bloody groups godamnit
Spent way too much time trying to get a systemd service running on grenzland.club.
Specifically for our Grenzland Mud
I don't think I will ever become friends with that software, but in this case it turned out to be not actually a systemd problem as such. But the usual vacuous journal entries didn't help either.
Seems I was running it with the wrong group the whole time. The result was that I could run the application manually without issues, and was able to access it via telnet, but when run via systemd it just did not want to give me access.
In the end I changed the group it was running as to the one other group the user had, and lo! it worked.
Could have spent that time with something more productive.
Just so I remember it, this was the unit file
[Unit]
Description=Script Daemon For Grenzland MUD
[Service]
Type=simple
User=username
Group=users
ExecStart=/home/username/application/autorun.pl
Restart=on-failure
StandardOutput=file:%h/log_file
[Install]
WantedBy=default.target
The user had exactly two groups. username and users.