dependency-injector

import os from dependency_injector import containers, providers from dependency_injector.wiring import Provide, inject class ConfigService: def __init__(self, api_key: str): self.api_key = api_key def get_api_key(self) -> str: return self.api_key class MyService: def __init__(self, config_service: ConfigService): self.config_service = config_service def do_something(self) -> str: api_key = self.config_service.get_api_key() return f"Doing something with API Key: {api_key[:4]}..." class Container(containers.DeclarativeContainer): config = providers.Configuration() config_service = providers.Singleton( ConfigService, api_key=config.api_key ) my_service = providers.Factory( MyService, config_service=config_service ) @inject def main_app_function( service: MyService = Provide[Container.my_service], ): print(service.do_something()) if __name__ == '__main__': container = Container() # Load configuration from environment variable (or .env file) container.config.api_key.from_env('MY_APP_API_KEY', as_=str, default='default_key_1234567890') # Example: Override during testing or development # container.config.api_key.override('test_key_abcde') container.wire(modules=[__name__]) # Set an environment variable for the example to work os.environ['MY_APP_API_KEY'] = os.environ.get('MY_APP_API_KEY', 'example_api_key_12345') main_app_function() # Clean up environment variable (optional) del os.environ['MY_APP_API_KEY']