[libvirt] [PATCH] libvirt-guests: wait for ntp service

[Michal Privoznik]

On 23.09.2014 08:06, Martin Kletzander wrote:
> On Mon, Sep 22, 2014 at 04:50:33PM -0600, Jim Fehlig wrote:
>> Michal Privoznik wrote:
>>> On 20.09.2014 01:36, Jim Fehlig wrote:
>>>> Martin Kletzander wrote:
>>>>> Unfortunately I'm not very familiar with systemd files, but my guess
>>>>> is that After=ntp-wait.service means it should be started after the
>>>>> time is synchronized if and only if the ntp-wait.service unit is
>>>>> enabled, otherwise it doesn't require it.
>>>>
>>>> Yes, this is my understanding too.
>>>
>>> And so is mine. The only concern I have is that syncing time on cold
>>> boot of the host may take ages.
>>
>> Yep, I have this concern too.  So I dug a bit further and see that
>> ntp-wait (a perl script) scrapes the output of `ntpq -c "rv 0`, waiting
>> for leap_alarm to change to leap_none, leap_add_sec, or leap_del_sec.
>> On my test system, this took ~16min on cold boot :-(.  ntp-wait.service
>> failed in the meantime, since it by default calls /usr/sbin/ntp-wait
>> with options to only wait 10min.
>>
>>> But on the other hand, it's better to start domains later and with
>>> correct time than start asap with inaccurate time. ACK then,
>>
>> Given the above observations, I'll wait to see if you change your mind.
>>
>
> What would you say to changing it to After=ntpdate.service?  That way
> it won't wait until the clock is synchronized, but it will be started
> with proper time if ntpdate.service is set up to start in the default
> runlevel (or is it target in systemd?).  I think that's a compromise
> that has no negative side-effects.

I wonder if we should be this specific or use time-sync.target:

time-sync.target

     Services responsible for synchronizing the system clock from a 
remote source (such as NTP client implementations) should pull in this 
target and order themselves before it. All services where correct time 
is essential should be ordered after this unit, but not pull it in. 
systemd automatically adds dependencies of type After= for this target 
unit to all SysV init script service units with an LSB header referring 
to the "$time" facility.

http://www.freedesktop.org/software/systemd/man/systemd.special.html#time-sync.target

So I'd say: After=time-sync.target is what we are looking for.

Michal