Discussion on: Angular dynamic modules at runtime with Module Federation

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Hello Sean,

Great article. Thank you for sharing.

I'm trying to do what you advise against: exposing AppModule and AppComponent.

So what I'm trying to achieve is the following:

have a host which lazily loads the remote on specific route
have a remote which has its own routes which lazily load modules

With your advice the code structure at remote app level will look like:
app.module.ts
|- feature.module.ts
__|- sub-feature1.module.ts
__|- sub-feature2.module.ts

By exposing tha app.module.ts and app.component.ts I would only have 1 router-outlet and flat structure at remote app level:
app.module.ts
_ |- feature1.module.ts
_ |- feature2.module.ts

Unfortunately I hit the wall with this approach (exposing the app.module.ts and app.component.ts). When the host loads the remote, the remote's sub-route gets loaded in the host's router-outlet, without running the remote's app.component.ts (nothing runs from the remote's app.component.ts and the content of app.component.html is not rendered).

So I figured I can enforce it by using named outlets. However it just breaks the app completely.

I also tried to rename the remote's app.component and app.module to avoid possible name collision, but nothing changed.

Do you know what causes the problem?

Sean Perkins • Jun 18 '21

In your example, does the feature.module.ts have a component with a router outlet and a router module declaration for forChild([...])? By exposing feature.module.ts in your remote's webpack config, you should be able to something similar to this in your shell/root's app routing module:

RouterModule.forRoot([
   {
       path: 'feature-path',
       loadChildren: () => loadRemoteModule({
            remoteEntry: 'http://localhost:xxxx/remoteEntry.js',
            remoteName: 'remoteExampleName',
            exposedModule: './FeatureModule'
       }).then(m => m['FeatureModuleName'])
   }
])

This should lazy-load your remote app's feature module contents when navigating to /feature-path and then defer to that module's structure for further nested lazy loading. I've done something similar where my shell loads different authentication experiences under the /authentication namespace and certain auth experiences have further lazy loading for forgot password & user registration screens.

If you can statically declare the module federation information, it's much easier. Otherwise, you'll have to have that information in a config and pass static tokens into the app module of the shell and override the ROUTES token as shown above.

If you eco-system is small enough or not having live reloading against the remote isn't a deal breaker, you can federate the AppModule from the remote and not run into any issues.