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Chapter 13. Pruning objects to reclaim resources
Over time, API objects created in Red Hat OpenShift Service on AWS can accumulate in the cluster’s etcd data store through normal user operations, such as when building and deploying applications.
A user with the dedicated-admin role can periodically prune older versions of objects from the cluster that are no longer required. 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.
13.1. Basic pruning operations
The CLI groups prune operations under a common parent command:
$ oc adm prune <object_type> <options>
This specifies:
-
The
<object_type>to perform the action on, such asgroups,builds,deployments, orimages. -
The
<options>supported to prune that object type.
13.2. Pruning groups
To prune groups records from an external provider, administrators can run the following command:
$ oc adm prune groups \
--sync-config=path/to/sync/config [<options>]| Options | Description |
|---|---|
|
| Indicate that pruning should occur, instead of performing a dry-run. |
|
| Path to the group blacklist file. |
|
| Path to the group whitelist file. |
|
| Path to the synchronization configuration file. |
Procedure
To see the groups that the prune command deletes, run the following command:
$ oc adm prune groups --sync-config=ldap-sync-config.yaml
To perform the prune operation, add the
--confirmflag:$ oc adm prune groups --sync-config=ldap-sync-config.yaml --confirm
13.3. Pruning deployment resources
You can prune resources associated with deployments that are no longer required by the system, due to age and status.
The following command prunes replication controllers associated with DeploymentConfig objects:
$ oc adm prune deployments [<options>]
To also prune replica sets associated with Deployment objects, use the --replica-sets flag. This flag is currently a Technology Preview feature.
| Option | Description |
|---|---|
|
| Indicate that pruning should occur, instead of performing a dry-run. |
|
|
Per the |
|
|
Per the |
|
|
Do not prune any replication controller that is younger than |
|
|
Prune all replication controllers that no longer have a |
Procedure
To see what a pruning operation would delete, run the following command:
$ oc adm prune deployments --orphans --keep-complete=5 --keep-failed=1 \ --keep-younger-than=60mTo actually perform the prune operation, add the
--confirmflag:$ oc adm prune deployments --orphans --keep-complete=5 --keep-failed=1 \ --keep-younger-than=60m --confirm
13.4. Pruning builds
To prune builds that are no longer required by the system due to age and status, administrators can run the following command:
$ oc adm prune builds [<options>]
| Option | Description |
|---|---|
|
| Indicate that pruning should occur, instead of performing a dry-run. |
|
| Prune all builds whose build configuration no longer exists, status is complete, failed, error, or canceled. |
|
|
Per build configuration, keep the last |
|
|
Per build configuration, keep the last |
|
|
Do not prune any object that is younger than |
Procedure
To see what a pruning operation would delete, run the following command:
$ oc adm prune builds --orphans --keep-complete=5 --keep-failed=1 \ --keep-younger-than=60mTo actually perform the prune operation, add the
--confirmflag:$ oc adm prune builds --orphans --keep-complete=5 --keep-failed=1 \ --keep-younger-than=60m --confirm
Developers can enable automatic build pruning by modifying their build configuration.
13.5. Automatically pruning images
Images from the OpenShift image registry that are no longer required by the system due to age, status, or exceed limits are automatically pruned. Cluster administrators can configure the Pruning Custom Resource, or suspend it.
Prerequisites
-
You have access to an Red Hat OpenShift Service on AWS cluster using an account with
dedicated-adminpermissions. -
Install the
ocCLI.
Procedure
-
Verify that the object named
imagepruners.imageregistry.operator.openshift.io/clustercontains the followingspecandstatusfields:
spec: schedule: 0 0 * * * 1 suspend: false 2 keepTagRevisions: 3 3 keepYoungerThanDuration: 60m 4 keepYoungerThan: 3600000000000 5 resources: {} 6 affinity: {} 7 nodeSelector: {} 8 tolerations: [] 9 successfulJobsHistoryLimit: 3 10 failedJobsHistoryLimit: 3 11 status: observedGeneration: 2 12 conditions: 13 - type: Available status: "True" lastTransitionTime: 2019-10-09T03:13:45 reason: Ready message: "Periodic image pruner has been created." - type: Scheduled status: "True" lastTransitionTime: 2019-10-09T03:13:45 reason: Scheduled message: "Image pruner job has been scheduled." - type: Failed staus: "False" lastTransitionTime: 2019-10-09T03:13:45 reason: Succeeded message: "Most recent image pruning job succeeded."
- 1
schedule:CronJobformatted schedule. This is an optional field, default is daily at midnight.- 2
suspend: If set totrue, theCronJobrunning pruning is suspended. This is an optional field, default isfalse. The initial value on new clusters isfalse.- 3
keepTagRevisions: The number of revisions per tag to keep. This is an optional field, default is3. The initial value is3.- 4
keepYoungerThanDuration: Retain images younger than this duration. This is an optional field. If a value is not specified, eitherkeepYoungerThanor the default value60m(60 minutes) is used.- 5
keepYoungerThan: Deprecated. The same askeepYoungerThanDuration, but the duration is specified as an integer in nanoseconds. This is an optional field. WhenkeepYoungerThanDurationis set, this field is ignored.- 6
resources: Standard pod resource requests and limits. This is an optional field.- 7
affinity: Standard pod affinity. This is an optional field.- 8
nodeSelector: Standard pod node selector. This is an optional field.- 9
tolerations: Standard pod tolerations. This is an optional field.- 10
successfulJobsHistoryLimit: The maximum number of successful jobs to retain. Must be>= 1to ensure metrics are reported. This is an optional field, default is3. The initial value is3.- 11
failedJobsHistoryLimit: The maximum number of failed jobs to retain. Must be>= 1to ensure metrics are reported. This is an optional field, default is3. The initial value is3.- 12
observedGeneration: The generation observed by the Operator.- 13
conditions: The standard condition objects with the following types:-
Available: Indicates if the pruning job has been created. Reasons can be Ready or Error. -
Scheduled: Indicates if the next pruning job has been scheduled. Reasons can be Scheduled, Suspended, or Error. -
Failed: Indicates if the most recent pruning job failed.
-
The Image Registry Operator’s behavior for managing the pruner is orthogonal to the managementState specified on the Image Registry Operator’s ClusterOperator object. If the Image Registry Operator is not in the Managed state, the image pruner can still be configured and managed by the Pruning Custom Resource.
However, the managementState of the Image Registry Operator alters the behavior of the deployed image pruner job:
-
Managed: the--prune-registryflag for the image pruner is set totrue. -
Removed: the--prune-registryflag for the image pruner is set tofalse, meaning it only prunes image metadata in etcd.
13.6. Pruning cron jobs
Cron jobs can perform pruning of successful jobs, but might not properly handle failed jobs. Therefore, the cluster administrator should perform regular cleanup of jobs manually. They should also restrict the access to cron jobs to a small group of trusted users and set appropriate quota to prevent the cron job from creating too many jobs and pods.
Additional resources
