#6144: Document the semantics of "comps"

[Fedora Release Engineering]

#6144: Document the semantics of "comps"
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 Reporter:  rholy            |       Owner:  rel-eng@…
     Type:  defect           |      Status:  new
Milestone:  Fedora 22 Final  |   Component:  other
 Keywords:                   |  Blocked By:
 Blocking:                   |
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 We, as the developers of DNF, miss a document that describes what "comps"
 mean and how should package managers work with them. Until it is
 documented, we cannot handle DNF bugs related to "comps" properly since we
 don't know what is the expected behaviour.

 E.g. what does "mandatory" packages mean? Could a "comp" be installed
 without a mandatory package (since it seems that there is a common
 practice to do that in kickstart files; e.g. RHBZ 1131969 and RHBZ
 1185408)? What should happen if a "comp" is installed and its mandatory
 package gets removed? What if multiple comps share the same mandatory
 packages? And so on... And please don't focus only on mandatory packages.
 If there is a piece of software that has to work with another one, the
 dependency has to be documented.

 Also another issue related to the mandatory packages comes to my mind.
 Since I understand "comps" as something that specifies which packages are
 the Fedora default (is true? can you document it?), what is the
 recommended approach to replace a default package (YUM) with a new default
 package (DNF) on all user systems? That is something that should be
 possible to be specified on the comps level IIUIC.

 Also it would be nice if there will be a way how to specify which packages
 are preferred over which ones since there are people that are convinced
 that Fedora e.g. prefers MariaDB over community-mysql so Fedora has to
 express it somehow.

 Anyway, we can discuss it once you finish the documentation. I just wanted
 to let you know about some use cases in case it would help you to design
 the semantics. It would be nice if you could fix it as soon as possible.

 (Actually, DNF uses "libcomps" to work with "comps" so in fact, we don't
 mind if it is documented on "comps.xml" level or on "libcomps" level but I
 assume that "libcomps" cannot be documented until "comps.xml" is
 documented anyway.)

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Ticket URL: <https://fedorahosted.org/rel-eng/ticket/6144>
Fedora Release Engineering <http://fedorahosted.org/rel-eng>
Release Engineering for the Fedora Project