Excellent article! The use of Lua solves a lot of potential issues here with competing writes to similar spaces for rate limiting, causing potential bizarre errors.

The one thing I would note that doesn't seem to be covered is if you are using a relatively large Lua script and running eval over and over it's getting cached every time, instead `SCRIPT LOAD ...` can be ran, which spits out a sha1 which can then be ran with `EVALSHA (sha1) (keys) (args)`. This can potentially speed stuff up as well as cutting back on memory.