@angular-architects/module-federation-tools

@angular-architects/module-federation-tools

Add-on for @angular-architects/module-federation helping to reduce boiler plate code.

The current release is focusing on combining web components with module federation for multi framework and multi version micro frontends:

By compiling and loading these web components via module federation, we can share libraries like Angular if they use the same version. Otherwise, module federation would decide at runtime to load a dedicated version of the lib for the micro frontend in question:

This can help to balance the trade-off between bundle size and isolation of micro frontends.

Disclaimer: Multi-Framework and -Version Micro increase the overall complexity and call for some workarounds. This library tries to hide some of them.

Examples

• Source Code (Shell, see branch multi-framework-version)
• Source Code for Micro Frontend
• Source Code for Micro Frontend with Routing

Providing a Web Component with Module Federation

Expose your Angular components via Angular Elements:

import { createCustomElement } from '@angular/elements';
[...]

@NgModule({
  [...]
  declarations: [
    AppComponent
  ],
  bootstrap: [] // No bootstrap components!
})
export class AppModule {
  constructor(private injector: Injector) {
  }

  ngDoBootstrap() {
    const ce = createCustomElement(AppComponent, {injector: this.injector});
    customElements.define('angular1-element', ce);
  }

}

Add @angular-architects/module-federation to your micro frontend:

ng add @angular-architects/module-federation

Make your webpack.config.js expose the whole bootstrap.ts that bootstraps your AppModule.

// webpack.config.js
name: "angular3",
library: { type: "var", name: "angular3" },
filename: "remoteEntry.js",
exposes: {
    './web-components': './src/bootstrap.ts',
},

Bootstrapping

Our bootstrap helper function bootstraps your shell and your micro frontend and takes care of some details needed in a multi-framework/ multi-version scenario (like sharing the platform used).

// main.ts
import { AppModule } from './app/app.module';
import { environment } from './environments/environment';
import { bootstrap } from '@angular-architects/module-federation-tools';

bootstrap(AppModule, {
  production: environment.production
});

Use this bootstrap helper for both, your shell and your micro frontends!

Routing to Web Components

The WebComponentWrapper helps you to route to web components:

export const APP_ROUTES: Routes = [
    [...]
    {
        path: 'angular1',
        component: WebComponentWrapper,
        data: {
        remoteEntry: 'https://nice-grass-018f7d910.azurestaticapps.net/remoteEntry.js',
        remoteName: 'angular1',
        exposedModule: './web-components',
        elementName: 'angular1-element'
        } as WebComponentWrapperOptions
    },
    [...]
}

Sub-Routes

If a web component has it's own router, you can use our UrlMatchers startsWith and endsWith to define, which part of the URL is intended for the shell and for the micro frontend:

// Shell
export const APP_ROUTES: Routes = [
    [...]
    {
        matcher: startsWith('angular3'),
        component: WebComponentWrapper,
        data: {
        remoteEntry: 'https://gray-river-0b8c23a10.azurestaticapps.net/remoteEntry.js',
        remoteName: 'angular3',
        exposedModule: './web-components',
        elementName: 'angular3-element'
        } as WebComponentWrapperOptions
    },
    [...]
}

// Micro Frontend
export const APP_ROUTES: Routes = [
    [...]
    { matcher: endsWith('a'), component: AComponent},
    { matcher: endsWith('b'), component: BComponent},
    [...]
}

In order to prevent issues with the "inner" router, use our helper function connectRouter.

// AppComponent in Micro Frontend
@Component({ ... })
export class AppComponent {

  constructor(private router: Router) { }

  ngOnInit(): void {
    connectRouter(this.router);
  }

}

Directly Loading a Web Component via Module Federation

The WebComponentWrapper can also be used as a traditional component:

<mft-wc-wrapper [options]="item"></mft-wc-wrapper>

item: WebComponentWrapperOptions = {
    remoteEntry: 'https://witty-wave-0a695f710.azurestaticapps.net/remoteEntry.js',
    remoteName: 'react',
    exposedModule: './web-components',
    elementName: 'react-element'
}, 

The optional properties props and events allow to defined properties and events for the web component:

props = {
    "message": "Hello from Shell"
}

events = {
    "clicked": (event) => {
        console.debug('clicked!', event);
    }
}

<mft-wc-wrapper [options]="item" [props]="props" [events]="events"></mft-wc-wrapper>

Sharing Zone.js

In order to share zone.js, call our shareNgZone helper when starting the shell.

import { Component, NgZone } from '@angular/core';
import { shareNgZone } from '@angular-architects/module-federation-tools';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
})
export class AppComponent {
  title = 'shell';

  constructor(private ngZone: NgZone) {
    shareNgZone(ngZone);
  }

}

The micro frontends will pick it up, if they are bootstrapped with the bootstrap helper (see above).

More about the underlying ideas

Please find more information on the underlying ideas in this blog article.