Nested Federation

Nested Federation Overview

Nested Federation 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 nested federation 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.

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

Module Federation Cheatsheet

Key Module Federation settings related to nested federation.

How Nested Federation Works in Module Federation

Nested Federation 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 Nested Federation

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

Common Mistakes

• Skipping error handling and edge cases when wiring up nested federation.
• Leaving nested federation untested, so regressions slip into production.
• Over-engineering nested federation before you actually need the extra flexibility.
• Ignoring documentation, which makes nested federation hard for the next developer to change.

Key Takeaways

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