use multiple runners for the multi-arch build

.gitea/workflows/ci.yml

@@ -63,46 +63,55 @@ jobs:
           token: ${{ secrets.CODECOV_TOKEN }}
   build:
     name: Build and push image
-    runs-on: ${{ matrix.runner }}
+    runs-on: ${{ matrix.arch.runner }}
     strategy:
       matrix:
-        runner: [ubuntu-latest, ubuntu-arm-latest]
+        arch:
+          - runner: ubuntu-latest
+            platform: linux/amd64
+          - runner: ubuntu-arm-latest
+            platform: linux/arm64
     permissions:
       packages: write
     needs: tests
     steps:
       - uses: actions/checkout@v4
+      - name: Prepare
+        run: |
+          platform=${{ matrix.arch.platform }}
+          echo "PLATFORM_PAIR=${platform//\//-}" >> $GITHUB_ENV
+      - name: Generate metadata
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
       - name: Login to the Container Registry
         uses: docker/login-action@v3
         with:
           registry: brosner.dev
           username: brosner
           password: ${{ secrets.CI_TOKEN }}
-      - name: Generate metadata
-        id: meta
-        uses: docker/metadata-action@v5
-        with:
-          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
-          tags: |
-            type=ref,event=branch
-            type=ref,event=pr
-            type=sha
-          labels: |
-            org.opencontainers.image.title=teufa
-            org.opencontainers.image.description=teufa container image
-            org.opencontainers.image.source=https://brosner.dev/brosner/teufa
-            org.opencontainers.image.licenses=MIT
-      - name: Set up QEMU
-        uses: docker/setup-qemu-action@v3
       - name: Setup docker buildx
         uses: docker/setup-buildx-action@v3
       - name: Build image
+        id: build
         uses: docker/build-push-action@v6
-        if: gitea.ref == 'refs/heads/main'
         with:
-          tags: ${{ steps.meta.outputs.tags }}
+          tags: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
           labels: ${{ steps.meta.outputs.labels }}
           annotations: ${{ steps.meta.outputs.annotations }}
           target: prod
-          platforms: ${{ matrix.runner == 'ubuntu-latest' && 'linux/amd64' || 'linux/arm64' }}
+          platforms: ${{ matrix.arch.platform }}
-          push: true
+          outputs: type=image,push-by-digest=true,name-canonical=true,push=true
+      - name: Export digest
+        run: |
+          mkdir -p ${{ runner.temp }}/digests
+          digest="${{ steps.build.outputs.digest }}"
+          touch "${{ runner.temp }}/digests/${digest#sha256:}"
+      - name: Upload digest
+        uses: actions/upload-artifact@v4
+        with:
+          name: digests-${{ env.PLATFORM_PAIR }}
+          path: ${{ runner.temp }}/digests/*
+          if-no-files-found: error
+          retention-days: 1