Visualize this outcome:
site1.example.com-> my single public IP -> Port forwarding 80 and 443 to LAN
192.168.1.10, a Mac mini running Apple macOS Server 5.3 on macOS 10.12 Sierra.
site2.example.com-> my single public IP -> LAN
192.168.1.10-> reverse proxy? -> :80 and :443 on LAN
192.168.1.15, another Mac mini running GitLab CE on Ubuntu 16.04.
This is on a network where I have no option of adding another public IP.
#1 is already up and running fine.
#2 is the hard part, mainly because I’m running macOS Server.app on #1, and the proxy setup does not seem to be the relatively straight-forward Apache one. Server has the Apache config files in odd places, and it likes to overwrite them with new changes made in the GUI, so it’s taken me a while to figure out the “right” way to do this under Server.app.