Ubuntu VirtualEnv Creation can be configured to place python at bin/local/python, causes nox failure to find pip

[crwilcox]

A user reported seeing this error to me. To be clear, the issue isn't in nox but instead in debian/virtualenv, but I wanted to open this so others that encounter this with nox can find the breadcrumbs.

TL;DR - you can set DEB_PYTHON_INSTALL_LAYOUT and revert to the previous way and you should be unblocked.

Error: python is not installed into the virtualenv, it is located at /usr/bin/python. Pass external=True into run() to explicitly allow this.

We spent some time digging, comparing configurations. Ultimately I requested they run virtualenv outside of nox.

https://askubuntu.com/questions/1406304/virtualenv-installs-envs-into-local-bin-instead-of-bin

This var, DEB_PYTHON_INSTALL_LAYOUT can be set and will allow virtualenv and nox to run as expected

export DEB_PYTHON_INSTALL_LAYOUT='deb'

Expected Behavior

Expect nox to create a virtualenv and successfully find pip, python, etc.

Environment

- OS: Linux (Debian Rodete)
- Python: 3.10.5
- Nox: 2022.1.7
- VirtualEnv:20.16.3

[crwilcox]

I think pypa/virtualenv#2350 is related to this.

[crwilcox]

Running sysconfig you can detect the issue

Fails

❯ python3.10 -m sysconfig

Platform: "linux-x86_64"
Python version: "3.10"
Current installation scheme: "posix_local"

Works

❯ python3.10 -m sysconfig

Platform: "linux-x86_64"
Python version: "3.10"
Current installation scheme: "posix_prefix"