Version Conflicts

Version Conflicts Overview

Version Conflicts 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 version conflicts 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.

new ModuleFederationPlugin({
  name: 'shell',
  shared: {
    react: { singleton: true, requiredVersion: '^18.2.0' },
    'react-dom': { singleton: true, requiredVersion: '^18.2.0' },
  },
});

Marking shared libraries as singletons ensures one React instance is used across all micro frontends.

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

Module Federation Cheatsheet

Key Module Federation settings related to version conflicts.

How Version Conflicts Works in Module Federation

Version Conflicts 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.

Marking shared libraries as singletons ensures one React instance is used across all micro frontends.

• 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 Version Conflicts

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

Key Takeaways

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