nx-monorepo

What this skill does

# Nx Monorepo

## Overview

Provides guidance for Nx monorepo management in TypeScript/JavaScript projects. Covers workspace creation, project generation, task execution, caching strategies, Module Federation, and CI/CD integration.

## When to Use

Use this skill when:
- Creating a new Nx workspace or initializing Nx in an existing project
- Generating applications, libraries, or components with Nx generators
- Running affected commands or executing tasks across multiple projects
- Setting up CI/CD pipelines for Nx projects (GitHub Actions, CircleCI, etc.)
- Configuring Module Federation with React or Next.js
- Implementing NestJS backend applications within Nx
- Managing TypeScript package libraries with buildable and publishable libs
- Setting up remote caching or Nx Cloud
- Optimizing monorepo build times and caching strategies
- Debugging dependency graph issues or circular dependencies

**Trigger phrases:** "create Nx workspace", "Nx monorepo", "generate Nx app", "Nx affected", "Nx CI/CD", "Module Federation Nx", "Nx Cloud"

## Instructions

### Workspace Creation

1. **Create a new workspace with interactive setup:**
   ```bash
   npx create-nx-workspace@latest
   ```
   Follow prompts to select preset (Integrated, Standalone, Package-based) and framework stack.

2. **Initialize Nx in an existing project:**
   ```bash
   nx@latest init
   ```

3. **Create with specific preset (non-interactive):**
   ```bash
   npx create-nx-workspace@latest my-workspace --preset=react
   ```
   **Verify:** `nx show projects` lists the new workspace projects

### Project Generation

1. **Generate a React application:**
   ```bash
   nx g @nx/react:app my-app
   ```

2. **Generate a library:**
   ```bash
   # React library
   nx g @nx/react:lib my-lib

   # TypeScript library
   nx g @nx/js:lib my-util
   ```
   **Verify:** `nx show projects` lists the new lib

3. **Generate a component in lib:**
   ```bash
   nx g @nx/react:component my-comp --project=my-lib
   ```

4. **Generate NestJS backend:**
   ```bash
   nx g @nx/nest:app my-api
   ```
   **Verify:** `nx show projects` lists `my-api` and `nx run my-api:build` succeeds

### Task Execution

1. **Run tasks for affected projects only:**
   ```bash
   nx affected -t lint test build
   ```

2. **Run tasks across all projects:**
   ```bash
   # Build all projects
   nx run-many -t build

   # Test specific projects
   nx run-many -t test -p=my-app,my-lib

   # Test by pattern
   nx run-many -t test --projects=*-app
   ```

3. **Run specific target on single project:**
   ```bash
   nx run my-app:build
   ```

4. **Visualize dependency graph:**
   ```bash
   nx graph
   ```

### Project Configuration

Each project has a `project.json` defining targets, executor, and configurations:

```json
{
  "name": "my-app",
  "projectType": "application",
  "sourceRoot": "apps/my-app/src",
  "targets": {
    "build": {
      "executor": "@nx/react:webpack",
      "outputs": ["{workspaceRoot}/dist/apps/my-app"],
      "configurations": {
        "production": {
          "optimization": true
        }
      }
    },
    "test": {
      "executor": "@nx/vite:test"
    }
  },
  "tags": ["type:app", "scope:frontend"]
}
```

### Dependency Management

1. **Set up project dependencies:**
   ```json
   {
     "targets": {
       "build": {
         "dependsOn": [
           { "projects": ["shared-ui"], "target": "build" }
         ]
       }
     }
   }
   ```

2. **Use tags for organization:**
   ```json
   { "tags": ["type:ui", "scope:frontend", "platform:web"] }
   ```

### Module Federation (Nx 17+)

1. **Generate a remote (micro-frontend):**
   ```bash
   nx g @nx/react:remote checkout --host=dashboard
   ```

2. **Generate a host:**
   ```bash
   nx g @nx/react:host dashboard
   ```

### CI/CD Setup

Use affected commands in CI to only build/test changed projects:

```yaml
# .github/workflows/ci.yml
- run: npx nx affected -t lint --parallel
- run: npx nx affected -t test --parallel
- run: npx nx affected -t build --parallel
```

## Examples

### Example 1: Create New React Workspace

**Input:** "Create a new Nx workspace with React and TypeScript"

**Steps:**
```bash
npx create-nx-workspace@latest my-workspace
# Select: Integrated Monorepo → React → Integrated monorepo (Nx Cloud)
```
**Verify:** `cd my-workspace && nx show projects` lists the created app

**Expected Result:** Workspace created with:
- `apps/` directory with React app
- `libs/` directory for shared libraries
- `nx.json` with cache configuration
- CI/CD workflow files ready

### Example 2: Run Tests for Changed Projects

**Input:** "Run tests only for projects affected by recent changes"

**Command:**
```bash
nx affected -t test --base=main~1 --head=main
```

**Expected Result:** Only tests for projects affected by changes between commits are executed, leveraging cached results from previous runs.

### Example 3: Generate and Build a Shared Library

**Input:** "Create a shared UI library and use it in the app"

**Steps:**
```bash
# Generate library
nx g @nx/react:lib shared-ui

# Generate component in library
nx g @nx/react:component button --project=shared-ui

# Import in app (tsconfig paths auto-configured)
import { Button } from '@my-workspace/shared-ui'
```
**Verify:** `nx run shared-ui:build` completes successfully and `nx graph` shows the dependency link to your app

**Expected Result:** Buildable library at `libs/shared-ui` with proper TypeScript path mapping configured.

### Example 4: Set Up Module Federation

**Input:** "Configure Module Federation for micro-frontends"

**Steps:**
```bash
# Create host app
nx g @nx/react:host dashboard

# Add remote to host
nx g @nx/react:remote product-catalog --host=dashboard

# Start dev servers
nx run dashboard:serve
nx run product-catalog:serve
```
**Verify:** Both servers start without errors and `nx graph` shows dashboard → product-catalog remote connection

**Expected Result:** Two separate applications running where product-catalog loads dynamically into dashboard at runtime.

### Example 5: Debug Build Dependencies

**Input:** "Why is my app rebuilding when unrelated lib changes?"

**Diagnosis:**
```bash
# Show project graph
nx graph --focused=my-app

# Check implicit dependencies
nx show project my-app --json | grep implicitDependencies
```

**Solution:** Add explicit dependency configuration or use `namedInputs` in `nx.json` to exclude certain files from triggering builds.

**Verify Fix Worked:** Make a change to the unrelated lib, run `nx affected -t build` — `my-app` should not appear in the affected projects list.

## Best Practices

- **Always use `nx affected` in CI** to only test/build changed projects
- **Organize libs by domain/business capability**, not by technical layer
- **Use tags consistently** (`type:app|lib`, `scope:frontend|backend|shared`)
- **Prevent circular dependencies** by configuring `workspaceLayout` boundaries in `nx.json`
- **Enable remote caching** with Nx Cloud for team productivity
- **Keep project.json simple** - use defaults from `nx.json` when possible
- **Leverage generators** instead of manual file creation for consistency
- **Configure `namedInputs`** to exclude test files from production cache keys
- **Use Module Federation** for independent deployment of micro-frontends
- **Keep workspace generators** in `tools/` for project-specific scaffolding

## Constraints and Warnings

- **Node.js 18.10+** is required for Nx 17+
- **Windows users**: Use WSL or Git Bash for best experience
- **First-time setup** may take longer due to package installation
- **Large monorepos** (50+ projects) should use distributed task execution
- **Module Federation** requires webpack 5+ and specific Nx configuration
- **Some generators** require additional plugins to be installed first
- **Cache location**: Default `~/.nx/cache` can grow large; configure `cacheDirectory` in `nx.json` if needed
- **Circular dependencies** will cause build failures; use `nx graph` to visualize
- **Preset migra