At work, we started using Kubernetes for stateless application. We frequently change the values of configmap/secrets especially in staging environments, however, this is still not baked in to k8s.
How to do it?
You have to replace a config to update it.
For example, if you create a configmap like this:
kubectl create configmap site-config --from-file=nginx.conf
If you want to update that, you have to add the command above with
--dry-run -o yaml | kubectl replace -f -
So it would become like this:
kubectl create configmap site-config --from-file=nginx.conf \
--dry-run -o yaml | kubectl replace -f -
But we are not done yet, in order for those configs to be visible in the running containers that need them, we have to do a new deployment.
The easiest way to do that is to patch the container. Say our deployment service is called nginx.
kubectl patch deployment nginx -p "{\"spec\":{\"template\":{\"metadata\":{\"annotations\":{\"date\":\"`date +'%s'`\"}}}}}"
This should issue a new deployment rollout and the changes in configmap are now propagated on the new containers.
I hope this helps you on your journey to Kubernetes, it’s a different way of thinking than previous ops but its a step forward in my opinion.