[NestJs] 추적번호 만들기

토이 프로젝트 진행 중 거래별로 추적번호를 만들어야 했다.

1.순서

• middleware에서 추적번호를 생성하여 request의 header에 입력한다.
• Interceptor에서 요청 및 응답 로그를 남긴다.
• Controller에서 Decorator를 사용해서 추적번호를 사용한다.

2.구현

1. 추적번호 생성
   - traceId.middle.ts

   import { Request, Response, NextFunction } from 'express';
   import { Injectable, NestMiddleware } from '@nestjs/common';
   import { randomUUID } from 'crypto';
   
   @Injectable()
   export class TraceIdMiddleware implements NestMiddleware {
     use(req: Request, res: Response, next: NextFunction) {
       const traceId = randomUUID();
       // 추적번호를 생성하여 header에 넣는다.
       req.headers['traceId'] = traceId;
   
       next();
     }
   }

2. 송수신 거래 로깅
   - Logging.interceptor.ts

   import { Observable } from 'rxjs';
   import { tap, catchError } from 'rxjs/operators';
   import { randomUUID } from 'crypto';
   
   import {
     Injectable,
     NestInterceptor,
     ExecutionContext,
     CallHandler,
     Logger,
   } from '@nestjs/common';
   
   @Injectable()
   export class LoggingInterceptor implements NestInterceptor {
     intercept(context: ExecutionContext, next: CallHandler): Observable<any> {
       const request = context.switchToHttp().getRequest();
       const method = request.method;
       const url = request.url;
       // header에서 추적번호를 찾는다.
       const traceId = request.headers['traceId'];
       const logger = new Logger(traceId);
   
       logger.log(
         `Request: ${method} ${url}, Header: ${JSON.stringify(request.headers)}`,
       );
       logger.log(
         `Request: ${method} ${url}, Body: ${JSON.stringify(request.body)}`,
       );
   
       const now = Date.now();
       return next.handle().pipe(
         tap((response) => {
           logger.log(
             `Response: ${method} ${url} ${Date.now() - now}ms ${JSON.stringify(response)}`,
           );
         }),
         catchError((error) => {
           logger.log(
             `Response: ${method} ${url} ${Date.now() - now}ms ${error.message}`,
           );
           throw error;
         }),
       );
     }
   }

3. 데코레이터 생성
   - traceId.decorator.ts

     import { createParamDecorator, ExecutionContext } from '@nestjs/common';
   
     export const TraceId = createParamDecorator(
       (data: unknown, ctx: ExecutionContext): string => {
         const request = ctx.switchToHttp().getRequest();
         return request.headers['traceId'] || null;
       },
     );

4. 적용

• app.module.ts

      import { MiddlewareConsumer, Module } from '@nestjs/common';
      import { AppController } from './app.controller';
      import { AppService } from './app.service';
      import { UserModule } from './user/user.module';
      import { LoggingInterceptor } from './util/interceptor/Logging.interceptor';
      import { APP_INTERCEPTOR } from '@nestjs/core';
      import { TraceIdMiddleware } from './util/middleware/traceId.middle';
  
      @Module({
        imports: [
          UserModule,
        ],
        controllers: [AppController],
        providers: [
          // 인터셉터를 전역으로 적용한다.
          { provide: APP_INTERCEPTOR, useClass: LoggingInterceptor },
          AppService,
        ],
      })
      export class AppModule {
        configure(consumer: MiddlewareConsumer) {
          // 미들웨어를 모든 주소에 적용한다.
          consumer.apply(TraceIdMiddleware).forRoutes('*');
        }
      }

5. 사용
   - user.controller.ts

   import {
     Controller,
     Post,
     Body,
     Logger,
   } from '@nestjs/common';
   import { UserService } from './user.service';
   import { CreateUserDto } from './dto/create-user.dto';
   import { ResponseUserDto } from './dto/response-user.dto';
   
   @Controller('user')
   export class UserController {
     constructor(private readonly userService: UserService) {}
   
     @Post('create')
     async create(
       @TraceId() traceId: string,
       @Body() createUserDto: CreateUserDto,
     ): Promise<ResponseUserDto> {
       Logger.log('traceId: ' + traceId);
       return this.userService.create(createUserDto);
     }
   }