Scriptcraft Modular Architecture

Scriptcraft Modular Architecture (SMA) adds support for modular plugins that live outside the scriptcraft root directory.

This provides isolation of custom plugin files, allowing plugins to live in their own repositories and be loaded via configuration - for example by mounting them in a docker container.

It also means that you can update the Scriptcraft version without impacting your own code.

Docker image

A built Docker image is available from Docker Hub:

docker pull magikcraft/scriptcraft

Scriptcraft Version

This uses Scriptcraft 3.4.0 patched to fix issue #410. See the README-Magikcraft.md file for instructions on building a patched version.

Uses the Scriptcraft Multi-engine plugin.

Base image

From 1.15.2, the base image is oracle/graalvm-ce:19.3.1-java8, to use the new Polyglot GraalVM.

Versions

• Paperclip build #71.
• H2 1.4.200
• CamundaPlugin

To Run

docker run -it -p 25665:25565 magikcraft/scriptcraft

For an example on starting the docker container with SMA plugins, refer to the example in the test directory.

Note on getting op

When the server starts, you need to give yourself op. At the server console, type this:

op {your-minecraft-name-goes-here}

Make sure that you put your minecraft username in there. So, for example, if your Minecraft name is Rob123, you would type:

op Rob123

Included plugins

• Minecraft REST console
• Holographic Displays
• Essentials
• Motd Manager Reloaded
• Multiverse Core
• ProtocolLib
• World Edit
• Boss Bar
• Durable Map

Run with Modular Plugins

See the run.sh file for an example of how to mount modular scriptcraft plugins in the Docker image.

Building

To build the image, run:

docker build -t magikcraft/scriptcraft .

Scriptcraft Modular Architecture

Rationale

We initially developed our plugins for Magikcraft and MCT1 (Minecraft for Type 1 Diabetes) inside Scriptcraft. This meant we had code spread between Scriptcraft's lib, module, and plugins folders. Upgrading Scriptcraft was a complex undertaking with multiple touch points.

Also, when we wanted to open source parts of our code base, we had to either get it accepted into Scriptcraft upstream, or make it available as a patch on top of Scriptcraft, or a fork of Scriptcraft.

We developed the Scriptcraft Modular Architecture to allow us to easily integrate code with Scriptcraft at run-time, while keeping it in a separate repository.

Implementation

1. We put a directory outside scriptcraft and load additional modules in there. So the directory structure looks like this:

   minecraft
       - scriptcraft-plugins
           - magikcraft
           - mct1
       - scriptcraft

2. We mount a custom bootstrap into scriptcraft/plugins via docker. This bootstrap is loaded by Scriptcraft's standard plugin loading.

3. The bootstrap:

• Replaces the standard scriptcraft implementation of require at run-time. This custom require adds the scriptcraft-plugins to the require resolution search paths.

• Scans each SMA plugin for a package.json file. If found, checks for a scriptcraft_load_dir key. If present, the contents of the directory specified in this key are autoloaded.

• If no package.json is found in an SMA plugin, or if it does not specify a scriptcraft_load_dir, then the bootstrap looks for a plugin folder in the SMA plugin, and loads everything in there if it is present.

Module Resolution

The SMA require searches the standard Scriptcraft locations first, then checks the scriptcraft-plugins directory. As an example, here is how magikcraft/fs gets resolved:

scriptcraft/lib/magicraft/fs
scriptcraft/modules/magikcraft/fs
scriptcraft/../scriptcraft-plugins/magikcraft/fs

Note: in SMA plugins you do not get the magic of searching lib and module subdirectories in your SMA plugin. The path is literal. So magikcraft/fs will resolve scriptcraft-plugins/magikcraft/fs, but not:

scriptcraft-plugins/magikcraft/lib/fs, or

scriptcraft-plugins/magikcraft/modules/fs.

Polyfills

The Scriptcraft Modular Architecture environment includes a number of ES6 polyfills. Our code at Magikcraft is written in TypeScript, and we missed a number of modern features while coding, so we added polyfills to the runtime to support the following:

• Array.prototype.find
• Array.prototype.from
• Array.prototype.includes
• EventEmitter
• Object.assign
• Promise
• String.prototype.includes
• String.prototype.repeat
• String.prototype.padStart
• String.prototype.padEnd

Making a SMA Plugin

The easiest way to make an SMA Plugin is using the Scriptcraft-SMA Yeoman generator.

For an example of a Scriptcraft SMA plugin, refer to MCT1.