proxy-nestjs.ts

import { NestMiddleware } from '@nestjs/common';
import { Request, Response, NextFunction } from 'express';
import axios, { AxiosRequestConfig } from 'axios';
export class ReverseProxyMiddleware implements NestMiddleware {
  after(str, substr): string {
    return str.slice(str.indexOf(substr) + substr.length, str.length);
  }

  use(req: Request, res: Response, next: NextFunction) {
    if (process.env.NODE_ENV != 'dev' || !process.env.PROXY) {
      return next();
    }

    const url = `${process.env.PROXY}${this.after(req.originalUrl, '/src')}`;

    const config = {
      headers: req.headers,
      method: req.method,
      url: url,
    } as AxiosRequestConfig;

    if (req.method === 'POST') {
      Object.assign(config, { data: JSON.stringify(req.body) });
    }
    axios(config).then(response => res.send(response.data));
  }
}