[FC-0099] feat: use synced enforcer

[BryanttV]

Description

This PR replaces the use of FastEnforcer with SyncEnforcer. The SyncedEnforcer is based on the Enforcer and provides synchronized access. It is thread-safe. With this new enforcer, the entire policy is automatically loaded every X amount of time, configurable using the CASBIN_AUTO_LOAD_POLICY_INTERVAL setting.

Supporting Information

• [FC-0099] refactor: use decorator to manage policy lifecycle for low-level APIs #86 (comment)

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 REST API endpoints in {lms-domain}/api-docs/#/authz

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]

I also evaluated adding a cache to the /permissions/validate/me view to avoid so many repetitive requests. Here’s what I found:

• Since it’s a POST method, the cache_page decorator doesn’t work, so the caching would have to be done manually.
• Caching the entire response may not be very effective, as multiple permissions are validated. A more granular approach might be better, caching each combination. Sometimes the validation could come from the cache, and other times from the enforcer itself.

My main concern with caching is how long we consider it acceptable to store the data. I initially set a default of 5 seconds (configurable with the PERMISSION_VALIDATION_CACHE_TIMEOUT setting), aligned with the interval used by the SyncEnforcer to load the policy, but I’d like to hear your thoughts on this.

@mariajgrimaldi @bmtcril

[bmtcril]

Overall looks good, can you add a test that confirms the policy changes show up without a reload? Something that sets the reload time to like 1 second, and makes a change, then confirms the change appears?

[BryanttV]

Thanks for your suggestion @bmtcril, I added a new unit test to check the auto-load policy: b882525

[bmtcril]

Looks good to me, thanks!

[mariajgrimaldi]

LGTM, thank you!