解析springBoot-actuator项目构造中health端点工作原理

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-actuator</artifactId>
</dependency>

<dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-actuator</artifactId>
      <version>2.1.0.RELEASE</version>
</dependency>

<dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-actuator-autoconfigure</artifactId>
      <version>2.1.0.RELEASE</version>
</dependency>

@Configuration
@EnableConfigurationProperties({ HealthEndpointProperties.class,
      HealthIndicatorProperties.class })
@AutoConfigureAfter(HealthIndicatorAutoConfiguration.class)
@Import({ HealthEndpointConfiguration.class,
      HealthEndpointWebExtensionConfiguration.class })
public class HealthEndpointAutoConfiguration {

}

@Bean
	@ConditionalOnMissingBean(HealthIndicatorRegistry.class)
	public HealthIndicatorRegistry healthIndicatorRegistry(
			ApplicationContext applicationContext) {
		return HealthIndicatorRegistryBeans.get(applicationContext);
	}

	public static HealthIndicatorRegistry get(ApplicationContext applicationContext) {
		Map<String, HealthIndicator> indicators = new LinkedHashMap<>();
		indicators.putAll(applicationContext.getBeansOfType(HealthIndicator.class));
		if (ClassUtils.isPresent("reactor.core.publisher.Flux", null)) {
			new ReactiveHealthIndicators().get(applicationContext)
					.forEach(indicators::putIfAbsent);
		}
		HealthIndicatorRegistryFactory factory = new HealthIndicatorRegistryFactory();
		return factory.createHealthIndicatorRegistry(indicators);
	}

@Configuration
@ConditionalOnSingleCandidate(HealthIndicatorRegistry.class)
class HealthEndpointConfiguration {

	@Bean
	@ConditionalOnMissingBean
	@ConditionalOnEnabledEndpoint
	public HealthEndpoint healthEndpoint(HealthAggregator healthAggregator,
			HealthIndicatorRegistry registry) {
		return new HealthEndpoint(
				new CompositeHealthIndicator(healthAggregator, registry));
	}
}

public class RedisHealthIndicator extends AbstractHealthIndicator {
	static final String VERSION = "version";
	static final String REDIS_VERSION = "redis_version";
	private final RedisConnectionFactory redisConnectionFactory;
	public RedisHealthIndicator(RedisConnectionFactory connectionFactory) {
		super("Redis health check failed");
		Assert.notNull(connectionFactory, "ConnectionFactory must not be null");
		this.redisConnectionFactory = connectionFactory;
	}
	@Override
	protected void doHealthCheck(Health.Builder builder) throws Exception {
		RedisConnection connection = RedisConnectionUtils
				.getConnection(this.redisConnectionFactory);
		try {
			if (connection instanceof RedisClusterConnection) {
				ClusterInfo clusterInfo = ((RedisClusterConnection) connection)
						.clusterGetClusterInfo();
				builder.up().withDetail("cluster_size", clusterInfo.getClusterSize())
						.withDetail("slots_up", clusterInfo.getSlotsOk())
						.withDetail("slots_fail", clusterInfo.getSlotsFail());
			}
			else {
				Properties info = connection.info();
				builder.up().withDetail(VERSION, info.getProperty(REDIS_VERSION));
			}
		}
		finally {
			RedisConnectionUtils.releaseConnection(connection,
					this.redisConnectionFactory);
		}
	}
}

@ConditionalOnEnabledHealthIndicator("myDb")
@Configuration
public class MyHealthIndicatorAutoConfiguration extends CompositeHealthIndicatorConfiguration<DataSourceHealthIndicator,DataSource> {
    @Bean
    @ConditionalOnMissingBean(name = "myDbHealthIndicator")
    public HealthIndicator dbHealthIndicator() {
        return new MyHealthIndicator();
    }
}
class MyHealthIndicator extends AbstractHealthIndicator{
    @Override
    protected void doHealthCheck(Health.Builder builder) {
        //这里定义组建健康的逻辑
        builder.up();
    }
}

management.endpoints.web.base-path=/actuator
management.endpoint.health.enabled=true
management.endpoint.health.show-details=never
management.endpoint.health.roles=admin
management.health.db.enabled=true