Add a Liveness Probe

In order to best maintain your pods, Kubernetes needs to know if a pod is alive or not. A liveness probe is an action that the Kubernetes system takes periodically to determine if a pod is working.

Tip

You can see examples of liveness probes in the Kubernetes documentation.

Configure Django

Django comes with a security measure that prevents the liveness probe from working. Add the following line to mysite/settings.py to defeat the allowed hosts protection, which is not needed when the app is running in Kubernetes:

ALLOWED_HOSTS = [ "*" ]

Rebuild the Container!

This change requires that you rebuild the container. You should commit the change to GitHub and wait for the new container to build.

The Liveness Probe

Since Django is a web application we can use a simple form of liveness probe: Having Kubernetes fetch a URL in our application. The configuration fragment shows how to configure the probe.

Add this to the container definition in deployment/mysite-pod.yaml:

livenessProbe:
  httpGet:
    path: /polls/
    port: 8000