Auto healing demo

Lets see some reasons why we are using kubernetes in the first place. We will use the blogging platform ghost because it is fast an easy to deploy and work with.

Deploy ghost

cat ghost-ephemeral.yaml | envsubst | kubectl apply -f -

Make edits

If you now go to https://ghost.yourdomain.com (wait a few seconds for the certificate to be claimed), you should see ghost startpage. Go to https://ghost.yourdomain.com/ghost and create an account. Make some changes. Go back to the site and see the changes.

Delete the pod

kubectl get pods

NAME                     READY   STATUS    RESTARTS   AGE
echo1-68949fd997-4g9k4   1/1     Running   0          20m
echo1-68949fd997-tqwwp   1/1     Running   0          20m
ghost-548879c755-bxvrx   1/1     Running   0          6m26s

kubectl delete pod ghost-548879c755-bxvrx

Wait for a few seconds an check again.

kubectl get pods

NAME                     READY   STATUS    RESTARTS   AGE
echo1-68949fd997-4g9k4   1/1     Running   0          22m
echo1-68949fd997-tqwwp   1/1     Running   0          22m
ghost-548879c755-zfffk   1/1     Running   0          14s

Yes! It just recreates it self. This is one of the great things with kubernetes. Even if this pod was running on a VPS that just died, it would be recreated on a different VPS (as long as you have multiple ones, of course).

No! The changes we made are lost! This is a brand new pod, and the data we saved has been deleted. Read the part about persistant storage to see more about how we can deal with this.