def get_hostname():
    """
    
    """
    # First we attempt to fetch the callable path from the config.
    try:
        callable_path = conf.get('core', 'hostname_callable')
    except AirflowConfigException:
        callable_path = None

    # Then we handle the case when the config is missing or empty. This is the
    # default behavior.
    if not callable_path:
        return socket.getfqdn()

    # Since we have a callable path, we try to import and run it next.
    module_path, attr_name = callable_path.split(':')
    module = importlib.import_module(module_path)
    callable = getattr(module, attr_name)
    return callable()