Chapter 19. Managing Volumes

Containers are not persistent by default; on restart, their contents are cleared. Volumes are mounted file systems available to pods and their containers which may be backed by a number of host-local or network attached storage endpoints.

The simplest volume type is EmptyDir, which is a temporary directory on a single machine. Administrators may also allow you to request a persistent volume that is automatically attached to your pods.

You can use the CLI command oc volume to add, update, or remove volumes and volume mounts for any object that has a pod template like replication controllers or deployment configurations. You can also list volumes in pods or any object that has a pod template.

The oc volume command uses the following general syntax:

$ oc volume <object_selection> <operation> <mandatory_parameters> <optional_parameters>

This topic uses the form <object_type>/<name> for <object_selection> in later examples, however you can choose one of the following options:

The <operation> can be one of --add, --remove, or --list.

Any <mandatory_parameters> or <optional_parameters> are specific to the selected operation and are discussed in later sections.

To add a volume, a volume mount, or both to pod templates:

$ oc volume <object_type>/<name> --add [options]

Examples

Add a new volume source emptyDir to deployment configuration registry:

$ oc volume dc/registry --add

Add volume v1 with secret $ecret for replication controller r1 and mount inside the containers at /data:

$ oc volume rc/r1 --add --name=v1 --type=secret --secret-name='$ecret' --mount-path=/data

Add existing persistent volume v1 with claim name pvc1 to deployment configuration dc.json on disk, mount the volume on container c1 at /data, and update the deployment configuration on the server:

$ oc volume -f dc.json --add --name=v1 --type=persistentVolumeClaim \
  --claim-name=pvc1 --mount-path=/data --containers=c1

Add volume v1 based on Git repository https://github.com/namespace1/project1 with revision 5125c45f9f563 for all replication controllers:

$ oc volume rc --all --add --name=v1 \
  --source='{"gitRepo": {
                "repository": "https://github.com/namespace1/project1",
                "revision": "5125c45f9f563"
            }}'

Updating existing volumes or volume mounts is the same as adding volumes, but with the --overwrite option:

$ oc volume <object_type>/<name> --add --overwrite [options]

Examples

Replace existing volume v1 for replication controller r1 with existing persistent volume claim pvc1:

$ oc volume rc/r1 --add --overwrite --name=v1 --type=persistentVolumeClaim --claim-name=pvc1

Change deployment configuration d1 mount point to /opt for volume v1:

$ oc volume dc/d1 --add --overwrite --name=v1 --mount-path=/opt

To remove a volume or volume mount from pod templates:

$ oc volume <object_type>/<name> --remove [options]

Some examples:

Remove a volume v1 from deployment config d1:

$ oc volume dc/d1 --remove --name=v1

Unmount volume v1 from container c1 for deployment configuration d1 and remove the volume v1 if it is not referenced by any containers on d1:

$ oc volume dc/d1 --remove --name=v1 --containers=c1

Remove all volumes for replication controller r1:

$ oc volume rc/r1 --remove --confirm

To list volumes or volume mounts for pods or pod templates:

$ oc volume <object_type>/<name> --list [options]

List volume supported options:

Examples

List all volumes for pod p1:

$ oc volume pod/p1 --list

List volume v1 defined on all deployment configurations:

$ oc volume dc --all --name=v1