Using DaprServer to expose endpoints from NestJs Webapp

Question

DaprServer allows to expose http api endpoints defined in an express middleware instance.

In a NestJs app, it is possible to get the application's internal express middleware instance and pass it to the DaprServer instance:

import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';
import { DaprServer } from '@dapr/dapr';
import type { Express } from 'express';

async function bootstrap() {
  const app = await NestFactory.create(AppModule);

  const middleware: Express = app.getHttpAdapter().getInstance();
  const daprServer = new DaprServer({
    serverHost: '127.0.0.1',
    serverPort: '3000',
    serverHttp: middleware,
  });

  await daprServer.start();
  // NestJs app.listen call is removed
  // await app.listen(3000);
}
bootstrap();

The DaprServer instance is started and the call to app.listen is removed, however endpoints defined in controllers are not available.

Is it possible to use DaprServer with NestJs in this way ?

Answer 1

The NestJs app instance was missing an initialization:

import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';
import { DaprServer } from '@dapr/dapr';
import type { Express } from 'express';

async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  // Initialize the Nest app instance
  const initedApp = await app.init();

  const middleware: Express = initedApp.getHttpAdapter().getInstance();
  const daprServer = new DaprServer({
    serverHost: '127.0.0.1',
    serverPort: '3000',
    serverHttp: middleware,
  });

  await daprServer.start();
  // NestJs app.listen call is removed
  // await app.listen(3000);
}
bootstrap();

It seems that app.listen calls app.init internally , now that we don't rely on app.listen we have to call app.init directly before getting the express middleware.