From the example given here - https://fastapi.tiangolo.com/tutorial/bigger-applications/

I have this kind of structure.

.
├── app
│   ├── __init__.py
│   ├── main.py
│   └── routers
│       ├── __init__.py
│       ├── items.py
│       └── users.py

I would like to read environment variables, when running/deploying my code, and then pass those variables to items.py and users.py

How do I achieve this?

Do I have to use tags or is that for some other purpose?