Allow system_site_packages=True in Virtualenv.create()

[PhoenixHe-NV]

Currently PEX could create virtualenv to populate bundled packages, and in PEX code it allows to create venv with "--system-site-packages", but there is no way to specify this parameter at runtime.

We want to run with venv and system-site-packages enabled, can we have an extra environment variable to specify this behavior?

[jsirois]

Did you know you can do this?:

PEX_TOOLS=1 ./my.pex venv here/ --help

Or use the pex-tools console script available when you install the pex tool:

pex-tools ./my.pex --help
pex-tools ./my.pex venv --help

Does that satisfy your requirements?

[PhoenixHe-NV]

@jsirois Thanks for your advice! It's a good idea to specify the option in pex-tools, but seems like it doesn't pass system-site-packages

https://github.com/pantsbuild/pex/blob/52c84031bc22781f59e6acba74be9c5736fb3598/pex/tools/commands/venv.py#L177-L183

[jsirois]

Aha, right. So, if a pex-tools venv --system-site-packages option were added, would that work for you then? If so I'll mark this as a feature request and if you want to implement that feature I'm happy to review; otherwise it will go into the current backlog tracked in #1975.

[PhoenixHe-NV]

@jsirois Adding a new option --system-site-packages would work for me. I don't have enough time to implement this feature, but I could modify pyenv.cfg after venv extracted. Anyway, please add this to backlog, thanks!

[PhoenixHe-NV]

@jsirois Now I'm blocked without this feature. If I manually modify pyvenv.cfg to change to include-system-site-packages = true, but the “pip” is extracted without --system-site-packages, then if I packed "pip", in extracted venv's pip, it will have #!/tmp/pex_venv/bin/python3.8 -sE at the first line, which will let pip list skip user local site ($HOME/.local)

Maybe I'll try to make a PR on this issue...