Cron

In Hyper, cron is a system service that runs scheduled jobs at given intervals or times, just like the cron unix service but work with the containers.

Cron expression

The original Cron reference documentation for this implementation is found at here, where Hyper Cron implementation differs:

Field name     Mandatory?   Allowed values    Allowed special characters
----------     ----------   --------------    --------------------------
Minutes        Yes          0-59              * / , -
Hours          Yes          0-23              * / , -
Day of month   Yes          1-31              * / , -
Month          Yes          1-12 or JAN-DEC   * / , -
Day of week    Yes          0-6 or SUN-SAT    * / , -
Year           No           1970–2099         * / , -

Asterisk ( * )

The asterisk indicates that the cron expression matches for all values of the field. E.g., using an asterisk in the 4th field (month) indicates every month.

Slash ( / )

Slashes describe increments of ranges. For example 3-59/15 in the minute field indicate the third minute of the hour and every 15 minutes thereafter. The form */... is equivalent to the form "first-last/...", that is, an increment over the largest possible range of the field.

Comma ( , )

Commas are used to separate items of a list. For example, using MON,WED,FRI in the 5th field (day of week) means Mondays, Wednesdays and Fridays.

Hyphen ( - )

Hyphens define ranges. For example, 2000-2010 indicates every year between 2000 and 2010 AD, inclusive.

Examples

Create a cron job which will ping an address every 5 minutes:

$ hyper cron create  --minute=*/5 --hour=* --name test-cron-job1 busybox ping -c 3 8.8.8.8

Check cron job list:

$ hyper cron ls
Name               Schedule            Image               Command
test-cron-job1     */5 * * * *         busybox             ping -c 3 8.8.8.8

Check the execution history of a cron job:

$ hyper cron history test-cron-job1
Container                   Start                           End                             Status              Message
test-cron-job1-1479265800   2016-11-16 03:10:00 +0000 UTC   2016-11-16 03:11:24 +0000 UTC   done                Job[test-cron-job1] is success to run
test-cron-job1-1479266100   2016-11-16 03:15:00 +0000 UTC   2016-11-16 03:15:25 +0000 UTC   done                Job[test-cron-job1] is success to run
test-cron-job1-1479266400   2016-11-16 03:20:00 +0000 UTC   2016-11-16 03:20:25 +0000 UTC   done                Job[test-cron-job1] is success to run
test-cron-job1-1479266700   2016-11-16 03:25:00 +0000 UTC   2016-11-16 03:25:25 +0000 UTC   done                Job[test-cron-job1] is success to run
test-cron-job1-1479267000   2016-11-16 03:30:00 +0000 UTC   -                               -                   Job[test-cron-job1] is running at 2016-11-16 03:30:00 +0000 UTC

Remove a cron job:

$ hyper cron rm test-cron-job1
test-cron-job1

Notes

  • All timestamps in Hyper Cron service is UTC+0.

  • When a cron job container finished, Hyper Cron service will try to get ExitCode of the container. If the value is non-zero, the cron job is failed.

  • By default, a notification email will be sent to your Hyper account's email address, when a cron job failed.

  • You may override to deliver the email to another address with --mailto flag.

  • You may control the notification policy with --mail flag:

    • on-failure (default): send notification only when a cron job failed

    • on-success: send notification only when a cron job succeeded

    • all: always send notification

  • The notification email contains the last 100 lines of log for the cron job container.

  • When the Hyper Cron service is under maintaince, some cron jobs may be missed. In such case, a schedule-missed email will be sent to user.

  • When a cron job container finished (either succeeded or failed), the container will be cleaned up within a minute.

  • When you remove a cron job, it could be possible that there are cron job containers running. In such case, the container will be left running. A manual cleanup is needed.

  • The cron service will not retry the failed cron job.

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