add option virtualenvs.prefer-shell-python

Author: finswimmer

src/poetry/config/config.py

@@ -38,6 +38,7 @@ class Config:
             "in-project": None,
             "path": os.path.join("{cache-dir}", "virtualenvs"),
             "options": {"always-copy": False, "system-site-packages": False},
+            "prefer-shell-python": False,
         },
         "experimental": {"new-installer": True},
         "installer": {"parallel": True, "max-workers": None},
@@ -138,6 +139,7 @@ def _get_normalizer(name: str) -> Callable:
             "virtualenvs.in-project",
             "virtualenvs.options.always-copy",
             "virtualenvs.options.system-site-packages",
+            "virtualenvs.options.prefer-shell-python",
             "experimental.new-installer",
             "installer.parallel",
         }:

src/poetry/console/application.py

@@ -1,4 +1,3 @@
-import contextlib
 import logging
 import re
 import subprocess
@@ -19,6 +18,7 @@
 from cleo.exceptions import CleoException
 from cleo.formatters.style import Style
 from cleo.io.inputs.argv_input import ArgvInput
+from cleo.io.outputs.output import Verbosity
 from poetry.core.utils._compat import PY37
 
 from poetry.__version__ import __version__
@@ -229,6 +229,30 @@ def _configure_io(self, io: "IO") -> None:
 
         return super()._configure_io(io)
 
+    def _detect_active_python(self, io: "IO") -> str:
+        executable = None
+
+        try:
+            io.write_line(
+                "Trying to detect current active python executable as specified in the config.",
+                verbosity=Verbosity.VERBOSE,
+            )
+            executable = decode(
+                subprocess.check_output(
+                    list_to_shell_command(
+                        ["python", "-c", '"import sys; print(sys.executable)"']
+                    ),
+                    shell=True,
+                ).strip()
+            )
+            io.write_line(f"Found: {executable}", verbosity=Verbosity.VERBOSE)
+        except CalledProcessError:
+            io.write_line(
+                "Unable to detect the current active python executable. Falling back to default.",
+                verbosity=Verbosity.VERBOSE,
+            )
+        return executable
+
     def register_command_loggers(
         self, event: "ConsoleCommandEvent", event_name: str, _: Any
     ) -> None:
@@ -288,27 +312,15 @@ def configure_env(
         poetry = command.poetry
 
         executable = None
-        find_compatible = None
 
-        # add on option to trigger this
-        with contextlib.suppress(CalledProcessError):
-            executable = decode(
-                subprocess.check_output(
-                    list_to_shell_command(
-                        [
-                            "python",
-                            "-c",
-                            '"import sys; print(sys.executable)"',
-                        ]
-                    ),
-                    shell=True,
-                ).strip()
-            )
-            find_compatible = True
+        if poetry.config.get("virtualenvs.prefer-shell-python"):
+            executable = self._detect_active_python(io)
 
         env_manager = EnvManager(poetry)
         env = env_manager.create_venv(
-            io, executable=executable, find_compatible=find_compatible
+            io,
+            executable=executable,
+            find_compatible=True if executable else None,
         )
 
         if env.is_venv() and io.is_verbose():

src/poetry/console/commands/config.py

@@ -78,6 +78,11 @@ def unique_config_values(self) -> Dict[str, Tuple[Any, Any, Any]]:
                 lambda val: str(Path(val)),
                 str(Path(CACHE_DIR) / "virtualenvs"),
             ),
+            "virtualenvs.prefer-shell-python": (
+                boolean_validator,
+                boolean_normalizer,
+                False,
+            ),
             "experimental.new-installer": (
                 boolean_validator,
                 boolean_normalizer,

tests/console/commands/test_config.py

@@ -56,6 +56,7 @@ def test_list_displays_default_value_if_not_set(
 virtualenvs.options.always-copy = false
 virtualenvs.options.system-site-packages = false
 virtualenvs.path = {venv_path}  # {config_cache_dir / 'virtualenvs'}
+virtualenvs.prefer-shell-python = false
 """
 
     assert expected == tester.io.fetch_output()
@@ -79,6 +80,7 @@ def test_list_displays_set_get_setting(
 virtualenvs.options.always-copy = false
 virtualenvs.options.system-site-packages = false
 virtualenvs.path = {venv_path}  # {config_cache_dir / 'virtualenvs'}
+virtualenvs.prefer-shell-python = false
 """
 
     assert config.set_config_source.call_count == 0
@@ -126,6 +128,7 @@ def test_list_displays_set_get_local_setting(
 virtualenvs.options.always-copy = false
 virtualenvs.options.system-site-packages = false
 virtualenvs.path = {venv_path}  # {config_cache_dir / 'virtualenvs'}
+virtualenvs.prefer-shell-python = false
 """
 
     assert config.set_config_source.call_count == 1