The settings which are normally prefixed `CELERYD_` are for worker-related config, but since we instantiate the Celery app with a namespace, the prefix for these config should actually be `CELERY_`.
- Change celery app to not be a Django app, more like a WSGI app
- Define a Celery task in the Django users app
- Write a test to execute the task
- Update scripts to use the new app to start workers
- Update documentation
Fix#865
## Description
Fixes#591.
## Rationale
We are currently not testing many combinations, we run Flake8 on the generated project with default options, but that rarely catch any issues.
## Use case(s) / visualization(s)
Catch problems with invalid combinations, for instance, it fails due to Whitenoise breaking flake8 with `django-compressor` because `STATIC_URL` was undefined here:
b91c70d755/%7B%7Bcookiecutter.project_slug%7D%7D/config/settings/production.py (L185)
* Create a test matrix on Travis CI to help testing multiple options
* Change test_docker.sh to fail if any command in it fails
* Run black on the CI with --check option
* Fix formatting of project files using black
* Install black in the docker container
* Exclude migrations in black checks
* Fix Black formatting violations
* Run black on the whole generated project & fix issues
[//]: # (Thank you for helping us out: your efforts mean great deal to the project and the community as a whole!)
[//]: # (Before you proceed:)
[//]: # (1. Make sure to add yourself to `CONTRIBUTORS.rst` through this PR provided you're contributing here for the first time)
[//]: # (2. Don't forget to update the `docs/` presuming others would benefit from a concise description of whatever that you're proposing)
## Description
[//]: # (What's it you're proposing?)
Added a note around CELERY_TASK_ALWAYS_EAGER = True in docker config for local development. This causes tasks to be executed on the 'main' thread rather than by the workers. I understand why that might be desirable, but thought it worth calling out incase (like me) it makes people think something is broken.
## Rationale
[//]: # (Why does the project need that?)
Ease of use/troubleshooting
## Use case(s) / visualization(s)
[//]: # ("Better to see something once than to hear about it a thousand times.")
sorl-thumbnail serialized and deserializes the storage class and during this
process location parameter is lost if factory is used. Using a full-fledge
storage class fixes this issue.
See: https://stackoverflow.com/a/18046120/104731
