set docker platform for cross-arch builds

Author: Mic92

.github/workflows/publish.yml

@@ -73,6 +73,16 @@ jobs:
         if: matrix.platform != 'amd64'
         uses: docker/setup-qemu-action@v3
 
+      - name: Set docker arch
+        run: |
+          platform=${{ matrix.platform }}
+          if [[ $platform == arm64v8 ]]; then
+            platform=arm64
+          elif [[ $platform == arm32v7 ]]; then
+            platform=arm
+          fi
+          echo "DOCKER_PLATFORM=$platform" >> $GITHUB_ENV
+
       - uses: actions/download-artifact@v3
         with:
           name: patchelf
@@ -100,7 +110,7 @@ jobs:
           else
               ENTRYPOINT=
           fi
-          docker run -e CXXFLAGS -v $(pwd):/gha ${{ matrix.platform }}/alpine:edge ${ENTRYPOINT} sh -ec "cd /gha && sh ./build.sh"
+          docker run --platform "$DOCKER_PLATFORM" -e CXXFLAGS -v $(pwd):/gha ${{ matrix.platform }}/alpine:edge ${ENTRYPOINT} sh -ec "cd /gha && sh ./build.sh"
       - name: Check binaries
         run: |
           cat <<EOF > check.sh
@@ -109,7 +119,7 @@ jobs:
           tar -xf ./dist/patchelf-*-*.tar.gz
           ./bin/patchelf --version
           EOF
-          docker run -v $(pwd):/gha ${{ matrix.platform }}/debian:unstable-slim sh -ec "cd /gha && sh ./check.sh"
+          docker run --platform "$DOCKER_PLATFORM" -v $(pwd):/gha ${{ matrix.platform }}/debian:unstable-slim sh -ec "cd /gha && sh ./check.sh"
       - uses: actions/upload-artifact@v3
         with:
           name: patchelf