[Freeipa-devel] [PATCHES 0001-0002] ipa-client-install NTP fixes

[Rob Crittenden]

Nathan Kinder wrote:
> 
> 
> On 02/26/2015 12:55 AM, Martin Kosek wrote:
>> On 02/26/2015 03:28 AM, Nathan Kinder wrote:
>>> Hi,
>>>
>>> The two attached patches address some issues that affect
>>> ipa-client-install when syncing time from the NTP server.  Now that we
>>> use ntpd to perform the time sync, the client install can end up hanging
>>> forever when the server is not reachable (firewall issues, etc.).  These
>>> patches address the issues in two different ways:
>>>
>>> 1 - Don't attempt to sync time when --no-ntp is specified.
>>>
>>> 2 - Implement a timeout capability that is used when we run ntpd to
>>> perform the time sync to prevent indefinite hanging.
>>>
>>> The one potentially contentious issue is that this introduces a new
>>> dependency on python-subprocess32 to allow us to have timeout support
>>> when using Python 2.x.  This is packaged for Fedora, but I don't see it
>>> on RHEL or CentOS currently.  It would need to be packaged there.
>>>
>>> https://fedorahosted.org/freeipa/ticket/4842
>>>
>>> Thanks,
>>> -NGK
>>
>> Thanks for Patches. For the second patch, I would really prefer to avoid new
>> dependency, especially if it's not packaged in RHEL/CentOS. Maybe we could use
>> some workaround instead, as in:
>>
>> http://stackoverflow.com/questions/3733270/python-subprocess-timeout
> 
> I don't like having to add an additional dependency either, but the
> alternative seems more risky.  Utilizing the subprocess32 module (which
> is really just a backport of the normal subprocess module from Python
> 3.x) is not invasive for our code in ipautil.run().  Adding some sort of
> a thread that has to kill the spawned subprocess seems more risky (see
> the discussion about a race condition in the stackoverflow thread
> above).  That said, I'm sure the thread/poll method can be made to work
> if you and others feel strongly that this is a better approach than
> adding a new dependency.

Why not use /usr/bin/timeout from coreutils?

rob