Python plugin¶

The Python plugin can be used for Python projects where you would want to do any of the following things:

Import Python modules with a requirements.txt file.
Build a Python project that has a setup.py or pyproject.toml file.
Install packages using pip.

Keywords¶

This plugin uses the common plugin keywords as well as those for sources.

Additionally, this plugin provides the plugin-specific keywords defined in the following sections.

python-requirements¶

Type: list of strings

List of paths to requirements files.

python-constraints¶

Type: list of strings

List of paths to constraint files.

python-packages¶

Type: list

A list of dependencies to install from PyPI. If needed, pip, setuptools and wheel can be upgraded here.

Environment variables¶

This plugin also sets environment variables in the build environment. These are defined in the following sections.

PARTS_PYTHON_INTERPRETER¶

Default value: python3

The interpreter binary to search for in PATH.

PARTS_PYTHON_VENV_ARGS¶

Default value: (empty string)

Additional arguments for venv.

Dependencies¶

By default this plugin uses Python from the base when it is available and appropriate to use. This depends on the tool and format in use.

The bases used by Rockcraft do not contain Python, so it will need to be supplied in ROCKs that use it.
Snaps that use strict confinement will use the version of Python in the base. Snaps that use classic confinement will use the host system’s Python.

If a different interpreter is desired, it must be bundled (including the venv module) and its path must be included in the PATH environment variable.

Use of python3-<python-package> in stage-packages will force the inclusion of the Python interpreter.

How it works¶

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

It creates a virtual environment directly into the ${CRAFT_PART_INSTALL} directory.
It uses pip to install the required Python packages as configured in the python-requirements, python-constraints and python-packages keywords.
If the source contains a setup.py or pyproject.toml file, those files are used to install the dependencies specified by the package itself.