fix: get CELERY_RESULT_BACKEND from ENV_TOKENS

[navinkarkera]

Description

Cherry pick of #30244

At Opencraft, we want to run multiple instances of celery workers in separate servers. The celery workers need to be able to share task results. Currently, the CELERY_RESULT_BACKEND is hard coded to use django-cache.

So this PR allows to setup CELERY_RESULT_BACKEND via configuration.

To use django ORM as celery backend, one can set CELERY_RESULT_BACKEND to django-db as described in docs.

Supporting information

• Task: https://tasks.opencraft.com/browse/BB-6077

Deadline

"None"

[openedx-webhooks]

Thanks for the pull request, @navinkarkera! I've created OSPR-6620 to keep track of it in JIRA, where we prioritize reviews. Please note that it may take us up to several weeks or months to complete a review and merge your PR.

Feel free to add as much of the following information to the ticket as you can:

• supporting documentation
• Open edX discussion forum threads
• timeline information ("this must be merged by XX date", and why that is)
• partner information ("this is a course on edx.org")
• any other information that can help Product understand the context for the PR

All technical communication about the code itself will be done via the GitHub pull request interface. As a reminder, our process documentation is here.

Please let us know once your PR is ready for our review and all tests are green.

[natabene]

@navinkarkera Thank you for your contribution. Is this ready for our review?

[kaustavb12]

Hi @natabene !

This is not ready for your review yet. I'll ping you here once ready.

[kaustavb12]

👍

Looks good to me

• I tested this: Tested in PR Sandbox
• I read through the code

[kaustavb12]

@natabene

Thank you for your patience here. This PR is now ready for your review.

[giovannicimolin]

Cherry-pick of #30244.

👍

• I tested this:

1. Checked that the default value retains previous behavior.
2. Checked that changing the variable allows configuring a different result backend for celery (verified it's working on a client instance)

• I read through the code
• I checked for accessibility issues
• Includes documentation: comment on code.

[openedx-webhooks]

@navinkarkera 🎉 Your pull request was merged! Please take a moment to answer a two question survey so we can improve your experience in the future.