How do I schedule jobs in Jenkins?

By setting the schedule period to 15 13 * * * you tell Jenkins to schedule the build every day of every month of every year at the 15th minute of the 13th hour of the day.

Jenkins used a cron expression, and the different fields are:

1. MINUTES Minutes in one hour (0-59)
2. HOURS Hours in one day (0-23)
3. DAYMONTH Day in a month (1-31)
4. MONTH Month in a year (1-12)
5. DAYWEEK Day of the week (0-7) where 0 and 7 are sunday

If you want to schedule your build every 5 minutes, this will do the job : */5 * * * *

If you want to schedule your build every day at 8h00, this will do the job : 0 8 * * *

For the past few versions (2014), Jenkins have a new parameter, H (extract from the Jenkins code documentation):

To allow periodically scheduled tasks to produce even load on the system, the symbol H (for “hash”) should be used wherever possible.

For example, using 0 0 * * * for a dozen daily jobs will cause a large spike at midnight. In contrast, using H H * * * would still execute each job once a day, but not all at the same time, better using limited resources.

Note also that:

The H symbol can be thought of as a random value over a range, but it actually is a hash of the job name, not a random function, so that the value remains stable for any given project.

More example of using 'H'

The format is as follows:

MINUTE (0-59), HOUR (0-23), DAY (1-31), MONTH (1-12), DAY OF THE WEEK (0-6)

The letter H, representing the word Hash can be inserted instead of any of the values. It will calculate the parameter based on the hash code of you project name.

This is so that if you are building several projects on your build machine at the same time, let’s say midnight each day, they do not all start their build execution at the same time. Each project starts its execution at a different minute depending on its hash code.

You can also specify the value to be between numbers, i.e. H(0,30) will return the hash code of the project where the possible hashes are 0-30.

Examples:

1. Start build daily at 08:30 in the morning, Monday - Friday: 30 08 * * 1-5

2. Weekday daily build twice a day, at lunchtime 12:00 and midnight 00:00, Sunday to Thursday: 00 0,12 * * 0-4

3. Start build daily in the late afternoon between 4:00 p.m. - 4:59 p.m. or 16:00 -16:59 depending on the projects hash: H 16 * * 1-5

4. Start build at midnight: @midnight or start build at midnight, every Saturday: 59 23 * * 6

5. Every first of every month between 2:00 a.m. - 02:30 a.m.: H(0,30) 02 01 * *