Python package import

Actually I think python package import is not a problem, until I meet this problem.
This project is devlopmented base on poetry , the project structure like this:

IM_bot/
    bot_controller/
        __init__.py
        __main__.py
        config.py
        db_models.py
    qq_bot/
        __init__.py
        config.py
        send_message.py

Each sub-dir is a small package, use poetry to manage, and bot_controller is the main management, which will import other package. Though I wanna put QQ_bot under bot_controller ...
Hey, why not? QQ_bot is a simple package without __main__.py, and I shouldn't build lots of package in one project.
Thank you dev-diary, now I will go to edit my code, see me later!
So I have changed the project structure, now it is like this

src/
    im_bot/
        bot_controller/
            __init__.py
            config.py
            db_models.py
        qq_bot/
            __init__.py
            config.py
            send_message.py
        __main__.py

No change? In the previous one struct, each module is a package, like bot_controller and qq_bot, they have self venv, but the enterpoint is bot_controller. In this version, both bot_controller and qq_bot is a package, and the enterpoint is on the previous level, so now I can import qq_bot easily.
It looks like a stupid question and i thought so too when i found it, anyway, it's not the main problem.
I really want to share is this:
When you use import .config in db_models.py, then run python3 IM_bot it will raise an error. This is because python can't find package, why? Because the workdir is IM_bot?
The answer is in this, so you will import __main__.config but not config.
To resolve it, you can use import im_bot.bot_controller.config.
By the way, you can also use import config to solve this, but when you build this package, it will throw error too.

Now, I wanna talk about my second question.
In this project, I use config.py to import database addresses, accounts, passwords and other sensitive information. In bot_controller, the config.py is:

import yaml
from logger import Logger

logger = Logger(__name__, log_file="bot_controller.log")

logger.info("start loading config")
with open("config.yml", "r") as stream:
    try:
        config = yaml.safe_load(stream).get("db_config", {})
    except yaml.YAMLError as exc:
        logger.exception(exc)
        raise

DB_HOST = config.get("host", "localhost")
DB_PORT = config.get("port", 5432)
DB_USER = config.get("user", "root")
DB_PASSWORD = config.get("password", "postgres")
DB_NAME = config.get("name", "default")
DB_URL = f"postgresql://{DB_USER}:{DB_PASSWORD}@{DB_HOST}:{DB_PORT}/{DB_NAME}"
logger.info("load config success")

And in db_model.py, it will import config.py then provide a scssionto db, the code is:

from im_bot.bot_controller.config import DB_URL
engine = create_engine(DB_URL)
Session = sessionmaker(bind=engine)
session = Session()

When db_model.py import the package, it will run all code, so I will get the DB_URL from config.yml before I make the db session.

That's all.