from typing import Tuple

from pydantic import BaseSettings
from pydantic.env_settings import SettingsSourceCallable


class Settings(BaseSettings):
    my_api_key: str

    class Config:
        @classmethod
        def customise_sources(
            cls,
            init_settings: SettingsSourceCallable,
            env_settings: SettingsSourceCallable,
            file_secret_settings: SettingsSourceCallable,
        ) -> Tuple[SettingsSourceCallable, ...]:
            # here we choose to ignore arguments from init_settings
            return env_settings, file_secret_settings


print(Settings(my_api_key='this is ignored'))
# requires: `MY_API_KEY` env variable to be set, e.g. `export MY_API_KEY=xxx`