Use PDM to manage macOS wheel dependencies

Use Drake's PDM-managed virtual environment (@python), rather than a
separate virtual environment, to manage the additional Python bits that
are needed to build a wheel. This allows us to pin the versions of these
dependencies, for better reproducibility and is one less place where
such things are being managed. Having the wheel dependencies installed
"up front" is also in line with how Linux wheels are built.

setup/python/pyproject.toml

@@ -2,12 +2,20 @@
 # the "locked" pdm output file via:
 #
 #     tools/workspace/python/venv_upgrade
+#
+# This file primarily defines the set of Python dependencies that are used by
+# Drake in various ways and are managed by tools/workspace/python/venv_sync.
+# It is the responsibility of tools/workspace/python/repository.bzl to decide
+# which dependency groups need to be installed.
 
 [project]
 name = "drake"
 # The supported Python major/minor version should match the minimum listed in
 # the root CMakeLists.txt and doc/_pages/from_source.md.
 requires-python = ">=3.10"
+
+# Dependencies needed to build Drake.
+#
 # WARNING for Drake Developers: This list must be kept in sync with
 # setup/mac/binary_distribution/requirements.txt.
 dependencies = [
@@ -20,12 +28,19 @@ dependencies = [
 ]
 
 [dependency-groups]
+# (Additional) dependencies needed to run Drake's tests.
 test = [
     "flask",
     "six",
     "u-msgpack-python",
     "websockets",
 ]
+# (Additional) dependencies needed to build a Drake wheel.
+wheel = [
+    "delocate",
+    "setuptools",
+    "wheel",
+]
 
 [tool.pdm]
 distribution = false

tools/wheel/image/provision-python.sh

@@ -47,8 +47,5 @@ pip install \
     semantic-version \
     setuptools \
     wheel \
-    auditwheel
-
-if [[ "$(uname)" == "Linux" ]]; then
-    pip install patchelf
-fi
+    auditwheel \
+    patchelf

tools/wheel/macos/build-wheel.sh

@@ -82,38 +82,25 @@ ln -s "$(bazel info bazel-bin)" "$build_root"/bazel-bin
 find "$build_root" -type d -print0 | xargs -0 chmod u+w
 
 # -----------------------------------------------------------------------------
-# Set up a Python virtual environment.
+# Obtain and activate Drake's Python virtual environment.
 # -----------------------------------------------------------------------------
 
-readonly pyvenv_root="/opt/drake-wheel-build/$python/python"
+readonly drake_python="$(bazel info output_base).drake_python"
+readonly venv_drake="$drake_python/venv.drake"
 
-# NOTE: Xcode ships python3, make sure to use the one from brew.
-"$python_executable" -m venv "$pyvenv_root"
-
-# We also need pythonX.Y-config, which isn't created as of writing (see also
-# https://github.com/pypa/virtualenv/issues/169). Don't fail if it already
-# exists, though, e.g. if the bug has been fixed.
-ln -s "$python_prefix/bin/$python-config" \
-      "$pyvenv_root/bin/$python-config" || true # Allowed to already exist.
-
-. "$pyvenv_root/bin/activate"
+. "$venv_drake/bin/activate"
 
 # -----------------------------------------------------------------------------
-# Install tools to build the wheel.
+# "Install" additional tools to build the wheel.
 # -----------------------------------------------------------------------------
 
-pip install --upgrade \
-    delocate \
-    setuptools \
-    wheel
-
 ln -s \
     "$build_root/bazel-bin/external/drake+/tools/wheel/strip_rpath" \
-    "$pyvenv_root/bin/strip_rpath"
+    "$venv_drake/bin/strip_rpath"
 
 ln -s \
     "$build_root/bazel-bin/external/drake+/tools/wheel/change_lpath" \
-    "$pyvenv_root/bin/change_lpath"
+    "$venv_drake/bin/change_lpath"
 
 # -----------------------------------------------------------------------------
 # Build the Drake wheel.

tools/wheel/wheel_builder/macos.py

@@ -8,7 +8,7 @@
 import shutil
 import subprocess
 
-from .common import create_snopt_tgz, die, wheel_name
+from .common import create_snopt_tgz, die, gripe, wheel_name
 from .common import build_root, resource_root, wheel_root, wheelhouse
 from .common import test_root, find_tests
 

tools/workspace/python/repository.bzl

@@ -41,6 +41,7 @@ load(
     "homebrew_prefix",
     "which",
 )
+load("//tools/workspace:os.bzl", "is_wheel_build")
 
 def _get_python_interpreter(repo_ctx):
     """Returns the tuple (python_interpreter_path, major_minor_version) based
@@ -131,7 +132,9 @@ def _prepare_venv(repo_ctx, python):
     repo_ctx.watch(pdmlock)
 
     # Choose which dependencies to install.
-    if repo_ctx.attr.requirements_flavor == "test":
+    if is_wheel_build(repo_ctx):
+        repo_ctx.file("@pdm-install-args", content = "-G wheel")
+    elif repo_ctx.attr.requirements_flavor == "test":
         repo_ctx.file("@pdm-install-args", content = "-G test")
     else:
         repo_ctx.file("@pdm-install-args", content = "--prod")