Add cibuildwheels action (#166)

Builds Python wheels as part of the CI release action. This should
automatically build the C software volume control added in #165 for easy
installation.

Author: kahrendt

.github/workflows/release.yml

@@ -7,15 +7,12 @@ env:
   PYTHON_VERSION: "3.12"
 
 jobs:
-  build:
-    name: Builds and prepares for publishing releases to PyPI
+  validate:
+    name: Validate release tag
     runs-on: ubuntu-latest
     outputs:
       version: ${{ steps.vars.outputs.tag }}
-    permissions:
-      id-token: write # Required for PyPI publishing
     steps:
-      - uses: actions/checkout@v5.0.1
       - name: Get tag
         id: vars
         run: echo "tag=${GITHUB_REF#refs/*/}" >> $GITHUB_OUTPUT
@@ -32,48 +29,90 @@ jobs:
               exit 1
             fi
           fi
+
+  build-sdist:
+    name: Build source distribution
+    needs: ['validate']
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v5.0.1
       - name: Set up Python ${{ env.PYTHON_VERSION }}
         uses: actions/setup-python@v6.0.0
         with:
           python-version: ${{ env.PYTHON_VERSION }}
-      - name: Install build
-        run: >-
-          pip install build tomli tomli-w
+      - name: Install build dependencies
+        run: pip install build
       - name: Set Python project version from tag
-        shell: python
-        run: |-
-          import tomli
-          import tomli_w
-
-          with open("pyproject.toml", "rb") as f:
-            pyproject = tomli.load(f)
-
-          pyproject["project"]["version"] = "${{ steps.vars.outputs.tag }}"
-
-          with open("pyproject.toml", "wb") as f:
-            tomli_w.dump(pyproject, f)
-      - name: Build python package
-        run: >-
-          python3 -m build
+        run: sed -i 's/^version = "0.0.0"/version = "${{ needs.validate.outputs.version }}"/' pyproject.toml
+      - name: Build sdist
+        run: python3 -m build --sdist
+      - uses: actions/upload-artifact@v5
+        with:
+          name: dist-sdist
+          path: ./dist/*.tar.gz
 
+  build-wheels:
+    name: Build wheels (${{ matrix.os }}, ${{ matrix.archs }})
+    needs: ['validate']
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        include:
+          - os: ubuntu-latest
+            archs: x86_64
+            qemu: false
+          - os: ubuntu-latest
+            archs: aarch64
+            qemu: true
+          - os: macos-latest
+            archs: x86_64 arm64
+            qemu: false
+          - os: windows-latest
+            archs: AMD64
+            qemu: false
+    steps:
+      - uses: actions/checkout@v5.0.1
+      - name: Set up Python ${{ env.PYTHON_VERSION }}
+        uses: actions/setup-python@v6.0.0
+        with:
+          python-version: ${{ env.PYTHON_VERSION }}
+      - name: Set Python project version from tag
+        shell: python
+        run: |
+          import pathlib
+          p = pathlib.Path("pyproject.toml")
+          p.write_text(p.read_text().replace('version = "0.0.0"', 'version = "${{ needs.validate.outputs.version }}"', 1))
+      - name: Set up QEMU
+        if: matrix.qemu
+        uses: docker/setup-qemu-action@v3
+        with:
+          platforms: arm64,arm
+      - name: Build wheels
+        uses: pypa/cibuildwheel@v2.23.3
+        env:
+          CIBW_ENVIRONMENT: "SENDSPIN_REQUIRE_C_EXT=1"
+          CIBW_BUILD: cp312-* cp313-*
+          CIBW_ARCHS: ${{ matrix.archs }}
+          CIBW_SKIP: "*-musllinux_*"
       - uses: actions/upload-artifact@v5
         with:
-          name: dist
-          path: ./dist
+          name: dist-wheels-${{ matrix.os }}-${{ strategy.job-index }}
+          path: ./wheelhouse/*.whl
 
   publish:
-    needs: ['build']
+    needs: ['build-sdist', 'build-wheels']
     environment: 'publish'
 
-    name: upload release to PyPI
+    name: Upload release to PyPI
     runs-on: ubuntu-latest
     permissions:
       id-token: write
     steps:
       - uses: actions/download-artifact@v6
         with:
-          name: dist
+          pattern: dist-*
           path: dist
+          merge-multiple: true
 
       - name: Publish release to PyPI
         uses: pypa/gh-action-pypi-publish@release/v1

setup.py

@@ -1,21 +1,30 @@
 """Build C extensions for sendspin."""
 
+import os
+
 from setuptools import Extension, setup
 from setuptools.command.build_ext import build_ext
 
+_REQUIRE_C_EXT = os.environ.get("SENDSPIN_REQUIRE_C_EXT") == "1"
+
 
 class OptionalBuildExt(build_ext):
     """A build_ext that treats C extensions as optional.
 
     If compilation fails (e.g. missing compiler or headers), the error is
     reported but does not abort the build, allowing the numpy fallback to be
     used at runtime.
+
+    Set SENDSPIN_REQUIRE_C_EXT=1 to make compilation failures fatal (used in
+    CI to ensure wheels always include the C extension).
     """
 
     def run(self) -> None:
         try:
             super().run()
         except Exception as exc:
+            if _REQUIRE_C_EXT:
+                raise
             print(
                 "WARNING: Building C extensions for sendspin failed; "
                 "falling back to numpy implementation. "
@@ -26,6 +35,8 @@ def build_extension(self, ext: Extension) -> None:
         try:
             super().build_extension(ext)
         except Exception as exc:
+            if _REQUIRE_C_EXT:
+                raise
             print(
                 f"WARNING: Failed to build extension {ext.name!r}; "
                 "continuing without it. "