monorepo-management

# Monorepo Management Build efficient, scalable monorepos that enable code sharing, consistent tooling, and atomic changes across multiple packages and applications. ## When to Use This Skill - Setting up new monorepo projects - Migrating from multi-repo to monorepo - Optimizing build and test performance - Managing shared dependencies - Implementing code sharing strategies - Setting up CI/CD for monorepos - Versioning and publishing packages - Debugging monorepo-specific issues ## Core Concepts ### 1. Why Monorepos? **Advantages:** - Shared code and dependencies - Atomic commits across projects - Consistent tooling and standards - Easier refactoring - Simplified dependency management - Better code visibility **Challenges:** - Build performance at scale - CI/CD complexity - Access control - Large Git repository ### 2. Monorepo Tools **Package Managers:** - pnpm workspaces (recommended) - npm workspaces - Yarn workspaces **Build Systems:** - Turborepo (recommended for most) - Nx (feature-rich, complex) - Lerna (older, maintenance mode) ## Turborepo Setup ### Initial Setup ```bash # Create new monorepo npx create-turbo@latest my-monorepo cd my-monorepo # Structure: # apps/ # web/ - Next.js app # docs/ - Documentation site # packages/ # ui/ - Shared UI components # config/ - Shared configurations # tsconfig/ - Shared TypeScript configs # turbo.json - Turborepo configuration # package.json - Root package.json ``` ### Configuration ```json // turbo.json { "$schema": "https://turbo.build/schema.json", "globalDependencies": ["**/.env.*local"], "pipeline": { "build": { "dependsOn": ["^build"], "outputs": ["dist/**", ".next/**", "!.next/cache/**"] }, "test": { "dependsOn": ["build"], "outputs": ["coverage/**"] }, "lint": { "outputs": [] }, "dev": { "cache": false, "persistent": true }, "type-check": { "dependsOn": ["^build"], "outputs": [] } } } ``` ```json // package.json (root) { "name": "my-monorepo", "private": true, "workspaces": ["apps/*", "packages/*"], "scripts": { "build": "turbo run build", "dev": "turbo run dev", "test": "turbo run test", "lint": "turbo run lint", "format": "prettier --write \"**/*.{ts,tsx,md}\"", "clean": "turbo run clean && rm -rf node_modules" }, "devDependencies": { "turbo": "^1.10.0", "prettier": "^3.0.0", "typescript": "^5.0.0" }, "packageManager": "pnpm@8.0.0" } ``` ### Package Structure ```json // packages/ui/package.json { "name": "@repo/ui", "version": "0.0.0", "private": true, "main": "./dist/index.js", "types": "./dist/index.d.ts", "exports": { ".": { "import": "./dist/index.js", "types": "./dist/index.d.ts" }, "./button": { "import": "./dist/button.js", "types": "./dist/button.d.ts" } }, "scripts": { "build": "tsup src/index.ts --format esm,cjs --dts", "dev": "tsup src/index.ts --format esm,cjs --dts --watch", "lint": "eslint src/", "type-check": "tsc --noEmit" }, "devDependencies": { "@repo/tsconfig": "workspace:*", "tsup": "^7.0.0", "typescript": "^5.0.0" }, "dependencies": { "react": "^18.2.0" } } ``` ## Detailed patterns and worked examples Detailed pattern documentation lives in `references/details.md`. Read that file when the navigation tier above is insufficient. ## Best Practices 1. **Consistent Versioning**: Lock dependency versions across workspace 2. **Shared Configs**: Centralize ESLint, TypeScript, Prettier configs 3. **Dependency Graph**: Keep it acyclic, avoid circular dependencies 4. **Cache Effectively**: Configure inputs/outputs correctly 5. **Type Safety**: Share types between frontend/backend 6. **Testing Strategy**: Unit tests in packages, E2E in apps 7. **Documentation**: README in each package 8. **Release Strategy**: Use changesets for versioning ## Common Pitfalls - **Circular Dependencies**: A depends on B, B depends on A - **Phantom Dependencies**: Using deps not in package.json - **Incorrect Cache Inputs**: Missing files in Turborepo inputs - **Over-Sharing**: Sharing code that should be separate - **Under-Sharing**: Duplicating code across packages - **Large Monorepos**: Without proper tooling, builds slow down ## Publishing Packages ```bash # Using Changesets pnpm add -Dw @changesets/cli pnpm changeset init # Create changeset pnpm changeset # Version packages pnpm changeset version # Publish pnpm changeset publish ``` ```yaml # .github/workflows/release.yml - name: Create Release Pull Request or Publish uses: changesets/action@v1 with: publish: pnpm release env: GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }} NPM_TOKEN: ${{ secrets.NPM_TOKEN }} ```