def __virtual__():
    if __grains__['kernel'] == 'Linux' \
            and salt.utils.systemd.booted(__context__):
        if salt.utils.systemd.version() is None:
            log.error('nspawn: Unable to determine systemd version')
        else:
            return __virtualname__
    return (False, 'The nspawn execution module failed to load: '
            'only work on systems that have been booted with systemd.')
Only work on systems that have been booted with systemd
dataset/ETHPy150Open saltstack/salt/salt/modules/nspawn.py/__virtual__