PR: Get and Cache List of Roles + Helper Functions: has_role?/2

[nelsonic]

This Pull Request adds:

• functions to check if a person has a role: RBAC.has_role?/2 (String) and RBAC.has_role_any?/2 (List)
• Code to fetch the list of roles from Auth App and cache them in ETS: Get List of Roles for App  auth#110

[codecov]

Codecov Report

Merging #7 into master will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master        #7   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            1         1           
  Lines            4        38   +34     
=========================================
+ Hits             4        38   +34     

Impacted Files	Coverage Δ
lib/rbac.ex	100.00% <100.00%> (ø)

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[nelsonic]

@th0mas this PR is in a reviewable state. 🔍 🙏
It's reasonably independent from dwyl/auth#85 as it already works. ✅
Please take a look at the code and if you want to improve any of it, go for it! 👍
Thanks. ☀️

[th0mas]

@nelsonic can you give me write access to this branch so I can push some of my refactoring commits?

[nelsonic]

@th0mas please confirm you have write access. Thanks. 🔑

[th0mas]

@nelsonic got it cheers

[nelsonic]

@th0mas I have made a few updates addressing all your PR review comments.
I think the code is now more versatile and there's a clear reason for having a separate re-useable module/repo.

RBAC no longer makes any assumption of using auth or auth_plug, it can be used 100% independently/offline.

You can call RBAC.has_role?([1,14,31], "admin") with a List of Integers as the first argument,
but I have left the RBAC.has_role?(conn, "admin") in as a convenience, with the appropriate transformation behind the scenes. Which means the Channels use case is still available (not depending on Plug.Conn).
I want to write RBAC.has_role_any?(conn, [:superadmin, :admin]) as I feel this code is brief but descriptive. 🤔

Please take another look at the PR when you're back at your desk tomorrow. 🙏

Note: get_role_from_cache/1 now logs an error with a stack trace so devs can fix their role name typos. 📣
get_role_from_cache/1 is only used internally but the function is public in case anyone wants to use it.
If you prefer to return an explicit :error in get_role_from_cache/1 we need to handle it in the calling function. 💭

LMK your thoughts. 👍

[th0mas]

Looks good 👍