pex is a library for generating .pex (Python EXecutable) files which are
executable Python environments in the spirit of virtualenvs.
pex is an expansion upon the ideas outlined in
and makes the deployment of Python applications as simple as
cp. pex files may even
include multiple platform-specific Python distributions, meaning that a single pex file
can be portable across Linux and OS X.
Still unsure about what pex does or how it works? Watch this quick lightning talk: WTF is PEX?.
pex is licensed under the Apache2 license.
To install pex, simply
$ pip install pex
You can also build pex in a git clone using tox:
$ tox -e package $ cp dist/pex ~/bin
This builds a pex binary in
dist/pex that can be copied onto your
The advantage to this approach is that it keeps your Python environment as empty as
possible and is more in-line with what pex does philosophically.
Launch an interpreter with
psutil in the environment:
$ pex requests flask 'psutil>2,<3'
Or instead freeze your current virtualenv via requirements.txt and execute it anywhere:
$ pex $(pip freeze) -o my_virtualenv.pex $ deactivate $ ./my_virtualenv.pex
Run webserver.py in an environment containing
flask as a quick way to experiment:
$ pex flask -- webserver.py
Launch Sphinx in an ephemeral pex environment using the Sphinx entry point
$ pex sphinx -e sphinx:main -- --help
Projects specifying a
console_scripts entry point in their configuration
can build standalone executables for those entry points.
To build a standalone
pex-tools-executable.pex binary that runs the
pex-tools console script found in all pex version
2.1.35 and newer distributions:
$ pex "pex>=2.1.35" --console-script pex-tools --output-file pex-tools-executable.pex
You can also build pex files that use a specific interpreter type:
$ pex "pex>=2.1.35" -c pex-tools --python=pypy -o pex-tools-pypy-executable.pex
Most pex options compose well with one another, so the above commands can be mixed and matched, and equivalent short options are available.
For a full list of options, just type
If you use tox (and you should!), a simple way to integrate pex into your
workflow is to add a packaging test environment to your
[testenv:package] deps = pex commands = pex . -o dist/app.pex
tox -e package will produce a relocatable copy of your application
that you can copy to staging or production environments.
More documentation about Pex, building .pex files, and how .pex files work is available at https://pex.readthedocs.io.
Pex uses tox for test and development automation. To run the test suite, just invoke tox:
If you don't have tox, you can generate a pex of tox:
$ pex tox -c tox -o ~/bin/tox
Tox provides many useful commands and options, explained at https://tox.readthedocs.io/en/latest/. Below, we provide some of the most commonly used commands used when working on Pex, but the docs are worth acquainting yourself with to better understand how Tox works and how to do more advanced commands.
To run a specific environment, identify the name of the environment you'd like to invoke by
tox --listenvs-all, then invoke like this:
$ tox -e format-run
To run MyPy:
$ tox -e typecheck
All of our tox test environments allow passthrough arguments, which can be helpful to run specific tests:
$ tox -e py37-integration -- -k test_reproducible_build
To run Pex from source, rather than through what is on your PATH, invoke via Python:
$ python -m pex
To contribute, follow these instructions: https://www.pantsbuild.org/docs/contributor-overview