Fails to parse crontab with full day of week name

[salamek]

Fails to parse crontab with full day of week name

[Salamek]

Umm since when is full day name allowed in CRON expression? Allowed formats are 3 char name (MON) or int 0-6 i have never seen anyone use full name of a day...

[Salamek]

Python-crontab is also using 3 char day names in it's docs...
https://pypi.org/project/python-crontab/

Looks like issue is in celery.schedules.crontab for some weir reason it accepts monday as valid day_of_week and then when it generates cron expression it generates invalid cron 0 2 monday * * correct format is 0 2 * * MON

[nijel]

Celery supports that (see referenced code). It might not be standard, though...

[Salamek]

@nijel how i now wrote in previous comment, it is issue of celery.schedules.crontab and when it builds crontab string it passes incorrect value there...

[Salamek]

celery.schedules,crontab should implement something like to_valid_cron():

c = crontab(hour=2, minute=0, day_of_week="monday")

# celery.schedules,crontab converts named days & months to their integer representation, use that instead!


minute, = c.minute
hour, = c.hour
day_of_week, = c.day_of_week

correct_cron = '{} {} {} {} {}'.format( 
    minute,
    hour,
    c._orig_day_of_month,
    c._orig_month_of_year,
    day_of_week
)
print(correct_cron)

Outputs 0 2 * * 1 that is valid cron

(this is put together to only work with your example parameters, do not use in production)

[nijel]

Yes, it might do a better job. But the way cron-descriptor crashed is not really helpful. I would not mind if it reported invalid input, but instead there is none exception message and the intermediate one contains something about 1DAY what has really nothing to do with the original string.

[Salamek]

Hehe, this is not cron expression validator for sure... :-) Also that 1DAY is result of 'monday '.upper().replace('MON', '1') on line

cron-descriptor/cron_descriptor/ExpressionParser.py

Line 174 in 0c575c6

expression_parts[5] = expression_parts[5].upper().replace(self._cron_days[day_number], str(day_number))

But i'll consider adding some kind of validation / better parsing exceptions...

[Salamek]

(Should be) Fixed in downstream...