yarnpkg / Berry

Fast, reliable, and secure dependency management.

Yarn is a modern package manager split into various packages. Its novel architecture allows to do things currently impossible with existing solutions:

• Yarn supports plugins; adding a plugin is as simple as adding it into your repository
• Yarn supports Node by default but isn't limited to it - plugins can add support for other languages
• Yarn supports workspaces natively, and its CLI takes advantage of that
• Yarn uses a bash-like portable shell to execute package scripts, guaranteeing they work the same way on Windows, Linux, and macOS
• Yarn is first and foremost a Node API that can be used programmatically (via @yarnpkg/core)
• Yarn is written in TypeScript and is fully type-checked

Our supports

Gold sponsors

All your environment variables, in one place. Stop struggling with scattered API keys, hacking together home-brewed tools, and avoiding access controls. Keep your team and servers in sync with Doppler.

But also

	Datadog has been sponsoring the time from our lead maintainer for more than a year now. They also upgraded our account so that we can benefit from long-term telemetry (RFC).
	Sysgears also sponsored time from very early in the 2.x development. In particular, their strong investment is the reason why Yarn 2 supports node_modules installs even better than it used to.
	Netlify has been the historical provider for our website. Each time we got issues, they jumped to our help. Their live previews have been super helpful in our development process.
	Cloudflare has also been an historical partner. While we don't directly mirror the npm registry anymore, they still power our website to make its delivery as fast as possible.
	Algolia contributed a lot to our documentation over the years. They still power the search engine we use on both versions of the documentation.

Installation

Consult the Installation Guide.

Migration

Consult the Migration Guide.

Documentation

The documentation can be found at yarnpkg.com.

API

The API documentation can be found at yarnpkg.com/api.

Current status

On top of our classic integration tests, we also run Yarn every day against the latest versions of the toolchains used by our community - just in case. Everything should be green!

Contributing

Consult the Contributing Guide.

Building your own bundle

Clone this repository, then run the following commands:

yarn build:cli

How it works

After building the CLI your global yarn will immediately start to reflect your local changes. This is because Yarn will pick up the yarnPath settings in this repository's .yarnrc.yml, which is configured to use the newly built CLI if available.

Works out of the box!

Note that no other command is needed! Given that our dependencies are checked-in within the repository (within the .yarn/cache directory), you don't even need to run yarn install. Everything just works right after cloning the project and is guaranteed to continue to work ten years from now 🙂

Yarn plugins

Default plugins

Those plugins typically come bundled with Yarn. You don't need to do anything special to use them.

• ★ plugin-compat contains various built-in patches that will be applied to packages that aren't compatible with the Plug'n'Play resolution out-of-the-box.
• ★ plugin-dlx adds support for the yarn dlx command.
• ★ plugin-essentials adds various commands deemed necessary for a package manager (add, remove, ...).
• ★ plugin-file adds support for using the file: protocol within your dependencies.
• ★ plugin-git adds support for cloning packages from Git repositories.
• ★ plugin-github adds support for using GitHub references as dependencies. This plugin doesn't use git.
• ★ plugin-http adds support for using straight URL references as dependencies (tgz archives only).
• ★ plugin-init adds support for the yarn init command.
• ★ plugin-link adds support for using link: and portal: references as dependencies.
• ★ plugin-nm adds support for installing packages through a node_modules folder.
• ★ plugin-npm adds support for using semver ranges as dependencies, resolving them to an NPM-like registry.
• ★ plugin-npm-cli adds support for the NPM-specific commands (yarn npm info, yarn npm login, yarn npm publish, ...).
• ★ plugin-pack adds support for the yarn pack command.
• ★ plugin-patch adds support for the patch: protocol.
• ★ plugin-pnp adds support for installing JavaScript dependencies through the Plug'n'Play specification.

Contrib plugins

Although developed on the same repository as Yarn itself, those plugins are optional and need to be explicitly installed through yarn plugin import @yarnpkg/<plugin-name>.

• ☆ plugin-constraints adds support for constraints to Yarn.
• ☆ plugin-exec adds support for using the exec: protocol within your dependencies.
• ☆ plugin-interactive-tools adds support for various interactive commands (yarn upgrade-interactive).
• ☆ plugin-stage adds support for the yarn stage command.
• ☆ plugin-typescript improves the user experience when working with TypeScript.
• ☆ plugin-version adds support for the new release workflow.
• ☆ plugin-workspace-tools adds support for the yarn workspaces foreach command.

Third-party plugins

Plugins can be developed by third-party entities. To use them within your applications, just specify the full plugin URL when calling yarn plugin import. Note that plugins aren't fetched from the npm registry at this time - they must be distributed as a single JavaScript file.

Creating a new plugin

To create your own plugin, please refer to the documentation.

Generic packages

The following packages are generic and can be used in a variety of purposes (including to implement other package managers, but not only):

• @yarnpkg/core allows any application to manipulate a project programmatically.
• @yarnpkg/fslib is a set of tools to abstract the filesystem through type-safe primitives.
• @yarnpkg/json-proxy allows to temporarily convert any POD object to an immutable object.
• @yarnpkg/libzip contains zlib+libzip bindings compiled to WebAssembly.
• @yarnpkg/nm contains the node_modules tree builder and hoister.
• @yarnpkg/parsers can be used to parse the language used by @yarnpkg/shell.
• @yarnpkg/pnp can be used to generate Plug'n'Play-compatible hooks.
• @yarnpkg/pnpify is a CLI tool to transparently add PnP support to various tools.
• @yarnpkg/sdks is a CLI tool to generate the PnP Editor SDKs.
• @yarnpkg/shell is a portable bash-like shell interpreter.

Yarn packages

The following packages are meant to be used by Yarn itself, and probably won't be useful to other applications:

• @yarnpkg/builder contains a CLI tool to package berry and its plugins.
• @yarnpkg/cli is a CLI entry point built on top of @yarnpkg/core.