EurekaServer在SpringCloud中的启动分析
1、@EnableEurekaServer
1、我们肯定是需要引用一些 jar 包，这个就不多说了，前面的文章中也有
2、在EurekaServer 项目中我们会在 Application 启动类上加上一个注解，@EnableEurekaServer 注解，那我们就从这个注解说起吧。
@SpringBootApplication
@EnableEurekaServer// 这里我们会添加这个注解开启 EurekaServer 服务
public class EurekaServer {
public static void main(String[] args) {
SpringApplication.run(EurekaServer.class, args);
}
}
下面就是 @EnableEurekaServer 在 jar 包中的位置
1.1 EurekaServerAutoConfiguration(自动装配的类)
@Configuration
// 这个类要注意了，其实重点就是这里。
@Import(EurekaServerInitializerConfiguration.class)
// 这个是就是一个条件判断，这个EurekaServerMarkerConfiguration.Marker.class其实在 @EnableEurekaServer注解里会 import 这个类
@ConditionalOnBean(EurekaServerMarkerConfiguration.Marker.class)
// 这时就是启用配置文件
@EnableConfigurationProperties({
EurekaDashboardProperties.class,
InstanceRegistryProperties.class })
// 这个刚刚在上面的截图中也可以看到，这个配置文件就在 jar 包对应的目录下
@PropertySource("classpath:/eureka/server.properties")
public class EurekaServerAutoConfiguration extends WebMvcConfigurerAdapter {
/**
* List of packages containing Jersey resources required by the Eureka server
*/
private static String[] EUREKA_PACKAGES = new String[] {
"com.netflix.discovery",
"com.netflix.eureka" };
// 这个应用管理器，我们在 EurekaServer启动的时候分析过，初始化的时候会去实例化这个类
@Autowired
private ApplicationInfoManager applicationInfoManager;
// 这个就是 EurekaServer 的配置类
@Autowired
private EurekaServerConfig eurekaServerConfig;
// EurekaServer 作为 client 的配置类
@Autowired
private EurekaClientConfig eurekaClientConfig;
// EurekaClient 类
@Autowired
private EurekaClient eurekaClient;
// 实例注册的属性类
@Autowired
private InstanceRegistryProperties instanceRegistryProperties;
// json 相关的类
public static final CloudJacksonJson JACKSON_JSON = new CloudJacksonJson();
//可以看出来大部分类就是 Eureka 中类
@Bean
public HasFeatures eurekaServerFeature() {
System.out.println(EurekaServerAutoConfiguration.class.getName() + ",enter eurekaServerFeature()....");
return HasFeatures.namedFeature("Eureka Server",
EurekaServerAutoConfiguration.class);
}
@Configuration
protected static class EurekaServerConfigBeanConfiguration {
@Bean
@ConditionalOnMissingBean
public EurekaServerConfig eurekaServerConfig(EurekaClientConfig clientConfig) {
System.out.println(EurekaServerAutoConfiguration.class.getName() + ",enter EurekaServerConfigBeanConfiguration.eurekaServerConfig()...."
+ ",shouldRegisterWithEureka:" + clientConfig.shouldRegisterWithEureka());
EurekaServerConfigBean server = new EurekaServerConfigBean();
if (clientConfig.shouldRegisterWithEureka()) {
// Set a sensible default if we are supposed to replicate
server.setRegistrySyncRetries(5);
}
return server;
}
}
@Bean
@ConditionalOnProperty(prefix = "eureka.dashboard", name = "enabled", matchIfMissing = true)
public EurekaController eurekaController() {
System.out.println(EurekaServerAutoConfiguration.class.getName() + ",enter eurekaController()....");
return new EurekaController(this.applicationInfoManager);
}
static {
CodecWrappers.registerWrapper(JACKSON_JSON);
EurekaJacksonCodec.setInstance(JACKSON_JSON.getCodec());
}
@Bean
public ServerCodecs serverCodecs() {
return new CloudServerCodecs(this.eurekaServerConfig);
}
private static CodecWrapper getFullJson(EurekaServerConfig serverConfig) {
CodecWrapper codec = CodecWrappers.getCodec(serverConfig.getJsonCodecName());
return codec == null ? CodecWrappers.getCodec(JACKSON_JSON.codecName()) : codec;
}
private static CodecWrapper getFullXml(EurekaServerConfig serverConfig) {
CodecWrapper codec = CodecWrappers.getCodec(serverConfig.getXmlCodecName());
return codec == null ? CodecWrappers.getCodec(CodecWrappers.XStreamXml.class)
: codec;
}
class CloudServerCodecs extends DefaultServerCodecs {
public CloudServerCodecs(EurekaServerConfig serverConfig) {
super(getFullJson(serverConfig),
CodecWrappers.getCodec(CodecWrappers.JacksonJsonMini.class),
getFullXml(serverConfig),
CodecWrappers.getCodec(CodecWrappers.JacksonXmlMini.class));
}
}
@Bean
public PeerAwareInstanceRegistry peerAwareInstanceRegistry(
ServerCodecs serverCodecs) {
// 这个也知道吧，就是可以感知eureka server集群的服务实例注册表
System.out.println(EurekaServerAutoConfiguration.class.getName() + ",enter peerAwareInstanceRegistry()...."
+ ",EurekaClient:" + JSONUtil.toJsonStr(eurekaClient));
// eurekaClient 此时是一个代理对象：org.springframework.cloud.netflix.eureka.CloudEurekaClient@527d48db
System.out.println(LocalDateTime.now() + "," + EurekaServerAutoConfiguration.class.getName() + ",enter peerAwareInstanceRegistry()...."
+ ",before getApplications()...");
// 去实例化 ApplicationInfoManager
this.eurekaClient.getApplications(); // force initialization
System.out.println(LocalDateTime.now() + "," + EurekaServerAutoConfiguration.class.getName() + ",enter peerAwareInstanceRegistry()...."
+ ",after getApplications()...");
return new InstanceRegistry(this.eurekaServerConfig, this.eurekaClientConfig,
serverCodecs, this.eurekaClient,
this.instanceRegistryProperties.getExpectedNumberOfRenewsPerMin(),
this.instanceRegistryProperties.getDefaultOpenForTrafficCount());
}
@Bean
@ConditionalOnMissingBean
public PeerEurekaNodes peerEurekaNodes(PeerAwareInstanceRegistry registry,
ServerCodecs serverCodecs) {
// 这个就是 PeerEurekaNods 嘛，代表某一个 EurekaServer 节点
System.out.println(EurekaServerAutoConfiguration.class.getName() + ",enter peerEurekaNodes()....");
return new PeerEurekaNodes(registry, this.eurekaServerConfig,
this.eurekaClientConfig, serverCodecs, this.applicationInfoManager);
}
@Bean
public EurekaServerContext eurekaServerContext(ServerCodecs serverCodecs,
PeerAwareInstanceRegistry registry, PeerEurekaNodes peerEurekaNodes) {
// 这个不就是EurekaServer上下文对象嘛
System.out.println(EurekaServerAutoConfiguration.class.getName() + ",enter eurekaServerContext()....");
return new DefaultEurekaServerContext(this.eurekaServerConfig, serverCodecs,
registry, peerEurekaNodes, this.applicationInfoManager);
}
@Bean
public EurekaServerBootstrap eurekaServerBootstrap(PeerAwareInstanceRegistry registry,
EurekaServerContext serverContext) {
// 这个类看着有点熟悉吧，是不是很像我们分析的 EurekaServer 启动类的入口类。
System.out.println(EurekaServerAutoConfiguration.class.getName() + ",enter eurekaServerBootstrap()....");
return new EurekaServerBootstrap(this.applicationInfoManager,
this.eurekaClientConfig, this.eurekaServerConfig, registry,
serverContext);
}
/**
* Register the Jersey filter
*/
@Bean
public FilterRegistrationBean jerseyFilterRegistration(
javax.ws.rs.core.Application eurekaJerseyApp) {
// 这里其实我们在 EurekaServer 源码里看到过就是在 web.xml 中配置的过滤器
FilterRegistrationBean bean = new FilterRegistrationBean();
bean.setFilter(new ServletContainer(eurekaJerseyApp));
bean.setOrder(Ordered.LOWEST_PRECEDENCE);
bean.setUrlPatterns(
Collections.singletonList(EurekaConstants.DEFAULT_PREFIX + "/*"));
return bean;
}
/**
* Construct a Jersey {@Linkjavax.ws.rs.core.Application} with all the resources
* required by the Eureka server.
*/
@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;
}
@Bean
public FilterRegistrationBean traceFilterRegistration(
@Qualifier("webRequestLoggingFilter") Filter filter) {
FilterRegistrationBean bean = new FilterRegistrationBean();
bean.setFilter(filter);
bean.setOrder(Ordered.LOWEST_PRECEDENCE - 10);
return bean;
}
}
好了，大概我们看一下这个自动装配的类，大部分对象就是我们之前分析的类。我覆盖了这个类，然后自己在代码里打了很多日志，然后可以在启动的时候观察一下日志输出，进而可以更好的理解代码的运行流程。建议使用 logger 打印，他可以打印出线程呀什么的信息，很方便。这里我只是为了方便，所以用了 System.out.println
1.2 EurekaServerInitializerConfigurationEurekaServerInitializerConfiguration(刚刚说了这个是重点要看的，从命名看应该是服务初始化配置类)
@Configuration
public class EurekaServerInitializerConfiguration
implements ServletContextAware, SmartLifecycle, Ordered {
private static final Log log = LogFactory.getLog(EurekaServerInitializerConfiguration.class);
@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) {
System.out.println(EurekaServerInitializerConfiguration.class.getName() + ",enter setServletContext()....");
this.servletContext = servletContext;
}
@Override
public void start() {
new Thread(new Runnable() {
@Override
public void run() {
try {
System.out.println(EurekaServerInitializerConfiguration.class.getName() + ",enter start()....");
//TODO: is this class even needed now?
// 这里有一个初始化方法的调用，我们来看一下他吧
eurekaServerBootstrap.contextInitialized(EurekaServerInitializerConfiguration.this.servletContext);
log.info("Started Eureka Server");
// 1、发布 Eureka 注册表可用的事件
publish(new EurekaRegistryAvailableEvent(getEurekaServerConfig()));
// 2、EurekaServer 初始化配置状态更新
EurekaServerInitializerConfiguration.this.running = true;
// 3、发布 EurekaServer 启动的事件
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;
}
}
1.3 EurekaServerBootstrap
public void contextInitialized(ServletContext context) {
try {
System.out.println(EurekaServerBootstrap.class.getName() + ",enter contextInitialized()....");
// 看到没有，这些代码熟悉不，不就是EurekaServer 的那些嘛，这不就是复制过来的嘛
initEurekaEnvironment();
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);
}
}
2、我们通过启动日志来分析一下流程
1、实例化 EurekaServerConfig(加载 eurekaServer 的配置)
org.springframework.cloud.netflix.eureka.server.EurekaServerAutoConfiguration,enter EurekaServerConfigBeanConfiguration.eurekaServerConfig()....
2、实例化 HasFeatures
org.springframework.cloud.netflix.eureka.server.EurekaServerAutoConfiguration,enter eurekaServerFeature()....
3、实例化 PeerAwareInstanceRegistry
org.springframework.cloud.netflix.eureka.server.EurekaServerAutoConfiguration,enter peerAwareInstanceRegistry()....
1)、开启 2 个定时任务
2)、renewsLastMin(上一分钟续约的数据)、DeltaRetentionTask(增量数据保留的定时任务,就是维护在一个 queue 中的数据，180s 后自动剔除)
4、创建 DiscoveryClient
2021-12-19 12:32:48.524 INFO 10272 --- [ main] o.s.c.n.eureka.InstanceInfoFactory : Setting initial instance status as: STARTING
2021-12-19 12:32:48.554 INFO 10272 --- [ main] com.netflix.discovery.DiscoveryClient : Initializing Eureka in region us-east-1
2021-12-19 12:32:48.554 INFO 10272 --- [ main] com.netflix.discovery.DiscoveryClient : Client configured to neither register nor query for data.
2021-12-19 12:32:48.559 INFO 10272 --- [ main] com.netflix.discovery.DiscoveryClient : Discovery Client initialized at timestamp 1639888368559 with initial instances count: 0
5、实例化 PeerEurekaNodes
org.springframework.cloud.netflix.eureka.server.EurekaServerAutoConfiguration,enter peerEurekaNodes()....
6、实例化 EurekaServerContext
org.springframework.cloud.netflix.eureka.server.EurekaServerAutoConfiguration,enter eurekaServerContext()....
2021-12-19 12:32:48.602 INFO 10272 --- [ main] c.n.eureka.DefaultEurekaServerContext : Initializing ...
1)、更新 eureka server 节点，并开启定时任务(10 分钟一次)
2)、初始化注册表信息：
PeerAwareInstanceRegistryImpl:
1>上一分钟 replication 数目定时任务开启
2>、初始化注册表缓存
3>、续约阈值更新定时任务
4>、初始化 regionRegistry
2021-12-19 12:32:48.604 INFO 10272 --- [ main] c.n.eureka.cluster.PeerEurekaNodes : Adding new peer nodes [http://localhost:8761/eureka/]
2021-12-19 12:32:49.510 INFO 10272 --- [ main] c.n.d.provider.DiscoveryJerseyProvider : Using JSON encoding codec LegacyJacksonJson
2021-12-19 12:32:49.510 INFO 10272 --- [ main] c.n.d.provider.DiscoveryJerseyProvider : Using JSON decoding codec LegacyJacksonJson
2021-12-19 12:32:49.510 INFO 10272 --- [ main] c.n.d.provider.DiscoveryJerseyProvider : Using XML encoding codec XStreamXml
2021-12-19 12:32:49.510 INFO 10272 --- [ main] c.n.d.provider.DiscoveryJerseyProvider : Using XML decoding codec XStreamXml
2021-12-19 12:32:49.595 INFO 10272 --- [ main] c.n.eureka.cluster.PeerEurekaNodes : Replica node URL: http://localhost:8761/eureka/
2021-12-19 12:32:49.599 INFO 10272 --- [ main] c.n.e.registry.AbstractInstanceRegistry : Finished initializing remote region registries. All known remote regions: []
2021-12-19 12:32:49.599 INFO 10272 --- [ main] c.n.eureka.DefaultEurekaServerContext : Initialized
7、实例化 EurekaServerBootstrap
org.springframework.cloud.netflix.eureka.server.EurekaServerAutoConfiguration,enter eurekaServerBootstrap()....
org.springframework.cloud.netflix.eureka.server.EurekaServerInitializerConfiguration,enter setServletContext()....
8、实例化 EurekaController
org.springframework.cloud.netflix.eureka.server.EurekaServerAutoConfiguration,enter eurekaController()....
9、开始服务注册
2021-12-19T12:32:49.705,org.springframework.cloud.netflix.eureka.serviceregistry.EurekaServiceRegistry, enter register()....
2021-12-19 12:32:49.705 INFO 10272 --- [ main] o.s.c.n.e.s.EurekaServiceRegistry : Registering application unknown with eureka with status UP
10、ApplicationInfoManager 设置 instanceStatus()，并发布事件
2021-12-19T12:32:49.706,com.netflix.appinfo.ApplicationInfoManager,enter setInstanceStatus()...{}
11、EurekaServerInitializerConfiguration 初始化(进入 start()，利用的是 spring 的生命周期触发)
org.springframework.cloud.netflix.eureka.server.EurekaServerInitializerConfiguration,enter start()....
1)、EureakaServerBootstrap 初始化
org.springframework.cloud.netflix.eureka.server.EurekaServerBootstrap,enter contextInitialized()....
1>、initEurekaEnvironment 初始化 eureka 环境变量
2>、initEurekaServerContext 初始化 eurekaServer 上下文
a、this.registry.syncUp() 相邻节点 registry(注册表) 拷贝
b、this.registry.openForTraffic
2021-12-19 12:32:49.755 INFO 10272 --- [ Thread-35] o.s.c.n.e.server.EurekaServerBootstrap : Setting the eureka configuration..
org.springframework.cloud.netflix.eureka.server.EurekaServerBootstrap,enter initEurekaEnvironment()....
2021-12-19 12:32:49.755 INFO 10272 --- [ Thread-35] o.s.c.n.e.server.EurekaServerBootstrap : Eureka data center value eureka.datacenter is not set, defaulting to default
org.springframework.cloud.netflix.eureka.server.EurekaServerBootstrap,enter initEurekaEnvironment()....{"listDelimiter":",","substitutor":{"escapeChar":"$","enableSubstitutionInVariables":false,"variableResolver":{"defaultLookup":{}}},"throwExceptionOnMissing":false,"errorListeners":[],"containerConfiguration":{"listDelimiter":",","substitutor":{"escapeChar":"$","enableSubstitutionInVariables":false,"variableResolver":{"defaultLookup":{}}},"throwExceptionOnMissing":false,"errorListeners":[],"delimiterParsingDisabled":false},"delimiterParsingDisabled":false}
2021-12-19 12:32:49.807 INFO 10272 --- [ Thread-35] o.s.c.n.e.server.EurekaServerBootstrap : Eureka environment value eureka.environment is not set, defaulting to test
org.springframework.cloud.netflix.eureka.server.EurekaServerBootstrap, enter initEurekaServerContext()....
2021-12-19 12:32:49.808 INFO 10272 --- [ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8761 (http)
2021-12-19 12:32:49.809 INFO 10272 --- [ main] .s.c.n.e.s.EurekaAutoServiceRegistration : Updating port to 8761
2021-12-19 12:32:49.813 INFO 10272 --- [ main] com.zhss.eureka.EurekaServer : Started EurekaServer in 12.769 seconds (JVM running for 14.8)
2021-12-19 12:32:49.817 INFO 10272 --- [ Thread-35] o.s.c.n.e.server.EurekaServerBootstrap : isAws returned false
2021-12-19 12:32:49.818 INFO 10272 --- [ Thread-35] o.s.c.n.e.server.EurekaServerBootstrap : Initialized server context
com.netflix.eureka.registry.PeerAwareInstanceRegistryImpl enter syncUp ....
com.netflix.eureka.registry.PeerAwareInstanceRegistryImpl=>>0,eurekaClient:{},apps:{}
2021-12-19 12:32:49.819 INFO 10272 --- [ Thread-35] c.n.e.r.PeerAwareInstanceRegistryImpl : Got 1 instances from neighboring DS node
2021-12-19 12:32:49.819 INFO 10272 --- [ Thread-35] c.n.e.r.PeerAwareInstanceRegistryImpl : Renew threshold is: 1
2021-12-19 12:32:49.819 INFO 10272 --- [ Thread-35] c.n.e.r.PeerAwareInstanceRegistryImpl : Changing status to UP
com.netflix.eureka.registry.AbstractInstanceRegistry,enter postInit()....
2021-12-19 12:32:49.824 INFO 10272 --- [ Thread-35] e.s.EurekaServerInitializerConfiguration : Started Eureka Server
2)、发布 Eureka 注册表可用的事件、EurekaServer 初始化配置状态更新、发布 EurekaServer 启动的事件
12、后续的定时任务：
2021-12-19 12:33:49.821 INFO 10272 --- [a-EvictionTimer] c.n.e.registry.AbstractInstanceRegistry : Running the evict task with compensationTime 0ms
com.netflix.eureka.registry.AbstractInstanceRegistry,enter evict()....{}
2021-12-19T12:33:49.821,com.netflix.eureka.registry.PeerAwareInstanceRegistryImpl,enter isLeaseExpirationEnabled()....true,numberOfRenewsPerMinThreshold:1,getNumOfRenewsInLastMin():0
2021-12-19 12:34:49.822 INFO 10272 --- [a-EvictionTimer] c.n.e.registry.AbstractInstanceRegistry : Running the evict task with compensationTime 0ms
3、启动流程图
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