BuildRequires

BuildRequires is a directive in an RPM spec file that declares packages that must be installed in the build environment in order to compile and build the software. It complements Requires, which lists runtime dependencies; BuildRequires specifies only what is needed during the building and packaging process.

When a package is built, the build system (such as rpmbuild in the local environment or a build system like mock or Koji) ensures that all BuildRequires packages are installed into the build chroot or environment. The resulting binary package typically does not list these build-time packages as runtime dependencies, unless they are also needed at runtime by the installed software.

Specifically, BuildRequires lines indicate the exact packages required to perform a successful build. They can include version constraints as well, such as BuildRequires: gcc >= 4.8.1 or BuildRequires: libfoo-devel. Some projects use the pkgconfig syntax, for example BuildRequires: pkgconfig(libxml-2.0), to ensure the necessary development metadata is available during compilation.

Best practices emphasize keeping BuildRequires focused on what is truly necessary for the build, specifying precise version constraints when applicable, and avoiding the inclusion of runtime-only libraries. Proper use of BuildRequires contributes to reproducible builds and reliable build environments, particularly for automated build systems like Koji, Mock, or other CI-like workflows used in RPM-based distributions.