Examples of Django and Celery: Periodic Tasks

Question

I have been fighting the Django/Celery documentation for a while now and need some help.

I would like to be able to run Periodic Tasks using django-celery. I have seen around the internet (and the documentation) several different formats and schemas for how one should go about achieving this using Celery...

Can someone help with a basic, functioning example of the creation, registration and execution of a django-celery periodic task? In particular, I want to know whether I should write a task that extends the PeriodicTask class and register that, or whether I should use the @periodic_task decorator, or whether I should use the @task decorator and then set up a schedule for the task's execution.

I don't mind if all three ways are possible, but I would like to see an example of at least one way that works. Really appreciate your help.

Solution

What's wrong with the example from the docs?

from celery.task import PeriodicTask
from clickmuncher.messaging import process_clicks
from datetime import timedelta


class ProcessClicksTask(PeriodicTask):
    run_every = timedelta(minutes=30)

    def run(self, **kwargs):
        process_clicks()

You could write the same task using a decorator:

from celery.task.schedules import crontab
from celery.task import periodic_task

@periodic_task(run_every=crontab(minute="*/30"))
def process_clicks():
    ....

The decorator syntax simply allows you to turn an existing function/task into a periodic task without modifying them directly.

For the tasks to be executed celerybeat must be running.