Federation Options

In this lesson you will learn federation options in Module Federation, why it matters within webpack configuration, and how to use it correctly with clear, copy-ready examples.

Federation Options Overview

Federation Options is a building block you will reach for often in Module Federation. It keeps related logic together and makes your intent obvious to reviewers and future maintainers.

When you learn federation options properly, you avoid the guesswork that leads to bugs and rework. The example below shows the shape you will use in most real Module Federation projects.

const { ModuleFederationPlugin } = require('webpack').container;

module.exports = {
  plugins: [
    new ModuleFederationPlugin({
      name: 'shell',
      remotes: { catalog: 'catalog@http://localhost:3001/remoteEntry.js' },
      exposes: {},
      shared: { react: { singleton: true }, 'react-dom': { singleton: true } },
    }),
  ],
};

ModuleFederationPlugin configures which modules an app exposes, consumes, and shares.

Federation Options Example

new ModuleFederationPlugin({
  name: 'app',
  filename: 'remoteEntry.js',
  exposes: { './Widget': './src/Widget' },
  remotes: { other: 'other@http://host/remoteEntry.js' },
  shared: { react: { singleton: true } },
});

Start from a minimal Federation Options example and grow it only as needed.
Keep configuration explicit so Federation Options behaves the same in every environment.
Name things clearly so teammates understand your Federation Options at a glance.
Add tests around Federation Options early to lock in expected behaviour.

Module Federation Cheatsheet

Key Module Federation settings related to federation options.

Option	Example	Purpose
name	`name: 'shell'`	Unique container name
filename	`filename: 'remoteEntry.js'`	Remote entry manifest
exposes	`exposes: { './X': './src/X' }`	Modules a remote shares
remotes	`remotes: { app: 'app@url' }`	Remotes a host consumes
shared	`shared: { react: { singleton: true } }`	Deduplicate libraries
lazy load	`import('remote/Module')`	Load remotes on demand
Suspense	`<Suspense fallback={...}>`	Handle async loading

How Federation Options Works in Module Federation

Federation Options builds on Module Federation's ability to load code from another independently built and deployed application at runtime. Each app can be a host, a remote, or both.

ModuleFederationPlugin configures which modules an app exposes, consumes, and shares.

Remotes expose modules through a remoteEntry.js manifest.
Hosts declare remotes and import exposed modules dynamically.
Shared dependencies are deduplicated, ideally as singletons.
Each micro frontend builds and deploys on its own schedule.

Practical Guidance for Federation Options

In production, federation options needs careful version management and graceful failure handling. Align shared dependency versions and always render a fallback when a remote cannot load.

Concern	Recommendation
Shared versions	Use singletons with requiredVersion
Runtime errors	Wrap remotes in error boundaries and fallbacks
Deployment	Resolve remotes from a runtime manifest
Performance	Lazy-load remotes and cache remoteEntry.js

Common Mistakes

Copying federation options snippets without understanding what each line does.
Skipping error handling and edge cases when wiring up federation options.
Leaving federation options untested, so regressions slip into production.
Over-engineering federation options before you actually need the extra flexibility.

Key Takeaways

Federation Options is a core part of working effectively with Module Federation.
Start small and keep federation options focused on a single responsibility.
Apply consistent patterns so federation options scales across your project.
Test and document federation options to keep it maintainable over time.

Pro Tip

Pair federation options with automated tests from day one. It is far cheaper to catch Module Federation regressions in CI than in production.