LG-7814: Cache USPS auth token as class member

[sheldon-b]

🎫 Ticket

LG-7814

🛠 Summary of changes

• Cache the USPS API authorization token as a class variable instead of an instance variable

[aduth]

It might be a good idea to test this against live APIs before it's deployed to production, but implementation LGTM 👍

[sheldon-b]

@aduth will definitely test it out in a lower environment, I'm thinking I'll go ahead and merge it and do some testing in dev. I added it as an A/C to the ticket

[zachmargolis]

Would it be safe to use Rails.cache for this to share across instances?

[sheldon-b]

I think so but is there a benefit to that over a class member?

[zachmargolis]

Class members can be hard to test/reason about sometimes mattr_reader vs cattr_reader and then have to be reset explicitly in tests, but Rails.cache has easy methods for clearing it.

Also with like 10+ boxes, with probably 4+ processes each, each one will have to cache separately, so having a shared cache (we use Redis to back our Rails.cache) might save extra requests to the API overall

[sheldon-b]

Oh cool it's shared across processes and instances? Yeah I'll go ahead and switch it to Rails.cache

[zachmargolis]

in prod, yes!, locally it might just be in-memory

[allthesignals]

Oops, seeing this conversation after PRing an identical approach. @sheldon-b will this be updated in a future PR? maybe we can pair on this and this one ...

[sheldon-b]

Yeah the original ticket is already marked Done and shipped to prod. I've created LG-7918 to move the caching to the rails cache

Happy to pair! I'll bring LG-7918 to refinement today