rpm 4.12 and weak dependencies

[Petr Spacek]

On 9.10.2014 09:27, Jan Zelený wrote:
> On 9. 10. 2014 at 08:57:42, Ralf Corsepius wrote:
>> On 10/09/2014 08:41 AM, Petr Spacek wrote:
>>> On 8.10.2014 23:04, Haïkel wrote:
>>>> 2014-10-08 20:31 GMT+02:00 Kevin Fenzi <kevin at scrye.com>:
>>>>> Greetings.
>>>>>
>>>>> This F21 change:
>>>>> http://fedoraproject.org//wiki/Changes/RPM-4.12
>>>>>
>>>>> has brought us 'weak dependencies', namely:
>>>>>
>>>>> Recommends, Suggests, Supplements and Enhances
>>>>>
>>>>> Rpm in f21 and rawhide sees these in spec files and builds fine with
>>>>> them. createrepo in those branches also exports this into the metadata.
>>>>>
>>>>> yum however doesn't do anything with that information.
>>>>> dnf does (although it's not clear to me what exactly it does do, so
>>>>> input from dnf maintainers would be great).
>>>>>
>>>>> There's 4 packages that are already using these weak deps, but our
>>>>> default package manager (yum) doesn't understand them. People
>>>>> installing via yum and installing via dnf will see different behavior.
>>>>>
>>>>> I filed a fesco ticket to ask that we ask maintainers to please not add
>>>>> these until we have guidelines and our default package manager
> supports
>>>>> this information:  https://fedorahosted.org/fesco/ticket/1353
>>>>>
>>>>> FESCo asked me to post here and see what folks think.
>>>>>
>>>>> Should we just ask folks not to use these for now (honor system).
>>>>>
>>>>> Should we add a check to redhat-rpm-macros to check packages and
> fail
>>>>> the build if they use these tags (for now).
>>>>>
>>>>> Should we just not care that people will see different behavior and
>>>>> leave it up to maintainers?
>>>>>
>>>>> Or should we do something else?
>>>>
>>>> Since our default package manager does not understand them, it's
>>>> harmless to leave it up to the maintainers.
>>>> Most importantly, we need to update packaging guidelines to explain
>>>> what are the semantic differences between these different tags. But
>>>> that's a minor update.
>>>>
>>>> Before dnf gets promoted as the default package manager, it would be
>>>> interesting to do some widespread testing.
>>>>
>>>> 1. document dnf behavior with weak dependencies and related
>>>> configuration options
>>>> 2. let people experiment and provide feedbacks
>>>> 3. based on feedbacks either propose guidelines or status quo if
>>>> that's ok
>>>
>>> I agree with Haïkel.
>>
>> I do not.
>
> I agree with Haikel and Petr, we have a great opportunity to test this and see
> how it works.
>
>>> Why should we ban weak dependencies if they really
>>> do nothing in YUM?
>>
>> We need a precise and detailed functional description about what these
>> "weak dependencies" are supposed to do.
>
> Do you mean something like this?
>
> http://rpm.org/wiki/PackagerDocs/Dependencies

It would be nice if words "weak dependencies" at
http://rpm.org/wiki/Releases/4.12.0
linked to
http://rpm.org/wiki/PackagerDocs/Dependencies#Weakdependencies

Jan, do you have rights to add the link to the rpm.org wiki? I don't have 
account myself ...

Petr^2 Spacek

>> Also, we would need a precise and detailed description of how weak deps
>> are seen by non-weak-deps aware programs.
>
> They are ignored (as demonstrated on the yum example), there is nothing else
> to it :-)
>
> Thanks
> Jan