Eureka running processes

Process Description

1, the boot process analysis

1.1 @EnableEurekaServer notes, to mark the start of registry functionality

@EnableDiscoveryClient
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Import(EurekaServerMarkerConfiguration.class)
public @interface EnableEurekaServer {

}

Source There are two important operations

1, using annotations @EnableDiscoveryClent, open SpringCloud Notes client service discovery, since SpringCloud Eureka found more than support the assembly, also supports such as Dubbo Alibaba, etc. in service.

2, Import (EurekaServerMarkerConfiguration.Class), introduced configuration class, the configuration also instantiates a class of Marker bean.

Look at the source code to automatically configure EurekaServerAutoConfiguration

@Configuration
@Import(EurekaServerInitializerConfiguration.class)
@ConditionalOnBean(EurekaServerMarkerConfiguration.Marker.class)
@EnableConfigurationProperties({ EurekaDashboardProperties.class,
        InstanceRegistryProperties.class })
@PropertySource("classpath:/eureka/server.properties")
public class EurekaServerAutoConfiguration extends WebMvcConfigurerAdapter {...

1）自动配置类实例化的前提是上下文中存在EurekaServerMarkerConfiguration.Marker这个bean

2）通过@EnableConfigurationProperties({ EurekaDashboardProperties.class, InstanceRegistryProperties.class })导入了两个配置类

　　EurekaDashboardProperties用于控制eureka面板的启动及打开路径。

　　InstanceRegistryProperties 设置续约数量和通信数量

3）使用@Import导入配置类EurekaServerInitializerConfiguration.class

4）PropertySource控制字符集编码的;

1.2 配置类EurekaServerAutoConfiguration

1）实例化bean

@Bean
    public HasFeatures eurekaServerFeature() {
        return HasFeatures.namedFeature("Eureka Server",
                EurekaServerAutoConfiguration.class);
    }

　　2）在静态内部类中有条件的实例化了eureka服务端配置,配置类为 EurekaServerConfig；

@Configuration
    protected static class EurekaServerConfigBeanConfiguration {
        @Bean
        @ConditionalOnMissingBean
        public EurekaServerConfig eurekaServerConfig(EurekaClientConfig clientConfig) {
            EurekaServerConfigBean server = new EurekaServerConfigBean();
            if (clientConfig.shouldRegisterWithEureka()) {
                // Set a sensible default if we are supposed to replicate
                server.setRegistrySyncRetries(5);
            }
            return server;
        }
    }

View Code

　　3）实例化了进入eureka控制面板的Controller类:EurekaController:用于展示eureka面板

@Bean
    @ConditionalOnProperty(prefix = "eureka.dashboard", name = "enabled", matchIfMissing = true)
    public EurekaController eurekaController() {
        return new EurekaController(this.applicationInfoManager);
    }

View Code

　　4）eureka服务的Context维护

@Bean
    public EurekaServerContext eurekaServerContext(ServerCodecs serverCodecs,
            PeerAwareInstanceRegistry registry, PeerEurekaNodes peerEurekaNodes) {
        return new DefaultEurekaServerContext(this.eurekaServerConfig, serverCodecs,
                registry, peerEurekaNodes, this.applicationInfoManager);
    }

　　5）实例化了eureka多个服务维持节点同步的bean;初始化注册表

 @Bean
    public PeerAwareInstanceRegistry peerAwareInstanceRegistry(
            ServerCodecs serverCodecs) {
        this.eurekaClient.getApplications(); // force initialization
        return new InstanceRegistry(this.eurekaServerConfig, this.eurekaClientConfig,
                serverCodecs, this.eurekaClient,
                this.instanceRegistryProperties.getExpectedNumberOfRenewsPerMin(),
                this.instanceRegistryProperties.getDefaultOpenForTrafficCount());
    }

　　6）管理每个eureka服务节点的生命周期

  @Bean
    @ConditionalOnMissingBean
    public PeerEurekaNodes peerEurekaNodes(PeerAwareInstanceRegistry registry,
            ServerCodecs serverCodecs) {
        return new PeerEurekaNodes(registry, this.eurekaServerConfig,
                this.eurekaClientConfig, serverCodecs, this.applicationInfoManager);
    }

　　7）通过tomcat维护管理eureka生命周期

@Bean
    public EurekaServerBootstrap eurekaServerBootstrap(PeerAwareInstanceRegistry registry,
            EurekaServerContext serverContext) {
        return new EurekaServerBootstrap(this.applicationInfoManager,
                this.eurekaClientConfig, this.eurekaServerConfig, registry,
                serverContext);
    }

1.3 Eureka服务的启动

　　1）在EurekaServerBootstrap类中我们看到了初始化方法:

 public void contextInitialized(ServletContext context) {
        try {

            //看源码可知这里主要初始化服务环境,配置信息;
            initEurekaEnvironment();
           
            //初始化了eureka服务端的上下文
            initEurekaServerContext();

            context.setAttribute(EurekaServerContext.class.getName(), this.serverContext);
        }
        catch (Throwable e) {
            log.error("Cannot bootstrap eureka server :", e);
            throw new RuntimeException("Cannot bootstrap eureka server :", e);
        }
    }

　　在这个方法中我们看到了初始化eureka-server环境配置及eureka-server上下文的操作,那么这个方法应该在一个地方有调用,通过查找调用发现:

@Configuration
@CommonsLog
public class EurekaServerInitializerConfiguration
        implements ServletContextAware, SmartLifecycle, Ordered {

   @Override
    public void start() {
        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    //TODO: is this class even needed now?
                     
eurekaServerBootstrap.contextInitialized(EurekaServerInitializerConfiguration.this.servletContext);
                    log.info("Started Eureka Server");

                    publish(new EurekaRegistryAvailableEvent(getEurekaServerConfig()));
                    EurekaServerInitializerConfiguration.this.running = true;
                    publish(new EurekaServerStartedEvent(getEurekaServerConfig()));
                }
                catch (Exception ex) {
                    // Help!
                    log.error("Could not initialize Eureka servlet context", ex);
                }
            }
        }).start();
    }


    @Override
    public void stop() {
        this.running = false;
        eurekaServerBootstrap.contextDestroyed(this.servletContext);
    }

 ..... 部分代码省略.....

}

　　EurekaServerInitializerConfiguration中操作如下：

　　　　1）start()初始化，

eurekaServerBootstrap.contextInitialized(EurekaServerInitializerConfiguration.this.servletContext);
                    log.info("Started Eureka Server");

　　　　2）发布EurekaServer的注册事件pubilsh

publish(new EurekaRegistryAvailableEvent(getEurekaServerConfig()));

　　　　3）发布Eureka Start事件的pubilsh

publish(new EurekaServerStartedEvent(getEurekaServerConfig()));

　　那么在启动eureka服务有哪些操作呢?深入跟进下源码.

 protected void initEurekaServerContext() throws Exception {
        // For backward compatibility
        JsonXStream.getInstance().registerConverter(new V1AwareInstanceInfoConverter(),
                XStream.PRIORITY_VERY_HIGH);
        XmlXStream.getInstance().registerConverter(new V1AwareInstanceInfoConverter(),
                XStream.PRIORITY_VERY_HIGH);

        if (isAws(this.applicationInfoManager.getInfo())) {
            this.awsBinder = new AwsBinderDelegate(this.eurekaServerConfig,
                    this.eurekaClientConfig, this.registry, this.applicationInfoManager);
            this.awsBinder.start();
        }

        EurekaServerContextHolder.initialize(this.serverContext);

        log.info("Initialized server context");

        // Copy registry from neighboring eureka node
　　　　　//服务同步
        int registryCount = this.registry.syncUp();
　　　　　//服务剔除
        this.registry.openForTraffic(this.applicationInfoManager, registryCount);

        // Register all monitoring statistics.
        EurekaMonitors.registerAllStats();
    }

在初始化eureka服务端initEurekaServerContext()方法中,主要做了初始化server上下文,同步了其他节点的信息,启动了剔除不可用eureka客户端的定时任务;

Spring Cloud Eureka service running process principles