[FC-0118] docs: add ADR for standardizing permissions usage

[taimoor-ahmed-1]

Description

Currently, authorization logic is implemented inconsistently across views, serializers, and custom access checks. This ADR will define a consistent approach using DRF permission classes, object-level permissions, and queryset scoping where appropriate.

Issue: #38163

[openedx-webhooks]

Thanks for the pull request, @taimoor-ahmed-1!

This repository is currently maintained by @openedx/wg-maintenance-openedx-platform.

Once you've gone through the following steps feel free to tag them in a comment and let them know that your changes are ready for engineering review.

🔘 Get product approval

If you haven't already, check this list to see if your contribution needs to go through the product review process.

• If it does, you'll need to submit a product proposal for your contribution, and have it reviewed by the Product Working Group.
  • This process (including the steps you'll need to take) is documented here.
• If it doesn't, simply proceed with the next step.

🔘 Provide context

To help your reviewers and other members of the community understand the purpose and larger context of your changes, feel free to add as much of the following information to the PR description as you can:

• Dependencies

  This PR must be merged before / after / at the same time as ...

• Blockers

  This PR is waiting for OEP-1234 to be accepted.

• Timeline information

  This PR must be merged by XX date because ...

• Partner information

  This is for a course on edx.org.

• Supporting documentation
• Relevant Open edX discussion forum threads

🔘 Get a green build

If one or more checks are failing, continue working on your changes until this is no longer the case and your build turns green.

Details

---

Where can I find more information?

If you'd like to get more details on all aspects of the review process for open source pull requests (OSPRs), check out the following resources:

• Overview of Review Process for Community Contributions
• Pull Request Status Guide
• Making changes to your pull request

When can I expect my changes to be merged?

Our goal is to get community contributions seen and reviewed as efficiently as possible.

However, the amount of time that it takes to review and merge a PR can vary significantly based on factors such as:

• The size and impact of the changes that it introduces
• The need for product review
• Maintenance status of the parent repository

💡 As a result it may take up to several weeks or months to complete a review and merge your PR.

[rodmgwgu]

My initial thoughts:

Although I'm not very familiar with DRF permission classes, this seems like a good approach, I just want to bring some points to the table:

My team is currently working on the RBAC AuthZ project, which aims to improve roles and permissions handling across Open edX, see: https://openedx.atlassian.net/wiki/spaces/OEPM/pages/5364121605/PRD+AuthZ+for+Course+Authoring

We are currently implementing the new permissions system over the CMS, specifically on Course Authoring features.

For now, we are focusing on direct replacements on old permission checks, we recently merged a decorator that is a direct replacement for a legacy one, which supports validating a permission either on the new system or the old one depending on a feature flag: #38156

I think we could probably implement the same thing with this approach (I'll do some reading on it).

However, there are some more involved cases, like the xblock endpoint being implemented here: #38179, where more granular permissions mean that different checks need to be done depending on the request params, I wonder if DRF permission classes could handle this, or we would need to refactor the endpoint (may not be feasible at least for this specific endpoint), or doing an exception.

Thanks for the proposal, I'll do some reading to get more familiar with DRF permissions so we can start using it in our project.

FYI @wgu-taylor-payne @dwong2708

[taimoor-ahmed-1]

My initial thoughts:

Although I'm not very familiar with DRF permission classes, this seems like a good approach, I just want to bring some points to the table:

My team is currently working on the RBAC AuthZ project, which aims to improve roles and permissions handling across Open edX, see: https://openedx.atlassian.net/wiki/spaces/OEPM/pages/5364121605/PRD+AuthZ+for+Course+Authoring

We are currently implementing the new permissions system over the CMS, specifically on Course Authoring features.

For now, we are focusing on direct replacements on old permission checks, we recently merged a decorator that is a direct replacement for a legacy one, which supports validating a permission either on the new system or the old one depending on a feature flag: #38156

I think we could probably implement the same thing with this approach (I'll do some reading on it).

However, there are some more involved cases, like the xblock endpoint being implemented here: #38179, where more granular permissions mean that different checks need to be done depending on the request params, I wonder if DRF permission classes could handle this, or we would need to refactor the endpoint (may not be feasible at least for this specific endpoint), or doing an exception.

Thanks for the proposal, I'll do some reading to get more familiar with DRF permissions so we can start using it in our project.

FYI @wgu-taylor-payne @dwong2708

@rodmgwgu Thanks for the detailed context — the RBAC AuthZ work and the CMS/Course Authoring rollout are exactly the kind of direction this ADR is meant to complement.

This proposal is intentionally about the DRF integration surface: we want HTTP APIs to express authorization through permission_classes (and related DRF hooks) so behavior is consistent, discoverable, and testable in one place.

The decorator you merged in #38156 and the broader AuthZ PRD seem to be about policy and enforcement mechanics (including feature-flagged dual implementation). The ADR is about where that enforcement is invoked from API code.

My only question is that whether permission classes were considered as an alternative to decorators?

[rodmgwgu]

My initial thoughts:
Although I'm not very familiar with DRF permission classes, this seems like a good approach, I just want to bring some points to the table:
My team is currently working on the RBAC AuthZ project, which aims to improve roles and permissions handling across Open edX, see: https://openedx.atlassian.net/wiki/spaces/OEPM/pages/5364121605/PRD+AuthZ+for+Course+Authoring
We are currently implementing the new permissions system over the CMS, specifically on Course Authoring features.
For now, we are focusing on direct replacements on old permission checks, we recently merged a decorator that is a direct replacement for a legacy one, which supports validating a permission either on the new system or the old one depending on a feature flag: #38156
I think we could probably implement the same thing with this approach (I'll do some reading on it).
However, there are some more involved cases, like the xblock endpoint being implemented here: #38179, where more granular permissions mean that different checks need to be done depending on the request params, I wonder if DRF permission classes could handle this, or we would need to refactor the endpoint (may not be feasible at least for this specific endpoint), or doing an exception.
Thanks for the proposal, I'll do some reading to get more familiar with DRF permissions so we can start using it in our project.
FYI @wgu-taylor-payne @dwong2708

@rodmgwgu Thanks for the detailed context — the RBAC AuthZ work and the CMS/Course Authoring rollout are exactly the kind of direction this ADR is meant to complement.

This proposal is intentionally about the DRF integration surface: we want HTTP APIs to express authorization through permission_classes (and related DRF hooks) so behavior is consistent, discoverable, and testable in one place.

The decorator you merged in #38156 and the broader AuthZ PRD seem to be about policy and enforcement mechanics (including feature-flagged dual implementation). The ADR is about where that enforcement is invoked from API code.

My only question is that whether permission classes were considered as an alternative to decorators?

No, they weren't considered, at this point our objective is to implement the new permissions as drop-in, compatible replacements to existing ones (with some additions), so we are focusing on adapting whatever was already there, which is inconsistent because we have a combination of endpoints that are DRF and other that aren't.

However, I think we should get to an unified way of doing things, we can consider transitioning to permission classes on a future phase of the RBAC project.

[feanil]

@taimoor-ahmed-1 I think the critical thing to verify and capture in this ADR is that we're moving to a new underlying permission system (casbin), and that using permission classes won't prevent us from using that underlying permission system and that even if you're using casbin under the hood, the permission checks for DRF view should be done with DRF permission classes. (The permission classes would use casbin under the hood where available.)

[taimoor-ahmed-1]

@taimoor-ahmed-1 I think the critical thing to verify and capture in this ADR is that we're moving to a new underlying permission system (casbin), and that using permission classes won't prevent us from using that underlying permission system and that even if you're using casbin under the hood, the permission checks for DRF view should be done with DRF permission classes. (The permission classes would use casbin under the hood where available.)

Great callout Feanil, I have updated the ADR accordingly.

[feanil]

@taimoor-ahmed-1 can you fix the commit messages so that it matches the conventional commit format. Then I think this is good to merge.