Changes/DynamicBuildRequires

Dynamic BuildRequires

Summary

Add possibility to generate build-time dependencies within RPM spec file and teach RPM and mock how to handle this.

Owner

• Name: Igor Gnatenko, Florian Festi, Miroslav Suchý
• Email: ignatenkobrain@fedoraproject.org, ffesti@redhat.com, miroslav@suchy.cz
• Release notes owner:

Current status

• Targeted release: Fedora 31
• Last updated: 2019-04-12
• Tracker bug: <will be assigned by the Wrangler>

Detailed Description

For many languages (Rust, Golang, Node.Js, Ruby, Python), BuildRequires can be automatically generated. All it takes, run some special tool which will output dependencies in RPM format.

rpmbuild

• New %generate_buildrequires section ("script" later in text) in spec file
• New option -br which will run script, check dynamic BuildRequires
  • If all of them are satisfied, generate src.rpm
  • If some of them are not satisfied or --nodeps is present, generate buildreqs.nosrc.rpm
• src.rpm produced by rpmbuild -ba will contain dynamic BuildRequires
• Option -bs does not change behavior

mock

• New option in config dynamic_buildrequires which controls support of new features
• Support for rpmbuild changes if this option enabled

Benefit to Fedora

Packagers won't have to pre-generate BuildRequires in the spec file which means it will be always updated (and correct) :

• Packagers can focus of making their packages better instead of spending all their packaging time copying BuildRequires from documentation and third party tools.
• BuildRequires are dropped as soon as they're no longer necessary
• Packages can be easily bumped without requiring a manual BuildRequires refresh
• BuildRequires and Requires generation can use similar utilities, making sure that the deps packages declare can also be used for second-level building. Packages no longer need to declare the deps of their second and n-th dependencies because someone forgot to declare them in the correct package.

Scope

• Proposal owners: Implement support for a feature in RPM and mock. Make use of it in interested ecosystems.
• Other developers: Maintainers of language stacks are advised to use this feature.
• Release engineering: #8129
  • List of deliverables: N/A
• Policies and guidelines: Packaging Guidelines need to be updated with instructions how to use this feature.
• Trademark approval: N/A (not needed for this Change)

Upgrade/compatibility impact

Packagers and users who use repoquery might be affected (src.rpm might not contain generated dependencies).

How To Test

1. Make sure you have new rpm-build (OPTION 1) or mock (OPTION 2).
2. Add %generate_buildrequires script into spec file which prints dependencies, remove static BuildRequires
3. Build package
   1. OPTION1: Run rpmbuild -ba with your usual workflow
   2. OPTION2: Run mock -r fedora-rawhide-x86_64 with your usual workflow
4. Check that your package builds fine, dependencies are getting checked/installed and final src.rpm contains generated BuildRequires

User Experience

Users won't notice differences.

Dependencies

Required feature needs to be implemented in RPM and mock.

Contingency Plan

• Contingency mechanism: (What to do? Who will do it?) Proposal Owners might still ship feature disabled for Fedora buildsystem but have it available for end-users, and move full completion to the next release.
• Contingency deadline: Beta Freeze
• Blocks release? No.
• Blocks product? No.

Documentation

TBD.

Release Notes

TBD.