I am writing a Node/Express web application as part of my university module. At the moment, the application is very simple and I have three files: db.js, app.js, and entry.js.

The db.js module creates Sequelize instance and exports it so it’s available to other modules. This is the entire code within db.js:

const { Sequelize } = require('sequelize');
const dbConfig = require('./dbconfig');

// Create Sequelize instance
const NODE_ENV = process.env.NODE_ENV.trim();
const sequelize = new Sequelize(dbConfig[NODE_ENV]);

module.exports = sequelize;

The app.js imports the express module, creates an express application and exports it:

const express = require("express");
const app = express();
module.exports = app;

The entry.js is run by npm run devstart from the terminal (cmd, Windows). It runs SET NODE_ENV=dev && nodemon ./app/bin/entry.js script within package.json.

I want to gracefully handle the closure of server and sequelize instances, so my entry.js looks like this:

const sequelize = require('../../db/db');
const app = require('../app');

const port = 3000;

// Test database connection
const testDatabaseConnection = async () => {
    try {
        await sequelize.authenticate();
        console.log('Database connection successfull.');
      } catch (error) {
        console.error('Unable to connect to the database:', error);
        throw(error);
    }
}

// Attempt to start the server
const serverStart = async () => {
    try {
        await testDatabaseConnection();
        const server = app.listen( port, () => {
            console.log(`Server listening on port ${port}.`);
        });
        return server;
    } catch(error) {
        console.error('Failed to start server:', error);
        process.exit(1);
    }
}

serverStart().then( (server) => {
    // Listen for process termination signals
    process.on('SIGINT', () => gracefulShutdown(server));
    process.on('SIGTERM', () => gracefulShutdown(server));
} );

// Gracefully close the application
const gracefulShutdown = async (server) => {
    
    console.log('Server is shutting down.');

    try {
        await new Promise( (resolve, reject) => {
            server.close( (error) => (error ? reject(error) : resolve()) );
        } );
        await sequelize.close();
        console.log('Database connection closed successfully.');

        process.exit(0);

    } catch(error) {
        console.error('Error during shutdown:', error);
        process.exit(1);
    }
};

When I start and terminate the nodemon process with Ctrl + c in the terminal (cmd, Windows), I sometimes get this output:

Executing (default): SELECT 1+1 AS result
Database connection successful.
Server listening on port 3000.
Server is shutting down.
^C^CTerminate batch job (Y/N)?

But, I am expecting it to be this:

Executing (default): SELECT 1+1 AS result
Database connection successful.
Server listening on port 3000.
Server is shutting down.
Database connection closed successfully.
^C^CTerminate batch job (Y/N)?

I am not sure why this happens. When I replace the nodemon with node in package.json script, the output seems to be consistent and I don’t get this issue.

I apologise if the question is too long.

Any input or feedback is greatly appreciated.
Many thanks.