start包配置
spring-cloud-netflix-eureka-server包结构
在这个包下面META-INF下面有个spring.factories这个配置文件
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
org.springframework.cloud.netflix.eureka.server.EurekaServerAutoConfiguration
使用了springboot EnableAutoConfiguration这个注解，在springboot应用启动的时候，会自动加载EurekaServerAutoConfiguration这个bean，后面主要看这个bean的源码
启动源码分析
EurekaServerAutoConfiguration
用于EurekaServer往beanfactory添加相关eureka-server功能bean
@Configuration
@Import(EurekaServerInitializerConfiguration.class)
@ConditionalOnBean(EurekaServerMarkerConfiguration.Marker.class)
@EnableConfigurationProperties({ EurekaDashboardProperties.class,
InstanceRegistryProperties.class })
@PropertySource("classpath:/eureka/server.properties")
public class EurekaServerAutoConfiguration extends WebMvcConfigurerAdapter {
// 此处省略大部分代码，仅抽取一些关键的代码片段
// 加载EurekaController, spring-cloud 提供了一些额外的接口，用来获取eurekaServer的信息
@Bean
@ConditionalOnProperty(prefix = "eureka.dashboard", name = "enabled", matchIfMissing = true)
public EurekaController eurekaController() {
return new EurekaController(this.applicationInfoManager);
}
// 配置服务节点信息，这里的作用主要是为了配置Eureka的peer节点，也就是说当有收到有节点注册上来
//的时候，需要通知给那些服务节点， （互为一个集群）
@Bean
@ConditionalOnMissingBean
public PeerEurekaNodes peerEurekaNodes(PeerAwareInstanceRegistry registry,
ServerCodecs serverCodecs) {
return new PeerEurekaNodes(registry, this.eurekaServerConfig,
this.eurekaClientConfig, serverCodecs, this.applicationInfoManager);
}
// EurekaServer的上下文
@Bean
public EurekaServerContext eurekaServerContext(ServerCodecs serverCodecs,
PeerAwareInstanceRegistry registry, PeerEurekaNodes peerEurekaNodes) {
return new DefaultEurekaServerContext(this.eurekaServerConfig, serverCodecs,
registry, peerEurekaNodes, this.applicationInfoManager);
}
// 这个类的作用是spring-cloud和原生eureka的胶水代码，通过这个类来启动EurekaSever
// 后面这个类会在EurekaServerInitializerConfiguration被调用，进行eureka启动
@Bean
public EurekaServerBootstrap eurekaServerBootstrap(PeerAwareInstanceRegistry registry,
EurekaServerContext serverContext) {
return new EurekaServerBootstrap(this.applicationInfoManager,
this.eurekaClientConfig, this.eurekaServerConfig, registry,
serverContext);
}
// 配置拦截器，ServletContainer里面实现了jersey框架，通过他来实现eurekaServer对外的restFull接口
@Bean
public FilterRegistrationBean jerseyFilterRegistration(
javax.ws.rs.core.Application eurekaJerseyApp) {
FilterRegistrationBean bean = new FilterRegistrationBean();
bean.setFilter(new ServletContainer(eurekaJerseyApp));
bean.setOrder(Ordered.LOWEST_PRECEDENCE);
bean.setUrlPatterns(
Collections.singletonList(EurekaConstants.DEFAULT_PREFIX + "/*"));
return bean;
}
// 拦截器实例
@Bean
public javax.ws.rs.core.Application jerseyApplication(Environment environment,
ResourceLoader resourceLoader) {
ClassPathScanningCandidateComponentProvider provider = new ClassPathScanningCandidateComponentProvider(
false, environment);
// Filter to include only classes that have a particular annotation.
//
provider.addIncludeFilter(new AnnotationTypeFilter(Path.class));
provider.addIncludeFilter(new AnnotationTypeFilter(Provider.class));
// Find classes in Eureka packages (or subpackages)
//
Set<Class<?>> classes = new HashSet<Class<?>>();
for (String basePackage : EUREKA_PACKAGES) {
Set<BeanDefinition> beans = provider.findCandidateComponents(basePackage);
for (BeanDefinition bd : beans) {
Class<?> cls = ClassUtils.resolveClassName(bd.getBeanClassName(),
resourceLoader.getClassLoader());
classes.add(cls);
}
}
// Construct the Jersey ResourceConfig
//
Map<String, Object> propsAndFeatures = new HashMap<String, Object>();
propsAndFeatures.put(
// Skip static content used by the webapp
ServletContainer.PROPERTY_WEB_PAGE_CONTENT_REGEX,
EurekaConstants.DEFAULT_PREFIX + "/(fonts|images|css|js)/.*");
DefaultResourceConfig rc = new DefaultResourceConfig(classes);
rc.setPropertiesAndFeatures(propsAndFeatures);
return rc;
}
}
1.@Configuration 表明这是一个配置类
2.@Import(EurekaServerInitializerConfiguration.class) 导入启动EurekaServer的bean
3.@ConditionalOnBean(EurekaServerMarkerConfiguration.Marker.class) 这个是表示只有在spring容器里面含有Market这个实例的时候，才会加载当前这个Bean（EurekaServerAutoConfiguration ），这个就是控制是否开启EurekaServer的关键，在@EableEurekaServer这个注解里面，就是创建了一个Market兑现，用来告诉他，我开启了Eureka服务
4.@EnableConfigurationProperties({ EurekaDashboardProperties.class, InstanceRegistryProperties.class })
5.@PropertySource("classpath:/eureka/server.properties") 加载配置文件。
EurekaServerInitializerConfiguration
从上面的代码分析上可以看到，在EurekaServerAutoConfiguration加载完成之后就会执行
EurekaServerInitializerConfiguration这个类的start方法， 这个类实现了spring的SmartLifecyl,后续会开个单章介绍这个类
/**
* @author Dave Syer
*/
@Configuration
@CommonsLog
public class EurekaServerInitializerConfiguration
implements ServletContextAware, SmartLifecycle, Ordered {
@Autowired
private EurekaServerConfig eurekaServerConfig;
private ServletContext servletContext;
@Autowired
private ApplicationContext applicationContext;
@Autowired
private EurekaServerBootstrap eurekaServerBootstrap;
private boolean running;
private int order = 1;
@Override
public void setServletContext(ServletContext servletContext) {
this.servletContext = servletContext;
}
@Override
public void start() {
// 启动一个线程
new Thread(new Runnable() {
@Override
public void run() {
try {
//初始化EurekaServer，同时启动Eureka Server ，后面着重讲这里
eurekaServerBootstrap.contextInitialized(EurekaServerInitializerConfiguration.this.servletContext);
log.info("Started Eureka Server");
// 发布EurekaServer的注册事件
publish(new EurekaRegistryAvailableEvent(getEurekaServerConfig()));
// 设置启动的状态为true
EurekaServerInitializerConfiguration.this.running = true;
// 发送Eureka Start 事件 ， 其他还有各种事件，我们可以监听这种时间，然后做一些特定的业务需求，后面会讲到。
publish(new EurekaServerStartedEvent(getEurekaServerConfig()));
}
catch (Exception ex) {
// Help!
log.error("Could not initialize Eureka servlet context", ex);
}
}
}).start();
}
private EurekaServerConfig getEurekaServerConfig() {
return this.eurekaServerConfig;
}
private void publish(ApplicationEvent event) {
this.applicationContext.publishEvent(event);
}
@Override
public void stop() {
this.running = false;
eurekaServerBootstrap.contextDestroyed(this.servletContext);
}
@Override
public boolean isRunning() {
return this.running;
}
@Override
public int getPhase() {
return 0;
}
@Override
public boolean isAutoStartup() {
return true;
}
@Override
public void stop(Runnable callback) {
callback.run();
}
@Override
public int getOrder() {
return this.order;
}
}
EurekaServerBootstrap
public void contextInitialized(ServletContext context) {
try {
// 初始化Eureka的环境变量
initEurekaEnvironment();
// 初始化Eureka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);
}
}
protected void initEurekaEnvironment() throws Exception {
log.info("Setting the eureka configuration..");
String dataCenter = ConfigurationManager.getConfigInstance()
.getString(EUREKA_DATACENTER);
if (dataCenter == null) {
log.info(
"Eureka data center value eureka.datacenter is not set, defaulting to default");
ConfigurationManager.getConfigInstance()
.setProperty(ARCHAIUS_DEPLOYMENT_DATACENTER, DEFAULT);
}
else {
ConfigurationManager.getConfigInstance()
.setProperty(ARCHAIUS_DEPLOYMENT_DATACENTER, dataCenter);
}
String environment = ConfigurationManager.getConfigInstance()
.getString(EUREKA_ENVIRONMENT);
if (environment == null) {
ConfigurationManager.getConfigInstance()
.setProperty(ARCHAIUS_DEPLOYMENT_ENVIRONMENT, TEST);
log.info(
"Eureka environment value eureka.environment is not set, defaulting to test");
}
else {
ConfigurationManager.getConfigInstance()
.setProperty(ARCHAIUS_DEPLOYMENT_ENVIRONMENT, environment);
}
}
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();
}
//初始化eureka server上下文
EurekaServerContextHolder.initialize(this.serverContext);
log.info("Initialized server context");
// Copy registry from neighboring eureka node
// 从相邻的eureka节点复制注册表
int registryCount = this.registry.syncUp();
// 默认每30秒发送心跳，1分钟就是2次
// 修改eureka状态为up
// 同时，这里面会开启一个定时任务，用于清理 60秒没有心跳的客户端。自动下线
this.registry.openForTraffic(this.applicationInfoManager, registryCount);
// Register all monitoring statistics.
EurekaMonitors.registerAllStats();
}
public void contextDestroyed(ServletContext context) {
try {
log.info("Shutting down Eureka Server..");
context.removeAttribute(EurekaServerContext.class.getName());
destroyEurekaServerContext();
destroyEurekaEnvironment();
}
catch (Throwable e) {
log.error("Error shutting down eureka", e);
}
log.info("Eureka Service is now shutdown...");
}
PeerAwareInstanceRegistryImpl
@Override
public void openForTraffic(ApplicationInfoManager applicationInfoManager, int count) {
// Renewals happen every 30 seconds and for a minute it should be a factor of 2.
// 计算每分钟最大续约数
this.expectedNumberOfRenewsPerMin = count * 2;
// 每分钟最小续约数
this.numberOfRenewsPerMinThreshold =
(int) (this.expectedNumberOfRenewsPerMin * serverConfig.getRenewalPercentThreshold());
logger.info("Got " + count + " instances from neighboring DS node");
logger.info("Renew threshold is: " + numberOfRenewsPerMinThreshold);
this.startupTime = System.currentTimeMillis();
if (count > 0) {
this.peerInstancesTransferEmptyOnStartup = false;
}
DataCenterInfo.Name selfName = applicationInfoManager.getInfo().getDataCenterInfo().getName();
boolean isAws = Name.Amazon == selfName;
if (isAws && serverConfig.shouldPrimeAwsReplicaConnections()) {
logger.info("Priming AWS connections for all replicas..");
primeAwsReplicas(applicationInfoManager);
}
logger.info("Changing status to UP");
// 设置实例的状态为UP
applicationInfoManager.setInstanceStatus(InstanceStatus.UP);
// 开启定时任务，默认60秒执行一次，用于清理60秒之内没有续约的实例
super.postInit();
}
PeerEurekaNodes
从上面的EurekaServerAutoConfiguration类，我们可以看到有个初始化EurekaServerContext的方法
@Bean
public EurekaServerContext eurekaServerContext(ServerCodecs serverCodecs,
PeerAwareInstanceRegistry registry, PeerEurekaNodes peerEurekaNodes) {
return new DefaultEurekaServerContext(this.eurekaServerConfig, serverCodecs,
registry, peerEurekaNodes, this.applicationInfoManager);
}
DefaultEurekaServerContext 这个类里面的的initialize()方法是被@PostConstruct 这个注解修饰的,在应用加载的时候，会执行这个方法
public void initialize() throws Exception {
logger.info("Initializing ...");
// 启动一个线程，读取其他集群节点的信息，后面后续复制
peerEurekaNodes.start();
//
registry.init(peerEurekaNodes);
logger.info("Initialized");
}
peerEurekaNodes.start()主要是启动一个只拥有一个线程的线程池，第一次进去会更新一下集群其他节点信息
然后启动了一个定时线程，每60秒更新一次，也就是说后续可以根据配置动态的修改节点配置。（原生的spring cloud config支持）
PeerEurekaNodes
public void start() {
taskExecutor = Executors.newSingleThreadScheduledExecutor(
new ThreadFactory() {
@Override
public Thread newThread(Runnable r) {
Thread thread = new Thread(r, "Eureka-PeerNodesUpdater");
thread.setDaemon(true);
return thread;
}
}
);
try {
// 首次进来，更新集群节点信息
updatePeerEurekaNodes(resolvePeerUrls());
// 搞个线程
Runnable peersUpdateTask = new Runnable() {
@Override
public void run() {
try {
updatePeerEurekaNodes(resolvePeerUrls());
} catch (Throwable e) {
logger.error("Cannot update the replica Nodes", e);
}
}
};
taskExecutor.scheduleWithFixedDelay(
peersUpdateTask,
serverConfig.getPeerEurekaNodesUpdateIntervalMs(),
serverConfig.getPeerEurekaNodesUpdateIntervalMs(),
TimeUnit.MILLISECONDS
);
} catch (Exception e) {
throw new IllegalStateException(e);
}
for (PeerEurekaNode node : peerEurekaNodes) {
logger.info("Replica node URL: " + node.getServiceUrl());
}
}
// 根据URL 构建PeerEurekaNode信息
protected PeerEurekaNode createPeerEurekaNode(String peerEurekaNodeUrl) {
HttpReplicationClient replicationClient = JerseyReplicationClient.createReplicationClient(serverConfig, serverCodecs, peerEurekaNodeUrl);
String targetHost = hostFromUrl(peerEurekaNodeUrl);
if (targetHost == null) {
targetHost = "host";
}
return new PeerEurekaNode(registry, targetHost, peerEurekaNodeUrl, replicationClient, serverConfig);
}
registry.init(peerEurekaNodes);这里面使用的是PeerAwareInstanceRegistryImpl ， 注册信息管理类里面的init方法
- 构建一个非空的ResponseCache
- 启动一个定时器，更新eureka的阈值 ，默认每15分钟执行一次 ， 这个阈值主要是用来判断是否开启自我保护机制 , 后面会单独开篇幅来讲解
@Override
public void init(PeerEurekaNodes peerEurekaNodes) throws Exception {
this.numberOfReplicationsLastMin.start();
this.peerEurekaNodes = peerEurekaNodes;
initializedResponseCache();
scheduleRenewalThresholdUpdateTask();
initRemoteRegionRegistry();
try {
Monitors.registerObject(this);
} catch (Throwable e) {
logger.warn("Cannot register the JMX monitor for the InstanceRegistry :", e);
}
}
至此，EurekaServer算是启动完毕 ， EurekaServerBootstrap是完全复制了原生EurekaBootstrap的代码， 因为原生的Eureka是在servlet应用，但是spring-cloud的应用是运行在内嵌的Tomcat等WEB服务器里面的，这里就是使用EurekaServerBootstrap来做替换，最终是Eureka能够在springboot中使用。
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