Create a mutating configmap

README.md

mutating-configmap

Steps to reproduce a changing configmap mounted as a volume to see the effects on a running pod.

Steps

1. Create the initial config map:

   kubectl create configmap my-cm --from-file configmap.txt --dry-run --output yaml | \
      grep -v creationTimestamp | \
      kubectl apply -f -

   Note: Above removes the creation timestamp so that subsequent applies don't trigger a change to the configmap.
2. Launch a simple pod with the configmap mounted as a volume:

   kubectl apply -f pod.yaml

3. Shell into the pod (may have to wait for it to come up):

   kubectl exec -it my-pod -- /bin/sh

4. Monitor the contents of the configmap file:

   while $(true); do echo $(date) $(md5sum /etc/my-cm-volume/configmap.txt); sleep 1; done

5. Mutate the contents of the file.
6. Apply the configmap again (redo step 1).