Federated Routing

Federated Routing Overview

Federated Routing 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 federated routing 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.

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

Module Federation Cheatsheet

Key Module Federation settings related to federated routing.

How Federated Routing Works in Module Federation

Federated Routing 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 Federated Routing

In production, federated routing 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 federated routing.
• Leaving federated routing untested, so regressions slip into production.
• Over-engineering federated routing before you actually need the extra flexibility.
• Ignoring documentation, which makes federated routing hard for the next developer to change.

Key Takeaways

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