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Minecraft Backup

CI codecov

Backup script for Minecraft servers on Linux. Supports servers running in screen, tmux, or with RCON enabled. Supports tar file or restic backup backends.

Features

  • Create backups of your world folder
  • Manage deletion of old backups
    • "thin" - keep last 24 hourly, last 30 daily, and use remaining space for weekly backups
    • "sequential" - delete oldest backup
  • Works on vanilla (no plugins required)
  • Print backup status to the Minecraft chat

Install

wget https://github.com/nicolaschan/minecraft-backup/releases/latest/download/backup.sh
chmod +x backup.sh

Make sure your system has tar and your chosen compression algorithm (gzip by default) installed. If using RCON, you will also need to have the xxd command.

Usage

# If connecting with RCON:
./backup.sh -c -i /home/user/server/world -o /mnt/storage/backups -s localhost:25575:secret -w rcon

# If running on screen called "minecraft":
./backup.sh -c -i /home/user/server/world -o /mnt/storage/backups -s minecraft

# If running on tmux session 0:
./backup.sh -c -i /home/user/server/world -o /mnt/storage/backups -s 0 -w tmux 

# Using restic (and RCON)
export RESTIC_PASSWORD="restic-pass-secret" # your password here
./backup.sh -c -i /home/user/server/world -r /mnt/storage/backups-restic -s localhost:25575:secret -w rcon

# Using Docker and RCON
# You will have to set up networking so that this Docker image can access the RCON server
# In this example, the RCON server hostname is `server-host`
docker run \ 
  -v /home/user/server/world:/mnt/server \
  -v /mnt/storage/backups:/mnt/backups \
  ghcr.io/nicolaschan/minecraft-backup -c -i /mnt/server -o /mnt/backups -s server-host:25575:secret -w rcon

This will show chat messages (-c) and save a backup of /home/user/server/world into /mnt/storage/backups using the default thinning deletion policy for old backups.

Command line options:

-a    Compression algorithm (default: gzip). Set to "none" for no compression
-c    Enable chat messages
-d    Delete method: thin (default), sequential, none
-e    Compression file extension, exclude leading "." (default: gz)
-f    Output file name (default is the timestamp)
-h    Shows this help text
-H    Set hostname for restic backup (restic only)
-i    Input directory (path to world folder, use -i once for each world)
-l    Compression level (default: 3)
-m    Maximum backups to keep, use -1 for unlimited (default: 128)
-o    Output directory
-p    Prefix that shows in Minecraft chat (default: Backup)
-q    Suppress warnings
-r    Restic repo name (if using restic)
-s    Screen name, tmux session name, or hostname:port:password for RCON
-t    Enable lock file (lock file not used by default)
-u    Lock file timeout seconds (empty = unlimited)
-v    Verbose mode
-w    Window manager: screen (default), tmux, RCON

Automate backups with cron

  • Edit the crontab with crontab -e
  • Example for hourly backups:
00 * * * * /path/to/backup.sh -c -i /home/user/server/world -o /mnt/storage/backups -s minecraft

Retrieving Backups

Always test your backups! Backups are in the tar format and compressed depending on the option you choose. To restore, first decompress if necessary and then extract using tar. You may be able to do this in one command if tar supports your compression option, as is the case with gzip:

Example:

mkdir restored-world
cd restored-world
tar -xzvf /path/to/backups/2019-04-09_02-15-01.tar.gz

The restored worlds should be inside the restored-world directory, possibly nested under the parent directories. Then you can move your restored world to your Minecraft server folder under the proper name and path so the Minecraft server uses it.

With restic

Use restic restore to restore from backup.

Why not use tar directly?

If you use tar while the server is running, you will likely get an error like this because Minecraft autosaves the world periodically:

tar: /some/path/here/world/region/r.1.11.mca: file changed as we read it

To fix this problem, the backup script disables autosaving with the save-off Minecraft command before running tar and then re-enables autosaving after tar is done.

Help

  • Make sure the compression algorithm you specify is installed on your system. (zstd is not installed by default)
  • Make sure your compression algorithm is in the crontab's PATH
  • Make sure cron has permissions for all the files involved and access to the Minecraft server's GNU Screen
  • It's surprising how much space backups can take--make sure you have enough empty space
  • Do not put trailing / in the SERVER_DIRECTORY or BACKUP_DIRECTORY
  • If "thin" delete method is behaving weirdly, try emptying your backup directory or switch to "sequential"

Known Issues

There is a Minecraft bug MC-217729 in recent Minecraft server versions that cause them to automatically save the world even after receiving the save-off command. Until this is fixed, there is a chance that the backup will fail because the world files are modified by Minecraft in the process of creating the backup. This script will try to detect and report this problem if it does occur.

Disclaimer

Backups are essential to the integrity of your Minecraft world. You should automate regular backups and check that your backups work. It is up to you to make sure that your backups work and that you have a reliable backup policy.

Some backup tips:

  • Drives get corrupted or fail! Backup to a different drive than the one your server is running on, so if your main drive fails then you have backups.
  • Automate backups so you never lose too much progress.
  • Check that your backups work from time to time.

Please refer to the LICENSE (MIT License) for the full legal disclaimer.