+1 for sled--I was working with it this morning for a personal project, and it's frankly just really well built. Beside the great documentation and easy use, I kept finding myself looking for architectural tips for structuring Config structs, etc. because I could do a lot worse than end up coding something that is similarly nice to use.
https://github.com/spacejam/sled
Itβs surprisingly mature and the person behind it is very committed to the project.