hatch-min-requirements 0.1.0

Hatchling plugin to create optional-dependencies pinned to minimum versions

hatch-min-requirements

Hatchling plugin to create optional-dependencies pinned to minimum versions

Rationale

When creating a library, it is often useful to specify the minimum version of a dependency that is required. However, pip's default behavior is to install the latest version of a package that satisfies your requirement. As a result, if aren't carefully testing your minimum dependencies, you may inadvertently introduce changes to your package that are not compatible with the minimum version you specified.

This plugin will inspect your packages dependencies and dynamically add an extra (named min-reqs by default) to the project.optional-dependencies table of your pyproject.toml file. This extra will contain all of your dependendencies pinned to their minimum version.

This makes it easy to test your package against your minimum stated dependencies on CI, or to install your package with the minimum dependencies for local development.

Usage

In your pyproject.toml make the following changes:

• Append hatch-min-requirements to [build-system.requires].
• Add a [tool.hatch.metadata.hooks.min_requirements] table.

[build-system]
requires = ["hatchling", "hatch-min-requirements"]
build-backend = "hatchling.build"

[tool.hatch.metadata.hooks.min_requirements]

Then, you can install your package using the min-reqs extra and it will dynamically use the minimum compatible versions of your dependencies.

pip install -e .[min-reqs]

Environment variables

Environment variables can be used to configure the behavior. Described in detail below:

Variable	Default	Description
MIN_REQS_EXTRA_NAME	min-reqs	The name of the extra to add to pyproject.toml
MIN_REQS_PIN_UNCONSTRAINED	True	Pin unconstrained dependencies to minimum available version on PyPI. (e.g. numpy -> numpy==1.3.0)
MIN_REQS_OFFLINE	False	Do not connect to PyPI to fetch available versions
MIN_REQS_TRY_PIP	True	Use pip to fetch available versions in online mode. Set to 0 to use stdlib tools only

Utilities

This package provides two convenience functions that can be used directly (without being a hatch plugin).

• hatch_min_requirements.sub_min_compatible_version

  Takes a pip requirement string and returns a new requirement string with the minimum compatible version substituted in.

  >>> sub_min_compatible_version("numpy")
  'numpy==1.3.0'
  >>> sub_min_compatible_version("numpy>=1.4.1")
  'numpy==1.4.1'
  >>> sub_min_compatible_version("numpy>1.3")
  'numpy==1.4.1'
  >>> sub_min_compatible_version("numpy[extra1,extra2]>=1.20,<2.0")
  'numpy[extra1,extra2]==1.20.0'
  >>> sub_min_compatible_version("numpy[extra]<2; python_version == '3.6'")
  "numpy[extra]==1.3.0 ; python_version == '3.6'"
  

• hatch_min_requirements.patch_pyproject

  Takes a path to a pyproject.toml file and patches it to include the min-reqs extra. The original file is backed up with a .BAK extension.

  >>> patch_pyproject("path/to/pyproject.toml")
  

Considerations

Dependencies with no constraints

In cases of dependencies declared without constraints (e.g. foo), the plugin will search for the minimum available version of the package from PyPI. The goal here is to encourage accurate requirement pinning. If you want to disable this behavior and leave unconstrained specifiers as is, you can either set the MIN_REQS_PIN_UNCONSTRAINED environment variable to 0 or False, or use offline mode with MIN_REQS_OFFLINE=1 (see below).

Offline Mode

In cases such as upper-bounds (<X.Y), non-inclusive lower bounds (>X.Y), and exclusions (!=X.Y), it's not possible to declare a minimum version without fetching available versions from PyPI. By default, this plugin will attempt to connect to PyPI in order to determine compatible minimum version strings. If you want to disable this behavior, you can set the MIN_REQS_OFFLINE environment variable to 1 or True.

MIN_REQS_OFFLINE=1 pip install -e .[min-reqs]

In offline mode, no attempt is made to guess the next compatible version of a package after a non-inclusive lower bound. Instead, the plugin will simply use your dependency as stated (meaning you won't be testing lower bounds). If you want to test lower bounds without connecting to PyPI, you should pin your dependencies with inclusive lower bounds:

[project]
dependencies = [
    "foo>=1.2.3"  # will be pinned to "foo==1.2.3"
    "baz~=1.2"    # will be pinned to "baz==1.2"
    "bar>1.2.3"   # will be unchanged
]

Usage of pip vs standard-lib tools

Fetching the available versions of a package is not trivial, and pip is the de facto tool for doing so. If pip is available in the build environment, this plugin will use it to fetch the available versions of a package. But, you must opt in to this behavior by adding pip to your build-system.requires in pyproject.toml:

[build-system]
requires = ["hatchling", "hatch-min-requirements", "pip"]

To explicitly opt out of using pip (even if it's available) and use standard library tools only, you can set the MIN_REQS_TRY_PIP environment variable to 0 or False.

TODO

• add offline and no-pip options to the min_requirements table in pyproject