route-discovery-app.module.ts

@Module({
  imports: [
    // Here we see each of our modules imported and registered:
    Module1,
    RouterModule.register([{path: 'module-1', module: Module1}]),
    Module2,
    RouterModule.register([{path: 'module-2', module: Module2}]),
  ],
})
export class RouteDiscoveryAppModule implements OnApplicationBootstrap {
  constructor(
    // Inject the global ModuleContainer so we can traverse modules:
    private modulesContainer: ModulesContainer,
    // Inject Reflector so we can get metadata:
    private reflector: Reflector
  ) {}

  onApplicationBootstrap() {
    const modules = Array.from(this.modulesContainer.values());
    const modulesWithPathPrefix = modules
      .map((module) => {
        // Use the native `Reflect` API to get all decorator metadata
        // on the modules's `class` (eg, metatype):
        const metadataKeys = Reflect.getMetadataKeys(module.metatype);
        // Look for a metadata key so we can use it to get path metadata:
        const pathKey = metadataKeys.find((key) =>
          String(key).startsWith('__module_path__')
        );

        // If we found a path key, pull the path out:
        const path = pathKey
          ? this.reflector.get(pathKey, module.metatype)
          : undefined;
        return {path, module};
      })
      // Filter out all modules with no paths:
      .filter(({path}) => Boolean(path));

    console.log(modulesWithPathPrefix);
  }
}