ci: Split multi-arch image builds into individual jobs

This commit splits the current "build" job that builds both amd64 and
arm64 images into individual jobs running on the corresponding the host
architecture building each image.

Splitting the image build jobs and building the images on the native
host without using QEMU reduces the build time significantly.

As part of splitting the build jobs, a new "merge" job was introduced
to create single Docker tag containing the manifests for both amd64 and
arm64 images.

Signed-off-by: Stephanos Ioannidis <root@stephanos.io>

.github/workflows/ci.yml

@@ -21,8 +21,19 @@ concurrency:
 
 jobs:
   build:
-    name: Build
-    runs-on: zephyr-runner-linux-x64-xlarge
+    name: Build (${{ matrix.variant.platform }})
+    runs-on: ${{ matrix.variant.builder }}
+
+    strategy:
+      fail-fast: true
+      matrix:
+        variant:
+        - platform: linux/amd64
+          arch: amd64
+          builder: zephyr-runner-linux-x64-xlarge
+        - platform: linux/arm64
+          arch: arm64
+          builder: zephyr-runner-linux-arm64-xlarge
 
     services:
       registry:
@@ -58,10 +69,10 @@ jobs:
           ghcr.io/zephyrproject-rtos/ci
         flavor: |
           latest=false
+          suffix=-${{ matrix.variant.arch }}
         tags: |
           type=ref,event=branch
           type=ref,event=tag
-          type=raw,value=latest,enable={{is_default_branch}}
 
     - name: Generate push metadata for Developer image
       if: ${{ github.event_name != 'pull_request' }}
@@ -73,13 +84,10 @@ jobs:
           ghcr.io/zephyrproject-rtos/zephyr-build
         flavor: |
           latest=false
+          suffix=-${{ matrix.variant.arch }}
         tags: |
           type=ref,event=branch
           type=ref,event=tag
-          type=raw,value=latest,enable={{is_default_branch}}
-
-    - name: Set up QEMU
-      uses: docker/setup-qemu-action@v1
 
     - name: Set up Docker Buildx
       uses: docker/setup-buildx-action@v1
@@ -91,7 +99,7 @@ jobs:
       with:
         context: .
         file: Dockerfile
-        platforms: linux/amd64,linux/arm64
+        platforms: ${{ matrix.variant.platform }}
         push: true
         tags: ${{ steps.meta_ci.outputs.tags }}
         labels: ${{ steps.meta_ci.outputs.labels }}
@@ -101,7 +109,7 @@ jobs:
       with:
         context: .
         file: Dockerfile.user
-        platforms: linux/amd64,linux/arm64
+        platforms: ${{ matrix.variant.platform }}
         push: true
         tags: ${{ steps.meta_developer.outputs.tags }}
         labels: ${{ steps.meta_developer.outputs.labels }}
@@ -126,14 +134,99 @@ jobs:
 
     - name: Push CI docker image
       if: ${{ github.event_name != 'pull_request' }}
-      uses: akhilerm/tag-push-action@v2.0.0
+      uses: stephanosio/tag-push-action@v2.1.0
       with:
         src: localhost:5000/zephyrproject-rtos/ci:${{ steps.meta_ci.outputs.version }}
         dst: ${{ steps.meta_ci_push.outputs.tags }}
 
     - name: Push Developer docker image
       if: ${{ github.event_name != 'pull_request' }}
-      uses: akhilerm/tag-push-action@v2.0.0
+      uses: stephanosio/tag-push-action@v2.1.0
       with:
         src: localhost:5000/zephyrproject-rtos/zephyr-build:${{ steps.meta_developer.outputs.version }}
         dst: ${{ steps.meta_developer_push.outputs.tags }}
+
+  merge:
+    name: Merge
+    runs-on: zephyr-runner-linux-x64-xlarge
+    needs: build
+    if: ${{ github.event_name != 'pull_request' }}
+
+    steps:
+    - name: Login to DockerHub
+      uses: docker/login-action@v1
+      with:
+        registry: docker.io
+        username: ${{ secrets.DOCKERHUB_USERNAME }}
+        password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+    - name: Login to GitHub Container Registry
+      uses: docker/login-action@v1
+      with:
+        registry: ghcr.io
+        username: ${{ github.repository_owner }}
+        password: ${{ secrets.GITHUB_TOKEN }}
+
+    - name: Generate push metadata for CI image
+      id: meta_ci_push
+      uses: docker/metadata-action@v3
+      with:
+        images: |
+          docker.io/zephyrprojectrtos/ci
+          ghcr.io/zephyrproject-rtos/ci
+        flavor: |
+          latest=false
+        tags: |
+          type=ref,event=branch
+          type=ref,event=tag
+          type=raw,value=latest,enable={{is_default_branch}}
+
+    - name: Generate push metadata for Developer image
+      id: meta_developer_push
+      uses: docker/metadata-action@v3
+      with:
+        images: |
+          docker.io/zephyrprojectrtos/zephyr-build
+          ghcr.io/zephyrproject-rtos/zephyr-build
+        flavor: |
+          latest=false
+        tags: |
+          type=ref,event=branch
+          type=ref,event=tag
+          type=raw,value=latest,enable={{is_default_branch}}
+
+    - name: Create multi-architecture image
+      run: |
+        archs=(amd64 arm64)
+        ci_image="ghcr.io/zephyrproject-rtos/ci:${{ steps.meta_ci_push.outputs.version }}"
+        developer_image="ghcr.io/zephyrproject-rtos/zephyr-build:${{ steps.meta_developer_push.outputs.version }}"
+
+        # Pull architecture-specific images
+        for arch in ${archs[@]}; do
+          docker pull ${ci_image}-${arch}
+          docker pull ${developer_image}-${arch}
+        done
+
+        # Create multi-architecture image
+        for arch in ${archs[@]}; do
+          ci_image_amend_flags+="--amend ${ci_image}-${arch} "
+          developer_image_amend_flags+="--amend ${developer_image}-${arch} "
+        done
+
+        docker manifest create ${ci_image} ${ci_image_amend_flags}
+        docker manifest create ${developer_image} ${developer_image_amend_flags}
+
+        docker manifest push ${ci_image}
+        docker manifest push ${developer_image}
+
+    - name: Push CI docker image
+      uses: stephanosio/tag-push-action@v2.1.0
+      with:
+        src: ghcr.io/zephyrproject-rtos/ci:${{ steps.meta_ci_push.outputs.version }}
+        dst: ${{ steps.meta_ci_push.outputs.tags }}
+
+    - name: Push Developer docker image
+      uses: stephanosio/tag-push-action@v2.1.0
+      with:
+        src: ghcr.io/zephyrproject-rtos/zephyr-build:${{ steps.meta_developer_push.outputs.version }}
+        dst: ${{ steps.meta_developer_push.outputs.tags }}