A proper application code to start the server and a service to connect to the database

index.js

// index.js

const http = require('http');

const kernel = require('@rezeus/kernel');

require('./services_database');

kernel.on('error', (err) => {
  // TODO Handle error
});

kernel.once('booted', () => {
  // Kernel was booted. Here you can start the server.

  // Code excerpted from https://nodejs.org/en/docs/guides/getting-started-guide/
  // and slightly modified

  const server = http.createServer(server.callback());

  const server = http.createServer((req, res) => {
    // Now you can use Sequelize to query some data;
    // kernel.sequelize.query('SELECT * FROM my_table').then((result) => { ... }).catch(...);

    res.statusCode = 200;
    res.setHeader('Content-Type', 'text/plain');
    res.end('Hello World\n');
  });

  server.listen('127.0.0.1', 3000, () => {
    console.log('Server running on port 3000');
  });
  
  kernel.once('shutdown_server', () => new Promise((resolve) => {
    server.close(() => { resolve(); });
  }));
});

// First register the listener against the kernel...
kernel.on('shutted_down', () => {
  process.exit();
});

process.on('SIGTERM', () => {
  // ...and then start shutting down (i.e. graceful shutdown)
  kernel.shutdown();

  // NOTE Beware that the `SIGTERM` signal may be signalled multiple times (hance `.on()` not `.once()`)
});

kernel.boot();

services_database.js

// services/database.js

const Sequelize = require('sequelize');

const kernel = require('@rezeus/kernel');

kernel.on('booting_backing', () => new Promise((resolve, reject) => {
  // Code excerpted from http://docs.sequelizejs.com/manual/installation/getting-started
  // and slightly modified

  // Setting up a connection
  const sequelize = new Sequelize('database', 'username', 'password', {
    host: 'localhost',
    dialect: 'mysql',
    operatorsAliases: false,

    pool: {
      max: 5,
      min: 0,
      acquire: 30000,
      idle: 10000
    },
  });

  // Test the connection
  sequelize
    .authenticate()
    .then(() => {
      console.log('Connection has been established successfully.');

      kernel.sequelize = sequelize;
      resolve();
    })
    .catch((err) => {
      console.error('Unable to connect to the database:', err);

      reject(err);
    });
  
  // NOTE We are just returning the result of the `.close()` method since the return value is Promise
  kernel.on('shutdown_service', () => sequelize.close());
}));