Micro Frontends Architecture with Module Federation · Lesson

Introducing Module Federation

Understand the main idea behind Module Federation and how it allows applications to expose and consume modules dynamically.

Introducing Module Federation is a free Micro Frontends Architecture with Module Federation lesson on CoddyKit — lesson 2 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Micro Frontends Architecture with Module Federation learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.

What is Module Federation?

Welcome! In this lesson, we'll dive into Module Federation, a powerful feature of Webpack that's key to building modern Micro Frontends.

It allows different JavaScript applications to share and consume code from each other dynamically at runtime.

The Monolith Problem

Traditionally, large web applications are built as a single, giant codebase – a monolith. This can lead to:

Slow development cycles
Difficulty scaling teams
Tight coupling between parts

Module Federation helps overcome these challenges by enabling a more modular approach.

Dynamic Code Sharing

The core idea of Module Federation is dynamic code sharing. Instead of bundling all code together at build time, it lets applications load pieces of code from other applications at runtime.

Think of it like an app saying, "I need this component, and I know where to get it from another running app!"

Key Players: Host & Remote

In a Module Federation setup, we have two main types of applications:

Remote Application: This app exposes its code (components, functions) for others to use.
Host Application: This app consumes or uses the code exposed by a remote application.

An app can be both a host and a remote simultaneously!

Exposing Modules: Remote Apps

A remote application uses Webpack's ModuleFederationPlugin to declare which parts of its code it wants to expose. These exposed modules become available for other applications to consume.

Here's a simplified example of how a remote app might expose a Button component:

/* webpack.config.js (Remote App) */
const { ModuleFederationPlugin } = require('webpack').container;

module.exports = {
  // ... other webpack config
  plugins: [
    new ModuleFederationPlugin({
      name: 'remoteApp',
      filename: 'remoteEntry.js',
      exposes: {
        './Button': './src/Button.js',
      },
    }),
  ],
};

Consuming Modules: Host Apps

A host application also uses the ModuleFederationPlugin to specify which remote applications it wants to consume modules from. It provides a URL where the remote's entry file (e.g., remoteEntry.js) can be found.

Here's how a host app might declare its intent to use remoteApp:

/* webpack.config.js (Host App) */
const { ModuleFederationPlugin } = require('webpack').container;

module.exports = {
  // ... other webpack config
  plugins: [
    new ModuleFederationPlugin({
      name: 'hostApp',
      remotes: {
        remoteApp: 'remoteApp@http://localhost:8081/remoteEntry.js',
      },
    }),
  ],
};

How it Works: The Entry File

When a host application starts, it doesn't immediately load all remote code. Instead, it first loads a tiny file from the remote called remoteEntry.js.

This file acts as a manifest, telling the host what modules the remote exposes and how to dynamically load them if needed. Code is fetched only when requested!

The Power of Independent Deployments

One of the biggest advantages of Module Federation is enabling independent deployments.

Teams can develop, test, and deploy their micro frontends separately without coordinating a large, synchronized release for the entire application. This speeds up delivery and reduces risk.

Sharing More Than UI

Module Federation isn't just for sharing UI components. You can expose and consume various types of code:

Utility functions
Data services
React hooks or similar logic
Shared styles or themes

This allows for robust code reuse across your federated applications.

Test Your Knowledge

Module Federation introduces new ways for applications to interact. Which of the following statements correctly describe the core concepts?

Module Federation Recap

Great job! You've grasped the fundamental idea of Module Federation.

It's a Webpack feature for dynamic code sharing.
Apps can be hosts (consuming) or remotes (exposing).
It enables independent deployments and efficient code reuse.

Next, we'll look deeper into how host and remote applications are set up!

Frequently asked questions

Is the “Introducing Module Federation” lesson free?

Yes — the full text of “Introducing Module Federation” is free to read here on the web, and the Micro Frontends Architecture with Module Federation course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Micro Frontends Architecture with Module Federation course, upgrade to CoddyKit PRO.

What will I learn in “Introducing Module Federation”?

Understand the main idea behind Module Federation and how it allows applications to expose and consume modules dynamically. You practise Micro Frontends Architecture with Module Federation with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start Micro Frontends Architecture with Module Federation?

No prior experience is required. Micro Frontends Architecture with Module Federation on CoddyKit is structured for beginners through advanced learners; this is — lesson 2 of 4, so you can start here or from the beginning and move at your own pace.

How long does the “Introducing Module Federation” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this Micro Frontends Architecture with Module Federation lesson?

Yes. Every Micro Frontends Architecture with Module Federation lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

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