Re: Guix's python has pip's user dir in its loadpath

[Development of GNU Guix and the GNU System distribution.]

> > I just saw this message and hurried myself up to test the patch to
> > python-build-system that I made. Unfortunately, it turns out the
> > "PYTHONNOUSERSITE=1" env var breaks pip which tries to install wheels to
> > the system site directory and fails due to a read-only filesystem.  
> 
> I'm not sure I follow; why would PYTHONNOUSERSITE affect pip?  I thought
> it should only appear in wrappers of Python executables, not be set in a
> profile's environment (thus not affecting pip) ?

Indeed. And once I make my change, PYTHONNOUSERSITE gets also placed in
the wrapper of the `pip` executable.

> Could you share the diff of the patch you tried so far?

I am attaching the patch file.

I was trying to test with

    ./pre-inst-env guix shell -C --network --no-cwd python-xmldiff coreutils 
python-pip
    pip install xmldiff==2.4
    echo > ~/.local/lib/python3.10/site-packages/xmldiff/main.py
    xmldiff --help

Without my patch, we get an error on 4th line. With my patch, we get
the "Read-only file system" error on the 2nd line

Best,
Wojtek

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From 6c2cd9679d52ac4f06e91026948da5fae2c2a29c Mon Sep 17 00:00:00 2001
Message-Id: <6c2cd9679d52ac4f06e91026948da5fae2c2a29c.1688740423.git.kos...@koszko.org>
From: Wojtek Kosior <kos...@koszko.org>
Date: Mon, 3 Jul 2023 10:53:41 +0200
Subject: [PATCH] guix: build: python-build-system: Don't process user site dir

* guix/build/python-build-system.scm (wrap): Define PYTHONNOUSERSITE for
programs so they don't incorrectly pick up local, pip-installed libraries.
---
 guix/build/python-build-system.scm | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/guix/build/python-build-system.scm b/guix/build/python-build-system.scm
index aa04664b25..bbcb861da0 100644
--- a/guix/build/python-build-system.scm
+++ b/guix/build/python-build-system.scm
@@ -241,12 +241,16 @@ (define* (wrap #:key inputs outputs #:allow-other-keys)
   (define %sh (delay (search-input-file inputs "bin/bash")))
   (define (sh) (force %sh))
 
-  (let* ((var `("GUIX_PYTHONPATH" prefix
-                ,(search-path-as-string->list
-                  (or (getenv "GUIX_PYTHONPATH") "")))))
+  (let* ((var-pythonpath `("GUIX_PYTHONPATH" prefix
+                           ,(search-path-as-string->list
+                             (or (getenv "GUIX_PYTHONPATH") ""))))
+         ;; Harden applications by preventing Python from automatically
+         ;; picking up libraries in user site directory.
+         (var-usersite '("PYTHONNOUSERSITE" = ("1"))))
     (for-each (lambda (dir)
                 (let ((files (list-of-files dir)))
-                  (for-each (cut wrap-program <> #:sh (sh) var)
+                  (for-each (cut wrap-program <> #:sh (sh)
+                                 var-pythonpath var-usersite)
                             files)))
               bindirs)))
 

base-commit: 08649cfcd41bc78ba4df0609798461816dda9496
-- 
2.40.1

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