I've used Caddy for some of my projects (e.g. https://github.com/fsmunoz/parlamentodb/blob/54e0b252485905e... ), but not for this intercept approach you mentioned, I will give it a look!

I'm not bothered by restart times but that's mostly because that has never been a priority... but one thing I have half-done is a controller that gathers per-namespace configs, and with that reload times will become more of an issue.

Part of the reason I chose Squid here was precisely because I found it interesting to reuse something that was such a staple of web architecture patterns.