rpm 4.12 and weak dependencies

Jan Zelený jzeleny at redhat.com
Thu Oct 9 07:27:48 UTC 2014


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

> 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


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