Pre steps

1. Add your login user
2. Ensure your user can run sudo -i to gain root (e.g. gpasswd -a youruser sudo).
3. Install your ssh key to the new user (e.g. sudo -u youruser -i then umask 077; mkdir -p ~/.ssh; cat >> ~/.ssh/authorized_keys paste in your key, then type ^D).
4. Try logging in.
5. Add PasswordAuthentication no to /etc/ssh/sshd_config
6. Maybe add your user to a special group, then add that gorup to /etc/ssh/sshd_config like so AllowGroups yourspecialgroup
7. sudo systemctl reload ssh
8. verify login still works

Set up your login user and the service account

sudo useradd -m -s /bin/bash minecraft

Then log into it via sudo -u minecraft -i.

New user files

In your new user add this to homedir, create the following files:

start.sh

#!/usr/bin/env bash
set -eu
. "${0%/*}/defaults.sh"
cd "$1"
[[ -r config.sh ]] && . config.sh
rlwrap java -Xmx${memmax} -Xms${memmin} -jar ~/jars/minecraft_server.${version}.jar nogui

defaults.sh

version=1.17.1
memmax=1024M
memmin=512M

jars/

Create a jars/ folder, download your minecraft_server.X.Y.Z.jar files here.

Example:

wget -o jars/minecraft_server.1.17.1.jar \
    https://launcher.mojang.com/v1/objects/a16d67e5807f57fc4e550299cf20226194497dc2/server.jar

worlds/

Create a worlds/ folder. Create a folder for your world in that folder - e.g. worlds/main/. Populate config.sh if you want to override stuff.

memmax=3500M
memmin=2500M

(Tuned for a vultr 4GB VPS with 2x cpu)

Starting

After setting up the files, log into your user via sudo -u minecraft -i then run tmux new -s minecraft ./start.sh worlds/main then detach using C-b d.

TODO

systemd unit for tmux minecraft.