接下来阅读SpringBoot项目启动时Nacos客户端将自己这个实例注册到Nacos服务端的流程。
程序的入口我们在使用Nacos作为注册中心时，会在pom.xml添加如下依赖：
<dependency>
<groupId>com.alibaba.cloud</groupId>
<artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
</dependency>
在依赖中查看自动装配文件spring.factories
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
com.alibaba.cloud.nacos.discovery.NacosDiscoveryAutoConfiguration,\
com.alibaba.cloud.nacos.endpoint.NacosDiscoveryEndpointAutoConfiguration,\
com.alibaba.cloud.nacos.registry.NacosServiceRegistryAutoConfiguration,\
com.alibaba.cloud.nacos.discovery.NacosDiscoveryClientConfiguration,\
com.alibaba.cloud.nacos.discovery.reactive.NacosReactiveDiscoveryClientConfiguration,\
com.alibaba.cloud.nacos.discovery.configclient.NacosConfigServerAutoConfiguration,\
com.alibaba.cloud.nacos.loadbalancer.LoadBalancerNacosAutoConfiguration,\
com.alibaba.cloud.nacos.NacosServiceAutoConfiguration,\
com.alibaba.cloud.nacos.utils.UtilIPv6AutoConfiguration
org.springframework.cloud.bootstrap.BootstrapConfiguration=\
com.alibaba.cloud.nacos.discovery.configclient.NacosDiscoveryClientConfigServiceBootstrapConfiguration
org.springframework.context.ApplicationListener=\
com.alibaba.cloud.nacos.discovery.logging.NacosLoggingListener
注入的对象很多，从类名可以看出NacosServiceRegistryAutoConfiguration就是我们要看的重点了。
NacosServiceRegistryAutoConfigurationNacosServiceRegistryAutoConfiguration注入了3个Bean：
- NacosServiceRegistry：负责具体的服务注册。
- NacosRegistration：收集当前实例的信息，如端口、IP、服务名等。
- NacosAutoServiceRegistration：管理服务自动注册的时机。
@Configuration(proxyBeanMethods = false)
@EnableConfigurationProperties
@ConditionalOnNacosDiscoveryEnabled
@ConditionalOnProperty(value = "spring.cloud.service-registry.auto-registration.enabled",
matchIfMissing = true)
@AutoConfigureAfter({ AutoServiceRegistrationConfiguration.class,
AutoServiceRegistrationAutoConfiguration.class,
NacosDiscoveryAutoConfiguration.class })
public class NacosServiceRegistryAutoConfiguration {
@Bean
public NacosServiceRegistry nacosServiceRegistry(
NacosServiceManager nacosServiceManager,
NacosDiscoveryProperties nacosDiscoveryProperties) {
return new NacosServiceRegistry(nacosServiceManager, nacosDiscoveryProperties);
}
@Bean
@ConditionalOnBean(AutoServiceRegistrationProperties.class)
public NacosRegistration nacosRegistration(
ObjectProvider<List<NacosRegistrationCustomizer>> registrationCustomizers,
NacosDiscoveryProperties nacosDiscoveryProperties,
ApplicationContext context) {
return new NacosRegistration(registrationCustomizers.getIfAvailable(),
nacosDiscoveryProperties, context);
}
@Bean
@ConditionalOnBean(AutoServiceRegistrationProperties.class)
public NacosAutoServiceRegistration nacosAutoServiceRegistration(
NacosServiceRegistry registry,
AutoServiceRegistrationProperties autoServiceRegistrationProperties,
NacosRegistration registration) {
return new NacosAutoServiceRegistration(registry,
autoServiceRegistrationProperties, registration);
}
}
先来看看NacosAutoServiceRegistration的父类AbstractAutoServiceRegistration，注意AbstractAutoServiceRegistration是SpringCloud提供的类。
public abstract class AbstractAutoServiceRegistration<R extends Registration>
implements AutoServiceRegistration, ApplicationContextAware, ApplicationListener<WebServerInitializedEvent> {
AbstractAutoServiceRegistration实现了ApplicationListener接口，并监听了WebServerInitializedEvent事件，在SpringBoot项目启动过程中会触发WebServerInitializedEvent事件，这样就会调用到onApplicationEvent()方法：
org.springframework.cloud.client.serviceregistry.AbstractAutoServiceRegistration#onApplicationEvent
public void onApplicationEvent(WebServerInitializedEvent event) {
bind(event);
}
@Deprecated
public void bind(WebServerInitializedEvent event) {
ApplicationContext context = event.getApplicationContext();
if (context instanceof ConfigurableWebServerApplicationContext) {
if ("management".equals(((ConfigurableWebServerApplicationContext) context).getServerNamespace())) {
return;
}
}
this.port.compareAndSet(0, event.getWebServer().getPort());
this.start();
}
public void start() {
if (!isEnabled()) {
if (logger.isDebugEnabled()) {
logger.debug("Discovery Lifecycle disabled. Not starting");
}
return;
}
// only initialize if nonSecurePort is greater than 0 and it isn't already running
// because of containerPortInitializer below
if (!this.running.get()) {
this.context.publishEvent(new InstancePreRegisteredEvent(this, getRegistration()));
register();
if (shouldRegisterManagement()) { // false
registerManagement();
}
this.context.publishEvent(new InstanceRegisteredEvent<>(this, getConfiguration()));
this.running.compareAndSet(false, true);
}
}
protected void register() {
this.serviceRegistry.register(getRegistration());
}
最终会调用到register()方法，而NacosAutoServiceRegistration实现了register()方法：
com.alibaba.cloud.nacos.registry.NacosAutoServiceRegistration#register
protected void register() {
if (!this.registration.getNacosDiscoveryProperties().isRegisterEnabled()) {
log.debug("Registration disabled.");
return;
}
if (this.registration.getPort() < 0) {
this.registration.setPort(getPort().get());
}
super.register();
}
上面的方法也没干啥，又回调到父类AbstractAutoServiceRegistration的register()。
org.springframework.cloud.client.serviceregistry.AbstractAutoServiceRegistration#register
protected void register() {
this.serviceRegistry.register(getRegistration());
}
最终会调用到serviceRegistry.register()，其中serviceRegistry是在NacosServiceRegistryAutoConfiguration中注入的NacosServiceRegistry。
NacosServiceRegistryNacosServiceRegistry负责具体的服务注册。
com.alibaba.cloud.nacos.registry.NacosServiceRegistry#register
public void register(Registration registration) {
if (StringUtils.isEmpty(registration.getServiceId())) {
log.warn("No service to register for nacos client...");
return;
}
// 获取NamingService
NamingService namingService = namingService();
String serviceId = registration.getServiceId();
String group = nacosDiscoveryProperties.getGroup();
// 将Registration封装为Instance
Instance instance = getNacosInstanceFromRegistration(registration);
try {
// 注册实例
namingService.registerInstance(serviceId, group, instance);
log.info("nacos registry, {} {} {}:{} register finished", group, serviceId,
instance.getIp(), instance.getPort());
}
catch (Exception e) {
if (nacosDiscoveryProperties.isFailFast()) {
log.error("nacos registry, {} register failed...{},", serviceId,
registration.toString(), e);
rethrowRuntimeException(e);
}
else {
log.warn("Failfast is false. {} register failed...{},", serviceId,
registration.toString(), e);
}
}
}
第一次创建时会通过groupname + servicename创建一个心跳实例并启动心跳检测定时任务。
com.alibaba.nacos.client.naming.NacosNamingService#registerInstance(java.lang.String, java.lang.String, com.alibaba.nacos.api.naming.pojo.Instance)
public void registerInstance(String serviceName, String groupName, Instance instance) throws NacosException {
NamingUtils.checkInstanceIsLegal(instance);
// groupname 和 servicename 组合,DEFAULT_GROUP@@serviceName
// 默认groupname为DEFAULT_GROUP
String groupedServiceName = NamingUtils.getGroupedName(serviceName, groupName);
if (instance.isEphemeral()) {
// 构建心跳实例
BeatInfo beatInfo = this.beatReactor.buildBeatInfo(groupedServiceName, instance);
// 启动心跳定时任务
this.beatReactor.addBeatInfo(groupedServiceName, beatInfo);
}
// 服务注册
this.serverProxy.registerService(groupedServiceName, groupName, instance);
}
发起Http调用，接口为/nacos/v1/ns/instance。
com.alibaba.nacos.client.naming.net.NamingProxy#registerService
public void registerService(String serviceName, String groupName, Instance instance) throws NacosException {
LogUtils.NAMING_LOGGER.info("[REGISTER-SERVICE] {} registering service {} with instance: {}", new Object[]{this.namespaceId, serviceName, instance});
Map<String, String> params = new HashMap(16);
params.put("namespaceId", this.namespaceId);
params.put("serviceName", serviceName);
params.put("groupName", groupName);
params.put("clusterName", instance.getClusterName());
params.put("ip", instance.getIp());
params.put("port", String.valueOf(instance.getPort()));
params.put("weight", String.valueOf(instance.getWeight()));
params.put("enable", String.valueOf(instance.isEnabled()));
params.put("healthy", String.valueOf(instance.isHealthy()));
params.put("ephemeral", String.valueOf(instance.isEphemeral()));
params.put("metadata", JacksonUtils.toJson(instance.getMetadata()));
this.reqApi(UtilAndComs.nacosUrlInstance, params, "POST");
}
BeatReactor负责发送心跳包，默认每隔5s发送一次。
com.alibaba.nacos.client.naming.beat.BeatReactor#addBeatInfo
public void addBeatInfo(String serviceName, BeatInfo beatInfo) {
LogUtils.NAMING_LOGGER.info("[BEAT] adding beat: {} to beat map.", beatInfo);
String key = this.buildKey(serviceName, beatInfo.getIp(), beatInfo.getPort());
BeatInfo existBeat = null;
if ((existBeat = (BeatInfo)this.dom2Beat.remove(key)) != null) {
existBeat.setStopped(true);
}
this.dom2Beat.put(key, beatInfo);
this.executorService.schedule(new BeatReactor.BeatTask(beatInfo), beatInfo.getPeriod(), TimeUnit.MILLISECONDS);
MetricsMonitor.getDom2BeatSizeMonitor().set((double)this.dom2Beat.size());
}
