Issues with React Router with Module Federation 1.5 interop

[foxaltus]

I have a bunch of legacy MFEs that use webpack with the ModuleFederationPlugin and I'm trying to update my shell app first to Rsbuild (1.1.13).

The MFEs have react-router-dom as a singleton in their shared dependencies.

When I use the builtin moduleFederation config in the shell, my MFEs are not working, as if there was an issue resolving the dependency:

However, if I use the legacy ModuleFederation v1 plugin instead (with the same configuration), everything works fine:

export default defineConfig({
  tools: {
    rspack: {
      plugins: [
        new rspack.container.ModuleFederationPluginV1({
          name: 'shell',
          remotes: {
            '@mfe_navigation': 'http://localhost:3001/remoteEntry.js`,
            // ...
          },
          shared: {
            ...dependencies,
            'react-router-dom': {
              singleton: true,
              requiredVersion: dependencies['react-router-dom'],
            },
            react: {
              singleton: true,
              requiredVersion: dependencies['react'],
            },
            'react-dom': {
              singleton: true,
              requiredVersion: dependencies['react-dom'],
            },
          },
        }),
      ],
    },
  },
  // ...
});

What could be the cause of the issue and how can I troubleshoot it? I thought the builtin moduleFederation config uses Module Federation V1.5 by default, which is compatible with V1?

Any help or suggestion appreciated 🙏

[foxaltus]

Ohhh I found that the problematic MFEs were missing the react-router-dom singleton in their config 🤦
For some reason it was working with Module Federation V1, but not V1.5. I guess it's for the better...