Remote Failure Handling

Remote Failure Handling Overview

Remote Failure Handling lets you structure Module Federation work so it stays readable, testable, and easy to scale. Instead of ad-hoc code, you follow a clear pattern that other developers can recognise immediately.

The key is to keep remote failure handling focused and predictable. Start from the minimal example here, then layer in only the complexity your feature actually needs.

// remote (webpack.config.js)
const { ModuleFederationPlugin } = require('webpack').container;

module.exports = {
  plugins: [
    new ModuleFederationPlugin({
      name: 'catalog',
      filename: 'remoteEntry.js',
      exposes: {
        './ProductList': './src/ProductList',
      },
      shared: ['react', 'react-dom'],
    }),
  ],
};

A remote exposes modules through remoteEntry.js so hosts can load them at runtime.

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

Module Federation Cheatsheet

Key Module Federation settings related to remote failure handling.

How Remote Failure Handling Works in Module Federation

Remote Failure Handling 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.

A remote exposes modules through remoteEntry.js so hosts can load them at runtime.

• 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 Failure Handling

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

Key Takeaways

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