Automatically generated Obsoletes tags?
Hi,
I'm working on a way to automatically generate Obsoletes tags for Python
packages. I.e. for each `python3-foo` package, the automatic generator
would create a tag `Obsoletes: python3.10-foo < X-Y` (assuming python3
version is 3.10).
Currently we automatically generate only Provides tags, but not
Obsoletes, and when updating to a newer "main" Python version, a user
might get file conflicts during the dnf transaction (e.g. files from
python3.10-requests would conflict with files from python3-requests). If
we have the automatic Obsoletes, `python3-foo` packages would always
take precedence over any older `python3.X-foo`, as they should.
To be frank, we don't truly need this in Fedora right now: We only ship
alternative Python interpreters (e.g. python3.8, python3.9), but we do
not ship additional packages for these alternative Pythons (e.g. we have
no python3.9-requests).
However, this will be useful for downstream distributors (e.g. CentOS,
RHEL, ...), or in cases where somebody builds custom packages for
alternative stacks in Fedora.
The downside is that we will have a few thousand (est. 3624 [1])
additional Obsoletes tags in the Fedora repos that are mostly useless.
Does anyone see a problem with this? Given the amount of tags already
present (e.g. 336 thousand provides [2], 80 thousand requires [3] and
7.5 thousand obsoletes [4]), I think it won't negatively affect
anything, but I might be mistaken.
I think it would be useful to have the generator enabled by default, but
of course to account for corner cases, I'd implement an opt-out macro
(similar to `%python_disable_dependency_generator`). And to make the
automatic generator consistent with the manual macros, I would modify
the `%py_provides` macro to also generate Obsoletes tags.
What do you think?
[1] repoquery --repo=rawhide --provides -a | grep '^python3\.10-' | wc -l
[2] repoquery --repo=rawhide --provides -a | wc -l
[3] repoquery --repo=rawhide --requires -a | wc -l
[4] repoquery --repo=rawhide --obsoletes -a | wc -l
All the best,
Tomas Orsava