Where to import pool.js file in my project file structure

Question

I am currently working on my e-commerce project in node js, here is my project file structure-

public
    - assets
      - js/
      - css/
      - images/
views
    - index.ejs
    - login.ejs
config/
    - pool.js
router/
    - login.js
    - index.js
    - signup.js
app.js
.env   

Here is the code for the **pool.js** file:

```   
     require('dotenv').config();
     const mysql = require('mysql')
     
     // pool  connection 
     const pool = mysql.createPool({
             host     : process.env.DB_HOST,
             user     : process.env.DB_USER,
             password : process.env.DB_PASS,
             database : process.env.DB_NAME
     })
    
     pool.on('enqueue', (connection)=>{
            console.log('Enqueue Event Triggred')
     })
     pool.on('acquire', (connection)=>{
            console.log('connection acquired with threatId: ' + connection.threadId)
     })
     module.exports = pool;
```

and here is my router/login.js file:

    const express = require('express')
    const router = express.Router()
    const pool = require('../config/pool')
    const bodyParser = require('body-parser') 
    const urlencodedParser = bodyParser.urlencoded({ extended: true })

router.post('/', urlencodedParser, (req, res, next)=>{
    pool.getConnection(...)
})

My main question is where to import the pool.js file that can be accessible to the all routers file. And what if my code for the pool.js file is replaced by the pool cluster connection code, any error??