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Repodata created with createrepo_c new defaults will not be compatible with fedora < 30 and RHEL < 8.4 (including RHEL 7,6..). | Repodata created with createrepo_c new defaults will not be compatible with fedora < 30 and RHEL < 8.4 (including RHEL 7,6..). | ||
This is mainly due to zstd compression but old YUM also cannot handle the changed mdtype of groups (it is compatible only with uncompressed "group" and compressed "group_XX" not compressed "group"). | This is mainly due to zstd compression but old YUM also cannot handle the changed mdtype of groups (it is compatible only with uncompressed "group" and compressed "group_XX" not compressed "group"). | ||
Regarding the sqlite databases if some other users would require them they can always download the xml metadata and use sqliterepo_c to generate them locally. | |||
== How To Test == | == How To Test == | ||
Revision as of 12:42, 13 March 2023
createrepo_c changes of defaults in 1.0.0
This document represents a proposed Change. As part of the Changes process, proposals are publicly announced in order to receive community feedback. This proposal will only be implemented if approved by the Fedora Engineering Steering Committee.
Summary
Update createrepo_c to 1.0.0, new release will include change of default compression to zstd, no longer generating metadata in sqlite database format by default and simplified comps xml type in repodata.
Owner
- Name: Aleš Matěj
- Email: amatej@redhat.com
Current status
- Targeted release: Fedora Linux 39
- Last updated: 2023-03-13
- FESCo issue: <will be assigned by the Wrangler>
- Tracker bug: <will be assigned by the Wrangler>
- Release notes tracker: <will be assigned by the Wrangler>
Detailed Description
- Switch default compression from gz to zstd. DNF is able to decompress zstd via libsolv since Fedora 30 and RHEL 8.4. It will still be possible to create gz compressed repodata by manually specifying gz compression. Further information: https://github.com/rpm-software-management/createrepo_c/issues/82, https://bugzilla.redhat.com/show_bug.cgi?id=1914876
- Stop generating metadata in sqlite database format by default. It will still be possible to create them using a --database switch or via sqliterepo_c tool. (It looks like the only user left is mdapi: https://github.com/fedora-infra/mdapi/issues/97). Further information: https://github.com/rpm-software-management/createrepo_c/issues/338 and https://pagure.io/releng/issue/10745
- When adding groups.xml to repodata createrepo_c currently adds two variants to repomd.xml. The specified file as is, uncompressed, with the type "group" and also a compressed variant with type "group_XX", where XX is compression suffix. This is atypical and unexpected. We propose to include just one variant of groups.xml using specified compression and repomd.xml type "group". If required users will still be able to create repositories with the old layout using modifyrepo_c. Further information: https://bugzilla.redhat.com/show_bug.cgi?id=2056318
- To reflect API and overall stability increase major version above 0.
Feedback
Benefit to Fedora
- Using zstd compression provides smaller metadata that are faster to decompress.
- Generating sqlite metadata is expensive, its slowing createrepo_c runs and it takes up space on mirrors. (For F37 updates repo: primary_db: 12.8 mb, filelists_db: 22.0 mb, other_db: 4.2 mb.)
- More consistent metadata, groups use the same logic as other metadata types. Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1904360
Scope
- Proposal owners: Implement specified changes, mostly changes of default.
- Other developers: There are no requirements on other developers.
- Release engineering: #Releng issue number
- Policies and guidelines: N/A (not needed for this Change)
- Trademark approval: N/A (not needed for this Change)
- Alignment with Objectives:
Upgrade/compatibility impact
Repodata created with createrepo_c new defaults will not be compatible with fedora < 30 and RHEL < 8.4 (including RHEL 7,6..). This is mainly due to zstd compression but old YUM also cannot handle the changed mdtype of groups (it is compatible only with uncompressed "group" and compressed "group_XX" not compressed "group").
Regarding the sqlite databases if some other users would require them they can always download the xml metadata and use sqliterepo_c to generate them locally.
How To Test
Repositories generated with updated createrepo_c have to work with dnf. Specifically we should ensure that groups are still loaded.
User Experience
The only noticeable effect should be smaller metadata thanks to zstd compression resulting in faster downloads (when zchunk is not used). The (de)compression speed up is not very noticeable.
For example for F37 fedora repo:
- primary.xml.gz: 18M -> primary.xml.zst: 14M
- filelists.xml.gz: 52M -> filelists.xml.zst: 41M
- other.xml.gz: 6.9M -> other.xml.zst: 5.4M
Dependencies
Updating createrepo_c does not require any other change requests to complete first.
These packages might be affected by the described changes if they use the default configuration:
bodhi-server copr-backend dnf5 libguestfs modulemd-tools prunerepo pungi retrace-server swid-tools anaconda-install-env-deps cobbler ddiskit koji-builder mock module-build perl-Fedora-Rebuild python3-dlrn python3-dnf-plugin-local python3-dnf-plugin-modulesync python3-rpmfluff retrace-server
Contingency Plan
- Contingency mechanism: There would be no action necessary. We can even ship only part of the changes as they don't depend on each other.
- Contingency deadline: 2023-08-08
- Blocks release? No
Documentation
Createrepo_c documentation will be updated accordingly.