Overview

This is a wrapper for cron jobs which implements common housekeeping tasks.

• Jitter
• Overlap protection
• Timeout
• Failure suppression
• Priority

Jitter

If enabled cronwrap will delay for a random amount of time up to a specified maximum before starting the job. This is useful for jobs that run on many machines but access a centralized service. The random number generator is seeded with the hostname of the machine so that the job runs at a consistent time on each machine.

cronwrap --jitter 5m <job>

Overlap Protection

If enabled cronwrap will not start multiple simultaneous copies of job. For example, you have a job that runs once an hour and usually completes in a minute. However, there's a chance it will get stuck and take more than an hour or even hang forever. You might not want cron to start another copy of the job while the previous job is still running.

cronwrap --overlap <job>

Timeout

If enabled cronwrap will terminate the process if it runs longer than the specified timeout. A SIGTERM will be sent to the job followed by a SIGKILL after 5 seconds.

cronwrap --timeout 1h <job>

Priority

Set process priority similar to the Unix utility nice

cronwrap --nice 19 <job>

Failure Suppression

If enabled cronwrap will suppress non-zero exit values and output unless the job exceeds the specified number of consecutive failures. This is useful for jobs that might fail occasionally due to extenuating circumstances but for which the occasional failure is acceptable as long as it the job starts running successfully again soon.

cronwrap --suppress 3 <job>

Database check (poor-man-cluster)

If enabled cronwrap will check if the hostname is present and active in a table on a db (see cronwrap.ini.sample for db config and code for the SELECT statement).

cronwrap --database <job>

Downloads

Tarballs available from the tags page.