Document how to use Raven in a Celery worker

There’s no documentation of how to configure Raven in a Celery worker.

Hints of such documentation were removed in commit 6c5afbf. That commit message says “Remove raven.contrib.celery.CeleryClient” but it does other odd unexplained stuff:

• adds a CeleryClient in raven.contrib.django.celery
• removes documentation showing how to use register_signal, but doesn’t remove that function (and I guess it is still the intended way to capture Celery task failures…?)
• removes a class CeleryMixin but adds a docstring referencing it, showing creation of a CeleryClient class like the one being removed.

[gtaylor]

For the sake of being helpful, I’ll point out that as of Celery 3.1, the Django integration looks like this:

http://docs.celeryproject.org/en/latest/django/first-steps-with-django.html

They suggest a celery.py module, which seems like the perfect place for this. Here’s what we have right now, which could be totally off:

from __future__ import absolute_import

import os

from celery import Celery
from raven import Client
from raven.contrib.celery import register_signal

from django.conf import settings

# set the default Django settings module for the 'celery' program.
os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'pathwright.settings')

app = Celery('pathwright')

# Using a string here means the worker will not have to
# pickle the object when using Windows.
app.config_from_object('django.conf:settings')
app.autodiscover_tasks(lambda: settings.INSTALLED_APPS)

if hasattr(settings, 'RAVEN_CONFIG'):
    # Celery signal registration
    client = Client(dsn=settings.RAVEN_CONFIG['dsn'])
    register_signal(client)


@app.task(bind=True)
def debug_task(self):
    print('Request: {0!r}'.format(self.request))

I hope this helps someone!

[umazalakain]

I tried this last config and, although my celery worker was outputting that errors were being send to sentry, nothing arrived on the sentry side.

Then I set the CELERYD_HIJACK_ROOT_LOGGER = False and 'disable_existing_loggers': True, in the logging configuration and all the messages arrived, but they arrived duplicated. So I deactivated the registration of raven for failed celery tasks thus, in the end, only tweaking the mentioned two settings, and everything seams to be logged fine.

Of course, the problem of this approach is that you take logging from the hands of celery back to yours but, as far as I see, this shouldn’t be any problem right?