Python Processes Spawned From `subproccess` Module Can't Import Deps

[waltaskew]

🐞 bug report

Affected Rule

py_binary, py_test

Is this a regression?

Yes, this works in 1.6.1

Description

New Python processes from subprocess calls are unable to import their dependencies when run from a bazel run. Something like this:

sv = subprocess.Popen(
    [sys.executable, "-c", "import requests"],
)

fails, even though it's being called from a py_binary which names requests as a dependency. Multiprocessing appears to work correctly, though.

Is there a special incantation to make this work? I've tried various permutations with env=os.environ, cwd=os.getcwd(), shell=True and such to no avail.

The above code works fine when run outside of a bazel run or when bazel run with the 1.6 rules_python release.

🔬 Minimal Reproduction

BUILD:

py_binary(
    name = "subprocess_test",
    srcs = ["subprocess_test.py"],
    visibility = ["//visibility:public"],
    deps = ["@pypi//requests"],
)

subprocess_test.py:

import subprocess
import sys

import requests


def main():
    sv = subprocess.Popen(
        [sys.executable, "-c", "import requests"],
        stdout=subprocess.PIPE,
        stderr=subprocess.PIPE,
        text=True,
    )
    out, err = sv.communicate()
    if sv.returncode > 0:
        raise RuntimeError("oh no " + err)


if __name__ == "__main__":
    main()

bazel run subprocess_test

🔥 Exception or Error

RuntimeError: oh no Traceback (most recent call last):
  File "<string>", line 1, in <module>
    import requests
ModuleNotFoundError: No module named 'requests'

🌍 Your Environment

Operating System:

  
Debian Linux
  

Output of bazel version:

  
bazel 8.3.1
  

Rules_python version:

  
1.7.0-rc4
  

Anything else relevant?