build: use containerd to load multi-platform images

Author: autumnjolitz

.github/workflows/main.yml

@@ -48,6 +48,10 @@ jobs:
       -
         name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
+      -
+        name: Set up containerd
+        uses: crazy-max/ghaction-setup-containerd@v2
+
       -
         id: image_env
         run: |
@@ -58,6 +62,7 @@ jobs:
             '${{ matrix.repository }}'
 
           docker pull "${SOURCE_IMAGE}" || true
+          echo "IMAGE_HOME=$(mktemp -d)" >> "$GITHUB_OUTPUT"
 
           echo ALPINE_VERSION="${ALPINE_VERSION}" >> "$GITHUB_OUTPUT"
           echo PYTHON_VERSION="${PYTHON_VERSION}" >> "$GITHUB_OUTPUT"
@@ -78,7 +83,10 @@ jobs:
           context: "."
           file: Dockerfile.alpine
           target: buildroot
+          cache-to: |
+            type=gha
           cache-from: |
+            type=gha
             type=registry,ref=${{ steps.image_env.outputs.IMAGE_TAG }}-buildroot
             type=registry,ref=${{ steps.image_env.outputs.SOURCE_IMAGE }}@${{ steps.image_env.outputs.BASE_IMAGE_DIGEST }}
           build-args: |
@@ -88,6 +96,7 @@ jobs:
               SOURCE_IMAGE=${{ steps.image_env.outputs.SOURCE_IMAGE }}
               BUILD_ROOT=/d
           tags: "${{ steps.image_env.outputs.IMAGE_TAG }}-buildroot"
+          outputs: type=oci,dest=${{ steps.image_env.outputs.IMAGE_HOME }}/buildroot.tar
       -
         name: distroless
         uses: docker/build-push-action@v6
@@ -100,33 +109,20 @@ jobs:
           file: Dockerfile.alpine
           # target: distroless-python
           cache-from: |
+              type=gha
               type=registry,ref=${{ steps.image_env.outputs.IMAGE_TAG }}
               type=registry,ref=${{ steps.image_env.outputs.IMAGE_TAG }}-buildroot
               type=registry,ref=${{ steps.image_env.outputs.SOURCE_IMAGE }}@${{ steps.image_env.outputs.BASE_IMAGE_DIGEST }}
+          cache-to: |
+              type=gha
           build-args: |
               ALPINE_VERSION=${{ steps.image_env.outputs.ALPINE_VERSION }}
               BASE_IMAGE_DIGEST=${{ steps.image_env.outputs.BASE_IMAGE_DIGEST }}
               PYTHON_VERSION=${{ steps.image_env.outputs.PYTHON_VERSION }}
               SOURCE_IMAGE=${{ steps.image_env.outputs.SOURCE_IMAGE }}
               BUILD_ROOT=/d
           tags: "${{ steps.image_env.outputs.IMAGE_TAG }}"
-
-      -
-        name: examples/simple-flask
-        uses: docker/build-push-action@v6
-        with:
-          context: "examples/simple-flask"
-          platforms: |
-            linux/amd64
-            linux/arm64/v7
-            linux/arm64/v8
-          cache-from: |
-              type=registry,ref=${{ steps.image_env.outputs.IMAGE_TAG }}
-              type=registry,ref=${{ steps.image_env.outputs.IMAGE_TAG }}-buildroot
-              type=registry,ref=${{ steps.image_env.outputs.SOURCE_IMAGE }}@${{ steps.image_env.outputs.BASE_IMAGE_DIGEST }}
-          build-args: |
-              SOURCE_IMAGE=${{ steps.image_env.outputs.IMAGE_TAG }}
-          tags: "${{ steps.image_env.outputs.IMAGE_TAG }}-example1-amd64"
+          outputs: type=oci,dest=${{ steps.image_env.outputs.IMAGE_HOME }}/image.tar
 
       -
         name: Login to GitHub Container Registry
@@ -157,7 +153,10 @@ jobs:
           context: "."
           file: Dockerfile.alpine
           target: buildroot
+          cache-to: |
+            type=gha
           cache-from: |
+            type=gha
             type=registry,ref=${{ steps.image_env.outputs.IMAGE_TAG }}-buildroot
             type=registry,ref=${{ steps.image_env.outputs.SOURCE_IMAGE }}@${{ steps.image_env.outputs.BASE_IMAGE_DIGEST }}
           build-args: |
@@ -180,7 +179,10 @@ jobs:
             linux/arm64/v7
             linux/arm64/v8
           file: Dockerfile.alpine
+          cache-to: |
+              type=gha
           cache-from: |
+              type=gha
               type=registry,ref=${{ steps.image_env.outputs.IMAGE_TAG }}
               type=registry,ref=${{ steps.image_env.outputs.IMAGE_TAG }}-buildroot
               type=registry,ref=${{ steps.image_env.outputs.SOURCE_IMAGE }}@${{ steps.image_env.outputs.BASE_IMAGE_DIGEST }}
@@ -204,6 +206,26 @@ jobs:
               index,manifest:distroless.alpine-version=${{ steps.image_env.outputs.ALPINE_VERSION }}
               index,manifest:distroless.base-image=alpine${{ steps.image_env.outputs.ALPINE_VERSION }}
 
+      -
+        name: examples/simple-flask
+        uses: docker/build-push-action@v6
+        with:
+          context: "examples/simple-flask"
+          platforms: |
+            linux/amd64
+            linux/arm64/v7
+            linux/arm64/v8
+          cache-from: |
+              type=gha
+              type=registry,ref=${{ steps.image_env.outputs.IMAGE_TAG }}
+              type=registry,ref=${{ steps.image_env.outputs.IMAGE_TAG }}-buildroot
+              type=registry,ref=${{ steps.image_env.outputs.SOURCE_IMAGE }}@${{ steps.image_env.outputs.BASE_IMAGE_DIGEST }}
+          build-args: |
+              SOURCE_IMAGE=${{ steps.image_env.outputs.IMAGE_TAG }}
+          tags: "${{ steps.image_env.outputs.IMAGE_TAG }}-example1-amd64"
+          outputs: type=oci,dest=${{ steps.image_env.outputs.IMAGE_HOME }}/example1.tar
+
+
   update-dockerhub-desc:
     needs: [docker]
     runs-on: "ubuntu-latest"