dotenv

$ npm install dotenv

//--------------------

on file .env 
//--------------------
DB_HOST=localhost
DB_USER=root
DB_PASS=s1mpl3
DB_NAME=banco_de_dados
DB_PORT=3306
//--------------------

import the config from .env file 
//--------------------

require('dotenv').config()
module.exports = {
    username:process.env.DB_USER,
    password:process.env.DB_PASS,
    database:process.env.DB_NAME,
    host:process.env.DB_HOST,
    dialect:"mysql"
}
npm install dotenv