Cron & Time Intervals¶

You may set your DAG to run on a simple schedule by setting its schedule argument to either a cron expression, a datetime.timedelta object, or one of the Cron Presets.

from airflow.models.dag import DAG

import datetime

dag = DAG("regular_interval_cron_example", schedule="0 0 * * *", ...)

dag = DAG("regular_interval_cron_preset_example", schedule="@daily", ...)

dag = DAG("regular_interval_timedelta_example", schedule=datetime.timedelta(days=1), ...)

Cron Presets¶

For more elaborate scheduling requirements, you can implement a custom timetable. Note that Airflow parses cron expressions with the croniter library which supports an extended syntax for cron strings. See their documentation in github. For example, you can create a DAG schedule to run at 12AM on the first Monday of the month with their extended cron syntax: 0 0 * * MON#1.

Tip

You can use an online editor for CRON expressions such as Crontab guru

preset	meaning	cron
`None`	Don’t schedule, use for exclusively “externally triggered” DAGs
`@once`	Schedule once and only once
`@continuous`	Run as soon as the previous run finishes
`@hourly`	Run once an hour at the end of the hour	`0 * * * *`
`@daily`	Run once a day at midnight (24:00)	`0 0 * * *`
`@weekly`	Run once a week at midnight (24:00) on Sunday	`0 0 * * 0`
`@monthly`	Run once a month at midnight (24:00) of the first day of the month	`0 0 1 * *`
`@quarterly`	Run once a quarter at midnight (24:00) on the first day	`0 0 1 /3 `
`@yearly`	Run once a year at midnight (24:00) of January 1	`0 0 1 1 *`

Your DAG will be instantiated for each schedule along with a corresponding DAG Run entry in the database backend.