Kraft Sync Script ⛏️🔄

AN experimental lightweight & simple and quick script that helps you to sync the content of a Minecraft Java instance.

The script will sync the following:

1. 🛠️ Mods (Alpha): In the experimental phase and subject to changes.
2. 🎨 Resource Packs (Highly Experimental): In the highly experimental phase and subject to changes.
3. ✨ Shader Packs (Not Implemented Yet): This feature is not available yet. Future updates may implement it
4. 🌐 In-Game Server List (Alpha): It is subject to potential changes or removal in future updates.
5. 🧩 Mods configurations (Not Implemented Yet): These may be synced initially, since each player can have their own configurations. We have not yet found a solution, except by enforcing the same mod settings for all players.
6. ⌨️ Keybindings (Not Implemented Yet): These may be synced initially since each player can have their own keybindings. We have not yet found a solution for this, except by enforcing the same keybindings for all players

If you're a player interested in joining a server, make sure you trust the server administration on this matter—unless you're confident you know what you're doing.

Caution

The script might introduce Breaking Changes as it's still in the early stages. We will provide migration instructions if there is any breaking change in each release. Some features might not be available yet, or unstable.

Kraft Sync is not affiliated with Mojang AB, Microsoft Corporation, or any of their subsidiaries.

📚 Table of Contents

• 📖 About
• ✨ Features
• 🔧 How it works
• ✅ Supported Launchers
• 🖥 Usage️
• 💬 Frequently Asked Questions
• 🔰 Admin Utility
• 🛠 Build from Source️
• 🤝 Contributing
• 📜 Acknowledgments

📖 About

Let's say you're running a Minecraft server and every time you add, remove, or update a mod, resource pack, or shader, each player has to make the changes manually each time you do it or let's say you're changing the server address, the players have to update it in the game manually.

It's designed for server owners, yet it can also be effective for mod-pack developers and other use cases. The script will run before each time when launching the game will make a GET request to a file you upload somewhere (GitHub for example) and it contains information about the sync information like the Mods and other configurations that allow you to customize the behavior, you don't need to upload the mods anywhere it will need a public download URL for the mod (e.g, Modrinth) and it will download the mod directly from there.

You don't have to do that manually, see Mods Info Converter 💾 for more info.

Tip

Kraft Sync
The meaning of this name:

• K: will depend on how you look at it, it could be Keep, which means keep a Minecraft instance synced
• Craft or Kraft: Indicating this is specific for Minecraft
  
• Sync: Indicating it's for syncing the content/assets/data

✨ Features

List the key features of the project:

• 🛠️ Easy to Use: Simple and customizable for various needs.
• 🔍 Validation Methods: Various ways to validate assets or disable file integrity checks.
• 🖥️ Simple GUI: Support both dark and light modes with different themes (can be disabled).
• 🚫 Error Handling: Manages different types of errors.
• 🌐 Multiplatform: Works on any JVM-compatible system. You don't need different binaries for different desktop platforms.
• 📦 Small Bundle Size: Compact and efficient.
• ⚙️ Java 11+ Compatibility: Works with Java 11 and newer versions.
• 📜 Public Source Code Fully documented and open-source code.
• 🔌 Game Restart is not required: No need to restart the game after syncing the data; it will work once you open the game.
• 🛡️ Server-Side Mod is not required: No need for a server-side mod on modded servers (e.g., Fabric, Quilt, NeoForge, Forge).
• 🧩 Flexible Sync Options: Define what to sync or exclude.
• 🔄 Client and Server Sync: Use the script for both client-side and server-side mod syncing. Exclude or include some mods to be downloaded on the client or the server.
• 💾 Mod Info Conversion: Convert mod info from other launchers.
• ⚡ Quick Play Feature: Automatically join a Minecraft server on launch (limited to supported launchers).

🔧 How it works

The process is straightforward.

1. The player launches the game.
2. The script will automate the syncing process.
3. Once the syncing process finishes, the game launches with the new synced content.

The script is designed to be independent of the used Minecraft Launcher, we highly recommend using a Minecraft launcher that has some features for optimal and seamless experience.

The script JAR file will need to be shipped to each player if you're using a Minecraft Launcher that supports Exporting and Importing. You can include it, so they only have to download the exported profile/instance and then import it, and the script will be executed once the player launches the game.

See Supported Launchers section for more details.

✅ Supported Launchers

The project can work with any Minecraft launcher, though we recommend a launcher that supports the following features for optimal experience:

1. Separation of data
   • What it does: Split all the data of Minecraft into instances/profiles, each instance/profile has its own data (e.g., worlds, servers, mods, resource-packs, shaders, mod loader, game version) which allow the player to switch between them
   • Why it’s recommended: The player can have more flexibility, this feature allows not affecting their own data in case if they want to join your modded server.
2. Hooks/Custom Commands
   • What it does: Supports running commands/hooks to allow executing the script before launching the game. Each instance supports running a command or executing something and waiting for the result before launching the game
   • Why it’s recommended: To allow executing the script before launching the game for seamless experience, this allows launching the game without doing anything else. Like running the script each time before launching the game manually.
3. Hooks/Custom commands environment variables:

   • What it does: An extension for the previous feature that allows to make the instance/profile portable to the players. The player only has to install the launcher, download the exported instance/profile, import it and launch the game.

   • Why it’s recommended: To avoid hardcoding the paths as each player has their own user profile/name and might have a different operating system or installed the launcher to somewhere else other than the default.

     The following environment variables are recommended:

     • Java Binary Executable: To execute the script using the same Java version that's used for launching Minecraft. Eliminating the needs for installing Java on the player system.
     • Instance Directory Path: To locate the script JAR file without hardcoding the instance path.

Click to expand the Tested Launchers

• MultiMC: has recommended features for an optimal experience. Take a look at MultiMC Instance Custom Commands Settings
• Prism Launcher: has recommended features for an optimal experience. Take a look at Prism Launcher Custom Commands
• ATLauncher: has recommended features for an optimal experience.
• Modrinth App: has recommended features except hooks environment variables. Take a look at the active Feature Request #952.
• GDLauncher Carbon: has recommended features except hooks environment variables. the project might not have an active issue, take a look at GDLauncher Issue Tracker for details.

Take a look at the Usage section.

If you use the official Minecraft Launcher, the player won't be able to:

• Switch between their own data and the synced content seamlessly, most Minecraft Launchers support profiles/instances.
• Sync the content and launch the game directly using the Play button in the launcher, instead will have to execute using a sh or bat script that run the project script and launch the game after that, which means the player will have to do this manually each time they want to launch the game.
• Import the instance/profile directly and launch without any additional setup or configurations.

🖥 Usage

We suggest to read How it works and Supported Launchers sections before starting reading this section.

The easiest way to start using the script 🚀:

Click to expand the steps

1. Download the JAR file from the Releases for both the script and the Admin Utility

2. Download and install a Minecraft Launcher that is supported by both the script (see Supported Launchers) and Admin Utility (see Admin Supported Launchers).

3. Create a new instance, choose the Minecraft Version, Mod Loader and download the Mods you want to use. This instance will be used to convert the Mods' info using Admin Utility into the Script data format.
   
   Consider using Modrinth as an asset provider to make the process faster as this will make the task offline.

4. Use the Admin Utility to extract the Mods' info and convert them into the Script data format, upload the file to somewhere public (e.g., GitHub)

5. Prepare the instance/profile that will be imported by the players, create a new instance, choose the same Minecraft Version and Mod Loader as Step 3. Refrain from downloading anything (e.g., Mods, Resource Packs) as this instance/profile will be configured to use the script.

6. Now we will install the script into the instance/profile from Step 5.

   The automated way to install the Script

   Use Script Installer to use the script into the newly created instance/profile from Step 5, the process is automated (limited to supported launchers).

   The manual way to install the Script

   Apply the following to the newly created instance/profile from Step 5:

   • Move the downloaded JAR file from Step 1 into the instance directory, the same directory that has the mods, resourcepacks and other Minecraft related folders.
   • Go to the settings of the instance/profile, navigate to the hooks/custom commands options, this process is manual and depends on the launcher.
   • Find the Pre-Launch option or something similar, enter the following:

   $INST_JAVA -jar $INST_MC_DIR/kraft-sync.jar
   

   Replace kraft-sync.jar with the JAR file name from Step 1 if necessary. You also might need to replace $INST_JAVA and $INST_MC_DIR with something else depending on the launcher, most launchers support those two environment variables.

7. Launch the game with the instance/profile that has the script installed in Step 6. The script will ask you for the URL from Step 4, once succeeded, the game will launch with the new synced content.

8. To avoid repeating those steps for all the players, export the instance from Step 6 that's configured to use the script. When the launcher asks you which files should be included or excluded, exclude the assets (e.g., Mods, Resource Packs) and include the JAR file (kraft-sync.jar) and kraft-sync-data folder. If you include the assets, the script will sync them if they are outdated, to make the instance smaller to share; we suggest to excluding those folders.

To update the assets that will be synced:

You only need to update the file from Step 4, you can extract the Mods' info once again and replace the content, the script will sync the content once the player starts the game.

💬 Frequently Asked Questions

This FAQ provides answers to some of the most commonly asked questions. Click on the question to expand and see the answer.

How to use this FAQ?

• Click on any question below to expand and reveal the answer.
• You can use the search functionality of your browser (Ctrl+F or Cmd+F) to find specific keywords within the questions and answers.

List of Questions:

1. Why not use sync mods?
2. Does it sync the Minecraft version, Mod loader, and Java version?
3. Is there a GUI for admins?
4. I have an issue/bug or feature request
5. What happens to the old script?
6. Can the JAR file be smaller?
7. Why not Mod packs?
8. Will there be Bedrock support?

Answers:

Why not use sync mods?

There are some mods that are required to be installed on both the client and server-side and it will simply sync the mods when you join a server by downloading the mods to a Minecraft server.

While those mods work great, depending on your use case, you might use one of those mods or use this script.

Some common issues encountered when using Minecraft mods that synchronize the mods include:

1. It will require running the HTTP server on a port other than the Minecraft port (e.g., 25565) which can be used by attackers to cause performance issues if you haven't implemented Rate Limit (otherwise some users might spam the server) and another security mechanism that might affect the network and traffic from your Minecraft hosting
2. You will constantly need to update the mod for Forge/Fabric or the mod loader you are using, and for a specific Minecraft version, while this script works independently of the Minecraft version and the mod loader
3. The users have to update the mods when joining the server, then restarting the game, so let's say a new Minecraft version has been released, and you were playing with your friends, you will have to wait for the mod that syncs the mods to be updated or update it yourself, then ask your friends to restart the game with the new version and manually update the sync mod, then you will have to update all the mods on the server, after when they launch the game once they launch the game they will have to update and then restart once again, when using the script, you only have to update the data as admin, then ask your friends and players to restart the game
4. Can only sync Minecraft mods (which might be exactly what you want)
5. Server and client-side mods are different: There are completely server-side mods like Geyser or Spawn Animations and including them on the client side will increase the size and require the players to download more, for example, Geyser is above 10 MB, Another client-side mod Physics Mod which is more than 130 MB, when using more and more mods not only the syncing process will be slower, it will also require more space on the disk and in some rare cases it could cause issues (if the server-side mod causes an exception when running on the client side) or it's not marked as a server-side mod
6. Uploading Minecraft developer mods and downloading them to the players from external sources other than the original might be violating the LICENSE
7. You might have large client-side mods like Physics Mod which might not be needed in the server mod
8. Only work with official Minecraft servers, you might use some other solution to play with your friends like Essential or you want to sync the content without using sync mods for some other reason

Also, there is an idea that is a mix of using a mod (server-side mod) and a script, yet this method could introduce issues later.

Does it sync the Minecraft version, Mod loader, and Java version?

Right now, the script won't download or sync the Java version, because the custom launcher you are using or even the official Minecraft launcher already has Java JRE installed, the script will use that installed Java instead of requiring the players to download and install Java on their system, launchers like official Minecraft and some other custom launchers will automate the process of updating and installing the required Java version for a specific Minecraft version

As for the Minecraft version, unfortunately, we currently don't sync it as some launchers might store such information, and we can't update and cover all the launchers, breaking changes might be introduced, and the goal of this script is to make it simple and work for most use cases, if there is a new Minecraft version, the player needs to update the Minecraft version along with the mod loader manually, launching the game to update the assets (e.g. Mods, Resource-packs) then they can get back to playing the game

We might add a feature that will display a warning or require the player to update the mod loader version using their launcher or manually downloading it from the web.

Or we might automate this process, until now we don't have plans.

Is there a GUI for admins?

For now, we don't have a GUI for downloading and configuring the mods and customizing the data, We might create a simple web interface where you can input some data and you will either get a URL to use in the script or just the raw JSON data, and you will need to upload it somewhere

We still haven't planned for some things, like whether we should add authentication and store the data on the server so each admin can access their multiple servers and update the assets (e.g. Mods, Resource-packs), or we should only provide add and edit functionalities, for the add you will insert all the data, for the edit you will provide the raw JSON data and then edit it in GUI and get the new one

The GUI should allow selecting assets (e.g., Mods, Resource-packs) from some providers like Modrinth, CurseForges, or by custom URL.

I have an issue/bug or feature request

File an issue in the issues with detailed information as much as you can, with the error and what are you trying to do and how to reproduce it. We will do our best to help fix it.

if you have a question, use the Discussions tab instead

What about MC Mods Sync?

We have another script called MC Mods Sync which is limited to syncing the mods only, requiring the admin to upload the mods on GitHub and then download them, other than many issues we discussed like storage limitation and LICENSE issues, it's easier to set up and maintain the admin side yet less flexible and simpler.

Can the JAR file be smaller?

Although the script has only one task, the bundle size is not too small. You might wonder why this is the case if Java is already installed on the system/launcher.

There are some technical reasons:

1. Written in Kotlin: Kotlin is fully compatible with Java, You don't need Kotlin installed on your machine to run the script as Kotlin will include everything it needs in the JAR file directly allowing it to use the existing Java JRE on your system/launcher, it's also use Kotlin Standard Library, the JAR file for Kotlin/JVM applications around 1.7 MB without dependencies, it does provide many features and advantages compared to this size
2. Compatible with older versions of Java: Thanks to Kotlin, it's possible to use recent language features like Sealed Classes Which is available in Java 17 and above, with Kotlin it's possible to use it even in Java 8, it provides modern syntax and makes developing JVM apps easier with many built-in features with more recent syntax, it also makes it easier to compile the script to native platforms using Kotlin/Native
3. Cross Platform: Java made it easy to write cross-platform apps, while it's also possible with Dart and other languages, it requires different operating systems (Linux, macOS, and Windows) to compile the script and build the binaries, which means you have to include 3 different versions of the script in your instance or provide separate ones for each operating system, Windows players have to download the Windows version of the instance in order to work, some of the solutions require installing the language on the machine, and the goal of the script is to make it as easy as possible to run without installing anything extra or too many manual configurations which is one reason why this script uses JVM as most Minecraft Java Launchers already have it installed, which make it easier to write a cross-platform script from a single code base, the script will use Java Swing for GUI support without making the bundle size larger, and we will use imports from Java when possible
4. Features: The script provides some features like dark and light mode support with different themes which makes the bundle size a little bit larger

We will try to find a good balance between the features and the bundle size. We use a tool called Proguard to shrink and minimize the JAR file.

Why not Mod packs?

It depends on your use case, there are some reasons that prevent some players from using Mod packs to use Minecraft mods with players

1. To allow your friends to use your mod pack to get the updates, you have to publish it to a provider that is supported by the launcher like Modrinth or Curse Forge.

   It will be listed publicly, a review is usually required, and you might only want to play it with your friends

2. Limited to the supported launchers, technically you can run this script without Minecraft. It can work on any launcher or even the official Minecraft Launcher, we recommend using any launcher that supports Instances and Pre-launch command feature, which most Minecraft launchers do

3. Server and Client Flexibility, Mod-packs are usually for syncing the client side, while it's possible to get the updates of a Minecraft mod pack into a server, or most server hosting providers already support a wide range of mod-packs with one click, this script allows you to split the used mods between the server and the client or use them on both sides, and it can work on any server even on localhost

4. Allow you to use a mix of mods from multiple providers, the script only needs the URL to the mod, and it can be from anywhere, it doesn't store anything specific about any mod provider, only the links to the mod providers which will be used to detect the mod provider, if it's unknown or unverified, then it will warn the user before continuing for the first time, the script doesn't store any data remotely by itself, which gives you more control over where to store it

5. License Compliance by avoiding re-uploading the mods somewhere other than the source, the script will download the mods as if you're downloading them from the website

6. It can only support mods; The term "Mod packs" typically refers to collections of mods, which can include resource packs as well. However, they might not always meet specific needs or preferences.

7. More features like the Quick Play support feature, see Features for more info

Will there be Bedrock support?

There are some reasons preventing us from providing support to Minecraft Bedrock Support

1. Built with different code and underline data, which requires us to do breaking changes, and make more steps to use the script with different data for resource-packs and behavior-packs, add-ons, and shaders for Bedrock and for Java which require different information to be stored or maybe both in the same URL or maybe provide two versions of the scripts
2. Lack of asset provider support for the Bedrock edition
3. The bedrock edition already has a way to sync the resource packs and behavior packs to all the players; it's much easier, all you have to enter the IP address join as a player, and click continue
4. Requires refactoring almost all the logic and abstracting it to different editions of Minecraft
5. It will require Java JRE installed on the machine since the script now will use JVM as Minecraft Java already needs it installed on the launcher/system, the script will use the same Java installation to run, if players are only interested in playing a Minecraft Bedrock edition, installing Java on the system might not be preferred, which requires us to bundle the JRE and provide native platform binaries or use Kotlin/Native with KMP to still use Kotlin/JVM for another module/source set
6. Sandbox limitations, which is a good thing and has many features. However, it doesn't allow reading or editing the content, nor an API or something else to edit with permission.
7. Bedrock Edition does not support multiple instances, each with its own data and configurations
8. The modifications are limited to the Bedrock edition, which reduces the necessity for using this script

There may be additional reasons, as discussed above, why using this script is less needed for the Bedrock edition; the bedrock edition already has something similar

We hope this FAQ helps!

If you have any further questions that are not covered here, feel free to file an issue or create a new discussion.

🔰 Admin Utility

We provide a utility program 🛠️ for the Admin which helps when dealing with the data or converting them from other launchers, for more details, navigate to the Admin Utility page.

🛠 Build from Source

If you want to build from source for the latest version:

1. Install the Development Prerequisites
2. Run ./gradlew assemble or ./gradlew.bat assemble on Microsoft Windows
3. Navigate to dist folder where you should find the JAR files.

🤝 Contributing

We greatly appreciate your time and effort.

To keep the project consistent and maintainable, we have a few guidelines that we ask all contributors to follow. These guidelines help ensure that everyone can understand and work with the code easier.

See Contributing for more details.

📜 Acknowledgments

We are incredibly grateful to many individuals and organizations who have played a role in the project. This includes the community, dedicated volunteers, talented developers and contributors, and the creators of the open-source tools we rely on.

Thanks to:

• The welcoming community, the volunteers who helped along the journey, developers, contributors and contributors who put time and effort into everything including making all the libraries, tools, and the information we rely on
• JetBrains for developing and maintaining Kotlin, IntelliJ IDEA Community Edition in along with other projects
• Square Community for developing and maintaining OkHttp
• GuardSquare for developing and maintaining Proguard