Authorization

Authorization Overview

At its core, authorization 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 authorization pays off across the whole codebase: fewer surprises, easier testing, and smoother onboarding. The snippet below is a solid starting point.

const ProductList = React.lazy(() =>
  import('catalog/ProductList').catch(() => ({
    default: () => <p>Catalog is temporarily unavailable</p>,
  })),
);

Always provide a fallback so a failing remote degrades gracefully instead of crashing the shell.

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

Module Federation Cheatsheet

Key Module Federation settings related to authorization.

How Authorization Works in Module Federation

Authorization 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.

Always provide a fallback so a failing remote degrades gracefully instead of crashing the shell.

• 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 Authorization

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

Common Mistakes

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

Key Takeaways

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