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Merge pull request #30509 from soltysh/cronjob_warning 

Add warning about using unsupported CRON_TZ
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Kubernetes Prow Robot 2021-11-17 07:17:54 -08:00 committed by GitHub
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content/en/docs/concepts/workloads/controllers/cron-jobs.md
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@ -17,8 +17,6 @@ A _CronJob_ creates {{< glossary_tooltip term_id="job" text="Jobs" >}} on a repe
One CronJob object is like one line of a _crontab_ (cron table) file. It runs a job periodically One CronJob object is like one line of a _crontab_ (cron table) file. It runs a job periodically
on a given schedule, written in [Cron](https://en.wikipedia.org/wiki/Cron) format. on a given schedule, written in [Cron](https://en.wikipedia.org/wiki/Cron) format.
In addition, the CronJob schedule supports timezone handling, you can specify the timezone by adding "CRON_TZ=<time zone>" at the beginning of the CronJob schedule, and it is recommended to always set `CRON_TZ`.
{{< caution >}} {{< caution >}}
All **CronJob** `schedule:` times are based on the timezone of the All **CronJob** `schedule:` times are based on the timezone of the
{{< glossary_tooltip term_id="kube-controller-manager" text="kube-controller-manager" >}}. {{< glossary_tooltip term_id="kube-controller-manager" text="kube-controller-manager" >}}.
@ -28,6 +26,16 @@ containers, the timezone set for the kube-controller-manager container determine
that the cron job controller uses. that the cron job controller uses.
{{< /caution >}} {{< /caution >}}
{{< caution >}}
The [v1 CronJob API](/docs/reference/kubernetes-api/workload-resources/cron-job-v1/)
does not officially support setting timezone as explained above.
Setting variables such as `CRON_TZ` or `TZ` is not officially supported by the Kubernetes project.
`CRON_TZ` or `TZ` is an implementation detail of the internal library being used
for parsing and calculating the next Job creation time. Any usage of it is not
recommended in a production cluster.
{{< /caution >}}
When creating the manifest for a CronJob resource, make sure the name you provide When creating the manifest for a CronJob resource, make sure the name you provide
is a valid [DNS subdomain name](/docs/concepts/overview/working-with-objects/names#dns-subdomain-names). is a valid [DNS subdomain name](/docs/concepts/overview/working-with-objects/names#dns-subdomain-names).
The name must be no longer than 52 characters. This is because the CronJob controller will automatically The name must be no longer than 52 characters. This is because the CronJob controller will automatically
@ -55,16 +63,15 @@ takes you through this example in more detail).
### Cron schedule syntax ### Cron schedule syntax
``` ```
# ┌────────────────── timezone (optional) # ┌───────────── minute (0 - 59)
# | ┌───────────── minute (0 - 59) # │ ┌───────────── hour (0 - 23)
# | │ ┌───────────── hour (0 - 23) # │ │ ┌───────────── day of the month (1 - 31)
# | │ │ ┌───────────── day of the month (1 - 31) # │ │ │ ┌───────────── month (1 - 12)
# | │ │ │ ┌───────────── month (1 - 12) # │ │ │ │ ┌───────────── day of the week (0 - 6) (Sunday to Saturday;
# | │ │ │ │ ┌───────────── day of the week (0 - 6) (Sunday to Saturday; # │ │ │ │ │ 7 is also Sunday on some systems)
# | │ │ │ │ │ 7 is also Sunday on some systems) # │ │ │ │ │
# | │ │ │ │ │ # │ │ │ │ │
# | │ │ │ │ │ # * * * * *
# CRON_TZ=UTC * * * * *
``` ```
@ -78,9 +85,9 @@ takes you through this example in more detail).
For example, the line below states that the task must be started every Friday at midnight, as well as on the 13th of each month at midnight (in UTC): For example, the line below states that the task must be started every Friday at midnight, as well as on the 13th of each month at midnight:
`CRON_TZ=UTC 0 0 13 * 5` `0 0 13 * 5`
To generate CronJob schedule expressions, you can also use web tools like [crontab.guru](https://crontab.guru/). To generate CronJob schedule expressions, you can also use web tools like [crontab.guru](https://crontab.guru/).