NestModule

NestModule is the interface that any NestJS module using middleware must implement. It requires a configure(consumer: MiddlewareConsumer) method where middleware is applied to routes.

export class AppModule implements NestModule {
  configure(consumer: MiddlewareConsumer) {
    consumer.apply(LoggerMiddleware).forRoutes('cats');
  }
}

The configure() method can be async for asynchronous middleware setup. Middleware is distinct from module configuration in @Module() — it cannot be declared in the decorator metadata and must use this interface.