[FEATURE] set USE_PROXY_PROTOCOL multisite compatible

[thelittlefireman]

What's needed and why?

My bunkerweb configuration is fully multisite with lots of reverse proxy. I would like to add stalwart as a new service which use proxy_protocol for it's configuration. https://stalw.art/docs/server/reverse-proxy/nginx
USE_PROXY_PROTOCOL is only available globally, I cannot enable USE_PROXY_PROTOCOL only for stalwart and leave all my other service with classic http reverse proxy (without proxy protocol)

Implementations ideas (optional)

No response

Code of Conduct

• I agree to follow this project's Code of Conduct

[TheophileDiot]

Thanks for the report, @thelittlefireman.

I dug into this a bit, and the short version is that there are two different PROXY protocol cases here.

USE_PROXY_PROTOCOL is global because it affects the NGINX listen socket itself. If multiple vhosts share the same ip:port, NGINX requires them to agree, so this cannot be made multisite on a shared port.

What Stalwart needs, though, is the outgoing side: forwarding PROXY protocol to the upstream in stream mode with proxy_protocol on;. That can be enabled per stream server, and it is separate from listen ... proxy_protocol.

So the current issue is really that BunkerWeb ties both behaviors to the same global setting. Incoming has to stay global, but outgoing stream proxying should be configurable per service.

This only applies to stream mode, not HTTP reverse proxying. We also plan to make these stream vs HTTP differences much clearer and more user-friendly in future versions.