`PIP_REQUIRE_VIRTUALENV` breaks installation of dependencies from `.tar.gz` URIs

[a-khabarov]

🐞 bug report

Affected Rule

This might be related to how wheel_installer is invoked.

Is this a regression?

No, 1.4.1 and #3115 (commit 75871bb) have this problem. 1.5.0 and 1.5.1 likely also have this problem, but I can't confirm since .tar.gz installation is broken in those releases (see #3131).

Description

Running a py_test target with PIP_REQUIRE_VIRTUALENV set to true results in errors if one of the dependencies is installed from a .tar.gz URI.
Adding common --action_env PIP_REQUIRE_VIRTUALENV=false to .bazelrc can be used as a workaround.

🔬 Minimal Reproduction

export PIP_REQUIRE_VIRTUALENV=true in the shell. Then follow the minimal reproduction steps in #3131 but for rules_python 1.4.1 or #3115 (commit 75871bb). 1.5.0 and 1.5.1 would fail with a different error due to #3131.

🔥 Exception or Error

 error: subprocess-exited-with-error

 × pip subprocess to install build dependencies did not run successfully.
 │ exit code: 3
 ╰─> [1 lines of output]
 ERROR: Could not find an activated virtualenv (required).
 [end of output]

 note: This error originates from a subprocess, and is likely not a problem with pip.
error: subprocess-exited-with-error

× pip subprocess to install build dependencies did not run successfully.
│ exit code: 3
╰─> See above for output.

🌍 Your Environment

Operating System:

 
Linux
 

Output of bazel version:

 
Bazelisk version: development
Build label: 8.1.1
Build target: @@//src/main/java/com/google/devtools/build/lib/bazel:BazelServer
Build time: Tue Feb 25 18:50:42 2025 (1740509442)
Build timestamp: 1740509442
Build timestamp as int: 1740509442
 

Rules_python version:

 
1.4.1, 75871bbb9b33723c60565de0d7959c3262f87337
 

Anything else relevant?

[aignas]

I am not sure I understand the issue here.

The action_env affects build actions, whereas the invocation of the wheel_installer happens before that (i.e. outside the bulid action).

Could you please explain why this env variable is important and what is the desired behaviour?

[a-khabarov]

Having PIP_REQUIRE_VIRTUALENV set to true in the shell environment helps prevent accidental pollution of the global pip directory. E.g. if you have some Python project that doesn't use rules_python (or uv, etc), you can forget to activate your virtual environment, and just run pip install by accident. So it is a good idea to always have it enabled.

At the moment rules_python crashes when the variable is set to true and the project has a .tar.gz dependency. rules_python should install the dependency without crashing regardless of what this variable is set to.

[aignas]

There are two complications:

1. The user may want to use a venv and rules python, where they decide to manage the interpreter outside rules python. In that case I assume the env variable would not do anything.
2. The user may want to use the toolchains provided by rules_python, in that case the env variable should be unset when building python wheels from sdist.

PRs that help solve this would be welcome and I can help dig arround the codebase.