Spring Boot Admin2 AdminServerAutoConfiguration详解

其他相关文章：

1. Spring Boot Admin 参考指南
2. SpringBoot Admin服务离线、不显示健康信息的问题
3. Spring Boot Admin2 @EnableAdminServer的加载

前面已经分析了@EnableAdminServer的作用，唯一的功能是将AdminServerMarkerConfiguration.Marker类加载到Spring中，并且知道了AdminServerAutoConfiguration类的加载依赖于AdminServerMarkerConfiguration.Marker类。
这篇文章主要来分析AdminServerAutoConfiguration的作用，加载了哪些东西。

首先AdminServerAutoConfiguration类头部有如下几个注解：

@Configuration(proxyBeanMethods = false)
@Conditional(SpringBootAdminServerEnabledCondition.class)
@ConditionalOnBean(AdminServerMarkerConfiguration.Marker.class)
@EnableConfigurationProperties(AdminServerProperties.class)
@ImportAutoConfiguration({ AdminServerInstanceWebClientConfiguration.class, AdminServerWebConfiguration.class })
@AutoConfigureAfter({ WebClientAutoConfiguration.class })
@Lazy(false)
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• @Configuration(proxyBeanMethods = false)
  表示是一个配置类，并且不被Spring 代理，如同普通类一样
• @Conditional(SpringBootAdminServerEnabledCondition.class)
  根据SpringBootAdminServerEnabledCondition做为条件判断是否加载该类，SpringBootAdminServerEnabledCondition中根据spring.boot.admin.server.enabled是否为true来处理，优先级最高
• @ConditionalOnBean(AdminServerMarkerConfiguration.Marker.class)
  判断Spring容器中是否存在AdminServerMarkerConfiguration.Marker 的Bean
• @EnableConfigurationProperties(AdminServerProperties.class)
  启用AdminServerProperties配置文件，AdminServerProperties能够做为Bean 注入该类，其是我们常用的spring.boot.admin 相关配置
• @ImportAutoConfiguration({ AdminServerInstanceWebClientConfiguration.class, AdminServerWebConfiguration.class })
  加载AdminServerInstanceWebClientConfiguration、AdminServerWebConfiguration配置类。AdminServerInstanceWebClientConfiguration 包括了一系列服务实例Http调用相关的Bean配置。AdminServerWebConfiguration定义了SBA2监控相关的接口Controller，以及ReactiveRestApiConfiguration和ServletRestApiConfirguation相关的配置
• @AutoConfigureAfter({ WebClientAutoConfiguration.class })
  顾名思义，表示该类将在WebClientAutoConfiguration载入后，再加载
• @Lazy(false)
  表示不延迟加载，覆盖默认配置

再往下看，是构造器部分

	private final AdminServerProperties adminServerProperties;

	public AdminServerAutoConfiguration(AdminServerProperties adminServerProperties) {
		this.adminServerProperties = adminServerProperties;
	}
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这里将AdminServerProperties配置以构造器的方式注入该类

继续看其他加载的配置

	@Bean
	@ConditionalOnMissingBean
	public InstanceRegistry instanceRegistry(InstanceRepository instanceRepository,
			InstanceIdGenerator instanceIdGenerator) {
		return new InstanceRegistry(instanceRepository, instanceIdGenerator);
	}
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该部分创建了一个用于管理实例注册的Bean，InstanceRepository 用于提供实例的持久化，InstanceIdGenerator 用于生成实例id

	@Bean
	@ConditionalOnMissingBean
	public ApplicationRegistry applicationRegistry(InstanceRegistry instanceRegistry,
			InstanceEventPublisher instanceEventPublisher) {
		return new ApplicationRegistry(instanceRegistry, instanceEventPublisher);
	}
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该部分创建一个用于管理所有已注册的应用

	@Bean
	@ConditionalOnMissingBean
	public InstanceIdGenerator instanceIdGenerator() {
		return new HashingInstanceUrlIdGenerator();
	}
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该部分创建了一个根据实例健康URL地址来生成实例ID的Bean

	@Bean
	@ConditionalOnMissingBean
	public StatusUpdater statusUpdater(InstanceRepository instanceRepository,
			InstanceWebClient.Builder instanceWebClientBulder) {
		return new StatusUpdater(instanceRepository, instanceWebClientBulder.build());
	}
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该部分创建了一个用于查询更新实例状态的Bean

	@Bean(initMethod = "start", destroyMethod = "stop")
	@ConditionalOnMissingBean
	public StatusUpdateTrigger statusUpdateTrigger(StatusUpdater statusUpdater, Publisher<InstanceEvent> events) {
		StatusUpdateTrigger trigger = new StatusUpdateTrigger(statusUpdater, events);
		trigger.setInterval(this.adminServerProperties.getMonitor().getStatusInterval());
		trigger.setLifetime(this.adminServerProperties.getMonitor().getStatusLifetime());
		return trigger;
	}
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StatusUpdateTrigger 会在加载的时候开启一个定时任务，用来检查所有实例的状态，检测周期和状态生存时间可以通过spring.boot.admin.monitor.status-interval和spring.boot.admin.monitor.status-lifetime配置。除此之外，其监听了实例变更事件，会在实例注册和实例更新的时候，触发去更新实例状态。

	@Bean
	@ConditionalOnMissingBean
	public EndpointDetector endpointDetector(InstanceRepository instanceRepository,
			InstanceWebClient.Builder instanceWebClientBuilder) {
		InstanceWebClient instanceWebClient = instanceWebClientBuilder.build();
		ChainingStrategy strategy = new ChainingStrategy(new QueryIndexEndpointStrategy(instanceWebClient),
				new ProbeEndpointsStrategy(instanceWebClient, this.adminServerProperties.getProbedEndpoints()));
		return new EndpointDetector(instanceRepository, strategy);
	}
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EndpointDetector 用于检测实例暴露的端点

	@Bean(initMethod = "start", destroyMethod = "stop")
	@ConditionalOnMissingBean
	public EndpointDetectionTrigger endpointDetectionTrigger(EndpointDetector endpointDetector,
			Publisher<InstanceEvent> events) {
		return new EndpointDetectionTrigger(endpointDetector, events);
	}
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EndpointDetectionTrigger 实例端点检测触发器，在实例状态变更和实例注册更新的时候，触发检测

	@Bean
	@ConditionalOnMissingBean
	public InfoUpdater infoUpdater(InstanceRepository instanceRepository,
			InstanceWebClient.Builder instanceWebClientBuilder) {
		return new InfoUpdater(instanceRepository, instanceWebClientBuilder.build());
	}
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InfoUpdater 调用info接口，更新实例信息

	@Bean(initMethod = "start", destroyMethod = "stop")
	@ConditionalOnMissingBean
	public InfoUpdateTrigger infoUpdateTrigger(InfoUpdater infoUpdater, Publisher<InstanceEvent> events) {
		InfoUpdateTrigger trigger = new InfoUpdateTrigger(infoUpdater, events);
		trigger.setInterval(this.adminServerProperties.getMonitor().getInfoInterval());
		trigger.setLifetime(this.adminServerProperties.getMonitor().getInfoLifetime());
		return trigger;
	}
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InfoUpdateTrigger 实例信息检查触发器，道理同StatusUpdateTrigger

	@Bean
	@ConditionalOnMissingBean(InstanceEventStore.class)
	public InMemoryEventStore eventStore() {
		return new InMemoryEventStore();
	}
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InMemoryEventStore 实例存储类，基于ConcurrentMap

	@Bean(initMethod = "start", destroyMethod = "stop")
	@ConditionalOnMissingBean(InstanceRepository.class)
	public SnapshottingInstanceRepository instanceRepository(InstanceEventStore eventStore) {
		return new SnapshottingInstanceRepository(eventStore);
	}
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SnapshottingInstanceRepository 实例持久化类，用于操作InstanceEventStore

到此AdminServerAutoConfiguration自动配置类结束