[Solved]-Celery No hostname was supplied. Reverting to default 'localhost'

Full document in this link.

you should just add the below line to __init__.py near settings.py

from .celery import app as celery_app

__all__ = ['celery_app']

project structure

- proj/
  - manage.py
  - proj/
    - __init__.py
    - settings.py
    - urls.py