利用SpringBoot Actuator 来构造/health /info 等监控接口

当我们用K8S 部署微服务时，很多时候需要调用 service的/health 等状态接口，已确定container的运行状态是否健康。

而Spring boot Actuator 就是用来快速构造这些状态接口的工具

引入依赖

xml 复制代码

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

启用/health 和 /info 接口

yaml 复制代码

management:
  endpoints:
    web:
      exposure:
        include: "info, health, loggers, env"
      base-path: /actuator

所有的接口介绍可以参考：

https://www.baeldung.com/spring-boot-actuators

bash 复制代码

/auditevents lists security audit-related events such as user login/logout. Also, we can filter by principal or type among other fields.
/beans returns all available beans in our BeanFactory. Unlike /auditevents, it doesn't support filtering.
/conditions, formerly known as /autoconfig, builds a report of conditions around autoconfiguration.
/configprops allows us to fetch all @ConfigurationProperties beans.
/env returns the current environment properties. Additionally, we can retrieve single properties.
/flyway provides details about our Flyway database migrations.
/health summarizes the health status of our application.
/heapdump builds and returns a heap dump from the JVM used by our application.
/info returns general information. It might be custom data, build information or details about the latest commit.
/liquibase behaves like /flyway but for Liquibase.
/logfile returns ordinary application logs.
/loggers enables us to query and modify the logging level of our application.
/metrics details metrics of our application. This might include generic metrics as well as custom ones.
/prometheus returns metrics like the previous one, but formatted to work with a Prometheus server.
/scheduledtasks provides details about every scheduled task within our application.
/sessions lists HTTP sessions, given we are using Spring Session.
/shutdown performs a graceful shutdown of the application.
/threaddump dumps the thread information of the underlying JVM.

配置/health 接口的具体输出信息

默认/health 只会输出 status up or down, 如下

bash 复制代码

[gateman@manjaro-x13 ~]$ curl 127.0.0.1:8080/actuator/health
{"status":"UP"}

当我们在application.yml 加上下面配置后。

yml 复制代码

management:
  endpoint:
    health:
      show-details: always

会令到 /health 接口输出额外的components 信息：

json 复制代码

{
    "status": "UP",
    "components": {
        "diskSpace": {
            "status": "UP",
            "details": {
                "total": 1038214316032,
                "free": 840063606784,
                "threshold": 10485760,
                "exists": true
            }
        },
        "ping": {
            "status": "UP"
        }
    }
}

这时，我们可以额外地从/health 接口知道ping 和磁盘使用的信息。

其实只要ping 和 diskSpace的状态任何1个status 为down, 这个/health的总status 就是down

但是通常来讲，只考虑这两个子状态是不足够的。

增加BigQuery conneciton 状态

举个例子，假如某个service 里面连接bigQuery, 我们需要在/health 接口加1个component ，去detect BQ 的connection 是否健康。如果这个BQ connection 为Down, 则/health status 为down

增加1个类 for checking the BQ connection

java 复制代码

@Component
@Slf4j
public class BigQueryHealthCheck {

    @Autowired
    private BigQuery bigQuery;

    public boolean isBigQueryHealthy() {
        CompletableFuture<Boolean> future = CompletableFuture.supplyAsync(() -> {
            try {
                bigQuery.listDatasets();
                return true;
            } catch (Exception e) {
                log.error("Error in BigQueryHealthCheck...", e);
                return false;
            }
        });

        try {
            // set time out to 5 seconds,  to wait for the return of future object.
            return future.get(5, TimeUnit.SECONDS);
        } catch (InterruptedException | ExecutionException | TimeoutException e) {
            log.error("Timeout or error while checking BigQuery connection", e);
            return false;
        }
    }
}

这里使用了CompletableFuture 类来设置1个5秒 timeout, 只要5秒内连不上BQ, 则认为BQ connection down

再增加1个类 for 增加1个BQ connection component to /health 接口

java 复制代码

@Component
public class BQHealthIndicator extends AbstractHealthIndicator {

    @Autowired
    private BigQueryHealthCheck bigQueryHealthCheck;

    @Override
    protected void doHealthCheck(Health.Builder builder) throws Exception {
        if (bigQueryHealthCheck.isBigQueryHealthy()) {
            //int i=1/0;
            builder.up();
        } else {
            builder.down();
        }
    }
}

注意这个类必须是1个bean, 而且类名的suffix 是 HealthIndicator

这样，当我们再次测试/health 接口时，就包括BQ connection的监测了！

json 复制代码

{
    "status": "UP",
    "components": {
        "BQ": {
            "status": "UP"
        },
        "diskSpace": {
            "status": "UP",
            "details": {
                "total": 1038214316032,
                "free": 839953145856,
                "threshold": 10485760,
                "exists": true
            }
        },
        "ping": {
            "status": "UP"
        }
    }
}

配置/info 接口的具体输出信息

默认下 /info 接口是什么信息都没有输出的，只有1个空的对象{}

如果我们想把service name, version 等信息写进info 接口，也不复杂。

把pom.xml 的version 写入application.yml

在spring boot 中，获取pom.xml 里面的具体字段值没有那么简单。

相对地，从application.yml 获取configuration item的值是很容易的。

幸运地，有1个方法可以把pom.xml 的内容写入application.yml

yml 复制代码

pom:
  version: @project.version@

在application yml里加入上面两行即可

添加1个类for /info的信息输出

java 复制代码

@Component
public class AppVersionInfo implements InfoContributor {

    @Autowired
    private Environment environment;

    @Value("${pom.version}") // https://stackoverflow.com/questions/3697449/retrieve-version-from-maven-pom-xml-in-code
    private String appVersion;

    @Override
    public void contribute(Info.Builder builder) {
        builder.withDetail("app", "Sales API")
                .withDetail("version", appVersion)
                .withDetail("description", "This is a simple Spring Boot application to demonstrate the use of BigQuery in GCP.");
    }
}

效果：

json 复制代码

{
    "app": "Sales API",
    "version": "1.0-SNAPSHOT",
    "description": "This is a simple Spring Boot application to demonstrate the use of BigQuery in GCP."
}

就是甘简单