csi-driver-configmap

It is a CSI driver to mount ConfigMap as ephemeral volume. Unlike the k8s builtin driver, it focuses on ConfigMap sharing and updating. That is,

1. Sharing ConfigMap between namespaces,
2. Updating ConfigMap while modifying mounted files, or delay the commit action until unmount the local volume,
3. Stay current with the ConfigMap if it is updated by other clients.

Installation

kubectl apply -f https://raw.githubusercontent.com/warm-metal/csi-driver-configmap/master/install/csi-driver-cm.yaml

Usage

apiVersion: v1
kind: Pod
metadata:
  name: 01-0
  namespace: foo
spec:
  containers:
  - image: docker.io/library/alpine:3
    command:
    - tail
    args:
    - -f
    - /dev/null
    name: 01-0
    volumeMounts:
    - mountPath: /mnt
      name: cm-foo
  volumes:
  - csi:
      driver: csi-cm.warm-metal.tech
      volumeAttributes:
        # Name of the ConfigMap to be mounted
        configMap: cm-foo

        # Namespace of the ConfigMap. If not set, the current namespace is used.
        namespace: bar
        
        # Same as subPath of the builtin ConfigMap driver
        subPath: foo.txt
        
        # Stay current with the ConfigMap if updated by other clients.
        keepCurrentAlways: "true"
        
        # When to commit changes of the local volume. Valid values are:
        # "" (a blank string), don't commit changes,
        # "unmount", commit changes when unmounting the volume,
        # "modify", commit changes after each modify(on inotify event IN_CLOSE_WRITE).
        commitChangesOn: "unmount"
        
        # Determine how to deal with conflicts while committing local changes.
        # REQUIRED if commitChangesOn is set.
        # Valid values are:
        # "override", override the remote changes if conflicts arise,
        # "discard", discard local changes.
        conflictPolicy: "override"

        # Specify how to update the ConfigMap if local size is over than the size limit, that is 1(one) MiB.
        # The policy would not apply to ConfigMap.BinaryData. If size of ConfigMap.BinaryData is over the limit,
        # all changes would be discarded.
        # REQUIRED if commitChangesOn is set.
        # Valid values are:
        # "truncateHead", truncates the content from the head,
        # "truncateTail", truncates the content from the tail,
        # "truncateHeadLine", truncateHead and the partial line at the beginning, 
        # "truncateTailLine", truncateTail as well as the partial line at the end.
        oversizePolicy: ""
    name: cm-foo

Notice that, even though enabling both keepCurrentAlways and commitChangesOn for the same volume is supported, users should avoid getting into this case.