The final beacon module

When all is said and done, our final beacon module will look like this:

'''
Send events covering nspawn containers

This beacon accepts a list of containers and whether they should be
running or absent:

    .. code-block:: yaml

        beacons:
          nspawn:
            vsftpd: running
            httpd: absent


This file should be saved as salt/beacons/nspawn.py
'''
import time

__virtualname__ = 'nspawn'


def __virtual__():
    '''
    Ensure that systemd-nspawn is available
    '''
    if 'nspawn.list_running' in __salt__:
        return __virtualname__
    return False


def validate(config):
    '''
    Validate the beacon configuration
    '''
    if not isinstance(config, dict):
        return False
    for key in config:
        if config[key] not in ('running', 'absent'):
            return False
    return True


def beacon...