How to set periodic tasks in Celery declaratively with a dictionary in app.conf = {...}?

Question

Celery

It works:

# tasks.py:
import celery

app = celery.Celery('tasks', broker='redis://127.0.0.1:6379')

@app.task
def show(arg):
    print(arg)

app.add_periodic_task(5, show.s(42), name='task-name')

And this doesn't work:

# tasks.py:
import celery

app = celery.Celery('tasks', broker='redis://127.0.0.1:6379')

@app.task
def show(arg):
    print(arg)

app.conf.beat_schedule = {
    'task-name': {
        'task': 'show',
        'schedule': 5.0,
        'args': (42,),
    },
}
app.conf.timezone = 'UTC'

Worker crashes with the following error:

[2019-08-26 18:09:16,333: ERROR/MainProcess] Received unregistered task of type 'show'.
The message has been ignored and discarded.
Did you remember to import the module containing this task?
Or maybe you're using relative imports?
Please see
docs.celeryq.org/en/latest/internals/protocol.html
for more information.
The full contents of the message body was:
b'[[42], {}, {"callbacks": null, "errbacks": null, "chain": null, "chord": null}]' (79b)
Traceback (most recent call last):
File "/home/oleg/projects/asm/.venv/lib/python3.6/site-packages/celery/worker/consumer/consumer.py", line 558,

I run it like this:

celery -A tasks beat -s ./celerybeat-schedule  # планировщик
celery -A tasks worker  # воркер

But I want to set tasks in the second way.
What's wrong?

Answer 1

Because it needs to be like this:

# tasks.py:
import celery

app = celery.Celery('tasks', broker='redis://127.0.0.1:6379')

@app.task
def show(arg):
    print(arg)

app.conf.beat_schedule = {
    'task-name': {
        'task': 'tasks.show',  # instead 'show'
        'schedule': 5.0,
        'args': (42,),
    },
}
app.conf.timezone = 'UTC'