Once you'ce created a Django app, you can install Celery like so:
$ heroku addons:create redisgreen
It will say something like:
Adding laughing-truly-3765 to jobappli-production... done
Setting REDISGREEN_URL and restarting jobappli-production... done, v10
Your RedisGreen server has been built and is now available at redis://x:firstname.lastname@example.org:11042/
Use `heroku addons:docs redisgreen` to view documentation.
Note, that REDISGREEN_URL is available in the environment vars:
$ heroku config
Meaning, in your settings.py you refer to Celery like so:
""" Get the environment variable or return exception """
# Django celery
# make sure celery does one thing at a time
CELERYD_CONCURRENCY = 1
BROKER_URL = get_env_variable('REDISGREEN_URL')
CELERY_RESULT_BACKEND = get_env_variable('REDISGREEN_URL')
CELERY_TASK_SERIALIZER = 'json'
CELERY_ACCEPT_CONTENT = ['json', ]
Now you have to make sure that Celery is also added to your Procfile:
web: sh -c 'cd src/ && gunicorn jobappli.wsgi --log-file -'
worker: sh -c 'cd src/ && celery worker --app=jobappli.celery.app'
And of course, scale your worker to 1:
$ heroku ps:scale worker=1