Djando Celery: Celery task does not create record in DB

Question

I want to create database records with celery task. But for some reason object.save() method is not working with task.apply_async() (Apply tasks asynchronousy).

Same record (Ticker) is saved in the database with a celery task while running it locally:

get_all_tickers.apply()

But is not saved with asynchronous mode:

get_all_tickers.apply_async()

In both cases INSERT statement is visible in the server log.

models.py

class Ticker(TimeStampedModel):
    ask = models.DecimalField(max_digits=18, decimal_places=8)
    bid = models.DecimalField(max_digits=18, decimal_places=8)
    pair = models.ForeignKey(Pair)

tasks.py

from celery import shared_task
...
@shared_task()
def get_all_tickers():
    pair = Pair.objects.last()
    ticker = Ticker(ask=Decimal(1.0), bid=Decimal(1.0), pair=pair)
    ticker.save()

Answer 1

Django server(root) and celery(celery_user) tasks were run by different users, therefore, celery_user has not got write access to the database. So then task.apply() is run by root and can save() records and task.apply_async() - by celery_user and cannot.

The short-term solution for this problem was to make celery_user the owner of the database (development env using sqlite3):

chown celery_user:celery_user db.sqlite3

Although, Adding a group to the celery_user would be more appropriate (for short-term).

Or long term - run everything with unprivileged users https://www.syncano.io/blog/configuring-running-django-celery-docker-containers-pt-1/

p.s.: I was having some problems with http://docs.celeryproject.org/en/latest/reference/celery.contrib.rdb.html (debugging tool for celery). Telnet was disconnected every time the task was received (i.e. every 30 seconds). Make sure that You are using task which is dedicated for debugging.