Mystery Snap

This is a simple MetaMask Snap that returns random numbers and answers. Below are the steps for publishing a Snap to NPM for anyone to use.

Prerequisite

Before you begin, you should familiarize yourself with the npm documentation for Contributing packages to the registry.

You will also need an npm account.

Setup

snap.manifest.json:

{
  "version": "1.0.0",
  "proposedName": "Mystery Snap",
  "description": "A simple MetaMask Snap that returns random numbers and answers.",
  "repository": {
    "type": "git",
    "url": "https://github.com/Montoya/random-snap.git"
  },
  "source": {
    "shasum": "05E9ZMYL2tHWlHoTF9z4vnDqbxMFw3KfeEvHyfQeMRE=",
    "location": {
      "npm": {
        "filePath": "dist/bundle.js",
        "iconPath": "images/icon.svg",
        "packageName": "mystery-snap",
        "registry": "https://registry.npmjs.org/"
      }
    }
  },
  "initialPermissions": {
    "snap_confirm": {}
  },
  "manifestVersion": "0.1"
}

source contains what will be published to NPM for distributing the Snap. Proposed package name is mystery-snap (this is the only field that needs to be modified from template-snap). Also, the icon at images/icon.svg should be changed to something unique.

package.json (partial):

{
  "name": "mystery-snap",
  "version": "1.0.0",
  "description": "A simple MetaMask Snap that returns random numbers and answers.",
  "repository": {
    "type": "git",
    "url": "https://github.com/Montoya/random-snap.git"
  },

Make sure that the version numbers in snap.manifest.json and package.json match.

Publishing

Once your Snap is ready for release, use the following command to publish:

npm publish

If you are running this for the first time, you may have to log in via the command line, then run this command again.

You should see output like this:

% npm publish
📦  [email protected]
=== Tarball Contents === 
2.7kB README.md         
1.7kB dist/bundle.js    
2.1kB images/icon.svg   
1.6kB package.json      
617B  snap.manifest.json
1.3kB src/index.js      
=== Tarball Details === 
name:          mystery-snap                            
version:       1.0.0                                   
filename:      mystery-snap-1.0.0.tgz                  
package size:  3.6 kB                                  
unpacked size: 10.1 kB                                 
shasum:        ...
integrity:     ...
total files:   6                                       

Publishing to https://registry.npmjs.org/
+ [email protected]

After publishing, you can visit your npm account dashboard and see your newly published Snap package:

Then, any dApp can use the published Snap ID to connect to this Snap:

const snapId = `npm:mystery-snap`;

MetaMask will automatically fetch the Snap from the npm registry.

This repository includes a simple dApp website that uses the Snap published to npm. You can try it here: https://montoya.github.io/random-snap.

Acknowledgements

Crystal Ball icon by OpenMoji.

License

This project is dual-licensed under Apache 2.0 and MIT terms:

• Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)