Remote Preloading

Remote Preloading Overview

At its core, remote preloading is about doing one thing well inside your Module Federation project. Once you understand the pattern, you can apply it consistently across features and teams.

Good remote preloading pays off across the whole codebase: fewer surprises, easier testing, and smoother onboarding. The snippet below is a solid starting point.

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.

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

Module Federation Cheatsheet

Key Module Federation settings related to remote preloading.

How Remote Preloading Works in Module Federation

Remote Preloading 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 Remote Preloading

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

Key Takeaways

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