Once the kuard process is up and running, we need a way to confirm that it is actually healthy and shouldn’t be restarted. Liveness probes are defined per container, which means each container inside a Pod is health checked separately.

apiVersion: v1
kind: Pod
metadata:
  name: kuard
spec:
  containers:
    - image: gcr.io/kuar-demo/kuard-amd64:blue
      name: kuard
      livenessProbe:
        httpGet:
          path: /healthy
          port: 8080
        initialDelaySeconds: 5
        timeoutSeconds: 1
        periodSeconds: 10
        failureThreshold: 3
      ports:
        - containerPort: 8080
          name: http
          protocol: TCP

The preceding Pod manifest uses an httpGet probe to perform an HTTP GET request against the /healthy endpoint on port 8080 of the kuard container. The probe sets an initialDelaySeconds of 5, and thus will not be called until 5 seconds after all the containers in the Pod are created. The probe must respond within the 1-second timeout, and the HTTP status code must be equal to or greater than 200 and less than 400 to be considered successful. Kubernetes will call the probe every 10 seconds. If more than three consecutive probes fail, the container will fail and restart.