Build backend for CMake based projects
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Scikit-build-core is a build backend for Python that uses CMake to build extension modules. It has a simple yet powerful static configuration system in pyproject.toml, and supports almost unlimited flexibility via CMake. It was initially developed to support the demanding needs of scientific users, but can build any sort of package that uses CMake.
Scikit-build-core is a ground-up rewrite of the classic Scikit-build. The key features of scikit-build classic (which is setuptools based) are also present here:
Scikit-build-core was built using Python packaging standards developed after scikit-build (classic) was written. Using it directly provides the following features over classic Scikit-build:
CMAKE_PREFIX_PATH
CMAKE_GENERATOR
build-dir
)The following limitations are present compared to classic scikit-build:
Some known missing features that will be developed soon:
Other backends are also planned:
The recommended interface is the native pyproject builder. There is also a WIP setuptools-based interface that is being developed to provide a transition path for classic scikit-build.
WARNING: Only the pyproject-based builder should be used; the setuptools backend is experimental and likely to move to a separate package before being declared stable, and internal API is still being solidified. A future version of this package will support creating new build extensions.
To use scikit-build-core, add it to your build-system.requires
, and specify
the scikit_build_core.build
builder as your build-system.build-backend
. You
do not need to specify cmake
or ninja
; scikit-build-core will require them
automatically if the system versions are not sufficient.
[build-system]
requires = ["scikit-build-core"]
build-backend = "scikit_build_core.build"
[project]
name = "scikit_build_simplest"
version = "0.0.1"
You can (and should) specify the rest of the entries in project
, but these are
the minimum to get started. You can also scikit-build-core[pyproject]
to
pre-load some dependencies if you want; in some cases this might be marginally
faster.
An example CMakeLists.txt
:
cmake_minimum_required(VERSION 3.15...3.27)
project(${SKBUILD_PROJECT_NAME} LANGUAGES C)
find_package(Python COMPONENTS Interpreter Development.Module REQUIRED)
Python_add_library(_module MODULE src/module.c WITH_SOABI)
install(TARGETS _module DESTINATION ${SKBUILD_PROJECT_NAME})
Scikit-build-core will backport FindPython from CMake 3.26.1 to older versions of Python, and will handle PyPy for you if you are building from PyPy. You will need to install everything you want into the full final path inside site-modules (so you will usually prefix everything by the package name).
More examples are in the tests/packages.
All configuration options can be placed in pyproject.toml
, passed via
-C
/--config-setting
in build or -C
/--config-settings
in pip
, or set
as environment variables. tool.scikit-build
is used in toml, skbuild.
for
-C
options, or SKBUILD_*
for environment variables. The defaults are listed
below:
[tool.scikit-build]
# The minimum version of CMake to use. If CMake is not present on the system or
# is older than this, it will be downloaded via PyPI if possible. An empty
# string will disable this check.
cmake.minimum-version = "3.15"
# A list of args to pass to CMake when configuring the project. Setting this in
# config or envvar will override toml. See also ``cmake.define``.
cmake.args = []
# A table of defines to pass to CMake when configuring the project. Additive.
cmake.define = {}
# Verbose printout when building.
cmake.verbose = false
# The build type to use when building the project. Valid options are: "Debug",
# "Release", "RelWithDebInfo", "MinSizeRel", "", etc.
cmake.build-type = "Release"
# The source directory to use when building the project. Currently only affects
# the native builder (not the setuptools plugin).
cmake.source-dir = "."
# The build targets to use when building the project. Empty builds the default
# target.
cmake.targets = []
# The minimum version of Ninja to use. If Ninja is not present on the system or
# is older than this, it will be downloaded via PyPI if possible. An empty
# string will disable this check.
ninja.minimum-version = "1.5"
# If CMake is not present on the system or is older required, it will be
# downloaded via PyPI if possible. An empty string will disable this check.
ninja.make-fallback = true
# The logging level to display, "DEBUG", "INFO", "WARNING", and "ERROR" are
# possible options.
logging.level = "WARNING"
# Files to include in the SDist even if they are skipped by default. Supports
# gitignore syntax.
sdist.include = []
# Files to exclude from the SDist even if they are included by default. Supports
# gitignore syntax.
sdist.exclude = []
# If set to True, try to build a reproducible distribution (Unix and Python 3.9+
# recommended). ``SOURCE_DATE_EPOCH`` will be used for timestamps, or a fixed
# value if not set.
sdist.reproducible = true
# If set to True, CMake will be run before building the SDist.
sdist.cmake = false
# A list of packages to auto-copy into the wheel. If this is not set, it will
# default to the first of ``src/<package>``, ``python/<package>``, or
# ``<package>`` if they exist. The prefix(s) will be stripped from the package
# name inside the wheel.
wheel.packages = ["src/<package>", "python/<package>", "<package>"]
# The Python tags. The default (empty string) will use the default Python
# version. You can also set this to "cp37" to enable the CPython 3.7+ Stable ABI
# / Limited API (only on CPython and if the version is sufficient, otherwise
# this has no effect). Or you can set it to "py3" or "py2.py3" to ignore Python
# ABI compatibility. The ABI tag is inferred from this tag.
wheel.py-api = ""
# Fill out extra tags that are not required. This adds "x86_64" and "arm64" to
# the list of platforms when "universal2" is used, which helps older Pip's
# (before 21.0.1) find the correct wheel.
wheel.expand-macos-universal-tags = false
# The install directory for the wheel. This is relative to the platlib root. You
# might set this to the package name. The original dir is still at
# SKBUILD_PLATLIB_DIR (also SKBUILD_DATA_DIR, etc. are available). EXPERIMENTAL:
# An absolute path will be one level higher than the platlib root, giving access
# to "/platlib", "/data", "/headers", and "/scripts".
wheel.install-dir = ""
# A list of license files to include in the wheel. Supports glob patterns.
wheel.license-files = ["LICEN[CS]E*", "COPYING*", "NOTICE*", "AUTHORS*"]
# If set to True (the default), CMake will be run before building the wheel.
wheel.cmake = true
# Target the platlib or the purelib. If not set, the default is to target the
# platlib if wheel.cmake is true, and the purelib otherwise.
wheel.platlib = ""
# A set of patterns to exclude from the wheel. This is additive to the SDist
# exclude patterns. This applies to the source files, not the final paths.
# Editable installs may not respect this exclusion.
wheel.exclude = []
# If CMake is less than this value, backport a copy of FindPython. Set to 0
# disable this, or the empty string.
backport.find-python = "3.26.1"
# Select the editable mode to use. Can be "redirect" (default) or "inplace".
editable.mode = "redirect"
# Turn on verbose output for the editable mode rebuilds.
editable.verbose = true
# Rebuild the project when the package is imported. The build-directory must be
# set.
editable.rebuild = false
# The components to install. If empty, all default components are installed.
install.components = []
# Whether to strip the binaries. True for scikit-build-core 0.5+.
install.strip = false
# The path (relative to platlib) for the file to generate.
generate[].path = ""
# The template to use for the file. This includes string.Template style
# placeholders for all the metadata. If empty, a template-path must be set.
generate[].template = ""
# The path to the template file. If empty, a template must be set.
generate[].template-path = ""
# The place to put the generated file. The "build" directory is useful for CMake
# files, and the "install" directory is useful for Python files, usually. You
# can also write directly to the "source" directory, will overwrite existing
# files & remember to gitignore the file.
generate[].location = "install"
# List dynamic metadata fields and hook locations in this table.
metadata = {}
# Strictly check all config options. If False, warnings will be printed for
# unknown options. If True, an error will be raised.
strict-config = true
# Enable early previews of features not finalized yet.
experimental = false
# If set, this will provide a method for backward compatibility.
minimum-version = "0.7" # current version
# The build directory. Defaults to a temporary directory, but can be set.
build-dir = ""
Most CMake environment variables should be supported, and CMAKE_ARGS
can be
used to set extra CMake args. ARCHFLAGS
is used to specify macOS universal2 or
cross-compiles, just like setuptools.
You can also specify [[tool.scikit-build.overrides]]
to customize values for
different systems. See the docs for details.
Scikit-build-core is a binary build backend. There are also other binary build backends:
cmake.*
entrypoints, but
folder-based).If you don't need a binary build, you don't need to use a binary build backend! There are some very good Python build backends; we recommend hatchling as a good balance between good defaults for beginners and good support for advanced use cases. This is the tool scikit-build-core itself uses.
Support for this work was provided by NSF grant OAC-2209877.