Error config Map volume mount read-only file system error

Question

I have a configmap for 3 files that are going to be mounted in  "fluentd/etc/" and the respective files are fluent.conf, Kubernetes.conf, systemd.conf, configmap in deployment.yaml is like this:

volumeMounts:
name: fluentd
mountPath: /fluentd/etc/
name: varlog
mountPath: /var/log
name: container1
mountPath: /var/lib/docker/containers
readOnly: true
securityContext:
privileged: true
terminationGracePeriodSeconds: 30
volumes:
name: varlog
hostPath:
path: /var/log
name: container1
hostPath:
path: /var/lib/docker/containers
name: fluentd
configMap:
name: fluentd-config

During deployment I am getting an error of mount as read-only, which is effecting fluent to read some of the mentioned sources in the configmap. How can I avoid this read-only error?

Answer 1

ConfigMaps are always mounted read-only.

If you need to modify a configmap in a pod, you should copy it from the configmap mount to a regular file in the pod and then modify it. 

To solve this issue :

• you should use an init container to mount the configmap

• copy the configmap into an `emptyDir` volume and

• share the volume with the main container.

• configmaps are mounted read-only so that you can't touch the files. 

• when the master configmap changes the mounted file also changes. so if you were to modify the local mounted file, it would be overwritten anyways.