snaps-cli

A CLI for developing MetaMask Snaps, formerly known as "plugins."

Installation

Always use node@10.17.0, the version currently used to develop MetaMask.
We recommend nvm for managing Node versions.

To install and access the examples (recommended):

1. git clone git@github.com:MetaMask/snaps-cli.git
2. cd snaps-cli
3. npm link

You can also simply install globally: npm install -g snaps-cli

Basic Usage

``bash
mkdir mySnap
cd mySnap
snap init
`

There is also an alias mm-snap in case of snap being taken.

MetaMask Snaps

MetaMask Snaps 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
Snap installation)
- See this interface
and examples in this repo for details.

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

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

$3

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 snap.config.json config file,
see below.

$3

This module uses permissions as defined in rpc-cap, MetaMask's JSON RPC
capabilities middleware.
See examples in this repo for details.

Usage

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

snap --help
`
Usage: snap [options]

Commands:
snap init Initialize Snap package [aliases: i]
snap build Build Snap from source [aliases: b]
snap eval Attempt to evaluate Snap bundle in SES [aliases: e]
snap manifest Validate project package.json as a Snap manifest
[aliases: m]
snap serve Locally serve Snap file(s) for testing [aliases: s]
snap watch Build Snap on change [aliases: w]

Options (build):
--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] [default: "bundle.js"]
--sourceMaps Whether building outputs sourcemaps
[boolean] [default: false]
--stripComments, --strip Whether to remove code comments from bundle
[boolean] [default: false]
--port, -p Local server port for testing
[number] [required] [default: 8081]
--eval, -e Attempt to evaluate Snap bundle in SES
[boolean] [default: true]
--manifest, -m Validate project package.json as a Snap
manifest [boolean] [default: true]
--populate Update Snap manifest properties of
package.json [boolean] [default: true]
--verboseErrors, -v, --verbose Display original errors
[boolean] [default: false]
--suppressWarnings, -w Suppress warnings [boolean] [default: false]

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

$3

- 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, snap, and outfileName must be file paths when specified
- dist and root must be directory paths when specified

$3

snap.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:
`json
{
"src": "lib",
"dist": "out",
"port": 9000
}
``