Cauldron CLI

This Documentation is correct for version 0.5.5 of CauldronCLI

What does this do?

CauldronCLI is a command line Minecraft launcher built on Cauldron Engine. It can launch vanilla and modded versions of the game, and create, import and manage modpacks.

It is designed to be used directly or controlled by other applications using headless mode.

License Information

This project is licensed under GPL 3.0 so please make sure that your project follows the license guidelines.

Setup

Download the binary for your system from the releases page.

System	File
Windows (x64)	cauldroncli-x86_64-pc-windows-msvc.exe
Linux (x64)	cauldroncli-x86_64-unknown-linux-gnu
macOS (Apple Silicon)	cauldroncli-aarch64-apple-darwin
macOS (Intel)	cauldroncli-x86_64-apple-darwin

Rename it to cauldroncli (cauldroncli.exe on Windows) and place it in a folder on your PATH.

On Linux and macOS, make the file executable:

chmod +x cauldroncli

Check that it works:

cauldroncli --version

Quick Start

# Launch 1.21.1 vanilla in demo mode
cauldroncli start -v 1.21.1

# Launch Forge with a Minecraft account
cauldroncli start -v 1.20.1 -l forge -m <minecraft_access_token>

Commands

Command	Description
start	Install and launch Minecraft
createMPack	Create a modpack
importMPack	Import a CurseForge / Modrinth pack
getMPack	List the mods in a modpack
modifyMPack	Add or remove mods
reset	Reset the Cauldron folder
uninstall	Remove the Cauldron folder

Run cauldroncli help <command> to see the options for a command.

Common Options

Most commands accept the following options.

• -g --headless: Skip interactive elements and output JSON. See Headless Mode
• -d --debug: Output extra debugging information

Headless Mode

When --headless is passed, the CLI writes one JSON object per line to stdout so other applications can read the output.

type	Description	Example
event	Progress message	{"type":"event","message":"..."}
data	Data returned by the command	{"type":"data","payload":{...}}
complete	The command finished	{"type":"complete","success":true,"payload":{...}}
error	The command failed	{"type":"error","message":"..."}

Configuration

cauldroncli_admin.json

Created in your home folder on first run.

{
  "FORCE_MODE": false,
  "CAULDRON_PATH": "/home/user/.cauldron",
  "RESOURCE_SERVER": "https://resources.cauldronmc.com"
}

• CAULDRON_PATH: Where Cauldron stores games, modpacks and sessions. See grabPath for the default
• RESOURCE_SERVER: Server used to fetch version and loader information

Run cauldroncli uninstall before changing CAULDRON_PATH so the old folder is removed.

custom_args.json

Place a custom_args.json file in the Cauldron folder to apply overrides to every launch.

{
  "jvm": { "ram": "6", "ram_low": "2" },
  "game": {}
}

Information

For information on how a launcher works, this blog post by Ryan Cao explains it brilliantly. Inside a Minecraft Launcher

Wiki.vg was a great resource that provided lots of information on how various parts of Minecraft works. It has been merged into Minecraft Wiki and can be viewed here