main.ts

import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';
import { SwaggerModule, DocumentBuilder } from '@nestjs/swagger';
import { ValidationPipe } from '@nestjs/common';
import * as fs from 'fs';

async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  app.enableCors({ credentials: true, origin: true});
  const options = new DocumentBuilder()
    .setBasePath('')
    .setTitle('Email service API')
    .setDescription('Service providing the method to send emails.')
    .setVersion('0.1')
    .addTag('email')
    .build();
  const document = SwaggerModule.createDocument(app, options);
  fs.writeFileSync('./swagger-spec.json', JSON.stringify(document));

  SwaggerModule.setup('api', app, document);
  app.useGlobalPipes(new ValidationPipe());

  await app.listen(3000);
}
bootstrap();