Spring Boot 自定义 Kubernetes 就绪探针

Question

我想实现自定义逻辑来确定我的 Pod 的准备情况，我回顾了这一点： https: //docs.spring.io/spring-boot/docs/current/reference/html/actuator.html#actuator.endpoints.kubernetes -probes.external-state他们提到了一个示例属性： management.endpoint.health.group.readiness.include=readinessState,customCheck

问题是 - 我如何覆盖customCheck？就我而言，我想使用 HTTP 探针，因此 yaml 如下所示：

readinessProbe:
  initialDelaySeconds: 10
  periodSeconds: 10
  httpGet:
    path: /actuator/health
    port: 12345

那么话又说回来 - 我应该在哪里以及如何应用逻辑来确定应用程序何时准备就绪（就像上面的链接一样，我想依赖外部服务才能使其准备就绪）

Answer 1

扩展 KrzysztofS 的答案：

首先，创建一个自定义健康指示器，如下所示：

import java.util.concurrent.atomic.AtomicBoolean;
import org.springframework.boot.actuate.availability.ReadinessStateHealthIndicator;
import org.springframework.boot.availability.ApplicationAvailability;
import org.springframework.boot.availability.AvailabilityState;
import org.springframework.boot.availability.ReadinessState;
import org.springframework.stereotype.Component;

@Component
public class MyCustomReadinessIndicator extends ReadinessStateHealthIndicator {
  private final AtomicBoolean ready = new AtomicBoolean();

  public MyCustomReadinessIndicator(ApplicationAvailability availability) {
    super(availability);
  }

  @Override
  protected AvailabilityState getState(ApplicationAvailability applicationAvailability) {
    return ready.get()
        ? ReadinessState.ACCEPTING_TRAFFIC
        : ReadinessState.REFUSING_TRAFFIC;
  }

  public void markAsReady() {
    if (ready.get()) {
      throw new IllegalStateException("Already initialized");
    }
    ready.set(true);
  }
}

这必须是一个 bean，否则 Spring 将无法发现它。

@Autowire您的组件连接到您的服务或另一个组件，并markAsReady()在该指示器应切换到“就绪”状态时调用其函数。

接下来，将 bean ¹的名称添加到 application.yaml 文件中“readiness”组的“include”块中（如果您使用的是 application.properties，请自行计算）。

management:
  endpoint:
    health:
      group:
        readiness:
          include: readinessState, myCustomReadinessIndicator
      show-components: always
      show-details: always
      probes:
        enabled: true

接下来，尝试运行您的应用程序并打开各种 Actuator 端点。

端点	ready 指标的状态	HTTP 响应 代码	JSON 响应
/actuator/health	false	503	{ "status": "OUT_OF_SERVICE", "components": { "myCustomReadinessIndicator": { "status": "OUT_OF_SERVICE" }, "livenessState": { "status": "UP" }, "readinessState": { "status": "UP" } }, "groups": ["liveness", "readiness"] }
/actuator/health/liveness	false	200	{"status":"UP"}
/actuator/health/readiness	false	503	{ "status": "OUT_OF_SERVICE", "components": { "myCustomReadinessIndicator": { "status": "OUT_OF_SERVICE" }, "readinessState": { "status": "UP" } } }
/actuator/health	true	200	{ "status": "UP", "components": { "myCustomReadinessIndicator": { "status": "UP" }, "livenessState": { "status": "UP" }, "readinessState": { "status": "UP" } }, "groups": ["liveness", "readiness"] }
/actuator/health/liveness	true	200	{"status":"UP"}
/actuator/health/readiness	true	200	{ "status": "UP", "components": { "myCustomReadinessIndicator": { "status": "UP" }, "readinessState": { "status": "UP" } } }

现在，您需要设置/actuator/health/readiness就绪探针的路径

readinessProbe:
  initialDelaySeconds: 10
  periodSeconds: 10
  httpGet:
    path: /actuator/health/readiness
    port: 12345

相关：将 liveness 探针的路径设置为/actuator/health/livenessnot to /actuator/health，因为/actuator/health如果您的指标尚未准备好，即使livenessState是“UP”，也会返回 503。

¹ Bean 名称通常是类的驼峰式名称，以小写字母开头，但您可以通过在组件注释中提供名称来覆盖它：@Component("overriddenName")

Answer 2

customCheck 是您的自定义 HealthIndicator 的关键。给定 HealthIndicator 的键是不带 HealthIndicator 后缀的 bean 名称

您可以阅读： https://docs.spring.io/spring-boot/docs/current/reference/html/actuator.html#actuator.endpoints.health.writing-custom-health-indicators

您正在定义 readinessProbe，因此点击 /actuator/health/readiness 可能是更好的选择。

public class CustomCheckHealthIndicator extends AvailabilityStateHealthIndicator {

    private final YourService yourService;

    public CustomCheckHealthIndicator(ApplicationAvailability availability, YourService yourService) {
        super(availability, ReadinessState.class, (statusMappings) -> {
            statusMappings.add(ReadinessState.ACCEPTING_TRAFFIC, Status.UP);
            statusMappings.add(ReadinessState.REFUSING_TRAFFIC, Status.OUT_OF_SERVICE);
        });
        this.yourService = yourService;
    }

    @Override
    protected AvailabilityState getState(ApplicationAvailability applicationAvailability) {
        if (yourService.isInitCompleted()) {
            return ReadinessState.ACCEPTING_TRAFFIC;
        } else {
            return ReadinessState.REFUSING_TRAFFIC;
        }
    }

}