Getting Started with Nx for Monorepo Management

Managing multiple related projects can quickly become complex. As your codebase grows, you need tools that help maintain consistency, share code efficiently, and optimize build times. Nx is a powerful solution designed specifically for these challenges.

This guide will show you how to set up and use Nx to manage a monorepo effectively. You’ll learn the core concepts, create a basic workspace, and understand how Nx’s intelligent features can dramatically improve your development workflow.

What is a Monorepo?

A monorepo is a version control strategy where multiple projects are stored in a single repository. Unlike having separate repositories for each project (polyrepo), a monorepo contains all related projects in one place.

Benefits of Monorepos

• Code sharing - Reuse code across projects without complex package management
• Atomic changes - Update multiple projects in a single commit
• Consistent tooling - Apply the same development standards across all projects
• Simplified dependencies - Manage project relationships in one place
• Coordinated releases - Synchronize updates across interdependent projects

However, monorepos introduce challenges like managing build dependencies and scaling as your codebase grows. This is where Nx comes in.

What is Nx?

Nx is an extensible build system designed specifically for monorepo management. Originally developed for Angular applications, Nx now supports multiple frontend and backend frameworks including React, Vue, Node.js, and more.

Key Features of Nx

• Smart caching - Avoids rebuilding unchanged code
• Dependency graph - Visualizes relationships between projects
• Affected commands - Only builds and tests what’s impacted by your changes
• Code generators - Creates consistent project structures
• Extensible plugins - Supports various frameworks and tools

Setting Up Your First Nx Workspace

Let’s create a basic Nx workspace with a React application and a shared library.

Prerequisites

• Node.js (v14 or later)
• npm or yarn

Creating an Nx Workspace

# Install the Nx CLI globally (optional)
npm install -g nx

# Create a new workspace
npx create-nx-workspace@latest my-workspace

During setup, you’ll be prompted to choose:

1. Which stack to use (select “React”)
2. Application name (e.g., “web-app”)
3. Style format (CSS, SCSS, etc.)
4. Nx Cloud setup (optional but recommended for team projects)

This creates a workspace with the following structure:

my-workspace/
├── apps/
│   └── web-app/
├── libs/
├── nx.json
├── package.json
└── tsconfig.base.json

Understanding the Workspace Structure

• apps/ - Contains your applications (frontend, backend, mobile)
• libs/ - Holds shared code libraries used across applications
• nx.json - Configures Nx behavior and plugins
• package.json - Manages dependencies for the entire workspace

Adding Projects to Your Workspace

Now let’s add a shared UI library and see how Nx manages dependencies.

Creating a Shared Library

nx g @nx/react:lib ui-components

This creates a library in libs/ui-components/ that can be imported by any application in your workspace.

Creating a Component in the Library

nx g @nx/react:component button --project=ui-components --export

This generates a Button component in your UI library and exports it for use in other projects.

Using the Library in Your Application

Edit your application to use the new component:

// apps/web-app/src/app/app.tsx
import { Button } from '@my-workspace/ui-components';

export function App() {
  return (
    <div>
      <h1>Welcome to My App</h1>
      <Button>Click me</Button>
    </div>
  );
}

Running Tasks with Nx

Nx provides a unified way to run tasks across your projects.

Common Commands

# Start the development server
nx serve web-app

# Build the application
nx build web-app

# Run tests
nx test web-app

# Lint the code
nx lint web-app

Running Tasks for All Projects

nx run-many --target=build --all

Leveraging Nx’s Intelligent Features

Nx’s power becomes apparent as your workspace grows. Let’s explore its most valuable features.

Visualizing Project Dependencies

nx graph

This opens an interactive visualization of your project dependencies, helping you understand the architecture of your monorepo.

Understanding Affected Projects

When you make changes, Nx can determine which projects are affected:

nx affected:graph

This shows only the projects impacted by your recent changes.

Building Only What Changed

nx affected --target=build

This builds only the projects affected by your changes, saving significant time in CI/CD pipelines.

Caching for Speed

Nx automatically caches task results. If you run the same task with the same inputs, Nx uses the cached result instead of running it again:

# First run (executes the task)
nx build web-app

# Second run (uses cache)
nx build web-app

Nx Workspace Configuration

The nx.json file controls how Nx behaves. Here’s a basic configuration:

{
  "npmScope": "my-workspace",
  "affected": {
    "defaultBase": "main"
  },
  "tasksRunnerOptions": {
    "default": {
      "runner": "nx/tasks-runners/default",
      "options": {
        "cacheableOperations": ["build", "lint", "test", "e2e"]
      }
    }
  },
  "targetDefaults": {
    "build": {
      "dependsOn": ["^build"]
    }
  }
}

Key settings:

• npmScope - The prefix for importing libraries
• affected.defaultBase - The git branch to compare against
• cacheableOperations - Tasks that should be cached
• dependsOn - Task dependencies (e.g., build libraries before applications)

Real-World Example: Full-Stack Application

Let’s create a more complete example with a React frontend and Node.js backend:

# Create a React app
nx g @nx/react:app client

# Create a Node.js API
nx g @nx/node:app api

# Create a shared types library
nx g @nx/js:lib shared-types

This gives you a workspace with:

1. A React client application
2. A Node.js API server
3. A shared library for common types

You can run both applications simultaneously:

nx run-many --target=serve --projects=api,client --parallel

Conclusion

Nx makes monorepo management straightforward and efficient. By handling the complexity of project dependencies and build optimization, it lets you focus on writing code rather than managing your repository structure. Start with a simple setup as shown in this guide, and expand as your project grows.

FAQs