versioneer

Versioneer is an open-source tool for Python packaging that automates management of a project's version number by deriving it from version control system tags, typically Git, and embedding it into the package during build. It helps keep release versions in sync with Git tags and reduces the need to manually edit version strings in source code.

At runtime, a project can retrieve the version from a generated interface rather than maintaining a hard-coded string. Versioneer creates a small version module inside the package (often named _version.py) and provides a helper script (versioneer.py) that exposes functions to obtain the current version, such as get_version(), and a setuptools-compatible cmdclass via get_cmdclass() for integration with build and sdist commands.

Usage typically involves installing Versioneer, running initialization commands in the project (for example, versioneer init and versioneer install) to configure the project and generate the necessary files, and then updating setup.py to use the version from Versioneer. When a Git tag like v1.2.3 is present, packaging and installations will report that version; if no tags exist, Versioneer can fall back to a placeholder such as 0+unknown or a development version.

Versioneer is primarily for Python projects and is one established approach among several for version management, offering a reproducible, tag-driven workflow that aligns package versions with source control tags. It is widely used in the Python ecosystem and maintained as an open-source project.