Bug 2169377

Summary:	Do not ship zchunk metadata for fedora repository that is never updated
Product:	[Fedora] Fedora	Reporter:	Jaroslav Mracek <jmracek>
Component:	pungi	Assignee:	Lubomír Sedlář <lsedlar>
Status:	NEW ---	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	unspecified	Docs Contact:
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Version:	39	CC:	admiller, hlin, jkeating, kevin, lsedlar, onosek, w
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Description Jaroslav Mracek 2023-02-13 13:23:16 UTC

Description of problem:
zchunk metadata type is a perfect way to optimize downloads for updated metadata where only modified parts are downloaded. But the format is bigger than standard GZ compress metadata because it contains additional checksums.  It make no sense to generate such a metadata for a repository that is never updated like fedora repository.

DNF does not know the future of any repository therefore it always download zchunk metadata if they are available. The consequence - bigger mirrors, more download required and it uses more disk space with no benefit - only the same setting is used by distribution to generate `fedora` and `updates` repositories.

I propose to not generate zchunk metadata

Comment 1 Kevin Fenzi 2023-02-13 17:01:26 UTC

I think this is a completely reasonable idea... perhaps pungi could not do zchunk on 'final' releases?

Moving to pungi for comment...

Comment 2 Lubomír Sedlář 2023-02-14 08:27:03 UTC

The idea definitely makes a lot of sense. If the RC compose is not updated at any point, zchunk metadata is just taking space.

That being said, I'm not sure Pungi can reasonably stop generating it. Pungi doesn't really know what it's creating here. The way how it's configured is that there is a generic `createrepo_extra_args` option set to value `["--zck", "--zck-dict-dir=/usr/share/fedora-repo-zdicts/rawhide"]`. This gets used in the createrepo_c command.

Would it be possible to remove this option when config is prepared for the RC?

Comment 3 Fedora Release Engineering 2023-08-16 07:06:50 UTC

This bug appears to have been reported against 'rawhide' during the Fedora Linux 39 development cycle.
Changing version to 39.