Disclaimer
This is just like a memo for myself. No detailed explanation. Please google the keywords if you need.

Goal

To launch Minecraft server for with friends (= outside of my LAN) using my old laptop.

Some said they want to play Java Edition (JE), whilst others wanted Bedrock Edition (BE). So I tryed running both versions simultaneously, which is now successfully working.

Requirements

Assuming up to 5 users' simultaneous connections
Shutdown automatically every morning, and reboot every evening (some people warn that one should not run a laptop for 24h as a server)
Assign one of my sub-domain for the server so that users can access the server easily.

Rig

ASUS UX305FA-5Y71

CPU: Core M-5Y71 (2 cores, 4 threads, 1.2 GHz base - 2.9 GHz max., TDP 4.5W)
RAM: 8GB
Strage: 128GB SSD

Ubuntu 20.04 LTS (with GUI) was already installed.

What I did

Unplug its inner battery

This is a very important step for safety. The rig is expected to be connected with the power plug while running as a server, which is an inadequate condition for the Li-ion battery.

Open the bottom cover of the laptop, and unplug the battery from the circuit board. Then, mask the battery-side connecter with tape to isolate electrically.

Preparation

Install Docker
Follow the instruction in Docker official document.
Install SSH Server (sudo apt install openssh-server)
Make Directories:
- ~/Minecraft
  - ./data
  - ./mc-backup
- ~/Minecraft-be
  - ./data
Disable GUI (sudo systemctl set-default multi-user.target)
(You can do this whenever you like, and redo this by sudo systemctl set-default graphical.target)
cf. https://tek2tech.com/ubuntu-2004-desktop-environment/

Pull Docker Image

https://hub.docker.com/r/itzg/minecraft-server
https://hub.docker.com/r/itzg/mc-backup
https://hub.docker.com/r/itzg/minecraft-bedrock-server

cf.
https://frontl1ne.net/2019/10/docker-minecraft/

Write `docker-compose.yml`

cf. https://oldbigbuddha.dev/posts/my-server-for-minecraft

~/Minecraft/docker-compose.yml

version: "3"

services:
  # Application
  mc-paper:
    image: itzg/minecraft-server
    ports:
      - 25565:25565
      - 25575:25575
    environment:
      EULA: "TRUE"
      TYPE: "PAPER"
      INIT_MEMORY: "1G"
      MAX_MEMORY: "4G"

      STOP_SERVER_ANNOUNCE_DELAY: 60

      # Disable following AutoPause-related settings
      # due to Spigot's error.
      #
      # ENABLE_AUTOPAUSE: "TRUE"
      # MAX_TICK_TIME: "-1"
      #  More aggressive settings for demo purposes
      # AUTOPAUSE_TIMEOUT_INIT: "30"
      # AUTOPAUSE_TIMEOUT_EST: "10"
      #
      # OVERRIDE_SERVER_PROPERTIES: "TRUE"
    volumes:
      - ./data:/data
      - /etc/timezone:/etc/timezone:ro
    tty: true
    stdin_open: true
    restart: always
    deploy:
      resources:
        limits:
          memory: 4500m

  # Backup
  backup:
    image: itzg/mc-backup
    environment:
      BACKUP_INTERVAL: "6h"
      PRUNE_BACKUPS_DAYS: 3
      PAUSE_IF_NO_PLAYERS: "false"
      INITIAL_DELAY: "10m"
    depends_on:
    - mc-paper
    volumes:
      - ./data:/data:ro
      - ./mc-backups:/backups
      - /etc/timezone:/etc/timezone:ro
    restart: unless-stopped
    network_mode: "service:mc-paper"

~/Minecraft-be/docker-compose.yml

version: "3"

services:
  # Application
  mc-be:
    image: itzg/minecraft-bedrock-server
    ports:
      - 19132:19132/udp
    environment:
      EULA: "TRUE"
      SERVER_NAME: "My_MineCraft_Bedrock"
    volumes:
      - ./data:/data
      - /etc/timezone:/etc/timezone:ro
    tty: true
    stdin_open: true
    restart: always
    deploy:
      resources:
        limits:
          memory: 2500m

To make the RAM resource limits effective, we need to desiginate --compatibility options when docker-compose up and down. This is not recommended, according to the docker official. If your machine has plenty amount of RAM, you may not need to determine the limit and use --compatibility option.

Allow the user to run `docker` without `sudo`

cf. https://qiita.com/DQNEO/items/da5df074c48b012152ee

bash

$ sudo groupadd docker
$ sudo gpasswd -a <USERNAME> docker
$ sudo systemctl restart docker

Then, reboot (or relogin) to enable the setting.

Define Firewall Ruleset

bash

$ sudo ufw status

ufw status

Status: active

To                         Action      From
--                         ------      ----
22                         ALLOW       192.168.11.0/24
25565/tcp                  ALLOW       Anywhere
25575                      ALLOW       192.168.11.0/24
19132                      ALLOW       Anywhere
25565/tcp (v6)             ALLOW       Anywhere (v6)
19132 (v6)                 ALLOW       Anywhere (v6)

Note:

Port 22 ... for SSH (only from LAN)
Port 25565 ... for Minecraft Java Edition (TCP)
Port 25575 ... for Minecraft Java RCON (only from LAN) (TCP)
Port 19132 ... for Minecraft Bedrock Edition (UDP (+TCP ?))

Don't forget setting the port forwarding up of the router.

Prevent the System from Sleep Mode When the Lid is Closed

Add HandleLidSwitch=ignore in /etc/systemd/logind.conf.

Prepare Shell Scripts for `docker-compose up` and `docker-compose down`

~/Minecraft/Minecraft-up.sh

#!usr/bin/bash -l

echo `date +%Y-%m-%dT%H:%M:%S`\| Launching JAVA Edition on mc-je screen
/usr/bin/screen -U -A -m -d -S mc-je /usr/local/bin/docker-compose --file /home/<USERNAME>/Minecraft/docker-compose.yml --compatibility up
echo `date +%Y-%m-%dT%H:%M:%S`\| Waiting for 5 min ...
sleep 300
echo `date +%Y-%m-%dT%H:%M:%S`\| Launching BedRock Edition on the mc-be screen
/usr/bin/screen -U -A -m -d -S mc-be /usr/local/bin/docker-compose --file /home/<USERNAME>/Minecraft-be/docker-compose.yml --compatibility up

~/Minecraft/Minecraft-down.sh

#!usr/bin/bash -l

echo `date +%Y-%m-%dT%H:%M:%S`\| Shutting Minecraft JAVA Edition down...
/usr/local/bin/docker-compose --file /home/<USERNAME>/Minecraft/docker-compose.yml --compatibility down -t 600

echo `date +%Y-%m-%dT%H:%M:%S`\| Shutting Minecraft BedRock Edition down...
/usr/local/bin/docker-compose --file /home/<USERNAME>/Minecraft-be/docker-compose.yml --compatibility down -t 600

Save backups and transfer them to NAS via FTP

cf. https://qiita.com/kabegamikamio/items/9c1a30c63de31be834da

For JAVA editon, we can use itzg/mc-backup docker package. However, for bedrock edition, we need to manage backup by ourselves.

~/Minecraft-be/be-backup.sh

#!/bin/bash

TARGET_DIR=/home/<USERNAME>/Minecraft-be/data/worlds

BACKUP_DIR=/home/<USERNAME>/Minecraft-be/backup/`date +%Y-%m-%d_%H:%M:%S`
BACKUP_FOLDER=/home/<USERNAME>/Minecraft-be/backup/

NUM_GENS=5

delete_file () {
    CNT=0
    for file in `ls -1t ${BACKUP_FOLDER}*.zip`
    do
        CNT=$((CNT+1))
        if [ $CNT -le $NUM_GENS ]; then
            continue
        fi
        eval "rm ${file}"
    done
}


makezip () {
    zip ${1} -r ${2}
}


make_zip $BACKUP_DIR $TARGET_DIR
delete_file

This code compresses the world folder to a timestamped zip file and delete past file to remain last NUM_GEN (=5, in this example) backups.

And, to keep these backups more solidly, I upload them onto my local NAS using FTP:

~/Minecraft/ftp-upload.sh

#!/usr/bin/bash -l

/usr/bin/ftp -n >> /home/<USERNAME>/Minecraft/ftp-upload.log << EOF
  verbose
  open <IP ADDRESS>
  user <FTP USERNAME> <FTP PASSWORD>
  prompt
  passive
  cd /mc-backup/je/
  lcd /home/<USERNAME>/Minecraft/mc-backups
  mput *
  cd /mc-backup/be
  lcd /home/<USERNAME>/Minecraft-be/backup
  mput *
  bye
EOF

Note: it may be better to designate "ftp -n -p" to make sure to use active mode.

Write `crontab` settings

bash

$ crontab -e

This command opens the crontab setting file with an editor. My setting is as below:

/var/spool/cron/crontabs/

# m h  dom mon dow   command
SHELL=/usr/bin/bash
PATH=/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin/
@reboot            bash -l /home/<USERNAME>/Minecraft/Minecraft-up.sh >> /home/(USERNAME)/Minecraft/Minecraft-up.log 2>&1

 00 1   *   *   *  bash -l /home/<USERNAME>/Minecraft-be/be-backup.sh >> /home/(USERNAME)/Minecraft-be/be-backup.log 2>&1
  5 8   *   *   *  bash -l /home/<USERNAME>/Minecraft/Minecraft-down.sh >> /home/(USERNAME)/Minecraft/Minecraft-down.log 2>&1
 10 8   *   *   *  bash -l /home/<USERNAME>/Minecraft-be/be-backup.sh >> /home/(USERNAME)/Minecraft-be/be-backup.log 2>&1
 15 8   *   *   *  bash -l /home/<USERNAME>/Minecraft/Minecraft-down.sh >> /home/(USERNAME)/Minecraft/Minecraft-down.log 2>&1

To set up auto scheduled shutdown and restart using rtcwake, we need to execute crontab under sudo:

bash

$ crontab -e

/var/spool/cron/crontabs/root

# m h  dom mon dow   command
SHELL=/usr/bin/bash
PATH=/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/sbin:/usr/local/bin

 20 8   *   *   *   /usr/sbin/rtcwake -s 36000 -m off >> /home/<USERNAME>/Minecraft/Minecraft-servershutdown.log 2>&1

This setting schedules automatic shutdown (=-m off) at 08:20 every morning and automatic reboot at 18:20 (= -s 36000 = 36,000 seconds = 10 hours after 08:20).

cf.
https://awnet.org/archives/53
https://freefielder.jp/blog/2018/07/ubuntu-cron-sudo.html

Appendix. Automatic Login when booted

This is possibly unnecessary for this work.

One may be need to create /etc/systemd/system/getty@tty1.service.d directory and override.conf file before execute the scripts above.

bash

sudo systemctl edit getty@tty1

/etc/systemd/system/getty@tty1.service.d/override.conf

[Service]
ExecStart=
ExecStart=-/sbin/agetty/ --noissue --autologin (USERNAME) %I $TERM
Type=idle

cf.
https://zenn.dev/noraworld/articles/ubuntu-reboot-auto-login
https://askubuntu.com/questions/819117/how-can-i-get-autologin-at-startup-working-on-ubuntu-server-16-04-1