In Kubernetes, how can I detect that my pod is ready?

Question

I have a Kubernetes pod using a readiness probe, and tied with the service this ensures that I don't receive traffic until I'm ready.

I'm using Spring Actuator as the health endpoint for this readiness probe.

But i'd like to trigger some actions whenever the pod is deemed ready by the kubelet.

What would be the simplest way to do this?

Perhaps implement your own HealthCheck. When you find that everything is ok for the first time, run your code — rjdkolb

rjdkolb rjdkolb · Accepted Answer · 2019-03-19T09:32:46

Perhaps implement your own HealthCheck. When you find that everything is ok for the first time, run your code.

I use a static variable firstHealthCheckOK is checked. Your logic should run only once.

I am assuming you are running Spring-boot 2.x and are calling a readiness probe on http://localhost:8080/actuator/health

The health() method below is called when Kubernetes calls http://localhost:8080/actuator/health

import org.springframework.boot.actuate.health.Health;
import org.springframework.boot.actuate.health.HealthIndicator;
import org.springframework.stereotype.Component;

@Component
public class HealthCheck implements HealthIndicator {

    static boolean firstHealthCheckOK = false;

    @Override
    public Health health() {
        int errorCode = check(); // perform health check
        if (errorCode != 0) {
            return Health.down()
              .withDetail("Error Code", errorCode).build();
        }
        if (firstHealthCheckOK == false){
            firstHealthCheckOK = true;
            doStartUpLogic();
        }
        return Health.up().build();
    }

    private int check() {
        //some logic
        return 0;
    }

    private void doStartUpLogic() {
        //some startup logic
    }
}

In Kubernetes, how can I detect that my pod is ready?

3 Answers