0. README in another language

Language	File
English (US)	README.md
简体中文	README_zh_CN.md

1. Inactive Development Notice

TL;DR

• I have no time to keep active development in this project.
• Only bug reporting issues will be accepted.
• So if you want some new features, just clone and work on the code. Note that this project is licensed under GPLv3.

Any PR is welcomed. Feel free to add your reasonable features, if you have written test cases for them.

A longer version

I decided to discontinue my development in this project. There are some major reasons:

1. As one of my toy projects, its code quality is not satisfying and refactoring takes too much effort. The git history is bad too.
2. The Mod is proven to be working well (at least the latest version on my server, with Minecraft 1.16.5) as a basic backup and rollback tool for the game. All important features for a backup Mod are implemented.
3. I need a tool which backs up the save to the filesystem on another computer, via network.

To solve these problems, I'm working on a new backup and rollback tool for Minecraft, which is based on rdiff-backup.

As a general incremental backup tool, it tends to be more solid and well-designed. Moreover, it is able to transfer backup files over network. Thus, I believe it is a good start point to reimplement an incremental backup Mod for Minecraft.

However, this tool is still a good choice for any Minecraft server (from 1.14.4 to 1.17.1) who wants to back up its world locally.

2. Usages

A server-only backup mod for fabric Minecraft server, which makes normal .zip backup of your world, or self-implemented incremental backup, with slower increasing disk usage.

Supported Minecraft version: 1.14.4, 1.15.2, 1.16.4/1.16.5, 1.17.1, 1.18.1

Fabric API is required!

2.1 Commands

• /kb or /kb help: show command list
• /kb list: show existing backups
• /kb backup [backup_name]: make a backup with given name or with the current system time by default
• /kb incbak [backup_name]: make an incremental backup which will be saved in incremental folder. (Incremental backup will create an index file which has an ext name of .kbi, and it will be saved in backups folder, which is the same with where .zip resides)
• /kb restore <backup_name>: restore to a certain backup. This command needs a confirmation to execute.
• /kb confirm: confirm executing restore operation. The operation is irreversible.
• /kb delete: delete an existing backup.
• /kb prev: Find and select the most recent backup file. After executing this command, you can use /kb restore 1 to restore to this backup.
• /kb cow-info: Check if copy-on-write backup is activated.

Only OPs can make backups and restore by default.

However, you can use permission management mods like LuckPerms to configure exactly what permissions normal players can use. Permission nodes of each command are listed below:

Command	Permission Required
/kb	kb.root
/kb help	kb.help
/kb list	kb.list
/kb backup	kb.backup
/kb incbak	kb.incbak
/kb restore	kb.restore
/kb delete	kb.delete
/kb confirm	kb.confirm
/kb cancel	kb.cancel
/kb prev	kb.prev

2.2 Configurations

Since version 1.8.0, plugin-wide config file kbackup.json is added in the server root directory (workdir).

The config file will be generated if not exist. The default is:

{
  "incbak_cow": false
}

• incbak_cow: (experimental) Enable filesystem CoW (copy-on-write) for incremental backup. Will fall back to normal file copy if the filesystem does not support CoW. Please read section 2.5 for more info.

Note: JSON comment is supported.

2.3 Script for auto-restart after restoring

Due to the nature of JVM: the Java language's running environment, there is no elegant way to restart Minecraft server in a server plugin. In order to auto restart after restoring, an outer system-based script is required, i.e. a batch or a shell script.

KBackup exit JVM with a special code 111 after restoring the level successfully. The startup script just check the exit code and restart Minecraft server if the code is 111.

I will give examples for some popular operating systems. To use these scripts, you should replace your start.bat or start.sh script with given code lines.

2.3.1 Script for Windows (Batch script)

@echo off
title Keuin's personal Minecraft server
:loop
java -Xms4G -Xmx4G -jar fabric-server-launch.jar nogui
if %errorlevel%==111 goto loop
rem kbackup restore auto restart
pause

2.3.2 Script for Linux (Shell script)

#!/bin/sh
STATUS=111
while [ $STATUS -eq 111 ]
do
    java -Xms4G -Xmx4G -jar fabric-server-launch.jar nogui
    STATUS=$?
done

2.4 Automatic Regular Backup

Currently, KBackup does not support automatic backup by itself. However, If application level scheduled tasks are available to you, such as crontab in Linux and Task Scheduler in Windows, you can use that to trigger backup tasks regularly.

2.4.1 On Linux

In order to run Minecraft command on your server as a Shell command, you need RCON client like mcrcon. You can get the binary executable from its homepage and put it into anywhere like /usr/bin.

Let's assume you are under Linux, run crontab -e and append this line to the configuration:

0 */6 * * * mcrcon -P <RCON port> -p <RCON password> "kb backup"

You can specify RCON port and password in server.properties.

This will cause cron to run kb backup for every 6 hours. To make incremental backups, simply replace kb backup to kb incbak.

The man page crontab(5) also contains useful information about using cron.

2.4.2 On Windows

For Windows users, please refer to tutorials available on Google for creating scheduled tasks. Note that mcrcon is also available on Windows.

2.5 Copy-on-write (CoW) backup

CoW will save even more disk space when making backups.

This feature requires platform-specific library KBackup-cow. Currently only Linux on x86_64 platform is supported. Please create a GitHub issue if you want other platforms.

This is an experimental feature. Please report if you encountered any error.

Requirements:

1. The server is running Linux on amd64.
2. Filesystem should support CoW (e.g. Bcachefs, Btrfs, XFS, OCFS2, ReFSv2). Please read https://www.ctrl.blog/entry/file-cloning.html for more info about CoW filesystems.
3. Backup directory and server world directory should on the same disk partition. This is required to clone a file.

3. To-Do List

• Legacy backup compatibility test
• A more friendly help menu (colored command help menu)
• New version checker
• Code refactor for maintainability
• Decoupling of plugin core and fabric api (preparing for Bukkit version)