CronJob concept implies that CronJob can schedule one-shot tasks for a specific future date

[sftim]

This is a Bug Report

Problem:
The CronJob concept page mentions:

CronJobs can also schedule individual tasks for a specific time, such as scheduling a Job for when your cluster is likely to be idle.

This sounds like at, which can schedule one-shot tasks for a specific future date / datetime; however, that page strongly implies that CronJob does not in fact provide “run exactly once and never repeat” semantics.

Technically you could define a CronJob and a ServiceAccount and authnz rules that let the CronJob delete itself after it has successfully run once. I don't think we want to mention that bodge. I'd rather see an addon that gives you a OneShotScheduledJob CRD or similar.

Proposed Solution:

Remove or reword the text “CronJobs can also schedule individual tasks for a specific time, such as scheduling a Job for when your cluster is likely to be idle.”

Page to Update:

https://kubernetes.io/docs/concepts/workloads/controllers/cron-jobs/

Additional Information:
/kind bug
/sig apps

[sftim]

@kubernetes/sig-apps-misc could you confirm this and /triage accepted if you agree?

[sftim]

I logged this after adding feedback for the v1.21 release announcement: #27233 (comment)

[soltysh]

@sftim yeah, I like your proposed wording, are you going to open a PR?
/triage accepted

[sftim]

This issue is open for an interested contributor to work on. I already have some other PRs / work-in-progress that I'm going to focus on first.

[sftim]

The wording I suggested was:

CronJobs are meant for performing regular scheduled actions such as backups, report generation, and so on. Each of those tasks should be configured to recur indefinitely (for example: once a day / week / month); you can define the point in time within that interval when the job should start.

[soltysh]

Lemme add that bit to #28229 where I'm updating CronJob related flag, in that case.

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/lifecycle stale

[k8s-triage-robot]

The Kubernetes project currently lacks enough active contributors to adequately respond to all issues and PRs.

This bot triages issues and PRs according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 30d of inactivity since lifecycle/rotten was applied, the issue is closed

You can:

• Mark this issue or PR as fresh with /remove-lifecycle rotten
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/lifecycle rotten

[soltysh]

This was fixed in #28229
/close

[k8s-ci-robot]

@soltysh: Closing this issue.

In response to this:

This was fixed in #28229
/close

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