Building manylinux-compatible Rust Binaries using cross

This is a sample repo demonstrating the building of manylinux2010-compatible Rust binaries using cross. It accompanies this Medium article, which gives more detail.

What This Repo Does

• Provides an example C-compatible external function
• Provides an example Cargo.toml which:
  • builds a cdylib
  • uses fat link-time-optimization
  • uses a single codegen unit
  • uses cbindgen to generate a C-compatible header
• Uses cross and its metadata file to build a manylinux2010 x86_64 compatible dynamic library
• embeds the correct rpath data for use when building Python extensions
• strips binaries

A Note on Building Python Extensions

This is a large and complex subject, but three things must be done:

1. Your Rust library's rpath info must be set correctly (see above)
2. setup.py must have extra_link_args set correctly
3. Your Rust library (rust_dylib) must additionally be available in a directory that is part of LD_LIBRARY_PATH

Assuming a directory structure for a Python library named my_python_library that looks like:

• setup.py
• setup.cfg
• manifest.in
• my_python_library
  • my_python_library.cutil
  • rust_dylib
  • header.h

where my_python_library.cutil is a pyx file which provides a thin wrapper around the exported Rust function(s) in rust_dylib, The following setup.py configuration should allow you to build a wheel:

from setuptools import setup, find_packages, Distribution, Extension
from Cython.build import cythonize


class BinaryDistribution(Distribution):
    def is_pure(self):
        return False


if "linux" in sys.platform:
    # from http://stackoverflow.com/a/10252190/416626
    # the $ORIGIN trick is not perfect, though
    ldirs = ["-Wl,-rpath", "-Wl,$ORIGIN"]
if sys.platform == "darwin":
    ldirs = ["-Wl,-rpath", "-Wl,@loader_path/"]

extensions = Extension(
    # pyx file which wraps your rust binary
    # users import it:
    # from python_library.cutil import double
    "my_python_library.cutil",
    sources=["my_python_library/cutil.pyx"],
    libraries=["rust_dylib"],
    include_dirs=["my_python_library"],
    library_dirs=["my_python_library"],
    extra_link_args=ldirs,
)
extensions = cythonize([extensions,])

setup(
    # other keywords are mandatory but not included here
    name="my_python_library",
    include_package_data=True,
    distclass=BinaryDistribution,
    packages=find_packages(),
    ext_modules=extensions,
)

Once this is done, you can build your wheel. You are strongly advised to use Multibuild in order to do this, as it's the most thorough and well-tested system for generating binary wheels. In order for multibuild's final step – repairing and correctly tagging your wheel – to work, you are strongly advised to do the following:

• Create a directory such as /usr/local/lib and add it to LD_LIBRARY_PATH:
  • export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/lib
• copy rust_dylib into the directory you just created, as this is where auditwheel searches for libraries to bundle.

License

The Blue Oak Model License 1.0.0