experimental/sources/: fromager-0.1.0 metadata and description

Simple index

Wheel maker

author_email Mark McLoughlin <markmc@redhat.com>, Doug Hellmann <dhellmann@redhat.com>
  • Development Status :: 5 - Production/Stable
  • Environment :: Console
  • Intended Audience :: Developers
  • License :: OSI Approved :: BSD License
  • Operating System :: OS Independent
  • Programming Language :: Python
  • Programming Language :: Python :: 3
  • Programming Language :: Python :: 3 :: Only
  • Programming Language :: Python :: 3.11
  • Programming Language :: Python :: 3.12
  • Programming Language :: Python :: Implementation :: CPython
  • Topic :: Utilities
description_content_type text/markdown
provides_extras build
  • html5lib
  • packaging
  • pkginfo
  • PyYAML
  • pyproject_hooks!=1.1.0,>=1.0.0
  • python-gitlab
  • python-pypi-mirror
  • requests
  • resolvelib
  • stevedore
  • tomli
  • pytest; extra == "test"
  • pytest-cov; extra == "test"
  • coverage!=4.4,>=4.0; extra == "test"
  • build; extra == "build"
  • twine; extra == "build"
requires_python >=3.11
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Fromager is a tool for completely re-building a dependency tree of Python wheels from source.

The goals are to support guaranteeing

  1. The binary package someone is installing was built from source in a known build environment compatible with their own environment
  2. All of the package’s dependencies were also built from source -- any binary package installed will have been built from source
  3. All of the build tools used to build these binary packages will also have been built from source


Fromager has different modes for bootstrapping and production builds. The bootstrap mode recursively processes all dependencies starting from the requirements specifications given to determine what needs to be built and what order to build it. The production build commands separate these steps and avoid recursive processing so each step can be performed in isolation.


The bootstrap command

Wheels are built by running pip wheel configured so it will only download dependencies from the local wheel repository. This ensures that all dependencies are being built in the correct order.

Production Builds

Production builds use separate commands for the steps described as part of bootstrapping, and accept arguments to control the servers that are used for downloading source or built wheels.

The download-source-archive command finds the source distribution for a specific version of a dependency on the specified package index and downloads it. It will be common to run this step with pypi.org, but for truly isolated and reproducible builds a private index server is more robust.

The prepare-source command unpacks the source archive downloaded from the previous step and applies any patches (refer to customization for details about patching).

The prepare-build command creates a virtualenv with the build dependencies for building the wheel. It expects a --wheel-server-url as argument to control where built wheels can be downloaded.

The build command prepares a wheel, compiling any extensions using the appropriate override environment settings (refer to customization for details about overrides).

Additional docs

What's with the name?

Python's name comes from Monty Python, the group of comedians. One of their skits is about a cheese shop that has no cheese in stock. The original Python Package Index (pypi.org) was called The Cheeseshop, in part because it hosted metadata about packages but no actual packages. The wheel file format was selected because cheese is packaged in wheels. And "fromager" is the French word for someone who makes or sells cheese.