Question

You mount a ConfigMap named app-config into a Deployment's pod using a volume with a subPath reference (mountPath: /etc/app/config.yaml, subPath: config.yaml). After editing the ConfigMap with 'kubectl edit configmap app-config', you notice the running pods still see the old file contents even after several minutes. Other Deployments that mount the same ConfigMap as a full directory (no subPath) do receive the update automatically. What is the correct explanation and fix?

Accepted Answer

ConfigMap volumes mounted with subPath do not receive automatic updates; you must trigger a rollout (e.g. 'kubectl rollout restart deployment') to pick up the new values.

Answer

ConfigMap updates only propagate to pods that reference the ConfigMap via envFrom; convert the mount to environment variables to fix it.

Answer

The kubelet sync period must be lowered on every node before subPath mounts will update; edit the kubelet config and restart it.

Answer

ConfigMaps become immutable once mounted with subPath; you must delete and recreate the ConfigMap with a new name and update the volume reference.