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Lerna Yarn Workspaces

Introduction​

Yarn Workspaces allow us to run yarn install only once, although we have several packages. Yarn uses a single lock file rather than a different one for each project, which means fewer conflicts. Once all the dependencies are installed together, Yarn can better optimize them. Its most important feature is that when we have one package depending on another package of our repository, yarn link them together, allowing us to use always the most up-to-date code available.

Yarn & Yarn Workspaces​

Set up yarn​

To configure Lerna to use yarn under the hood, we need to go to the lerna.json file and add the npmClient key with the value yarn. Its value is npm by default.

{
  "packages": [
    "packages/*",
  ],
  "version": "0.0.0",
  "npmClient": "yarn"
}

Set up yarn workspaces​

To configure Lerna to use Yarn Workspaces, first, we need to Set up yarn. Then we have to configure it in the lerna.json and package.json files.

To do so, let's use the following folder structure as an example:

fullstack-pro
├── packages
│   ├── sample-core/
│   ├── sample-platform/
│   │   ├── browser
│   │   └── server/
│   ...
├── portable-devices
│   └── desktop
│   └── mobile
├── packages-modules
│   └── counter
│   │   ├── browser/
│   │   └── server/
├── servers
│   ├── backend-server/
│   ├── frontend-server/
│   ...
|── package.json
└── lerna.json

In the package.json file, we add the workspaces key with a list of globs that indicates the folders where we want to store our packages.

{
  "name": "root",
  "private": true,
  "workspaces": [
    "packages": [
      "portable-devices/*",
      "packages-modules/**",
      "packages/**",
      "servers/*"
    ]
  ],
  "devDependencies": {
    "lerna": "^3.22.1"
  }
}

In the lerna.json file, we can remove the packages key because the workspaces key in the package.json file overrides it. We also need to add the useWorkspaces key with the value true.

{
  "version": "0.0.0",
  "npmClient": "yarn",
  "useWorkspaces": true
}

Lerna​