kubernetes
/
website
mirror of https://github.com/kubernetes/website.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Improve CronJob concept page 

Co-Authored-By: Zach Corleissen <zacharysarah@users.noreply.github.com>
This commit is contained in:
Tim Bannister 2020-02-23 11:25:54 +00:00
parent f85277d6d4
commit 80e05e4e52
1 changed files with 25 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

30
content/en/docs/concepts/workloads/controllers/cron-jobs.md
View File

@ -12,7 +12,7 @@ weight: 80
{{< feature-state for_k8s_version="v1.8" state="beta" >}}
A _Cron Job_ creates [Jobs](/docs/concepts/workloads/controllers/jobs-run-to-completion/) on a time-based schedule.
A _CronJob_ creates {{< glossary_tooltip term_id="job" text="Jobs" >}} on a repeating schedule.
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.
@ -27,14 +27,26 @@ The name must be no longer than 52 characters. This is because the CronJob contr
append 11 characters to the job name provided and there is a constraint that the
maximum length of a Job name is no more than 63 characters.
For instructions on creating and working with cron jobs, and for an example of a spec file for a cron job, see [Running automated tasks with cron jobs](/docs/tasks/job/automated-tasks-with-cron-jobs).
{{% /capture %}}
{{% capture body %}}
## Cron Job Limitations
## CronJob
CronJobs are useful for creating periodic and recurring tasks, like running backups or
sending emails. CronJobs can also schedule individual tasks for a specific time, such as
scheduling a Job for when your cluster is likely to be idle.
### Example
This example CronJob manifest prints the current time and a hello message every minute:
{{< codenew file="application/job/cronjob.yaml" >}}
([Running Automated Tasks with a CronJob](/docs/tasks/job/automated-tasks-with-cron-jobs/)
takes you through this example in more detail).
## CronJob limitations {#cron-job-limitations}
A cron job creates a job object _about_ once per execution time of its schedule. We say "about" because there
are certain circumstances where two jobs might be created, or no job might be created. We attempt to make these rare,
@ -66,3 +78,11 @@ The CronJob is only responsible for creating Jobs that match its schedule, and
the Job in turn is responsible for the management of the Pods it represents.
{{% /capture %}}
{{% capture whatsnext %}}
[Cron expression format](https://pkg.go.dev/github.com/robfig/cron?tab=doc#hdr-CRON_Expression_Format)
documents the format of CronJob `schedule` fields.
For instructions on creating and working with cron jobs, and for an example of CronJob
manifest, see [Running automated tasks with cron jobs](/docs/tasks/job/automated-tasks-with-cron-jobs).
{{% /capture %}}