uv plugin

The uv plugin can be used for Python projects that use the uv build tool.

Keywords

In addition to the common plugin and sources keywords, this plugin provides the following plugin-specific keywords:

uv-extras

Type: list of strings

Extra dependencies to build with. Each element of the list is passed exactly as --extra EXTRA.

uv-groups

Type: list of strings

Extra dependency groups to build with. Each element of the list is passed exactly as --group GROUP.

Environment variables

Along with the variables defined by the Python plugin, this plugin responds to its own special variables.

Note

This section describes how this plugin uses uv-specific environment variables. For more information, as well as a complete list of environment variables for uv, see the uv environment documentation.

UV_FROZEN

Default value: true

Whether or not to update the uv.lock file. If true, uv.lock must exist and will be used as the single source of truth for dependency versions, with no attempt made to update them before installation.

UV_PROJECT_ENVIRONMENT

Default value: See below

A path to the Python virtual environment to build with. By default, this variable populates itself with the directory in which this plugin will create the virtual environment.

UV_PYTHON_DOWNLOADS

Default value: “never”

Whether or not to automatically download Python if the requested version is missing.

UV_PYTHON

Default value: ${PARTS_PYTHON_INTERPRETER}

The version of Python that uv should use. See Python plugin environment variables for more information.

UV_PYTHON_PREFERENCE

Default value: “only-system”

Possible values: only-system, only-managed, system, managed

Whether uv should prefer (or exclusively use) system or uv-managed Python versions.

Dependencies

Whether the Python interpreter needs to be included in the snap depends on its confinement. Specifically:

  • Projects with strict or devmode confinement can safely use the base snap’s interpreter, so they typically do not need to include Python.

  • Projects with classic confinement cannot use the base snap’s interpreter and thus must always bundle it (typically via stage-packages).

  • In both cases, a specific/custom Python installation can always be included in the snap. This can be useful, for example, when using a different Python version or building an interpreter with custom flags.

Snapcraft will prefer an included interpreter over the base’s, even for projects with strict and devmode confinement.

How it works

During the build step, the plugin performs the following actions:

  • It creates a virtual environment in the ${CRAFT_PART_INSTALL} directory.

  • It uses uv sync to install the required Python packages from the provided uv.lock file.

See also

Python plugin

Poetry plugin