index.js

//Main starting point of the application
const express = require("express");
require("dotenv").config();

//const http = require("http");
const bodyParser = require("body-parser");
const morgan = require("morgan");

const router = require("./router");
const mongoose = require("mongoose");

const app = express();

//DB Setup
const mongoUri = `${process.env.MONGO_URI}`;
const connectDb = async () => {
  try {
    await mongoose.connect(mongoUri, {
      useNewUrlParser: true,
      useUnifiedTopology: true,
      useCreateIndex: true,
      useFindAndModify: false
    });
    console.log("MongoDB Connected...");
  } catch (err) {
    console.log(err.message);
    // Exit process with failure
    process.exit(1);
  }
};

connectDb();
// App setup
app.use(morgan("combined"));
app.use(bodyParser.json());
app.use(function (req, res, next) {
  res.header("Access-Control-Allow-Origin", "*");
  res.setHeader(
    "Access-Control-Allow-Methods",
    "GET, POST, OPTIONS, PUT, PATCH, DELETE"
  );
  res.header(
    "Access-Control-Allow-Headers",
    "Origin, X-Requested-With,authorization,content-type, Content-Type, Accept, Authorization, authorization"
  );
  next();
});

router(app);

// Server Setup
const port = process.env.PORT || 5000;
app.listen(port);

console.log("App is listening on port " + port);

function exitHandler(options, exitCode) {
  if (options.cleanup) console.log("clean");
  if (exitCode || exitCode === 0) console.log(exitCode);
  if (options.exit) process.exit();
}
//do something when app is closing
process.on("exit", exitHandler.bind(null, { cleanup: true }));

//catches ctrl+c event
process.on("SIGINT", exitHandler.bind(null, { exit: true }));

// catches "kill pid" (for example: nodemon restart)
process.on("SIGUSR1", exitHandler.bind(null, { exit: true }));
process.on("SIGUSR2", exitHandler.bind(null, { exit: true }));
process.on("uncaughtException", exitHandler.bind(null, { exit: true }));