How can I schedule task with celery which runs at the end of month?

Question

I need to set celery crontab to run at the end of month even different day as end of month(28~31). I know how to set crontab run at the end of month on shell command like this:

55　23　28-31 * * /usr/bin/test $( date -d '+1 day' +%d ) -eq 1 && exec something

But on celery schedule I don't know how to do this setting. Is there any way to schedule task which runs at the end of month on celery?
It seems only way is to override is_due method on celery.schedules.crontab .

Answer 1

If you don't mind a bit of overhead - you can set the task to run every day in CELERYBEAT_SCHEDULE.

And then in the task itself you can check if the day is the last day of the month:

import calendar
from datetime import datetime

@task
def task_to_run_at_end_of_month():
    today = datetime.today()
    day_in_month = today.day
    month = today.month
    year = today.year
    day_of_week, number_of_days_in_month = calendar.monthrange(year, month)
    if day_in_month != number_of_days_in_month:
        # not last day of month yet, do nothing
        return
    # process stuff on last day of month
    ...

Answer 2

Celery comes with a module that does exactly this.

The way to run it from the command line is like this

celery -A $project_name beat

Where normally you would use worker instead of beat

Then include in your celery_config.py a definition of the CELERYBEAT_SCHEDULE . Something like this

from celery.schedules import crontab

CELERYBEAT_SCHEDULE = {
        "end_of_month_task": {
            "task": "module.task_name", # this is the task name
            "schedule": crontab(0, 0, day_of_month=0),
            "args": the_arguments_to_this_function
        }
    }