Kubernetes Course Labs

Lab Solution

Your Pod spec will look like this - you can use the sample in solution/lab.yaml:

apiVersion: v1
kind: Pod
metadata:
  name: sleep-lab
spec:
  containers:
    - name: app
      image: courselabs/bad-sleep

Deploy it in the usual way with Kubectl:

kubectl apply -f labs/pods/solution/lab.yaml

Now watch the Pod status:

kubectl get pod sleep-lab --watch

After around 30 seconds, the application in the container ends, so the container exits - then Kubernetes restarts the Pod. You'll see a new line in the watch output, with the restart count increased to 1:

NAME        READY   STATUS    RESTARTS   AGE
sleep-lab   1/1     Running   0          3s
sleep-lab   0/1     Completed   0          33s
sleep-lab   1/1     Running     1          35s

Pods restart by creating a new container not by restarting the existing container

The new container runs until the app exits after 30 seconds. Kubernetes restarts the Pod - but if the Pod containers keep exiting, Kubernetes adds an increasing delay before restarting.

The status changes to Completed then Running again, but eventually the Pod enters CrashLoopBackOff status:

NAME        READY   STATUS    RESTARTS   AGE
sleep-lab   1/1     Running   0          3s
sleep-lab   0/1     Completed   0          33s
sleep-lab   1/1     Running     1          35s
sleep-lab   0/1     Completed   1          64s
sleep-lab   0/1     CrashLoopBackOff   1          79s
sleep-lab   1/1     Running            2          80s
sleep-lab   0/1     Completed          2          110s
sleep-lab   0/1     CrashLoopBackOff   2          2m4s
sleep-lab   1/1     Running            3          2m17s

You can delete the Pod by name:

kubectl delete pod sleep-lab

Or by using the delete command with your YAML file:

kubectl delete -f labs/pods/solution/lab.yaml

Back to the exercises.

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