Creating a PEX from a python script

pex.md

So you want to create a pex that packages your script and its dependencies?

Ok - first to make our script! Call it foo.py:

import requests

if __name__ == '__main__':
  req = requests.get("https://raw.githubusercontent.com/pantsbuild/pex/master/README.rst")
  print req.text.split("\n")[0]

It's a requests hello world program. To package it we need a minimal setup.py for distributing a script. Put it in the same directory:

from distutils.core import setup
setup(name='foo',
    version='1.0',
    scripts=['foo.py'],
    )

Now that our script is packageable we can use pex to build an executable out of it:

$ pex . requests -c foo.py -o foo.pex -f dist

Briefly - requests and . are our dependencies. -c foo.py tells pex what to run. And -o foo.pex creates the output file.

You should get a foo.pex file in the same directory. Run it to see the script execute:

$ ./foo.pex
PEX

And you can unzip the pex to see the contents including the packaged dependencies:

$ unzip -t foo.pex
... much output not shown...

Thank you! this is super helpful. My main script works, but complains it can't find other local files.

queueBuildUntilFrontOfLine.py

#!/usr/bin/env python
import sys
import time
import circleci #local file
import environment #local file

do stuff...

layout

 ls -l src/*.py
-rwxr-xr-x  1 n0158588  staff  1419 Apr 12 12:50 src/queueBuildUntilFrontOfLine.py
-rw-r--r--  1 n0158588  staff  1131 Apr 12 12:50 src/circleci.py
-rw-r--r--  1 n0158588  staff   209 Apr 12 08:47 src/environment.py
-rw-r--r--  1 n0158588  staff   161 Apr 12 15:07 src/setup.py

python foo.py works fine, but the packaged pex fails.

pex src requests -c queueBuildUntilFrontOfLine.py -o queueBuildUntilFrontOfLine.pex -f src
./queueBuildUntilFrontOfLine.pex

ImportError: No module named circleci

Do you have any advice? I'm struglging to make sense of https://pex.readthedocs.io/en/stable/buildingpex.html#specifying-requirements

If you find the answer please post it here. I find the docs for pants and pex to be terrible. There is no single complete example and all the descriptions are overly technical and examples too simple.

try to make circleci.py a module, ie, put it in a directory like this:

circleci
  |__ circleci/circleci.py
  |__ circleci/__init__.py
  |__ setup.py

in setup.py write this:

from distutils.core import setup
setup(name='circleci',
    version='1.0',
    packages=['circleci'],
    )

By following the original content I get:
Unable to parse /home/zangetsu/.pex/install/foo-1.0-py3-none-any.whl.ee5c21cd6d1cd79925b2f4a751c96970ec7248cf/foo-1.0-py3-none-any.whl/bin/foo.py. PEX script support only supports Python scripts.

Ok, issue with Python 3.6 and print function change....

Shameless self-promotion, but I've just put together a simple demo repo for packaging python scripts as PEX files, because the documentation was rubbish. https://www.shearn89.com/2021/04/15/pex-file-creation with source code here: https://github.com/shearn89/pex-demo

Thanks so much for the article, I got it working finally :). One extra thing I needed to do to make this work was to add a python shebang #!/usr/bin/env python3 on top of main.py file. Supposedly there's been a change in pex 2.1.46 making this necessary. Note that this particular shebang works on Debian and its derivatives, but might be different for other distros (not sure though).

@Caleb9 ah cool, glad it helped! I'll update the article with a link to that post, cheers for the heads up!