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Simple Minecraft systemd startup script

Sometimes you just want to run a Minecraft server on your server, but you don’t want to run it in a screen session, or you want to run it as a different user. This is where systemd comes in.

Goals

  • Run the Minecraft server as a different user
  • Be able to stop the server
  • Be able to start the server
  • Be able to see the server logs
  • Enable the server to start on boot
  • Properly shutdown the server on system shutdown without corruption

Bash itself is not flexible enough to create a safe wrapper script. You can do things with unconnected pipes, but minecraft does not like unconnected pipes. If you try to connect a pipe, you either will be unable to capture the exit code, or make the script needlessly complicated

I came up with the following solution using a python wrapper script instead (my server is stored in /home/minecraft/server and the server jar is server.jar)

Files

/etc/systemd/system/minecraft.service

[Unit]
Description=Run minecraft server
After=network.target
 
[Service]
Restart=always
RestartSec=5
KillMode=mixed
ExecStart=/root/server/minecraft-via-systemd
WorkingDirectory=/home/minecraft/server
User=minecraft
 
[Install]
WantedBy=multi-user.target

/root/server/minecraft-via-systemd

#!/usr/bin/env python3
import signal
import subprocess
 
java_process = subprocess.Popen(["./start.sh"], stdin=subprocess.PIPE)
# java_process.stdin.write(b"op <your user name>\n")
 
def handle_signal(signum, frame):
  java_process.stdin.write(b"stop\n")
  java_process.stdin.flush()
 
signal.signal(signal.SIGTERM, handle_signal)
signal.signal(signal.SIGINT, handle_signal)
 
status_code = java_process.wait()
exit(status_code)

We now need to define the start script for the server, in this case, I am using a simple shell script that starts the server with 1GB of memory

/home/minecraft/server/start.sh

#!/bin/sh -ex
exec java -Xmx1024M -Xms1024M -jar server.jar

After we created all these files, the last step is to enable the service, do not forge tto place your server jar in the server directory, together with a file to accept the EULA

systemctl daemon-reload # This is needed to load the new service file
systemctl enable minecraft # This will enable the service to start on boot
systemctl start minecraft # This will start the service now
journalctl -fu minecraft # This will show the logs of the server in real time, so we can see the server starting

Commands

Since you might not been familiar with systemd, here are some commands to help you manage the server:

  • Check the status of the server: systemctl status minecraft
  • Start the server: systemctl start minecraft
  • Stop the server: systemctl stop minecraft
  • Restart the server: systemctl restart minecraft
  • See the logs: journalctl -u minecraft
  • See a live view of the logs: journalctl -fu minecraft
  • Enable the server to start on boot: systemctl enable minecraft
  • Disable the server to start on boot: systemctl disable minecraft

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