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Pruning Objects

Overview

Over time, API objects created in OpenShift Container Platform can accumulate in the etcd data store through normal user operations, such as when building and deploying applications.

As an administrator, you can periodically prune older versions of objects from your OpenShift Container Platform instance that are no longer needed. For example, by pruning images you can delete older images and layers that are no longer in use, but are still taking up disk space.

Basic Prune Operations

The CLI groups prune operations under a common parent command.

$ oadm prune <object_type> <options>

This specifies:

  • The <object_type> to perform the action on, such as builds, deployments, or images.

  • The <options> supported to prune that object type.

Pruning Deployments

In order to prune deployments that are no longer required by the system due to age and status, administrators may run the following command:

$ oadm prune deployments [<options>]
Table 1. Prune Deployments CLI Configuration Options
Option Description

--confirm

Indicate that pruning should occur, instead of performing a dry-run.

--orphans

Prune all deployments whose deployment config no longer exists, status is complete or failed, and replica count is zero.

--keep-complete=<N>

Per deployment config, keep the last N deployments whose status is complete and replica count is zero. (default 5)

--keep-failed=<N>

Per deployment config, keep the last N deployments whose status is failed and replica count is zero. (default 1)

--keep-younger-than=<duration>

Do not prune any object that is younger than <duration> relative to the current time. (default 60m)

To see what a pruning operation would delete:

$ oadm prune deployments --orphans --keep-complete=5 --keep-failed=1 \
    --keep-younger-than=60m

To actually perform the prune operation:

$ oadm prune deployments --orphans --keep-complete=5 --keep-failed=1 \
    --keep-younger-than=60m --confirm

Pruning Builds

In order to prune builds that are no longer required by the system due to age and status, administrators may run the following command:

$ oadm prune builds [<options>]
Table 2. Prune Builds CLI Configuration Options
Option Description

--confirm

Indicate that pruning should occur, instead of performing a dry-run.

--orphans

Prune all builds whose build config no longer exists, status is complete, failed, error, or canceled.

--keep-complete=<N>

Per build config, keep the last N builds whose status is complete. (default 5)

--keep-failed=<N>

Per build config, keep the last N builds whose status is failed, error, or canceled (default 1)

--keep-younger-than=<duration>

Do not prune any object that is younger than <duration> relative to the current time. (default 60m)

To see what a pruning operation would delete:

$ oadm prune builds --orphans --keep-complete=5 --keep-failed=1 \
    --keep-younger-than=60m

To actually perform the prune operation:

$ oadm prune builds --orphans --keep-complete=5 --keep-failed=1 \
    --keep-younger-than=60m --confirm

Pruning Images

In order to prune images that are no longer required by the system due to age, status, or exceed limits, administrators may run the following command:

$ oadm prune images [<options>]

Currently, to prune images you must first log in to the CLI as a user with an access token. The user must also have the cluster role system:image-pruner or greater (for example, cluster-admin).

Pruning images removes data from the integrated registry. For this operation to work properly, ensure your registry is configured with storage:delete:enabled set to true.
Table 3. Prune Images CLI Configuration Options
Option Description

--certificate-authority

The path to a certificate authority file to use when communicating with the OpenShift Container Platform-managed registries. Defaults to the certificate authority data from the current user’s config file.

--confirm

Indicate that pruning should occur, instead of performing a dry-run.

--keep-tag-revisions=<N>

For each image stream, keep up to at most N image revisions per tag. (default 3)

--keep-younger-than=<duration>

Do not prune any image that is younger than <duration> relative to the current time. Do not prune any image that is referenced by any other object that is younger than <duration> relative to the current time. (default 60m)

--prune-over-size-limit

Prune each image that exceeds the smallest limit defined in the same project. This flag cannot be combined with --keep-tag-revisions nor --keep-younger-than.

OpenShift Container Platform uses the following logic to determine which images and layers to prune:

  • Remove any image "managed by OpenShift Container Platform" (images with the annotation openshift.io/image.managed) that was created at least --keep-younger-than minutes ago and is not currently referenced by:

    • any pod created less than --keep-younger-than minutes ago.

    • any image stream created less than --keep-younger-than minutes ago.

    • any running pods.

    • any pending pods.

    • any replication controllers.

    • any deployment configurations.

    • any build configurations.

    • any builds.

    • the --keep-tag-revisions most recent items in stream.status.tags[].items.

  • Remove any image "managed by OpenShift Container Platform" (images with the annotation openshift.io/image.managed) that is exceeding the smallest limit defined in the same project and is not currently referenced by:

    • any running pods.

    • any pending pods.

    • any replication controllers.

    • any deployment configurations.

    • any build configurations.

    • any builds.

  • There is no support for pruning from external registries.

  • When an image is pruned, all references to the image are removed from all image streams that have a reference to the image in status.tags.

  • Image layers that are no longer referenced by any images are removed as well.

--prune-over-size-limit cannot be combined with --keep-tag-revisions nor --keep-younger-than flags. Doing so will return an information that this operation is not allowed.

To see what a pruning operation would delete:

  1. Keeping up to three tag revisions, and keeping resources (images, image streams and pods) younger than sixty minutes:

    $ oadm prune images --keep-tag-revisions=3 --keep-younger-than=60m

  2. Pruning every image that exceeds defined limits:

    $ oadm prune images --prune-over-size-limit

To actually perform the prune operation for the previously mentioned options accordingly:

$ oadm prune images --keep-tag-revisions=3 --keep-younger-than=60m --confirm

$ oadm prune images --prune-over-size-limit --confirm