Implementation:Cypress io Cypress Yarn Workspace Install

Knowledge Sources	Cypress
Domains	Build, Monorepo
Last Updated	2026-02-12 00:00 GMT

Overview

Concrete tool for installing and linking all monorepo dependencies via Yarn workspaces with post-install compilation provided by the root package.json scripts.

Description

The root package.json defines workspace paths and a postinstall script that runs scripts/run-postInstall.js (L1-13). The postinstall dispatcher determines whether to run the CI or local postinstall pipeline, which includes patch-package, yarn-deduplicate, native module rebuilds, and a full build.

Usage

Run yarn install from the repository root. The postinstall pipeline handles all subsequent setup automatically.

Code Reference

Source Location

• Repository: cypress-io/cypress
• Files:
  • package.json:L47 (postinstall script)
  • scripts/run-postInstall.js:L1-13 (postinstall dispatcher)
  • scripts/ensure-dependencies.sh:L1-16 (dependency verification)
  • scripts/check-node-version.js:L1-22 (Node version validation)

Signature

{
  "workspaces": ["cli", "packages/*", "npm/*", "tooling/*", "system-tests", "scripts"],
  "scripts": {
    "postinstall": "node ./scripts/run-postInstall.js",
    "build": "lerna run build --stream"
  }
}

Import

# Just run yarn from repo root
yarn install

I/O Contract

Inputs

Name	Type	Required	Description
Git clone	directory	Yes	Cloned cypress-io/cypress repository
Node.js 22.19.0	runtime	Yes	Required Node.js version (.node-version)
yarn 1.22.22	package manager	Yes	Required Yarn version

Outputs

Name	Type	Description
node_modules	directory	All dependencies installed with workspace links
Built packages	dist/ directories	All packages compiled and ready for development

Usage Examples

Initial Setup

git clone https://github.com/cypress-io/cypress.git
cd cypress
yarn install
# postinstall runs automatically:
# - patch-package
# - yarn-deduplicate
# - lerna run build
# - yarn build-v8-snapshot-dev

Related Pages

Implements Principle

• Principle:Cypress_io_Cypress_Monorepo_Dependency_Management

Requires Environment

• Environment:Cypress_io_Cypress_Node_Runtime_Environment