/actuator/health

此节点可以检查各个组件的健康状态，例如调用接口时，DB组件会返回OK。

HealthMvcEndpoint && HealthEndpoint

• /actuator/health接口是由HealthMvcEndpoint的invoke方法来处理的。
• HealthMvcEndpoint的底层是通过HealthEndpoint来实现的。
• HealthMvcEndpoint初始化代码

    @Bean
    @ConditionalOnBean(HealthEndpoint.class)
    @ConditionalOnMissingBean
    @ConditionalOnEnabledEndpoint("health")
    public HealthMvcEndpoint healthMvcEndpoint(HealthEndpoint delegate,
            ManagementServerProperties managementServerProperties) {
        HealthMvcEndpoint healthMvcEndpoint = new HealthMvcEndpoint(delegate,
                this.managementServerProperties.getSecurity().isEnabled(),
                managementServerProperties.getSecurity().getRoles());
        if (this.healthMvcEndpointProperties.getMapping() != null) {
            healthMvcEndpoint
                    .addStatusMapping(this.healthMvcEndpointProperties.getMapping());
        }
        return healthMvcEndpoint;
    }

• HealthEndpoint初始化代码

    @Bean
    @ConditionalOnMissingBean
    public HealthEndpoint healthEndpoint() {
        return new HealthEndpoint(
                this.healthAggregator == null ? new OrderedHealthAggregator()
                        : this.healthAggregator,
                this.healthIndicators == null
                        ? Collections.<String, HealthIndicator>emptyMap()
                        : this.healthIndicators);
    }

自定义组件的健康状态检查

某些情况下，当我们需要对我们新建的一个模块进行健康监控的话，可以把这些监控信息统一归纳到health节点下，只需要实现HealthIndicator接口即可。

/**
 * Strategy interface used to provide an indication of application health.
 *
 * @author Dave Syer
 * @see ApplicationHealthIndicator
 */
public interface HealthIndicator {

    /**
     * Return an indication of health.
     * @return the health for
     */
    Health health();

}

一般都是通过继承AbstractHealthIndicator来实现的，添加@Component即可。

/**
 * Base {@link HealthIndicator} implementations that encapsulates creation of
 * {@link Health} instance and error handling.
 * <p>
 * This implementation is only suitable if an {@link Exception} raised from
 * {@link #doHealthCheck(org.springframework.boot.actuate.health.Health.Builder)} should
 * create a {@link Status#DOWN} health status.
 *
 * @author Christian Dupuis
 * @since 1.1.0
 */
public abstract class AbstractHealthIndicator implements HealthIndicator {

    private final Log logger = LogFactory.getLog(getClass());

    @Override
    public final Health health() {
        Health.Builder builder = new Health.Builder();
        try {
            doHealthCheck(builder);
        }
        catch (Exception ex) {
            this.logger.warn("Health check failed", ex);
            builder.down(ex);
        }
        return builder.build();
    }

    /**
     * Actual health check logic.
     * @param builder the {@link Builder} to report health status and details
     * @throws Exception any {@link Exception} that should create a {@link Status#DOWN}
     * system status.
     */
    protected abstract void doHealthCheck(Health.Builder builder) throws Exception;

}