Managing Pinned Dependencies for Python Packages with uv

Note#126

notes
Published

2023-10-04

There was pip-tools, but now there is uv.

pipx install uv

What is uv

uv should replace pip, pip-tools, and even virtualenv.

A drop-in compatible API

This initial release centers on what we refer to as uv’s pip API. It’ll be familiar to those that have used pip and pip-tools in the past:

Instead of pip install, run uv pip install to install Python dependencies from the command line, a requirements file, or a pyproject.toml.

Instead of pip-compile, run uv pip compile to generate a locked requirements.txt.

Instead of pip-sync, run uv pip sync to sync a virtual environment with a locked requirements.txt.

Advanced Resolution Strategies

  • uv supports alternate resolution strategies. By default, uv follows the standard Python dependency resolution strategy of preferring the latest compatible version of each package. But by passing --resolution=lowest, library authors can test their packages against the lowest-compatible version of their dependencies.

  • uv allows for resolutions against arbitrary target Python versions. While pip and pip-tools always resolve against the currently-installed Python version (generating, e.g., a Python 3.12-compatible resolution when running under Python 3.12), uv accepts a --python-version parameter, enabling you to generate, e.g., Python 3.7-compatible resolutions even when running under newer versions.

  • uv allows for dependency “overrides”. uv takes pip’s “constraints” concepts a step further via overrides (-o overrides.txt), which allow the user to guide the resolver by overriding the declared dependencies of a package. Overrides give the user an escape hatch for working around erroneous upper bounds and other incorrectly-declared dependencies.

References