spring boot health indicator原理及其使用

作用

sping boot health 可以通过暴露的接口来提供系统及其系统组件是否可用。默认通过/health来访问。返回结果如下：

{"status": "UP","discoveryComposite": {"description": "Spring Cloud Eureka Discovery Client","status": "UP","discoveryClient": {"description": "Spring Cloud Eureka Discovery Client","status": "UP","services": ["..."]},"eureka": {"description": "Remote status from Eureka server","status": "UP","applications": {"AOMS-MOBILE": 1,"DATA-EXCHANGE": 1,"CLOUD-GATEWAY": 2,"AOMS": 1,"AOMS-AIIS": 0,"AOMS-EUREKA": 2}}},"diskSpace": {"status": "UP","total": 313759301632,"free": 291947081728,"threshold": 10485760},"refreshScope": {"status": "UP"},"hystrix": {"status": "UP"}
}

状态说明：

• UNKNOWN:未知状态，映射HTTP状态码为503

• UP：正常，映射HTTP状态码为200

• DOWN：失败，映射HTTP状态码为503

• OUT_OF_SERVICE:不能对外提供服务，但是服务正常。映射HTTP状态码为200

  注意：UNKNOWN，DOWN，OUT_OF_SERVICE在为微服务环境下会导致注册中心中的实例也为down状态，请根据具体的业务来正确使用状态值。

自动配置的Health Indicator

自动配置的HealthIndicator主要有以下内容：

分组

可以通过一个别名来启用一组指标的访问。配置的格式如下：

management.endpoint.health.group.<name>
//demo:
management.endpoint.health.group.mysys.include=db,redis,mail
management.endpoint.health.group.custom.exclude=rabbit

如何管理Health Indicator

开启

可以通过management.health.key.enabled来启用key对应的indicator。例如：

management.health.db.enabled=true

关闭

management.health.db.enabled=false

RedisHealthIndicator源码解析

下面，通过RedisHealthIndicator源码来为什么可以这么写。

代码结构

自动配置的health indicator有HealthIndicator和HealthIndicatorAutoConfiguration两部分组成。HealthIndicator所在包在org.springframework.boot.actuate，

HealthIndicatorAutoConfiguration所在包在org.springframework.boot.actuate.autoconfigure下

//RedisHealthIndicator.java
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;}@Overrideprotected 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);}}}

• 主要实现doHealthCheck方法来实现具体的判断逻辑。注意，操作完成后在finally中释放资源。
• 在父类AbstractHealthIndicator中，对doHealthCheck进行了try catch,如果出现异常，则返回Down状态。

	//AbstractHealthIndicator.java@Overridepublic final Health health() {Health.Builder builder = new Health.Builder();try {doHealthCheck(builder);}catch (Exception ex) {if (this.logger.isWarnEnabled()) {String message = this.healthCheckFailedMessage.apply(ex);this.logger.warn(StringUtils.hasText(message) ? message : DEFAULT_MESSAGE,ex);}builder.down(ex);}return builder.build();}

RedisHealthIndicatorAutoConfiguration完成RedisHealthIndicator的自动配置

@Configuration
@ConditionalOnClass(RedisConnectionFactory.class)
@ConditionalOnBean(RedisConnectionFactory.class)
@ConditionalOnEnabledHealthIndicator("redis")
@AutoConfigureBefore(HealthIndicatorAutoConfiguration.class)
@AutoConfigureAfter({ RedisAutoConfiguration.class,RedisReactiveHealthIndicatorAutoConfiguration.class })
public class RedisHealthIndicatorAutoConfiguration extendsCompositeHealthIndicatorConfiguration<RedisHealthIndicator, RedisConnectionFactory> {private final Map<String, RedisConnectionFactory> redisConnectionFactories;public RedisHealthIndicatorAutoConfiguration(Map<String, RedisConnectionFactory> redisConnectionFactories) {this.redisConnectionFactories = redisConnectionFactories;}@Bean@ConditionalOnMissingBean(name = "redisHealthIndicator")public HealthIndicator redisHealthIndicator() {return createHealthIndicator(this.redisConnectionFactories);}}

• 重点说明ConditionalOnEnabledHealthIndicator:如果management.health..enabled为true,则生效。
• CompositeHealthIndicatorConfiguration 中会通过HealthIndicatorRegistry注册创建的HealthIndicator

自定义Indicator

@Component
@ConditionalOnProperty(name="spring.dfs.http.send-url")
@Slf4j
public class DfsHealthIndicator implements HealthIndicator {@Value("${spring.dfs.http.send-url}")private String dsfSendUrl;@Overridepublic Health health() {log.debug("正在检查dfs配置项...");log.debug("dfs 请求地址：{}",dsfSendUrl);Health.Builder up = Health.up().withDetail("url", dsfSendUrl);try {HttpUtils.telnet(StringUtils.getIpFromUrl(dsfSendUrl),StringUtils.getPortFromUrl(dsfSendUrl));return up.build();} catch (IOException e) {e.printStackTrace();log.error("DFS配置项错误或网络超时");return up.withException(e).build();}}
}

返回值：

{"dfs": {"status": "UP","url": "10.254.131.197:8088","error": "java.net.ConnectException: Connection refused (Connection refused)"}
}