For the http.reverse_proxy module, having the option of specifying a HTTP/SOCKS proxy for the http.Transport of the reverse proxy client in the configuration file would be ideal. It's currently configurable only via http.ProxyFromEnvironment and may impact functionality of other modules.

I've implemented the proposed changes and they seem to work well but I'm new to contributing to the project so there's a chance that they're naive. I'll submit a PR for review.

P.S. Caddy is amazing. It's become a critical component in so many of my projects and I'm very grateful for all the thoughtful hard work. ❤️