Where is the best and most competent way to place a file that connects to the database?

Question

Node.js

Good morning!
I have a problem... I don't know where it would be more correct to place the file that connects to the meringue data.
The directory structure is as follows:

-src
--middleware
---errorHandler.js
---routes.js

--models
--- Тут модели для подключения и выполнения операций CRUD c определенными таблицами.

--modules

---auth
----auth.js (тут роуты "/auth", который импортируется в routes.js)

---user
----user.js (тут роуты "/users", который импортируется в routes.js)

---car
----car.js (тут роуты "/cars", который импортируется в routes.js)

--services

--index.js (app.js)
--config.js (файл конфигурации)

I used to just use mysql , but now I decided to use an ORM, namely the bookshelfjs library/package .
Tell me, please, where exactly is it better to save the connection file, where is the most logical? The purpose of the question is to implement everything correctly.
Thank you very much in advance!)