MetaMask Plugin Utility

A CLI tool for building MetaMask plugins.

Installation

Always use node@10.16.3, the version currently used to develop MetaMask.

1. git clone git@github.com:MetaMask/mm-plugin.git
2. cd mm-plugin
3. npm install -g .

Basic Usage

mkdir myPlugin
cd myPlugin
mm-plugin init

MetaMask Plugins

MetaMask plugins consist of two things: a JSON manifest and a JavaScript bundle. For a variety of reasons, we decided to follow NPM conventions. Thus, the manifest file is simply package.json, with the following required standard fields:

• name
• version
• description
• main (relative path to source entry point, not the bundle)
• repository

In addition, we use the following, required custom fields:

• web3Wallet (object)
  • bundle (object)
    • local (string; relative path to bundle)
    • url (string; absolute URL to bundle)
      • Set to e.g. localhost:8081/dist/bundle.js for local development.
  • initialPermissions ({ string: object }; permissions to be requested on plugin installation)
    • See this interface and examples in this repo for details.

If you exclude any required fields from package.json, your plugin may not work properly or install at all.

We recommend building your plugin using this tool. You can bundle your plugin using your own tools, but it must run in the browser, run in SES, and its contents must be wrapped in an anonymous function (() => ( ... )).

Assumed Project Structure

This tool has default arguments assuming the following project structure:

 .
 |- index.js
 |- dist/
 |-- bundle.js
 |- ... (all other project files and folders)

Source files other than index.js are located through its imports. The defaults can be overwritten using the mm-plugin.config.json config file, see below.

Permissions

This module uses permissions as defined in json-rpc-capabilities-middleware or rpc-cap. See examples in this repo for details.

Usage

Always use node@10.16.3, the version currently used to develop MetaMask.

mm-plugin --help

Usage: mm-plugin [command] [options]

Commands:                                                                                    
  mm-plugin init      Initialize plugin package                     [aliases: i]
  mm-plugin build     Build plugin from source                      [aliases: b]
  mm-plugin eval      Call 'eval' on plugin bundle to ensure it works                        
                                                                    [aliases: e]
  mm-plugin manifest  Validate project package.json as a plugin manifest                     
                                                                    [aliases: m]
  mm-plugin serve     Locally serve plugin file(s)                  [aliases: s]             
  mm-plugin watch     Build file(s) on change                       [aliases: w]

Options (build):
  --version               Show version number                          [boolean]
  --verboseErrors, -v     Display original errors     [boolean] [default: false]
  --suppressWarnings, -w  Suppress warnings           [boolean] [default: false]
  --help, -h              Show help                                    [boolean]
  --src, -s               Source file  [string] [required] [default: "index.js"]
  --dist, -d              Output directory
                                          [string] [required] [default: "dist"]
  --outfileName, -n      Output file name                              [string]
  --eval, -e              Call 'eval' on plugin bundle to ensure it works
                                                       [boolean] [default: true]
  --manifest, -m          Validate project package.json as a plugin manifest
                                                       [boolean] [default: true]
  --populate, -p          Update plugin manifest properties of package.json
                                                       [boolean] [default: true]

Examples:
  mm-plugin init                            Initialize plugin package from
                                            scratch
  mm-plugin build -s index.js -d out        Build 'plugin.js' as
                                            './out/bundle.js'
  mm-plugin build -s index.js -d out -n     Build 'plugin.js' as
  plugin.js                                 './out/plugin.js'
  mm-plugin serve -r out                    Serve files in './out' on port 8080
  mm-plugin serve -r out -p 9000            Serve files in './out' on port 9000
  mm-plugin watch -s index.js -d out        Rebuild './out/bundle.js' on changes
                                            to files in 'index.js' parent and
                                            child directories

Usage Notes

• Commands
  • watch --src ... --dist ... rebuilds on all changes in the parent directory of src and its children except:
    • node_modules/
    • test/ and tests/
    • The specified dist directory
    • Dotfiles
  • serve --root ... --port ... serves the root directory on localhost:port
    • By default, root serves the current working directory: .
• Arguments
  • src, plugin, and outfileName must be file paths when specified
  • dist and root must be directory paths when specified

Configuration File

mm-plugin.config.json can be placed in the project root directory. It should have string keys matching command arguments. Values become argument defaults, which can still be overriden on the command line. Example:

{
  "src": "src",
  "dist": "plugins",
  "port": 9000
}