Proposed structure

[juandav]

Frist

@Module({
  modules: [ 
    UsersModule, 
    AdminModule,
    InterceptorsModule.use(
      InterceptorX,
      InterceptorY,
    ),
    GuardsModule.use(
      GuardX,
      GuardY
    ),
    MiddlewaresModule.configure(
      {
        middleware: MiddlewareX,
        forRoutes: []
      }
    )
  ],
  controllers: [HealthCheckController],
}) 
export class AppModule { }

Second

@Module({
  modules: [ UsersModule, AdminModule ],
  controllers: [ HealthCheckController ],
  routes: {
    path: '/',
    // NOTE: In theory we could add more stuff here (e.g. Middleware)
    children: [
      { path: '', routes: HealthCheckController },
      { path: '/users', routes: UsersModule },
      { path: '/admin', routes: AdminModule }
      // This also allows to mount another express app, e.g.
      { path: '/external', mount: express() }
    ]
  }
}) export class AppModule { }

Third

@Module({
  modules: [ 
    UsersModule, 
    AdminModule,
    RouterModule.configure({
      path: '/',
      children: [
        { path: '/users', routes: UsersModule },
        { path: '/admin', routes: AdminModule },
      ]
    })
  ],
  controllers: [HealthCheckController],
}) 
export class AppModule { }