ci: build musllinux wheels and test them on Alpine

.github/workflows/ci.yml

@@ -59,9 +59,35 @@ jobs:
       - name: Run tests
         run: pytest tests/ -v
 
+  test-musl:
+    name: Test (musllinux wheel on Alpine)
+    needs: lint
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Build musllinux wheel
+        uses: PyO3/maturin-action@v1
+        with:
+          target: x86_64
+          args: --release --out dist
+          manylinux: musllinux_1_2
+      # Alpine marks its system Python as externally managed (PEP 668), so the
+      # wheel is installed into a venv. --no-index is the real assertion here:
+      # if the wheel is not tagged musllinux, pip finds no candidate at all and
+      # the job fails, which is precisely the breakage being guarded against.
+      - name: Install wheel and run tests on Alpine
+        run: |
+          docker run --rm -v "$PWD:/io" -w /io alpine:latest sh -euc '
+            apk add --no-cache python3
+            python3 -m venv /venv
+            /venv/bin/pip install pytest
+            /venv/bin/pip install --no-index --find-links dist ormar-utils
+            /venv/bin/pytest tests/ -v
+          '
+
   build:
-    name: Build wheels (${{ matrix.os }}-${{ matrix.target }})
-    needs: test
+    name: Build wheels (${{ matrix.os }}-${{ matrix.target }}-${{ matrix.manylinux || 'auto' }})
+    needs: [test, test-musl]
     if: startsWith(github.ref, 'refs/tags/v')
     runs-on: ${{ matrix.os }}
     strategy:
@@ -71,6 +97,15 @@ jobs:
             target: x86_64
           - os: ubuntu-latest
             target: aarch64
+          # musl builds for Alpine and other musl-libc distros. glibc wheels are
+          # not installable there, so without these pip falls back to the sdist
+          # and requires a Rust toolchain on the target machine.
+          - os: ubuntu-latest
+            target: x86_64
+            manylinux: musllinux_1_2
+          - os: ubuntu-latest
+            target: aarch64
+            manylinux: musllinux_1_2
           - os: macos-latest
             target: x86_64
           - os: macos-latest
@@ -89,11 +124,14 @@ jobs:
         with:
           target: ${{ matrix.target }}
           args: --release --out dist
-          manylinux: auto
+          manylinux: ${{ matrix.manylinux || 'auto' }}
+      # The manylinux value is part of the name because the glibc and musl
+      # builds otherwise collide on os+target, and upload-artifact@v4 rejects
+      # duplicate artifact names.
       - name: Upload wheels
         uses: actions/upload-artifact@v4
         with:
-          name: wheels-${{ matrix.os }}-${{ matrix.target }}
+          name: wheels-${{ matrix.os }}-${{ matrix.target }}-${{ matrix.manylinux || 'auto' }}
           path: dist
 
   sdist: