What is a CronJob?

Learn scheduled tasks with a CronJob.

What is a CronJob?

A CronJob creates Jobs on a schedule: nightly backups, hourly reports, weekly cleanup. The schedule is in Unix cron format: minute hour day-of-month month day-of-week:

"0 3 * * *"      every day at 03:00
"*/15 * * * *"   every 15 minutes
"0 9 * * 1"      every Monday at 09:00
"0 0 1 * *"      midnight on the 1st of every month

The time zone defaults to the kube-controller-manager's (usually UTC); it can be changed with timeZone: "Europe/Istanbul".

Managing a CronJob

A CronJob can also be created with a command. To trigger it by hand without waiting for the next run, a Job is produced from it; to pause it temporarily, suspend is used:

kubectl create cronjob temizlik --image=busybox:1.36 --schedule="0 4 * * *" -- sh -c "echo temizlendi"
kubectl create job temizlik-elle --from=cronjob/temizlik
kubectl patch cronjob temizlik -p '{"spec":{"suspend":true}}'
kubectl get cronjobs

Exercise A scheduled cleanup

Write three commands: create a CronJob temizlik with the busybox:1.36 image running echo temizlendi every day at 04:00 ("0 4 * * *"); produce a Job temizlik-elle from it by hand; list the CronJobs.

Show example solution

kubectl create cronjob temizlik --image=busybox:1.36 --schedule="0 4 * * *" -- echo temizlendi
kubectl create job temizlik-elle --from=cronjob/temizlik
kubectl get cronjobs

Test yourself

When does the schedule "30 2 * * 0" run?
- Every Sunday at 02:30
- Every day at 02:30
- On the 30th of every month
- Every 30 minutes
Show answer

Every Sunday at 02:30 — Day of week 0 is Sunday.

Produce a Job from a CronJob by hand.

kubectl create job temizlik-elle ____=cronjob/temizlik

Show answer

kubectl create job temizlik-elle --from=cronjob/temizlik

Match the schedules.

0 3 * * *

Every day 03:00
*/15 * * * *

Every 15 minutes
0 9 * * 1

Monday 09:00
0 0 1 * *

The 1st at 00:00

Next lesson: CronJob YAML

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