check-sdist

Have you ever shipped broken SDists with missing files or possibly dirty SDists with files that shouldn't have been there? Have you noticed that standards compliant tools aren't making the same SDist that flit build is? Is hatchling adding .DSStore files when you ship from your macOS? No matter what build-backend you use, check-sdist can help!

Check-sdist builds an SDist and compares the contents with your Git repository contents. It can even temporarily inject common junk files (like pycache files or OS specific files) and help verify that those aren't getting bundled into your SDist. If you are getting files you didn't expect or missing files you did expect, consult your build backend's docs to see how to include or exclude files.

Quick start

To run with pipx:

$ pipx run check-sdist[uv]

Or, if you like uv instead (faster):

$ uvx check-sdist

You can add --no-isolation to disable build isolation (faster, but must preinstall build dependencies), --source-dir to select a different source directory to check, --inject-junk to temporarily inject some common junk files while running, and -v/--verbose to also print the SDist contents. You can select an installer for build to use with --installer=, choices are uv, pip, or uv|pip, which will use uv if available (the default).

check-sdist exits 0 if the SDist matches git. Otherwise it returns a bitfield: 1 if the SDist has files not tracked by git, 2 if it is missing files that are tracked by git, and 3 if both.

If you need the latest development version:

$ pipx run --spec git+https://github.com/henryiii/check-sdist check-sdist
$ uvx --from git+https://github.com/henryiii/check-sdist check-sdist

Pre-commit integration

To use the pre-commit integration, put this in your .pre-commit-config.yaml:

- repo: https://github.com/henryiii/check-sdist
  rev: v1.6.0
  hooks:
    - id: check-sdist
      args: [--inject-junk]
      additional_dependencies: [] # list your build deps here

This requires your build dependencies, but in doing so, it can cache the environment, making it quite fast. The installation is handled by pre-commit; see pre-commit-uv if you want to try to optimize the initial setup. You can also use prek, which is a Rust pre-commit compatible runner that uses uv. If uv is present (including in your additional_dependencies), the build will be slightly faster, as uv is used to do the build. If you don't mind slower runs and don't want to require a build dependency listing:

- repo: https://github.com/henryiii/check-sdist
  rev: v1.6.0
  hooks:
    - id: check-sdist-isolated
      args: [--inject-junk]

This one defaults to including uv in additional_dependencies; you shouldn't have to specify anything else.

Configuration

To configure, these options are supported in your pyproject.toml file:

[tool.check-sdist]
sdist-only = []
git-only = []
default-ignore = true
recurse-submodules = true
mode = "git"
build-backend = "auto"

You can add .gitignore style lines here, and you can turn off the default ignore list, which adds some default git-only files.

By default, check-sdist recursively scans the contents of Git submodules, but you can disable this behavior (e.g. to support older Git versions that don't have this capability).

You can also select mode = "all", which will instead check every file on your system. Be prepared to ignore lots of things manually, like *.pyc files, if you use this.

You can tell check-sdist to look for exclude lists for a specific build backend with build-backend, or "none" to only use its own exclude list. Build backends supported are listed below. The default, "auto", will try to detect the build backend if build-system.build-backend is set to a known value.

check-sdist will ignore *.dist-info in SDists, since those are generated. If the build backend is clearly setuptools and default-ignore is on, it will also ignore *.egg-info and setup.cfg, as setuptools can generate this. If you've wrapped your build backend, you'll need to add this to the sdist-only ignore list manually.

If default-ignore is on, a few common generated file settings will be read and included in sdist-only:

• setuptools-scm version file (modern version_file in pyproject.toml only, write_to is not supported)
• hatch-vcs version file (pyproject.toml only)
• pdm-backend version file
• scikit-build-core's generate feature

Plugins

Every build backend is a plugin registered under the check_sdist.backends entry-point group, keyed by its build-system.build-backend string. The following backends ship with check-sdist:

• setuptools.build_meta (setuptools)
• flit_core.buildapi (flit-core)
• hatchling.build (hatchling)
• scikit_build_core.build (scikit-build-core)
• pdm.backend (pdm-backend)
• poetry.core.masonry.api (poetry-core)
• maturin (maturin)
• uv_build (uv)

You can add support for another backend (or override a built-in one) by shipping a small class and registering it under that group. Once installed, auto detection will pick it up, and the build-backend config option will accept its name too.

from __future__ import annotations

from collections.abc import Iterator
from pathlib import Path
from typing import Any, ClassVar


class MyBackend:
    # build-system.build-backend strings this plugin claims (may be several)
    build_backends: ClassVar[tuple[str, ...]] = ("my_backend.api",)

    def git_only_excludes(
        self, pyproject: dict[str, Any], files: frozenset[str], source_dir: Path
    ) -> frozenset[str]:
        """Drop files the backend intentionally keeps out of the SDist."""
        return files

    def sdist_only_ignores(self, pyproject: dict[str, Any]) -> Iterator[str]:
        """Yield gitignore-style patterns expected in the SDist but absent from git."""
        yield from ()

[project.entry-points."check_sdist.backends"]
"my_backend.api" = "my_package._check_sdist:MyBackend"

See also

• check-manifest: A (currently) setuptools specific checker that can suggest possible ways to include/exclude files.
• Scientific Python Development Guide: Guidelines on which this package was designed.