[2.3, snap] NTP not running when split rack controller is a snap

[Andres Rodriguez]

Region Controller is package based.
Rack Controller is on separate machine running from a snap:

Failure: twisted.internet.error.ProcessTerminated: A process has ended with a probable error condition: process ended with exit code 1.
2017-08-17 17:02:55 provisioningserver.rackdservices.ntp: [critical] Failed to update NTP configuration.

Traceback (most recent call last):
  File "/snap/maas/375/lib/python3.5/site-packages/twisted/internet/defer.py", line 434, in errback
    self._startRunCallbacks(fail)
  File "/snap/maas/375/lib/python3.5/site-packages/twisted/internet/defer.py", line 501, in _startRunCallbacks
    self._runCallbacks()
  File "/snap/maas/375/lib/python3.5/site-packages/twisted/internet/defer.py", line 587, in _runCallbacks
    current.result = callback(current.result, *args, **kw)
  File "/snap/maas/375/lib/python3.5/site-packages/twisted/internet/defer.py", line 1241, in gotResult
    _inlineCallbacks(r, g, deferred)
--- <exception caught here> ---
  File "/snap/maas/375/lib/python3.5/site-packages/twisted/internet/defer.py", line 1183, in _inlineCallbacks
    result = result.throwExceptionIntoGenerator(g)
  File "/snap/maas/375/lib/python3.5/site-packages/twisted/python/failure.py", line 389, in throwExceptionIntoGenerator
    return g.throw(self.type, self.value, self.tb)
  File "/snap/maas/375/lib/python3.5/site-packages/provisioningserver/utils/service_monitor.py", line 318, in restartService
    yield self._performServiceAction(service, "restart")
  File "/snap/maas/375/lib/python3.5/site-packages/twisted/internet/defer.py", line 1185, in _inlineCallbacks
    result = g.send(result)
  File "/snap/maas/375/lib/python3.5/site-packages/provisioningserver/utils/service_monitor.py", line 422, in _performServiceAction
    raise ServiceActionError(error_msg)
provisioningserver.utils.service_monitor.ServiceActionError: Service 'ntp_rack' failed to restart:

further logs:

Aug 17 20:48:35 withkvm ntpd[31248]: Command line: /snap/maas/x1/usr/sbin/ntpd -n -d -c /var/snap/maas/x1/etc/ntp.conf
Aug 17 20:48:35 withkvm ntpd[31248]: proto: precision = 0.241 usec (-22)
Aug 17 20:48:35 withkvm ntpd[31248]: unable to bind to wildcard address :: - another process may be running - EXITING

[Andres Rodriguez (andreserl)]

The problem may be that NTP is installed in the host machine, which causes the snap to fail.