Python plugin (v2)¶

The Python plugin (v2) is the successor to the Python plugin. It 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 with pip.

Keys¶

This plugin provides the following unique keys.

python-requirements¶

Type: list of strings

List of paths to requirements files.

python-packages¶

Type: list of strings

Additional Python packages to install with pip.

Environment variables¶

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

PIP_PYTHON¶

Default value: The first instance of python3 in the PATH.

The Python interpreter for pip to use.

Dependencies¶

The Python plugin (v2) needs the python3 executable, but it does not provision it itself and won’t use a system-wide executable.

The recommended way of providing python3 is to install it as a stage-package. The recommended way of providing a Python executable to the plugin is to install it as a stage-package. Alternatively, a part can be added to build python3 from source and stage the binary. Then, the consuming part can declare its dependence on the binary by using the after key, like so:

parts:
  python-bin:
    plugin: autotools
    source: https://github.com/python/cpython.git
    stage:
      - ./python

  python-app:
    plugin: python
    source: .
    after:
      - python-bin

How it works¶

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

It sets PIP_USER to 1, equivalent to the --user argument. The the pip documentation describes this argument in detail.
The PYTHONUSERBASE is set to the part’s install directory, which pip uses as a destination.
Pip is used to install all of the requirements from python-requirements and packages from python-packages. This step will also install the project described in the setup.py or pyproject.toml file, if present.
A sitecustomize file is created, which adds the files from the part’s install directory to Python’s runtime import path.