ducktools-env 0.1.0

Virtual environment management tools and application bundle builder

DuckTools: Env

ducktools-env intends to provide a few tools to aid in running and distributing applications and scripts written in Python that require additional dependencies.

What is this for?

Or: uv/hatch/pipx already exist, why are you creating yet another packaging tool?

PEP-723 introduced inline script metadata which allows users to declare dependencies for single python files in a standardized format.

Using this format requires the use of an extra package such as 'UV' or 'hatch' using a specific command such as uv run my_script.py or hatch run my_script.py.

ducktools.env provides a similar command python ducktools.pyz run my_script.py or python -m ducktools.env run my_script.py.

The problem that ducktools.env seeks to solve is what if you want to share your script or application with someone who doesn't already have uv or hatch or any other script runner that recognises this format.

To aid this, ducktools.env provides the bundle command.

python ducktools.pyz bundle my_script.py

This will generate a zipapp from your script that will automatically extract and run it in the same way as with the run command.

This bundle will include ducktools-env and the pip zipapp in order to bootstrap the unbundling process. UV will be downloaded and installed on unbundling if it is available (on PyPI) for the platform.

Environment data and the application itself will be stored in the following locations:

• Windows: %LOCALAPPDATA%\ducktools\env
• Linux/Mac/Other: ~/.ducktools/env

Discovering Python Installs

When you run a script with ducktools-env it will look at the inline dependencies.

It will use ducktools-pythonfinder to attempt to find the newest valid python install (not a venv) that satisfies any python requirement. See its own page for which python installs it can find.

Usage

Either install the tool from PyPI or simply download the zipapp from github.

If using the tool from PyPI the commands are python -m ducktools.env <command> with the zipapp they are python ducktools.pyz <command>

Run a script that uses inline script metadata: python ducktools.pyz run my_script.py

Bundle the script into a zipapp: python ducktools.pyz bundle my_script.py

Clear the temporary environment cache: python ducktools.pyz clear_cache

Clear the full ducktools/env install directory: python ducktools.pyz clear_cache --full

Build the env folder from the installed package Generally you should not need to do this from the zipapp python -m ducktools.env rebuild_env

Locking environments

When generating zipapp bundles it may be desirable to also generate a lockfile to make sure that the versions of installed dependencies do not change between generation and execution without having to over specify in the original script.

This generation feature uses uv which will be automatically installed. uv is not required to use the generated lockfile (but will usually be installed).

Create a lockfile without running a script python ducktools.pyz generate_lock my_script.py

Run a script and output the generated lockfile (output as my_script.py.lock) python ducktools.pyz run --generate-lock my_script.py

Run a script using a pre-generated lockfile python ducktools.pyz run --with-lock my_script.py.lock my_script.py

Bundle a script and generate a lockfile (that will be bundled) python ducktools.pyz bundle --generate-lock my_script.py

Bundle a script with a pre-generated lockfile python ducktools.pyz bundle --with-lock my_script.py.lock my_script.py

Including data files with script bundles

If you wish to include data files with your script you can do so using a tool table in the toml block.

# /// script
# requires-python = ">=3.10"
# dependencies = ["cowsay"]
# 
# [tool.ducktools.env]
# bundle.data = ["path/to/folder", "path/to/file.txt"]
# ///

If this is made into a bundle these files and folders will be collected into a bundle_data folder included in the zipapp.

This data can be retrieved on demand using get_data_folder from ducktools.env.bundled_data which will create a temporary folder containing a copy of the data files and return the path to the folder.

Note: Paths are relative to the script folder. If you include a folder, the folder itself will be included, not just its contents. This means that if you include ./ you will get the name of the folder the script is in (along with all of its contents).

# /// script
# requires-python = ">=3.12"
# dependencies = ["ducktools-env>=0.1.0"]
# 
# [tool.ducktools.env]
# bundle.data = ["./"]
# ///
from pathlib import Path

from ducktools.env.bundled_data import get_data_folder 

with get_data_folder() as fld_name:
    for f in Path(fld_name).rglob("*"):
        print(f)

Goals

Future goals for this tool:

• Optionally bundle requirements inside the zipapp for use without a connection.
• Allow bundling of local wheel files unavailable on PyPI
• Create 'permanent' named environments for stand-alone applications and update them
  • Currently there is a maximum of 2 temporary environments that expire in a day (this is due to the pre-release nature of the project, the future defaults will be higher/longer)
• Automatically install required Python if UV is available

Dependencies

Currently ducktools.env relies on the following tools.

Subprocesses:

• venv (via subprocess on python installs)
  • (Might eventually use virtualenv as there are python installs without venv)
• pip (as a zipapp via subprocess)
• uv where available as a faster installer and for locking dependencies for bundles

PyPI:

• ducktools-classbuilder (A lazy, faster implementation of the building blocks behind things like dataclasses)
• ducktools-lazyimporter (A simple class based tool to handle deferred imports)
• ducktools-scriptmetadata (The parser for inline script metadata blocks)
• ducktools-pythonfinder (A tool to discover python installs available for environment creation)
• packaging (for comparing dependency lists to cached environments)
• tomli (for Python 3.10 and earlier to support the TOML format)

Other tools in this space

zipapp

The standard library zipapp is at the core of how ducktools-env works. However it doesn't support running with C extensions and it has no inbuilt way to control which Python it will run under.

By contrast ducktools-env will respect a specified python version and required extensions, these can be bundled or downloaded on first launch via pip.

Shiv

shiv allows you to bundle zipapps with C extensions, but doesn't provide for any online installs and will extract everything into one ~/.shiv directory unless otherwise specified. ducktools-env will create a separate environment for each unique set of requirements for temporary environments by matching specification.

PEX

pex provides an assortment of related tools for developers alongside a .pex bundler. It doesn't (to my knowledge) have support for inline script metadata and it makes .pex files instead of .pyz files.

PyInstaller

Pyinstaller will generate an executable from your script but will also bundle all of your dependencies in a platform specific way. It also bundles Python itself, which while convenient if python is not installed, is unnecessary if we can treat Python as a shared library.

Hatch

Hatch allows you to run scripts with inline dependencies, but requires the user on the other end already have hatch installed. The goal of ducktools-env is to make it so you can quickly bundle the script into a zipapp that will work on the other end with only Python as the requirement.

pipx

pipx is another tool that allows you to install packages from PyPI and run them as applications based on their [project.scripts] and [project.gui-scripts]. This is a goal of ducktools.env, except it would build separate zipapps for each script and the apps would share the same cached python environment.