连接NestJS WebSocketGateway时出现'socket hang up'错误的解决

问题场景 #

我按照NestJS官方文档编写了简单的WebSocket网关，相关代码如下：

网关代码 #

import { WebSocketGateway, SubscribeMessage, WebSocketServer, MessageBody } from '@nestjs/websockets';
import { Server } from 'socket.io';

@WebSocketGateway(30001)
export class AppGateway {
  @WebSocketServer() server: Server;

  @SubscribeMessage('test')
  handleEvent(@MessageBody() data: string): string {
    return data;
  }
}

App模块代码 #

import { Module } from '@nestjs/common';

import { AppService } from './app.service';
import { AppGateway } from './app.gateway';

@Module({
  imports: [],
  controllers: [],
  providers: [AppService, AppGateway],
})
export class AppModule { }

自测试main代码 #

import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';
import * as WebSocket from 'ws';


async function bootstrap() {
  const app = await NestFactory.create(AppModule, { cors: true, httpsOptions: { rejectUnauthorized: false } });
  await app.listen(3001);
}

function test() {
  const ws = new WebSocket('ws://localhost:30001');


  ws.onopen = function () {
    console.log('open WebSocket');


    ws.send(JSON.stringify({
      event: 'test',
      data: { message: 'Hello world!' }
    }));
  };

  ws.onmessage = function (event) {
    console.log('Server get messega:', event.data);
  };

  ws.onerror = function (error) {
    console.log('Error WebSocket:', error);
  };

  ws.onclose = function () {
    console.log('WebSocket closed');
  };
}

bootstrap();
test();

报错信息 #

运行后出现如下错误：

[Nest] 5916  - 23.09.2024, 13:38:42     LOG [NestFactory] Starting Nest application...
[Nest] 5916  - 23.09.2024, 13:38:42     LOG [InstanceLoader] AppModule dependencies initialized +11ms
[Nest] 5916  - 23.09.2024, 13:38:42     LOG [WebSocketsController] AppGateway subscribed to the "test" message +35ms
[Nest] 5916  - 23.09.2024, 13:38:42     LOG [NestApplication] Nest application successfully started +3ms
Error WebSocket: ErrorEvent {
  [Symbol(kTarget)]: WebSocket {
    _events: [Object: null prototype] {
      open: [Function],
      message: [Function],
      error: [Function],
      close: [Function]
    },
    _eventsCount: 4,
    _maxListeners: undefined,
    _binaryType: 'nodebuffer',
    _closeCode: 1006,
    _closeFrameReceived: false,
    _closeFrameSent: false,
    _closeMessage: <Buffer >,
    _closeTimer: null,
    _extensions: {},
    _paused: false,
    _protocol: '',
    _readyState: 2,
    _receiver: null,
    _sender: null,
    _socket: null,
    _bufferedAmount: 0,
    _isServer: false,
    _redirects: 0,
    _autoPong: true,
    _url: 'ws://localhost:30001/',
    _req: null,
    [Symbol(kCapture)]: false
  },
  [Symbol(kType)]: 'error',
  [Symbol(kError)]: Error: socket hang up
      at connResetException (node:internal/errors:683:14)
      at Socket.socketOnEnd (node:_http_client:471:23)
      at Socket.emit (node:events:377:35)
      at endReadableNT (node:internal/streams/readable:1312:12)
      at processTicksAndRejections (node:internal/process/task_queues:83:21) {
    code: 'ECONNRESET'
  },
  [Symbol(kMessage)]: 'socket hang up'
}
WebSocket closed

排查过程 #

尝试过更换端口、配置CORS等操作，用Postman测试也返回相同的'socket hang up'错误。即使运行NestJS官方示例，使用wscat和Postman连接时也会出现该错误。

解决方法 #

最终发现问题在于NestJS默认的Socket适配器是socket.io，更换为WsAdapter后问题解决。修改后的main代码如下：

import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';
import { WsAdapter } from '@nestjs/platform-ws';


async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  app.useWebSocketAdapter(new WsAdapter(app));
  await app.listen(30001);
}

bootstrap();

内容的提问来源于stack exchange，提问作者Sergei Illarionov