I’ve define a Celery app in a module, and now I want to start the worker from the same module in its __main__, i.e. by running the module with python -m instead of celery from the command line. I tried this:

app = Celery('project', include=['project.tasks'])

# do all kind of project-specific configuration
# that should occur whenever this module is imported

if __name__ == '__main__':
    # log stuff about the configuration
    app.start(['worker', '-A', 'project.tasks'])

but now Celery thinks I’m running the worker without arguments:

Usage: worker <command> [options] 

Show help screen and exit.

Options:
  -A APP, --app=APP     app instance to use (e.g. module.attr_name)
[snip]

The usage message is the one you get from celery --help, as if it didn’t get a command. I’ve also tried

app.worker_main(['-A', 'project.tasks'])

but that complains about the -A not being recognized.

So how do I do this? Or alternatively, how do I pass a callback to the worker to have it log information about its configuration?

using app.worker_main method (v3.1.12):

± cat start_celery.py
#!/usr/bin/python

from myapp import app


if __name__ == "__main__":
    argv = [
        'worker',
        '--loglevel=DEBUG',
    ]
    app.worker_main(argv)

Based on code from Django-Celery module you could try something like this:

from __future__ import absolute_import, unicode_literals

from celery import current_app
from celery.bin import worker


if __name__ == '__main__':
    app = current_app._get_current_object()

    worker = worker.worker(app=app)

    options = {
        'broker': 'amqp://guest:[email protected]:5672//',
        'loglevel': 'INFO',
        'traceback': True,
    }

    worker.run(**options)

Since Celery 5 things have been changed

The worker_main results now:

AttributeError: 'Celery' object has no attribute 'worker_main'

For Celery 5 do following:

app = celery.Celery(
    'project',
    include=['project.tasks']
)

if __name__ == '__main__':
    worker = app.Worker(
        include=['project.tasks']
    )
    worker.start()

See here celery.apps.worker and celery.worker.WorkController.setup_defaults for details (hope it will be documented better in the future).

worker_main was put back in celery 5.0.3 here:
https://github.com/celery/celery/pull/6481

This worked for me on 5.0.4:

self.app.worker_main(argv = ['worker', '--loglevel=info', '--concurrency={}'.format(os.environ['CELERY_CONCURRENCY']), '--without-gossip'])

I think you are just missing wrapping the args so celery can read them, like:

queue = Celery('blah', include=['blah'])
queue.start(argv=['celery', 'worker', '-l', 'info'])