A very basic, but functional, minecraft service description for systemd.

minecraft.service

[Unit]
Description=Minecraft Server

[Service]
# Adjust these to your liking, the service assumes that minecraft_server.jar and eula.txt already
# exists in this directory, and that the User specified has write access to the WorkingDirectory
#
# To send commands to minecraft, do:
# echo "command" >> minecraft-input

WorkingDirectory=/srv/minecraft
User=minecraft
Group=minecraft
Environment="JavaOptions=-Xmx1024M -Xms1024M"

Restart=on-failure
ExecStartPre=/bin/bash -c 'touch minecraft-input && test -w minecraft-input'
ExecStart=/bin/bash -c 'exec java $JavaOptions -jar minecraft_server.jar nogui < <(tail -n0 -f minecraft-input)'
ExecStop=/bin/bash -c 'echo "stop" >> minecraft-input'
ExecStop=/bin/bash -c 'while kill -0 "$MAINPID" > /dev/null 2>&1; do sleep 1; done'

[Install]
WantedBy=multi-user.target