The python plugin

The python plugin can be used by either Python 2 or Python 3 based parts using one of the following:

• a requirements.txt file used to import Python modules
• a setup.py script for building the project
• packages installed directly from pip

This plugin uses the common plugin keywords as well as those for “sources”. For more information, see Snapcraft parts metadata.

Plugin-specific features and syntax are dependent on which base is being used, as outlined below:

• base: core20
• base: core18 | core

See Python applications for a simple example, or search GitHub for projects already using the plugin.

base: core20

This plugin uses the following plugin-specific keywords:

• requirements (array)
  List of paths to requirements.txt file(s)
• constraints (string)
  Path to a constraints file.
• python-packages (list)
  A list of dependencies to install using pip. This supports the same syntax as the pip install command.

This plugin also interprets these specific build-environment entries:

• SNAPCRAFT_PYTHON_INTERPRETER
  (default: python3)
  The interpreter binary to search for in PATH.

• SNAPCRAFT_PYTHON_VENV_ARGS
  Additional arguments for venv.

By default, this plugin uses Python from the base snap. If a part using this plugin uses a build-base other than that of the base, or a different interpreter is desired, it must be bundled in the snap (including venv) and must be in PATH.

It is required to bundle python when creating a snap that uses classic confinement, this can be accomplished on Ubuntu by adding stage-packages (i.e.; python3-venv).

Use of python3- in stage-packages will force the inclusion of the python interpreter.

Requires Snapcraft version 4.0+.

base: core18 | core

This plugin uses the following plugin-specific keywords:

• requirements (array)
  List of paths to requirements.txt file(s)

• constraints (string)
  Path to a constraints file

• process-dependency-links (bool; default: false)
  Enable the processing of dependency links in pip, which allow one
  project to provide places to look for another project

• python-packages (list)
  A list of dependencies to install using pip. This supports the same syntax as the pip install command. For example:

  python-packages:
    - docopt == 0.6.1  # Install specific versions
    - git+https://github.com/inuits/mkdocs-factsheet.git  # Install from a git repository
    - https://github.com/cmacmackin/markdown-include/archive/v0.5.1.tar.gz  # Install from an archive
  

  See the pip install docs for more information.

• python-version (string; default: python3)
  The python version to use. Valid options are python2 and python3

The python plugin also searches <stage-dir>/usr/bin/<python-interpreter> for a Python interpreter with a basename matching python-version in the <stage> directory. If detected, this takes preference and stage-packages will not use its own interpreter.