django + celery - How do I set up a crontab schedule for celery in my django app?

Question

I am following the instructions here:

http://celery.readthedocs.org/en/latest/userguide/periodic-tasks.html#crontab-schedules

I'm supposed to be able to do the following: from celery.schedules import crontab

In my settings.py I have:

from kombu import serialization
serialization.registry._decoders.pop("application/x-python-serialize")
import djcelery
djcelery.setup_loader()
from celery.schedules import crontab

...

CELERYBEAT_SCHEDULE = {
    'first_task': {
        'task': 'apps.icecream.tasks.sync_flavors',
        'schedule': crontab(minute='*/30', hour='1, 3, 6, 8-20, 22')
    },
    'second_task': {
        'task': 'apps.robots.tasks.run_robots',
        'schedule': crontab(minute='*/6')
    }
}

However, I'm getting an error: "No module named schedules"

If I switch to the other way of scheduling, using timedelta, then everything is fine and I can get my periodic tasks to run:

CELERYBEAT_SCHEDULE = {
    'first_task': {
        'task': 'apps.icecream.tasks.sync_flavors',
        'schedule': timedelta(minutes=30)
    },
    'second_task': {
        'task': 'apps.robots.tasks.run_robots',
        'schedule': timedelta(minutes=6)
    }
}

Why can't I use the crontab approach?

Answer 1

This happens because you have a celery.py file in the same package as your settings.py, which shadows the global celery package.

To get around this, insert the following string at the beginning of the settings.py:

from __future__ import absolute_import

Hope it helps!