microapp.md

Micro apps

Generate production ready micro apps

Steps

npx create-universal-react
select micro-app

Main Features

• Module federation: Inject micro app or its part as remote module
• Manifest: Mount micro app in target DOM element using micro app loader
• HTML: Deploy and host micro apps as standalone apps
• Shadow root: True isolation in your micro apps. No more conflicts!

Examples with Next JS app

Module federation

webpack.config.js Generated by universal react

App name - package.json name
Remote name - <App name>_remote
Expose path - src/index
Expose name - /app

next.config.json Enable module federation and add remote entry

module.exports = {
  webpack: (config, options) => {
    const { ModuleFederationPlugin } = options.webpack.container;
    config.plugins.push(
      new ModuleFederationPlugin({
        remotes: {
          header: 'header_remote@http://localhost:4000/remoteEntry.js'
        },
        shared: []
      })
    );
    return config;
  }
};

React component Access module via import

const Header = () => {
  const ref = useRef(null);
  const renderFn = async () => {
    const remote = await import('header/app');
    remote.render(ref.current, {});
  };
  useEffect(() => {
    renderFn();
  }, []);
  return <div ref={ref}></div>;
};

Micro app loader

Inject micro app script in DOM target

Loader utility

const renderFn = async (domTarget, props, appName) => {
  const domain = 'http://localhost:4001';
  const res = await fetch(`${domain}/manifest.json`);
  const data = await res.json();
  const scriptUrl = `${domain}/${data['main.js']}`;

  const element = document.createElement('script');
  element.src = scriptUrl;
  element.type = 'text/javascript';
  element.async = true;

  element.onload = () => {
    window[appName].render(domTarget, props);
  };

  document.head.appendChild(element);
};

React component

const Header = () => {
  const ref = useRef(null);
  useEffect(() => {
    renderFn(ref.current, { shadowROOT: true }, 'header');
  }, []);
  return <div ref={ref}></div>;
};

Standalone apps

All Micro apps have index.html file. You can deploy and share link.

http://localhost:4000/

Render method params

• element: HTML target to mount micro app
• config: Following are defaults. You can always add more.
  1. props (object): React props object passed to root element
  2. shadowROOT (boolean): set true to enable shadow DOM at element