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：

Key	Name	Description
cassandra	CassandraDriverHealthIndicator	Checks that a Cassandra database is up.
couchbase	CouchbaseHealthIndicator	Checks that a Couchbase cluster is up.
datasource	DataSourceHealthIndicator	Checks that a connection to DataSource can be obtained.
diskspace	DiskSpaceHealthIndicator	Checks for low disk space.
elasticsearch	ElasticsearchRestHealthIndicator	Checks that an Elasticsearch cluster is up.
hazelcast	HazelcastHealthIndicator	Checks that a Hazelcast server is up.
influxdb	InfluxDbHealthIndicator	Checks that an InfluxDB server is up.
jms	JmsHealthIndicator	Checks that a JMS broker is up.
ldap	LdapHealthIndicator	Checks that an LDAP server is up.
mail	MailHealthIndicator	Checks that a mail server is up.
mongo	MongoHealthIndicator	Checks that a Mongo database is up.
neo4j	Neo4jHealthIndicator	Checks that a Neo4j database is up.
ping	PingHealthIndicator	Always responds with UP.
rabbit	RabbitHealthIndicator	Checks that a Rabbit server is up.
redis	RedisHealthIndicator	Checks that a Redis server is up.
solr	SolrHealthIndicator	Checks that a Solr server is up.

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;
	}

	@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);
		}
	}

}

• 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
	@Override
	public 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 extends
		CompositeHealthIndicatorConfiguration<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;
    @Override
    public 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)"
    }
}