Use native runners

Author: rubenhensen

.github/workflows/ci.yml

@@ -71,21 +71,72 @@ jobs:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           # CARGO_REGISTRY_TOKEN: ${{ secrets.CARGO_REGISTRY_TOKEN }}
 
-  # Build and push Docker image.
-  # - push to main (no release)  → ghcr.io/.../cryptify:edge
-  # - push to main (release)     → ghcr.io/.../cryptify:edge + ghcr.io/.../cryptify:0.1.3
-  # - pull request               → ghcr.io/.../cryptify:pr-123
+  # Build each platform on its native runner and push by digest (no tag yet).
   build:
-    name: Build Docker image
-    needs: [release-plz-release]
-    if: always()
-    runs-on: ubuntu-latest
+    name: Build (${{ matrix.name }})
+    runs-on: ${{ matrix.runner }}
     permissions:
       contents: read
       packages: write
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - platform: linux/amd64
+            runner: ubuntu-24.04
+            name: amd64
+          - platform: linux/arm64
+            runner: ubuntu-24.04-arm
+            name: arm64
     steps:
       - name: Checkout repository
         uses: actions/checkout@v6
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+      - name: Log in to GHCR
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+      - name: Build and push by digest
+        id: build
+        uses: docker/build-push-action@v6
+        with:
+          platforms: ${{ matrix.platform }}
+          outputs: type=image,name=ghcr.io/${{ github.repository }},push-by-digest=true,name-canonical=true,push=true
+      - name: Export digest
+        run: |
+          mkdir -p /tmp/digests
+          digest="${{ steps.build.outputs.digest }}"
+          touch "/tmp/digests/${digest#sha256:}"
+      - name: Upload digest
+        uses: actions/upload-artifact@v4
+        with:
+          name: digest-${{ matrix.name }}
+          path: /tmp/digests/*
+          if-no-files-found: error
+          retention-days: 1
+
+  # Merge platform digests into a single multi-platform manifest and apply tags.
+  # - push to main (no release)  → ghcr.io/.../cryptify:edge
+  # - push to main (release)     → ghcr.io/.../cryptify:edge + cryptify:0.1.3
+  # - pull request               → ghcr.io/.../cryptify:pr-123
+  finalize:
+    name: Finalize Docker manifest
+    needs: [build, release-plz-release]
+    if: always() && needs.build.result == 'success'
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+    steps:
+      - name: Download digests
+        uses: actions/download-artifact@v4
+        with:
+          path: /tmp/digests
+          pattern: digest-*
+          merge-multiple: true
       - name: Docker metadata
         id: meta
         uses: docker/metadata-action@v5
@@ -95,8 +146,6 @@ jobs:
             type=edge,branch=main
             type=ref,event=pr
             type=raw,value=${{ needs.release-plz-release.outputs.version }},enable=${{ needs.release-plz-release.outputs.releases_created == 'true' }}
-      - name: Set up QEMU
-        uses: docker/setup-qemu-action@v3
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
       - name: Log in to GHCR
@@ -105,10 +154,9 @@ jobs:
           registry: ghcr.io
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
-      - name: Build and push
-        uses: docker/build-push-action@v6
-        with:
-          push: true
-          platforms: linux/amd64,linux/arm64
-          tags: ${{ steps.meta.outputs.tags }}
-          labels: ${{ steps.meta.outputs.labels }}
+      - name: Create and push manifest
+        working-directory: /tmp/digests
+        run: |
+          docker buildx imagetools create \
+            $(jq -cr '.tags | map("-t " + .) | join(" ")' <<< "$DOCKER_METADATA_OUTPUT_JSON") \
+            $(printf 'ghcr.io/${{ github.repository }}@sha256:%s ' *)