[FC-0099] fix: load policy in role and permissions views

[BryanttV]

Description

This PR adds an initial policy load in the DynamicScopePermission class. This is necessary because this class validates whether the user has permissions using the is_user_allowed method, so it’s important to have the most up-to-date policies at the time of validation.

Related Issues

• GET endpoints are not updating the UI after an action is send #116

Testing Instructions

Using Tutor:

1. Install this plugin with the changes in this PR.
2. Run the migrations by running tutor dev exec lms python manage.py lms migrate
3. Load the default policies by running tutor dev exec lms python manage.py lms load_policies
4. Test all endpoints and check that the permissions are returned correctly according to the assignations.

Merge Checklist:

Check off if complete or not applicable:

• Version bumped
• Changelog record added
• Documentation updated (not only docstrings)
• Fixup commits are squashed away
• Unit tests added/updated
• Manual testing instructions provided
• Noted any: Concerns, dependencies, migration issues, deadlines, tickets

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[BryanttV]

Regarding these changes, my only concern is with the permissions/validate/me endpoint, since loading the entire policy every time the request is made might not be the best option, considering it will be the most heavily used endpoint. For the other endpoints, I don’t think there’s a problem, as they won’t handle a large number of requests, but it's important to have the most up-to-date policies at the time.

What do you think? @mariajgrimaldi @bmtcril

[mariajgrimaldi]

I don't think we should load the policies in the permissions/validate/me, what would be the consequences of waiting for the auto loader instead?

[bmtcril]

LGTM

[bmtcril]

Oops, I missed the discussion on /validate/me I agree that we shouldn't reload for that, otherwise there's no point in the caching. I think the only effect of this is what we already expect from the caching - it may take a few seconds for someone's permissions to be updated after a change, which is a fairly common situation on large systems.

[rodmgwgu]

I also agree that we shouldn't reload the policies in permissions/validate/me for performance reasons. Ideally this endpoint should have some kind of caching.

[BryanttV]

Hi! According to my local tests, the validate/me endpoint has a strange behavior, as the policy loaded in memory by the enforcer appears to be cleared at times, resulting in incorrect permission validation, indicating that the user does not have permissions even though they are present in the DB.

The most immediate solution is to perform a hard load in the validate/me view before enforcement. This would be a temporary solution while we investigate in depth the reasons behind the issue and come up with a more efficient approach.

@mariajgrimaldi @bmtcril @rodmgwgu