Table of Contents:

• Overview
• Prerequisites
• Installing & getting started
• How to create injectable module and expose it to host sites
• How to import a remote module and use it
• How to inject current redux store slices into the parent site redux store
• Available scripts

Micro frontend inner

• Uses module federation plugin from webpack to create injectable module.
• This app is the remote entry of Micro frontend container app
• And the host of Micro frontend second inner app

Note: This app uses live reloading for local development.

Prerequisites

• nodeJS > 14.X.X or Docker

Installing / Getting Started

Development (locally):

• Clone repo => git clone git@github.com:react-custom-projects/webpack-react-boilerplate.git
• Navigate to project directory cd webpack-react-boilerplate
• Install dependencies => yarn install
• Start the development server => yarn start

Development (using Docker):

• Clone repo => git clone git@github.com:react-custom-projects/webpack-react-boilerplate.git
• Navigate to project directory cd webpack-react-boilerplate
• Install dependencies (required for prettier) => yarn install
• Start the development server => docker-compose up web-dev

Docker for production (basic setup) (modify it to your needs):

• Update the production section of the Dockerfile to meet your needs
• Run the following command to build your image => docker-compose up web-prod

How to create injectable module and expose it to host sites

• Open webpack.common.js file.
  1- Import ModuleFederationPlugin:

  const { ModuleFederationPlugin } = require('webpack').container
  

  2- Pass ModuleFederationPlugin to the plugins array:

  plugins: [
              new ModuleFederationPlugin({
  

  3- Specify the name of the current app (must be unique) in ModuleFederationPlugin:

  new ModuleFederationPlugin({
      name: 'inner_app',
  

  4- Set the exposed file name in ModuleFederationPlugin:

  filename: 'remoteEntry.js',
  

  5- Define the modules you want to expose from the current app in ModuleFederationPlugin:

  exposes: {
      './App': path.join(PATHS.src, 'RemoteApp'),
  },
  

  Note: The key you specify for each module you expose in exposes object will be used in the host app to import that module: /inner_app/App.

  6- Add the shared dependencies in ModuleFederationPlugin:
  

  new ModuleFederationPlugin({
      shared: ['react', 'react-dom'],
  }),
  

• Create the component you want to expose.

• Create bootstrap.js file and move into it all the code from index.jsx file.

• Import bootstrap.js inside index.jsx file.
  

    import('./bootstrap');
  

How to import a remote module and use it

• Open webpack.common.js file.
  1- Import ModuleFederationPlugin:

  const { ModuleFederationPlugin } = require('webpack').container
  

  2- Pass ModuleFederationPlugin to the plugins array:

  new ModuleFederationPlugin({
  

  3- Specify the name of the current app (must be unique) in ModuleFederationPlugin:

  name: 'inner_app',
  

  4- Add the link of the remote module in remotes object of the ModuleFederationPlugin, example:

  new ModuleFederationPlugin({
    remotes: {
      second_inner_app: `second_inner_app@${
          isDevelopment ? remoteDevUrl : remoteProdUrl
        }/remoteEntry.js`,
    },
  

  Notes:

  • You must use the name of the remote module that you specified in the remote module webpack setup.
  • You can add as many remote modules as you like by adding them to the remotes object
  • /buildTools/constants contains remoteDevUrl and remoteProdUrl of the remote module.

  5- Add the shared dependencies in ModuleFederationPlugin:

  new ModuleFederationPlugin({
    shared: ['react', 'react-dom'],
  }),
  

  6- Install external-remotes-plugin and add it below ModuleFederationPlugin in the plugins array:

  //used to make sure that remote modules are loaded before the main bundle
  new ExternalTemplateRemotesPlugin(),
  

• Import the remote module lazily in the required place, example:

  const RemoteApp = lazy(() => import('second_inner_app/App'));
  

• Use it inside ErrorBoundary component:

  <ErrorBoundary
      FallbackComponent={RemoteEntryErrorBoundaryFallback}
      onReset={() => {
        //Reset the state of your app so the error doesn't happen again
        console.log('Try again clicked');
      }}
    >
      <Suspense
        fallback={
          <div className="loader-wrapper">
            <LoadingIcon />
          </div>
        }
      >
        <RemoteApp />
      </Suspense>
    </ErrorBoundary>
  

How to inject current redux store slices into the parent site redux store

• Create RemoteApp component:
  1- Import current store slices:

    import { reducerSlices } from './js/store/reducerSlices';
  

  2- Import app:

  import App from './App';
  

  3- Import middle wares if any:

  import loggingMiddleware from '@/js/store/middlewares/loggingMiddleWare';
  

  4- Pass injectSlices, store and injectMiddleWares as props:

  const RemoteApp = ({ injectSlices, store, injectMiddleWares }) => {
  

  Notes:

  • injectSlices: function used to inject current app redux slices into the host app store
  • store: host app store
  • injectMiddleWares: function used to inject current app redux middlewares into the host app

  5- Create a boolean state which is used to indicate whether the current store slices have been injected into the host store or not:

  const [isSlicesInjected, setIsSlicesInjected] = useState(false);
  

  6- Create refs to store injectSlices and injectMiddleWares functions:

  const _injectSlices = useRef(injectSlices),
    _injectMiddleWares = useRef(injectMiddleWares);
  

  7- Use injectSlices and injectMiddleWares functions:

  useEffect(() => {
    _injectSlices.current(reducerSlices);
    _injectMiddleWares.current([loggingMiddleware]);
  }, []);
  

  8- Set isLoaded flag to true when current redux slices have been injected successfully into the host store:

  useEffect(() => {
      const state = store.getState ? store.getState() : {};
      //remove loader once our first redux slice has been injected into the parent store
      if (state.innerApp) {
        setIsSlicesInjected(true);
      }
  }, [store]);
  

  Notes:

  • Make sure to prefix current redux slices with a unique name to avoid conflicts between slices names in the host store

  9- Show the app:

  <Provider store={store || {}}>
      {isSlicesInjected ? (
          <App />
      ) : (
          <div className="d-flex justify-content-center">
              <LoadingIcon />
          </div>
      )}
  </Provider>
  

Available Scripts

In the project directory, you can run:

yarn start

Runs the app in the development mode.
It will open http://localhost:3001 automatically in the browser to see your app.

All changes will be injected automatically without reloading the page.

You will see in the console the following:

• All redux store related changes
• Any of the following errors:
  1. Linting errors.
  2. Code format errors (because of prettier)

yarn build

Builds the app for production to the dist folder.
It correctly bundles React in production mode and optimizes the build for the best performance.

The build is minified and the filenames include the hashes.
Your app is ready to be deployed!

yarn build:serve

Serves the app on http://localhost:8081 from the dist folder to check the production version.

Note: Use this script only if you ran the build script yarn build.

yarn analyze-bundle

It allows you to analyze the bundle size.