I was using StrippedSourceFiles , but am not anymore. Regardless, I needed to determine the prefix/path to setup.py

Cool, so yeah, I think you will want to set

PEX_EXTRA_SYS_PATH

so that source roots are handled properly. Then, to get the path to your

setup.py

, you can do something like: inspect

source_files.snapshot.files

for a value ending in

setup.py

. I’m not sure what your assumptions are about if there’s >1 setup.py file in the source files -- Taking a step back, what is the rule of the

setup.py

playing here? Did you already have these

setup.py

files in your repo, or you’re adding them for the sake of this plugin? Are you using

python_library(sources=["setup.py"])

, or might it make sense to have a new target type like

cython_setup_py()

?