Resolving the RouterModule.forRoot() Error in Angular's Module Federation Architecture

Описание: Encountering the 'RouterModule.forRoot() called twice' error in Angular's Module Federation? Discover effective solutions to manage routing in remote applications while ensuring styles and assets load correctly.
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Resolving the RouterModule.forRoot() Error in Angular's Module Federation Architecture: A Complete Guide

If you’re working with Angular and diving into the world of Module Federation using Webpack, you might run into a frustrating issue: the RouterModule.forRoot() called twice error. This problem typically arises when trying to integrate remote applications within a shell application, leading to an unwelcome interruption in your development process.

In this post, we’ll explore the roots of this problem, why it occurs, and, more importantly, how to fix it. We’ll provide clear guidance on handling routing effectively in a Module Federation setup, ensuring that your applications run smoothly and assets load correctly.

Understanding the Problem

When integrating micro-frontends with Angular, it's essential to understand how Angular's routing system works. The error message you're encountering states:

[[See Video to Reveal this Text or Code Snippet]]

What Causes This Error?

RouterModule.forRoot() vs RouterModule.forChild(): The forRoot() method is designed for the root application module. In contrast, lazy-loaded modules (like those from a remote app in a Module Federation scenario) should use forChild(). When both modules attempt to initialize the router, you end up with this error.

Module Federation Architecture: In a Module Federation setup, you typically have a host application and one or more remote applications. If a remote application attempts to call RouterModule.forRoot(), it can conflict with the routing setup of the host application.

Assets and Styles Loading: When you modify routing by using forChild(), you may notice that styles and assets don't load correctly, as they are served from the host app instead of the remote.

Solution Steps

Now that you've identified the issue, let’s break down the solution. Here’s how you can resolve the RouterModule.forRoot() error while ensuring assets load correctly.

Step 1: Update Routing Configuration

Make sure that the routing in your remote application utilizes the RouterModule.forChild() method instead of forRoot(). Here’s a simple example of what that could look like in your remote app's module:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Adjust Public Path

In your Webpack configuration, adjust the publicPath to point to the URL serving your microfrontend, rather than using the default auto. For example:

Change:

[[See Video to Reveal this Text or Code Snippet]]

To:

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This will ensure that the browser correctly fetches the assets and styles for your remote application from the designated server.

Step 3: Verify Application Configuration

Ensure that both the host and remote applications share the same versions for crucial Angular packages. This avoids compatibility issues that can arise due to version mismatches.

In your Webpack configuration, you might have something like:

[[See Video to Reveal this Text or Code Snippet]]

Make sure that both applications are using compatible versions of Angular, Angular Material, and Angular Router.

Conclusion

By following the steps outlined above, you should be able to resolve the RouterModule.forRoot() called twice error while ensuring your styles and assets are loaded correctly from your remote applications. This way, you can confidently navigate the complexities of a Module Federation architecture without running into frustrating errors.

If you encounter other issues related to Angular and Webpack Module Federation, don’t hesitate to reach out to the community or revisit your configurations. Debugging can sometimes lead