Installing

This package is uploaded to PyPI at https://pypi.python.org/pypi/zstandard. So, to install this package:

$ pip install zstandard

Binary wheels are made available for some platforms. If you need to install from a source distribution, all you should need is a working C compiler and the Python development headers/libraries. On many Linux distributions, you can install a python-dev or python-devel package to provide these dependencies.

Packages are also uploaded to Anaconda Cloud at https://anaconda.org/indygreg/zstandard. See that URL for how to install this package with conda.

Requirements

This package is designed to run with Python 3.5, 3.6, 3.7, 3.8, and 3.9 on common platforms (Linux, Windows, and OS X). On PyPy (both PyPy2 and PyPy3) we support version 6.0.0 and above. x86 and x86_64 are well-tested on Windows. Only x86_64 is well-tested on Linux and macOS.

CFFI Backend

In order to build/run the CFFI backend/bindings (as opposed to the C/Rust backend/bindings), you will need the cffi package installed. The cffi package is listed as an optional dependency in setup.py and may not get picked up by your packaging tools.

If you wish to use the CFFI backend (or have to use it since your Python distribution doesn’t support compiled extensions using the Python C API - this is the case for PyPy for example), be sure you have the cffi package installed.

One way to do this is to depend on the zstandard[cffi] dependency. e.g. pip install 'zstandard[cffi]' or add zstandard[cffi] to your pip requirements file.

Legacy Format Support

To enable legacy zstd format support which is needed to handle files compressed with zstd < 1.0 you need to provide an installation option:

$ pip install zstandard --install-option="--legacy"

and since pip 7.0 it is possible to have the following line in your requirements.txt:

zstandard --install-option="--legacy"

All Install Arguments

setup.py accepts the following arguments for influencing behavior:

--legacy
Enable legacy zstd format support in order to read files produced with zstd < 1.0.
--system-zstd

Attempt to link against the zstd library present on the system instead of the version distributed with the extension.

The Python extension only supports linking against a specific version of zstd. So if the system version differs from what is expected, a build or runtime error will result.

--warning-as-errors
Treat all compiler warnings as errors.
--no-c-backend
Do not compile the C-based backend.
--no-cffi-backend
Do not compile the CFFI-based backend.
--rust-backend
Compile the Rust backend (not yet feature complete).

If you invoke setup.py, simply pass the aforementioned arguments. e.g. python3.9 setup.py --no-cffi-backend. If using pip, use the --install-option argument. e.g. python3.9 -m pip install zstandard --install-option --warning-as-errors. Or in a pip requirements file: zstandard --install-option="--rust-backend".

In addition, the following environment variables are recognized:

ZSTD_EXTRA_COMPILER_ARGS
Extra compiler arguments to compile the C backend with.
ZSTD_WARNINGS_AS_ERRORS
Equivalent to setup.py --warnings-as-errors.

Building Against External libzstd

By default, this package builds and links against a single file libzstd bundled as part of the package distribution. This copy of libzstd is statically linked into the extension.

It is possible to point setup.py at an external (typically system provided) libzstd. To do this, simply pass --system-zstd to setup.py. e.g.

python3.9 setup.py --system-zstd or python3.9 -m pip install zstandard --install-option="--system-zstd".

When building against a system libzstd, you may need to specify extra compiler arguments to help Python’s build system find the external library. These can be specified via the ZSTD_EXTRA_COMPILER_ARGS environment variable. e.g. ZSTD_EXTRA_COMPILER_ARGS="-I/usr/local/include" python3.9 setup.py --system-zstd.

python-zstandard can be sensitive about what version of libzstd it links against. For best results, point this package at the exact same version of libzstd that it bundles. See the bundled zstd/zstd.h or zstd/zstdlib.c for which version that is.

When linking against an external libzstd, not all package features may be available. Notably, the multi_compress_to_buffer() and multi_decompress_to_buffer() APIs are not available, as these rely on private symbols in the libzstd C source code, which require building against private header files to use.