fix multiplatform builds

ref BerkeleyLibrary/gha-testing#3

Author: anarchivist

.github/workflows/build.yml

@@ -20,9 +20,11 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        runner:
-          - ubuntu-24.04
-          - ubuntu-24.04-arm
+        include:
+          - platform: linux/amd64
+            runner: ubuntu-24.04
+          - platform: linux/arm64
+            runner: ubuntu-24.04-arm
     steps:
       - name: Checkout code
         uses: actions/checkout@v4
@@ -66,6 +68,7 @@ jobs:
         name: Build/push the arch-specific image
         uses: docker/build-push-action@v6
         with:
+          platforms: ${{ matrix.platform }}
           build-args: |
             BUILD_TIMESTAMP=${{ github.event.repository.updated_at }}
             BUILD_URL=${{ steps.set_build_url.outputs.build_url }}
@@ -86,14 +89,16 @@ jobs:
           echo "image-${RUNNER_ARCH,,}=${{ steps.get-registry.outputs.registry }}@${{ steps.build.outputs.digest }}" | tee -a "$GITHUB_OUTPUT"
 
   merge:
-    runs-on: ubuntu-24.04
+    runs-on: ubuntu-latest
     needs:
       - build
     env:
       DOCKER_APP_IMAGE_ARM64: ${{ needs.build.outputs.build-image-arm }}
       DOCKER_APP_IMAGE_X64: ${{ needs.build.outputs.build-image-x64 }}
     outputs:
       build-image: ${{ steps.meta.outputs.tags }}
+      build-image-arm: ${{ needs.build.outputs.build-image-arm }}
+      build-image-x64: ${{ needs.build.outputs.build-image-x64 }}
     steps:
       - name: Checkout code
         uses: actions/checkout@v4
@@ -123,7 +128,7 @@ jobs:
             "$DOCKER_APP_IMAGE_ARM64" "$DOCKER_APP_IMAGE_X64"
 
   test:
-    runs-on: ubuntu-24.04
+    runs-on: ubuntu-latest
     needs:
       - merge
     env:
@@ -152,16 +157,21 @@ jobs:
           docker compose exec app bin/test
 
   push:
-    runs-on: ubuntu-24.04
+    runs-on: ubuntu-latest
     needs:
       - merge
       - test
     env:
       DOCKER_APP_IMAGE: ${{ needs.merge.outputs.build-image }}
+      DOCKER_APP_IMAGE_ARM64: ${{ needs.merge.outputs.build-image-arm }}
+      DOCKER_APP_IMAGE_X64: ${{ needs.merge.outputs.build-image-x64 }}
     steps:
       - name: Checkout code
         uses: actions/checkout@v4
 
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
       - name: Login to GitHub Container Registry
         uses: docker/login-action@v3
         with:
@@ -181,6 +191,5 @@ jobs:
 
       - name: Retag and push the image
         run: |
-          docker pull "$DOCKER_APP_IMAGE"
-          echo "$DOCKER_METADATA_OUTPUT_TAGS" | tr ' ' '\n' | xargs -n1 docker tag "$DOCKER_APP_IMAGE"
-          docker push --all-tags "$(echo "$DOCKER_APP_IMAGE" | cut -f1 -d:)"
+          docker buildx imagetools create \
+            $(jq -cr '.tags | map("--tag " + .) | join(" ")' <<< "$DOCKER_METADATA_OUTPUT_JSON") $DOCKER_APP_IMAGE_ARM64 $DOCKER_APP_IMAGE_X64

.github/workflows/release.yml

@@ -17,9 +17,6 @@ jobs:
       - name: Checkout code
         uses: actions/checkout@v4
 
-      - name: Set up QEMU
-        uses: docker/setup-qemu-action@v3
-
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
 
@@ -41,7 +38,7 @@ jobs:
         env:
           BASE_IMAGE: ${{ steps.get-base-image.outputs.tags }}
         run: |
-          docker pull "$BASE_IMAGE"
+          docker manifest inspect "$BASE_IMAGE"
 
       - name: Produce release tags
         id: tag-meta
@@ -59,5 +56,6 @@ jobs:
         env:
           BASE_IMAGE: ${{ steps.get-base-image.outputs.tags }}
         run: |
-          echo "$DOCKER_METADATA_OUTPUT_TAGS" | tr ' ' '\n' | xargs -n1 docker tag "$BASE_IMAGE"
-          docker push --all-tags "$(echo "$BASE_IMAGE" | cut -f1 -d:)"
+          docker buildx imagetools create \
+            $(jq -cr '.tags | map("--tag " + .) | join(" ")' <<< "$DOCKER_METADATA_OUTPUT_JSON") \
+            "$(echo "$BASE_IMAGE" | cut -f1 -d:)"