClassBySpringCGLIB$$458f0ac6.invoke(<generated>) at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:228) at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:365) at org.springframework.cloud.netflix.eureka.server.EurekaServerAutoConfiguration$$EnhancerBySpringCGLIB$$ef07d99b.peerAwareInstanceRegistry(<generated>) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:582) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1247) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1096) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:535) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:495) at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:317) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:315) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:251) at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1135) at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1062) at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:818) at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:724) at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:474) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1247) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1096) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:535) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:495) at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:317) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:315) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:251) at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1135) at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1062) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:583) at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:90) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:372) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1341) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:572) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:495) at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:317) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:315) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:759) at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:869) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550) at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140) at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:780) at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:412) at org.springframework.boot.SpringApplication.run(SpringApplication.java:333) at org.springframework.boot.SpringApplication.run(SpringApplication.java:1277) at org.springframework.boot.SpringApplication.run(SpringApplication.java:1265) at com.ctrip.framework.apollo.configservice.ConfigServiceApplication.main(ConfigServiceApplication.java:33)最终咱们就定位到这一行，定位问题的过程是一个非常复杂的事件。所以这里间接写明，并不是一开始我就晓得关键点在这里，这个须要平时多积攒知识面，能力疾速定位关键点
at com.netflix.discovery.DiscoveryClient.<init>(DiscoveryClient.java:414)。代码逻辑如下：if (clientConfig.shouldFetchRegistry() && !fetchRegistry(false)) { fetchRegistryFromBackup();}下面的异样就是这个中央触发的，在初始化eurekaClient时，会通过判断fetchRegistry来触发拉取eurekaServer端的注册表信息，然而这个时候eurekaServer还没筹备好，所以抛了如上的异样。fetchRegistry对应了Spring 初始化eurekaClient的一个配置，如：
//是否拉取注册表信息，如果配置为false，则代表只注册，通过eurekaClient获取不到任何实例eureka.client.fetch-registry=trueeurekaClient的结构
理解了异样触发的起因和触发的节点后，在来具体理解下eurekaClient在spring下是如何被加载的。间接定位到EurekaClientAutoConfiguration.java文件，找到如下的代码：
@Bean(destroyMethod = "shutdown")@ConditionalOnMissingBean(value = EurekaClient.class, search = SearchStrategy.CURRENT)@org.springframework.cloud.context.config.annotation.RefreshScope@Lazypublic EurekaClient eurekaClient(ApplicationInfoManager manager, EurekaClientConfig config, EurekaInstanceConfig instance) { manager.getInfo(); // force initialization return new CloudEurekaClient(manager, config, this.optionalArgs, this.context);}能够看到EurekaClientConfig是从上下文中注入到这个办法的，而且这个办法贴上了@RefreshScope的标记，代表这个实例能够被动静的刷新，有了这两个个性，咱们的解决方案就根本出炉了。通过程序动态控制eurekaClient的fetchRegistry加载机会也就变得可行了。
施行解决方案
最终的解决方案分成了两个关键步骤，如下：
- 1、configService启动前，设置fetchRegistry为false。
- 2、监听EurekaClient的注册事件，判断是否注册胜利，注册胜利则从新设置fetchRegistry为true，刷新eurekaClient上下文
针对步骤一，间接批改configService模块的bootstrap.yml配置文件，新增fetchRegistry为false的配置，如：
eureka: instance: hostname: ${hostname:localhost} preferIpAddress: true status-page-url-path: /info health-check-url-path: /health server: peerEurekaNodesUpdateIntervalMs: 60000 enableSelfPreservation: false client: serviceUrl: # This setting will be overridden by eureka.service.url setting from ApolloConfigDB.ServerConfig or System Property # see com.ctrip.framework.apollo.biz.eureka.ApolloEurekaClientConfig defaultZone: http://${eureka.instance.hostname}:8080/eureka/ healthcheck: enabled: true eurekaServiceUrlPollIntervalSeconds: 60 fetch-registry: falsemanagement: health: status: order: DOWN, OUT_OF_SERVICE, UNKNOWN, UP针对步骤二，新增了一个eurekaClient的配置类，如：
/** * @author : kl * After startup, set FetchRegistry to true, refresh eureka client **/@Configuration@ConditionalOnProperty(value = "eureka.client.enabled", havingValue = "true", matchIfMissing = true)public class ConfigServerEurekaClientConfigure { private static final String EUREKACLIENT_BEANNAME = "eurekaClient"; private final ApolloEurekaClientConfig eurekaClientConfig; private final AtomicBoolean isRefresh = new AtomicBoolean(false); private final RefreshScope refreshScope; public ConfigServerEurekaClientConfigure(ApolloEurekaClientConfig eurekaClientConfig, RefreshScope refreshScope) { this.eurekaClientConfig = eurekaClientConfig; this.refreshScope = refreshScope; } @EventListener public void listenEurekaInstanceRegisteredEvent(EurekaInstanceRegisteredEvent event) { InstanceInfo.InstanceStatus status = event.getInstanceInfo().getStatus(); if (InstanceInfo.InstanceStatus.UP.equals(status) && !eurekaClientConfig.isFetchRegistry()) { this.refreshEurekaClient(); } } private void refreshEurekaClient() { if (isRefresh.compareAndSet(false, true)) { eurekaClientConfig.setFetchRegistry(true); refreshScope.refresh(EUREKACLIENT_BEANNAME); } }}结语
通过革新后，存在了这么久的异样终于隐没了。整个过程还是有一些波折的，最后曾尝试过，自定义EurekaClient的初始化，妄想try住整个的实例化过程，接住异样自行处理，然而疏忽了fetchRegistry的过程是在一个新的线程里了。其次，最后的时候认为将fetchRegistry设置为false就ok了，而后在metaService服务获取configService时候啥也获取不到，才明确了fetchRegistry的真正用意。还尝试过将刷新EurekaClient的逻辑放在ApplicationRunner的run办法内，这个造成了后果时好时坏。最终随着对Eureka的深刻，才采纳了当初的计划，目前的计划还算完满。最初，心愿失去大家的测验反馈，早点合并到主干道，解决这个烦人的问题。