1. Redis를 사용하려는 이유

• 백엔드 서버를 이중화하여 운영할 경우, socket 통신에 사용되는 세션 정보를 백엔드 서버 간 공유
• Redis를 Message Queue 서버로 사용

2. Redis와 Socket.io로 채팅 구현

1. 라이브러리 설치

• install 명령 실행

  npm i --save socket.io-redis @nestjs/platform-socket.io
  

• 트러블 슈팅

  • socket.io-redis import 시 has no call signatures 오류 발생

    → socket.io-redis 버전 다운그레이드

    RedisIoAdapter has no call signatures

    → 버전 업그레이드를 위해서는 adapter를 직접 구현해야 함

    Update socket.io to 3.0 in @nestjs/platform-socket.io package · Issue #5676 · nestjs/nest

2. Adapter 추가

• RedisIoAdapter 추가

  // adapters/redis.adapter.ts
  import { IoAdapter } from '@nestjs/platform-socket.io';
  import * as redisIoAdapter from 'socket.io-redis';
  
  export class RedisIoAdapter extends IoAdapter {
    createIOServer(port: number): any {
      const server = super.createIOServer(port);
      const redisAdapter = redisIoAdapter({
        host: 'localhost',
        port: 6379,
      });
  
      server.adapter(redisAdapter);
      return server;
    }
  }
  
  // main.ts
  import { NestFactory } from '@nestjs/core';
  import { RedisIoAdapter } from './adapters/redis.adapter';
  import { AppModule } from './app.module';
  
  async function bootstrap() {
    const app = await NestFactory.create(AppModule);
  
    app.useWebSocketAdapter(new RedisIoAdapter());
  
    await app.listen(3000);
  }
  
  bootstrap();
  
  

3. message 이벤트 모듈 추가

• MessageGateway 추가

  // message-events/message.gateway.ts
  import {
    SubscribeMessage,
    WebSocketGateway,
    OnGatewayInit,
    WebSocketServer,
    OnGatewayConnection,
    OnGatewayDisconnect,
    WsResponse,
  } from '@nestjs/websockets';
  import { Logger } from '@nestjs/common';
  import { Socket } from 'socket.io';
  import { Server } from 'ws';
  
  @WebSocketGateway({ namespace: '/chat' })
  export class MessageGateway
    implements OnGatewayInit, OnGatewayConnection, OnGatewayDisconnect {
    @WebSocketServer() server: Server;
  
    private logger: Logger = new Logger('MessageGateway');
  
    public afterInit(server: Server): void {
      return this.logger.log('Init');
    }
  
    public handleConnection(client: Socket): void {
      return this.logger.log(`Client connected: ${client.id}`);
    }
  
    public handleDisconnect(client: Socket): void {
      return this.logger.log(`Client disconnected: ${client.id}`);
    }
  
    @SubscribeMessage('joinRoom')
    public joinRoom(client: Socket, room: string): void {
      client.join(room);
      client.emit('joinedRoom', room);
    }
  
    @SubscribeMessage('leaveRoom')
    public leaveRoom(client: Socket, room: string): void {
      client.leave(room);
      client.emit('leftRoom', room);
    }
  
    @SubscribeMessage('msgToServer')
    public handleMessage(client: Socket, payload: any): Promise<WsResponse<any>> {
      return this.server.to(payload.room).emit('msgToClient', payload);
    }
  }
  
  // message-events/message.module.ts
  import { Module } from '@nestjs/common';
  import { MessageGateway } from './message.gateway';
  
  @Module({
    imports: [],
    controllers: [],
    providers: [MessageGateway],
  })
  export class MessageModule {}
  
  

4. Docker-compose로 Redis 실행

• docker-compose.yml

  version: '3.9'
  
  volumes:
    redis_data: {}
  
  services:
  	redis:
      image: redis
      volumes:
        - redis_data:/var/lib/redis
      ports:
        - 6379:6379
  
  

5. ConfigModule을 사용해서 RedisIoAdapter 설정하기

• App Context로부터 ConficService 를 얻어 RedisIoAdapter로 주입

  // main.ts
  import { ConfigService } from '@nestjs/config';
  import { NestFactory } from '@nestjs/core';
  import { RedisIoAdapter } from './adapters/redis.adapter';
  import { AppModule } from './app.module';
  
  async function bootstrap() {
    const app = await NestFactory.create(AppModule);
    const configService = app.get(ConfigService);
  
    app.useWebSocketAdapter(new RedisIoAdapter(app, configService));
  
    await app.listen(configService.get('api.port') ?? 3000);
  }
  
  bootstrap();
  
  // adapters/redis.adapter.ts
  import { ConfigService } from '@nestjs/config';
  import { IoAdapter } from '@nestjs/platform-socket.io';
  import * as redisIoAdapter from 'socket.io-redis';
  
  export class RedisIoAdapter extends IoAdapter {
    constructor(app, private readonly configService: ConfigService) {
      super(app);
    }
  
    createIOServer(port: number): any {
      const server = super.createIOServer(port);
      const redisAdapter = redisIoAdapter({
        host: this.configService.get('redis.host'),
        port: +this.configService.get('redis.port'),
      });
  
      server.adapter(redisAdapter);
      return server;
    }
  }
  
  

3. 참고 링크

• NestJS

  Documentation - adapter | NestJS - A progressive Node.js framework

  Documentation - standalone-applications | NestJS - A progressive Node.js framework

  How about making configService available to RedisIoAdapter?

• etc.

  Build a real-time chat application with Websocket, Socket.IO, Redis, and Docker in NestJS.