Yarn v2 Monorepo

This is a short guide on how to set up a new monorepo using only Yarn v2.

It is expected that you already have installed Node and Git, otherwise have a look at the other monorepo guide where this is explained Yarn-Lerna Monorepo.

Install Yarn v2

As of this writing the recommended way of instaling Yarn v2 is per-project. This means you still have NPM or Yarn v1 as the default global binary and you only enable Yarn v2 in projects where needed.

To enable Yarn v2 per-project you simply go to your project folder root and run this command → yarn set version berry. Now this project is using Yarn v2, you can check it by running yarn --version.

Setup Yarn v2 monorepo

To create a monorepo is very easy, just go to your monorepo folder and initialize Yarn with yarn init. Now you should have a package.json file in the root.

Now we need to modifiy the package.json as follows:

• It needs the private flag to be set "private": true.
• It needs to have Workspaces declared with "workspaces" entry. This accepts an array of glob patterns. For example → "workspaces": ["packages/*"], this will search for projects inside packages folder.

Usefull notes about how to use Yarn v2 monorepo

New resolution protocol workspace

When there is a need to prevent a package being resolved from the remote registry we can use the workspace resolution protocol. Here is an example (let's asume the current version is 1.5.0):

{
  "dependencies": {
    "foo": "workspace:*",
    "bar": "workspace:^1.2.3",
    "baz": "workspace:path/to/baz"
  }
}

will be resolved to:

{
  "dependencies": {
    "foo": "1.5.0",
    "bar": "1.2.3",
    "baz": "1.5.0"
  }
}

Usefull CLI commands

Run a command within the specified workspace (yarn workspace)

Usage:

yarn workspace <workspaceName> <commandName>

Example: Install React in components package

yarn workspace components add -D react

Run a command on all workspaces

This command needs workspace-tools to be installed. They should be already by default otherwise use yarn plugin import workspace-tools to install them.

Usage:

yarn workspaces foreach [-a,--all] [-v,--verbose] [-p,--parallel] [-i,--interlaced] [-j,--jobs #0] [-t,--topological] [--topological-dev] [--include #0] [--exclude #0] [--private] <commandName> ...

Example: Run build script on current and all descendant packages in parallel, building dependent packages first

yarn workspace foreach -pt run build

For more consult Yarn v2 documentation