server.js

const mongoose = require('mongoose');
const dotenv = require('dotenv');

process.on('uncaughtException', err => {
  console.log(err.name, err.message);
  console.log('UNCAUGHT EXCEPTION! Shutting down...');
  server.close(() => {
    process.exit(1);
  });
});

dotenv.config({ path: './config.env' });
const app = require('./app');

const DB = process.env.DATABASE.replace(
  '<PASSWORD>',
  process.env.DATABASE_PASSWORD
);
//const DB = 'mongodb://localhost:27017/natours';
mongoose
  .connect(DB, {
    useNewUrlParser: true,
    useCreateIndex: true,
    useFindAndModify: false,
    useUnifiedTopology: true
  })
  .then(() => console.log('DB connection successful!'))
  .catch(err => {
    console.log('error', err);
  });

const port = process.env.PORT || 3000;
const server = app.listen(port, () => {
  console.log(
    `App running in ${process.env.NODE_ENV} mode on port: ${port}...`
  );
});

process.on('unhandledRejection', err => {
  console.log(err.name, err.message);
  console.log('UNHANDLED REJECTION! 💥 Shutting down...');
  server.close(() => {
    process.exit(1);
  });
});

process.on('SIGTERM', () => {
  console.log('🖐️SIGTERM RECEIVED, Shutting down gracefully');
  server.close(() => {
    console.log('💥 Process terminated!');
  });
});