[SOLVED] Airflow schedule a task to run on the Monday before the 15th of the month

Issue

Is it possible to schedule an airflow DAG to run at a specific time on the Monday directly before the 15th of each month? I think this cron string might do it but I'm not sure that I have understood correctly

0 10 8-14 * MON

So I think that this should run at 10:00 on a Monday only between the 8th and the 14th of each month. As there can only be one Monday between the 8th and the 14th, this should run only once a month and it will be the Monday preceding the 15th of the month.

Is that correct?

Solution

The croniter module (which Airflow uses for the execution date/time calculations) supports the hash symbol for the day-of-week field which would allow you to schedule, what I believe will work, the second Monday of each month.

For example, "30 7 * * 1#2" says to run at 7:30AM, every month, on the second Monday. Using this code to test it:

from croniter import croniter 
from datetime import datetime 
cron = croniter("30 7 * * 1#2") 
for i in range(10):
    print(cron.get_next(datetime))

yields:

datetime.datetime(2018, 10, 8, 7, 30)
datetime.datetime(2018, 11, 12, 7, 30)
datetime.datetime(2018, 12, 10, 7, 30)
datetime.datetime(2019, 1, 14, 7, 30)
datetime.datetime(2019, 2, 11, 7, 30)
datetime.datetime(2019, 3, 11, 7, 30)
datetime.datetime(2019, 4, 8, 7, 30)
datetime.datetime(2019, 5, 13, 7, 30)
datetime.datetime(2019, 6, 10, 7, 30)
datetime.datetime(2019, 7, 8, 7, 30)

Answered By - joebeeson

Answer Checked By - Marilyn (WPSolving Volunteer)