Helper to access a Juju config option when charmhelpers is not available.

    :param str option_name: Name of the config option to get the value of

def config_get(option_name):
    """
    Helper to access a Juju config option when charmhelpers is not available.

    :param str option_name: Name of the config option to get the value of
    """
    try:
        raw = subprocess.check_output(['config-get', option_name, '--format=yaml'])
        return yaml.load(raw.decode('UTF-8'))
    except ValueError:
        return None