rpm 4.12 and weak dependencies

[Petr Spacek]

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. Why should we ban weak dependencies if they really do 
nothing in YUM?

DNF & weak dependencies are very new/experimental and for now it seems as a 
perfect situation: We can test weak dependencies without breaking conservative 
users with yum.

Petr^2 Spacek

>
> Regards,
> H.
>
>> Additionally, if we decide to not allow them for now, is anyone wanting
>> to work on a guidelines draft / document for when to use them? It would
>> depend on how dnf treats them I suspect.