Python plugin¶

The Python plugin builds charms written in Python. It’s typically used in conjunction with the Operator framework.

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.

python-keep-bins¶

Type: boolean Default: False

Whether to keep python scripts in the virtual environment’s bin directory.

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¶

This plugin creates a Python virtual environment in the venv directory of your charm using the version of Python included with your base and the requirements files provided in the python-requirements key.

Note

The python plugin prevents pip from installing dependencies for the required packages. Therefore, requirements must include indirect dependencies as well as direct dependencies. It is recommended that you use a tool such as pip-compile or uv to manage the contents of your requirements.txt file.

How it works¶

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

It creates a virtual environment in the ${CRAFT_PART_INSTALL}/venv directory.
It uses pip to install the required Python packages specified by the python-requirements, python-constraints and python-packages keys.
It copies any existing src and lib directories from your charm project into the final charm.

Example¶

The following charmcraft.yaml file can be used with a standard charm structure to build a charm for Ubuntu 24.04:

name: my-charm
type: charm
title: My Python charm
summary: An operator charm that uses the python plugin
description: |
  An operator charm using the Python plugin.
base: [email protected]
platforms:
  amd64:
parts:
  my-charm:
    source: .
    plugin: python
    python-requirements:
      - requirements.txt