Walkthrough of Fedora 45's Package Building Process from Git Push to Release Artifacts

Introduction to Fedora's Build Process

This document provides a comprehensive walkthrough of the Fedora 45 'sausage factory,' detailing how source code and packages are converted into the final artifacts users download and install. These artifacts include ISOs, cloud images, container images, and OSTree deployments. The guide aims to be updated periodically to reflect changes in the Fedora release cycle.

Starting Point: dist-git

The process initiates when a packager pushes a commit to a package's Git repository. Fedora stores source definitions for each package in individual Git repositories at src.fedoraproject.org. Each repository contains an RPM spec file, downstream patches, and a sources file linking to upstream tarballs in a separate lookaside cache. Large binary files are kept out of Git, while other files are version-controlled within Git.

Packagers typically use the `fedpkg` CLI tool to interact with these repositories, performing operations like cloning, uploading source tarballs, submitting builds, and creating updates. The `fedpkg build` command constructs a URL pointing to a specific Git commit and passes it to Koji, ensuring build reproducibility from that commit hash. Repository branches correspond to releases, such as `rawhide` for development and `f44` for Fedora 44. The hosting is transitioning from Pagure to Forgejo.

Building Packages: Koji

Upon submission of the Git URL by `fedpkg build`, Koji, Fedora's build system, takes over. Koji has been in use since Fedora 7 and is responsible for building nearly all Fedora components.