[Freeipa-devel] [PATCH 0373] Upgrade: Fix IPA version comparison

[Martin Kosek]

On 12/14/2015 07:21 AM, Jan Cholasta wrote:
> On 11.12.2015 19:01, Tomas Babej wrote:
>>
>>
>> On 12/11/2015 09:36 AM, Martin Kosek wrote:
>>> On 12/10/2015 05:09 PM, Martin Basti wrote:
>>>>
>>>>
>>>> On 10.12.2015 15:49, Tomas Babej wrote:
>>>>>
>>>>> On 12/10/2015 11:23 AM, Martin Basti wrote:
>>>>>>
>>>>>> On 10.12.2015 09:13, Lukas Slebodnik wrote:
>>>>>>> On (09/12/15 19:22), Martin Basti wrote:
>>>>>>>> https://fedorahosted.org/freeipa/ticket/5535
>>>>>>>>
>>>>>>>> Patch attached.
>>>>>>> >From 8ef93485d61e8732166fb0c5b6c4559209740f3e Mon Sep 17 00:00:00
>>>>>>> 2001
>>>>>>>> From: Martin Basti <mbasti at redhat.com>
>>>>>>>> Date: Wed, 9 Dec 2015 18:53:35 +0100
>>>>>>>> Subject: [PATCH] Fix version comparison
>>>>>>>>
>>>>>>>> Use RPM library to compare vendor versions of IPA for redhat platform
>>>>>>>>
>>>>>>>> https://fedorahosted.org/freeipa/ticket/5535
>>>>>>>> ---
>>>>>>>> freeipa.spec.in             |  2 ++
>>>>>>>> ipaplatform/redhat/tasks.py | 19 +++++++++++++++++++
>>>>>>>> 2 files changed, 21 insertions(+)
>>>>>>>>
>>>>>>>> diff --git a/freeipa.spec.in b/freeipa.spec.in
>>>>>>>> index
>>>>>>>> 9f82b3695fb10c4db65cc31278364b3b34e26098..09feba7b8324f5e645da3e8010de86b6c3ee5ab9
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> 100644
>>>>>>>> --- a/freeipa.spec.in
>>>>>>>> +++ b/freeipa.spec.in
>>>>>>>> @@ -166,6 +166,8 @@ Requires: %{etc_systemd_dir}
>>>>>>>> Requires: gzip
>>>>>>>> Requires: python-gssapi >= 1.1.0
>>>>>>>> Requires: custodia
>>>>>>>> +Requires: rpm-python
>>>>>>>> +Requires: rpmdevtools
>>>>>>> Could you explain why do you need the 2nd package?
>>>>>>> It does not contains any python modules
>>>>>>> and I cannot see usage of any binary in this patch
>>>>>>>
>>>>>>> LS
>>>>>> Thanks for this catch, it is actually located in yum package, I rather
>>>>>> copy stringToVersion function from there to IPA, to avoid dependency
>>>>>> hell
>>>>>>
>>>>>> Updated patch attached.
>>>>>>
>>>>>>
>>>>> Looking good. The __cmp__ function, however, is not available in Python
>>>>> 3. As we will eventually support python3 in RHEL as well, maybe we
>>>>> should make sure even platform-dependent parts are python3 compatible?
>>>>> For the future's sake.
>>>>>
>>>>> Tomas
>>>>>
>>>> Thanks,
>>>>
>>>> python 3 compatible patch attached.
>>>
>>> I wonder why we have to add so much code here and reimplement RPM
>>> version checking if it is already provided by rpmdevtools:
>>>
>>> ~~~
>>> $ /usr/bin/rpmdev-vercmp ipa-4.2.0-15.el7 4.2.0-15.el7_2.3; echo $?
>>> WARNING: hyphen in release1: 4.2.0-15.el7
>>>
>>> rpmdev-vercmp <epoch1> <ver1> <release1> <epoch2> <ver2> <release2>
>>> rpmdev-vercmp <EVR1> <EVR2>
>>> rpmdev-vercmp # with no arguments, prompt
>>>
>>> Exit status is 0 if the EVR's are equal, 11 if EVR1 is newer, and 12 if
>>> EVR2
>>> is newer.  Other exit statuses indicate problems.
>>>
>>> ipa-4.2.0-15.el7 < 4.2.0-15.el7_2.3
>>> 12
>>> ~~~
>>>
>>> which could be directly called from __eq__ or __lt__, since we are in
>>> platform specific code anyway already.
>>>
>>> Martin
>>
>> Imho we should generally prefer reaching out to a Python library rather
>> launching a subprocess to compare the versions, it's unnecessary overhead.

I would not be too worried about miliseconds longer execution on a function
called during RPM upgrade.

>> That said, the main argument for the usage of rpm-python over
>> rpmdevtools I see is that rpm-python is very likely to be present on the
>> system (i.e. it is yum's own dependency), while rpmdevtools will not be
>> present by default.
>>
>>  From the standpoint of trying to minimize the size of freeipa
>> installation (i.e recent wget -> curl migration), we should keep the
>> spirit here and do not introduce a dependency for a collection of
>> developer tools.
>>
>> /2 cents
> 
> +1, also a single function is hardly "much code".

Ok then. If you all want to add yet another N-V-R parsing function in the
FreeIPA code, I can live with it (with raised eyebrows though).