@metamask/template-snap-monorepo

This repository demonstrates how to develop a snap with TypeScript. For detailed instructions, see the MetaMask documentation.

MetaMask Snaps is a system that allows anyone to safely expand the capabilities of MetaMask. A snap is a program that we run in an isolated environment that can customize the wallet experience.

Snaps is pre-release software

To interact with (your) Snaps, you will need to install MetaMask Flask, a canary distribution for developers that provides access to upcoming features.

Getting Started

Clone the template-snap repository using this template and setup the development environment:

yarn install && yarn start

Cloning

This repository contains GitHub Actions that you may find useful, see .github/workflows and Releasing & Publishing below for more information.

If you clone or create this repository outside the MetaMask GitHub organization, you probably want to run ./scripts/cleanup.sh to remove some files that will not work properly outside the MetaMask GitHub organization.

Note that the action-publish-relase.yml workflow contains a step that publishes the frontend of this snap (contained in the public/ directory) to GitHub pages. If you do not want to publish the frontend to GitHub pages, simply remove the step named "Publish to GitHub Pages" in that workflow.

If you don't wish to use any of the existing GitHub actions in this repository, simply delete the .github/workflows directory.

Contributing

Testing and Linting

Run yarn test to run the tests once.

Run yarn lint to run the linter, or run yarn lint:fix to run the linter and fix any automatically fixable issues.

Releasing & Publishing

The project follows the same release process as the other libraries in the MetaMask organization. The GitHub Actions action-create-release-pr and action-publish-release are used to automate the release process; see those repositories for more information about how they work.

1. Choose a release version.

• The release version should be chosen according to SemVer. Analyze the changes to see whether they include any breaking changes, new features, or deprecations, then choose the appropriate SemVer version. See the SemVer specification for more information.

2. If this release is backporting changes onto a previous release, then ensure there is a major version branch for that version (e.g. 1.x for a v1 backport release).

• The major version branch should be set to the most recent release with that major version. For example, when backporting a v1.0.2 release, you'd want to ensure there was a 1.x branch that was set to the v1.0.1 tag.

3. Trigger the workflow_dispatch event manually for the Create Release Pull Request action to create the release PR.

• For a backport release, the base branch should be the major version branch that you ensured existed in step 2. For a normal release, the base branch should be the main branch for that repository (which should be the default value).
• This should trigger the action-create-release-pr workflow to create the release PR.

4. Update the changelog to move each change entry into the appropriate change category (See here for the full list of change categories, and the correct ordering), and edit them to be more easily understood by users of the package.

• Generally any changes that don't affect consumers of the package (e.g. lockfile changes or development environment changes) are omitted. Exceptions may be made for changes that might be of interest despite not having an effect upon the published package (e.g. major test improvements, security improvements, improved documentation, etc.).
• Try to explain each change in terms that users of the package would understand (e.g. avoid referencing internal variables/concepts).
• Consolidate related changes into one change entry if it makes it easier to explain.
• Run yarn auto-changelog validate --rc to check that the changelog is correctly formatted.

5. Review and QA the release.

• If changes are made to the base branch, the release branch will need to be updated with these changes and review/QA will need to restart again. As such, it's probably best to avoid merging other PRs into the base branch while review is underway.

6. Squash & Merge the release.

• This should trigger the action-publish-release workflow to tag the final release commit and publish the release on GitHub.

7. Publish the release on npm.

• Be very careful to use a clean local environment to publish the release, and follow exactly the same steps used during CI.
• Use npm publish --dry-run to examine the release contents to ensure the correct files are included. Compare to previous releases if necessary (e.g. using https://unpkg.com/browse/[package name]@[package version]/).
• Once you are confident the release contents are correct, publish the release using npm publish.

Notes

• Babel is used for transpiling TypeScript to JavaScript, so when building with the CLI, transpilationMode must be set to localOnly (default) or localAndDeps.
• For the global wallet type to work, you have to add the following to your tsconfig.json:

  {
    "files": ["./node_modules/@metamask/snap-types/global.d.ts"]
  }