The python plugin

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The python plugin can be used by either Python 2 or Python 3 based parts using a setup.py script for building the project, or using a package published to PyPI, and optionally any of the following:

  • A requirements.txt file used to import Python modules.
  • Packages installed directly from pip.

This plugin uses the common plugin key as well as those for sources. For details about these keys, see the reference on parts directives.

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

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

ⓘ This is a snapcraft plugin. See Snapcraft plugins and Supported plugins for further details on how plugins are used.

base: core24 | core22

This plugin uses the following plugin-specific keywords:

  • python-requirements (list) List of paths to requirements.txt file(s). Paths are relative to the value provided by the source key.
  • python-constraints (list) List of paths to constraint files.
  • python-packages (list, default: [pip, setuptools, wheel])
    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:

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

  • PARTS_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 7.0+ for core22.

Requires Snapcraft version 8.0+ for core24.

base: core20

This plugin uses the following plugin-specific keywords:

  • requirements (array) List of paths to requirements.txt file(s). Paths are relative to the value provided by the source key.
  • 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). Paths are relative to the value provided by the source key.

  • 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.

2

This plugin now supports quite an old version of Python 3 which should be perhaps upgraded to 3.6 or 3.7.

Python 3.5.2 (default, Nov 12 2018, 13:43:14) 
[GCC 5.4.0 20160609] on linux
1 Like
3

Update the GitHub search query to https://github.com/search?q=path%3A**%2Fsnapcraft.yaml+%22plugin%3A+python%22&type=code using the path qualifier

4

Thanks for the suggestion - your search query doesn’t work for me. Is there any advantage to this approach?

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GitHub-Search-Snapcraft
GitHub-Search-Snapcraft1013×689 50 KB

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image
image937×573 46.2 KB

7

This documentation doesn’t seem to mention pyproject.toml while the source code does.

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To me it really wasn’t clear that these paths seem to be relative to the source keyword, and therefore cannot be used to add requirements to a build pulling from an external git repo. I would suggest slightly rewording these lines to - for example - “(list) List of paths to requirements.txt file(s). Paths are relative to the value provided by the source key”

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Thanks so much for raising this, and for the suggestion. I’ve updated the document accordingly.

10

This is incorrect; setting this variable results in only those arguments being passed to python3 -m venv; see here