#5967: Enable source repo generation

[Fedora Release Engineering]

#5967: Enable source repo generation
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  Reporter:  mizdebsk     |      Owner:  rel-eng@…
      Type:  enhancement  |     Status:  new
 Milestone:               |  Component:  koji
Resolution:               |   Keywords:  meeting
Blocked By:               |   Blocking:
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Comment (by mizdebsk):

 Koschei prioritizes package rebuilds according to changes in build
 dependency tree.  After new repo for f22-build is generated, Koschei
 has to calculate differences in build deps between previous and newly
 generated repo, for all packages it tracks.

 Koschei generates package build dependency tree using hawkey library,
 which is also used by DNF. Hawkey works with YUM metadata. In this
 case metadata for both source and binary packages is needed. Source
 repo contains the SRPM and info about its build requires, binary repo
 contains dependency info for all RPMs which may be transitive build
 deps.  For binary repository Koschei simply downloads metadada for
 f22-build from Koji, but there is no repo for source RPMs, so Koschei
 has to construct it by itself. To do this it downloads SRPMs from Koji
 and runs createrepo_c on them.

 Current solution works, but it has disadvantages:

 * extra storage required for SRPMs (about 46 GiB),
 * SRPMs have to be transfered from Koji over network,
 * extra code has to be maintained.

 We can keep current solution, but enabling source repo generation
 for f22-build would make things considerably simpler. Additionally
 I think such repository could be used in other ways too and as such it
 would be worth enabling.

 One problem mentioned during the meeting was arch-dependant SRPMs
 (SRPMs which have different contents depending on what architecture
 they have been built). SRPM contents depend not only on architecture,
 but a number of other things too. Theoretically spec file can contain
 line like:
 {{{
 %{lua: if(os.time()%2==0) then print("BuildRequires: foo"); end}
 }}}
 which will add BuildRequires semi-randomly. I think that there is no
 way to properly fix all such cases. If some package has
 non-deterministic build then it's a problem in that package and we
 shouldn't try to workaround it.

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Ticket URL: <https://fedorahosted.org/rel-eng/ticket/5967#comment:5>
Fedora Release Engineering <http://fedorahosted.org/rel-eng>
Release Engineering for the Fedora Project