Initial setup guide:
https://steamcommunity.com/sharedfiles/filedetails/?id=680514371
Follow this first to get the basic manual session working.
I decided to take it one step further, and execute the whole thing from Systemd automatically on my server. This did require a bit of tweaking.
NOTE: In my usage, I named the user steam
(not steamuser
), it's in the group users
, and its home directory is /var/home/steam
; adjust any paths, etc. below to suit your actual details.