main.ts

import session from 'express-session';
import { NestFactory } from '@nestjs/core';
import { ConfigService } from '@nestjs/config';
import { DocumentBuilder, SwaggerModule } from '@nestjs/swagger';
import { json, urlencoded } from 'body-parser';
import { useContainer } from 'class-validator';
import helmet from 'helmet';
import cookieParser from 'cookie-parser';

import { AppModule } from './app.module';
import { ConfigNames } from './common/config';
import { createWriteStream } from 'fs';
import { get } from 'http';
import { INestApplication } from '@nestjs/common';

async function bootstrap() {
  const app = await NestFactory.create<INestApplication>(AppModule, {
    cors: true,
  });

  const configService: ConfigService = app.get(ConfigService);

  const baseUrl = configService.get<string>(ConfigNames.FE_URL)!;

  app.enableCors({
    origin:
      process.env.NODE_ENV === 'development' ||
      process.env.NODE_ENV === 'staging'
        ? [
            `http://localhost:3001`,
            `http://127.0.0.1:3001`,
            `http://0.0.0.0:3001`,
            baseUrl,
          ]
        : [baseUrl],
    credentials: true,
    exposedHeaders: ['Content-Disposition'],
  });

  useContainer(app.select(AppModule), { fallbackOnErrors: true });

  app.use(cookieParser());

  const sessionSecret = configService.get<string>(ConfigNames.SESSION_SECRET)!;

  app.use(
    session({
      secret: sessionSecret,
      resave: false,
      saveUninitialized: false,
    }),
  );
  app.use(json({ limit: '5mb' }));
  app.use(urlencoded({ limit: '5mb', extended: true }));

  const config = new DocumentBuilder()
    .addBearerAuth()
    .setTitle('Job Launcher API')
    .setDescription('Swagger Job Launcher API')
    .setVersion('1.0')
    .build();
  const document = SwaggerModule.createDocument(app, config);
  SwaggerModule.setup('swagger', app, document);

  const host = configService.get<string>(ConfigNames.HOST)!;
  const port = configService.get<string>(ConfigNames.PORT)!;

  app.use(helmet());
  await app.listen(port, host, async () => {
    console.info(`API server is running on http://${host}:${port}`);
  });

  //Download files to serve them as static files when the app is deployed on vercel
  if (process.env.NODE_ENV === 'development') {
    // write swagger ui files
    get(
      `http://${host}:${port}/swagger/swagger-ui-bundle.js`,
      function (response: { pipe: (arg0: any) => void }) {
        response.pipe(createWriteStream('swagger-static/swagger-ui-bundle.js'));
      },
    );

    get(
      `http://${host}:${port}/swagger/swagger-ui-standalone-preset.js`,
      function (response: { pipe: (arg0: any) => void }) {
        response.pipe(
          createWriteStream('swagger-static/swagger-ui-standalone-preset.js'),
        );
      },
    );

    get(
      `http://${host}:${port}/swagger/swagger-ui.css`,
      function (response: { pipe: (arg0: any) => void }) {
        response.pipe(createWriteStream('swagger-static/swagger-ui.css'));
      },
    );
  }
}

void bootstrap();