fix: split CPU docker build into native amd64/arm64 jobs to prevent 6h timeout

The CPU container job was using QEMU to cross-compile linux/arm64 on a
single x86 runner, consistently hitting the 6-hour GitHub Actions limit.
All recent releases (v5.1.3 through v5.3.1) failed to publish latest-cpu.

Fix: split into two native jobs (ubuntu-22.04 and ubuntu-22.04-arm),
mirroring the existing GPU build pattern. Remove QEMU. Merge into a
multi-arch manifest in the manifests job using buildx imagetools.

Also: add weekly schedule trigger (Sunday midnight UTC) so the devcontainer
image stays fresh between releases, and bump build-push-action to v6.

Author: sbryngelson

.github/workflows/docker.yml

@@ -3,11 +3,13 @@ name: Containerization
 on:
   release:
     types: [published]
+  schedule:
+    - cron: '0 0 * * 0'
   workflow_dispatch:
     inputs:
       tag:
         description: 'tag to containerize'
-        required: true
+        required: false
 
 concurrency:
   group: Containerization
@@ -18,9 +20,10 @@ jobs:
     strategy:
       matrix:
         config:
-            - { name: 'cpu', runner: 'ubuntu-22.04',         base_image: 'ubuntu:22.04' }
-            - { name: 'gpu', runner: 'ubuntu-22.04',         base_image: 'nvcr.io/nvidia/nvhpc:23.11-devel-cuda_multi-ubuntu22.04' }
-            - { name: 'gpu', runner: 'ubuntu-22.04-arm',     base_image: 'nvcr.io/nvidia/nvhpc:23.11-devel-cuda_multi-ubuntu22.04' }
+            - { name: 'cpu', runner: 'ubuntu-22.04',     base_image: 'ubuntu:22.04' }
+            - { name: 'cpu', runner: 'ubuntu-22.04-arm', base_image: 'ubuntu:22.04' }
+            - { name: 'gpu', runner: 'ubuntu-22.04',     base_image: 'nvcr.io/nvidia/nvhpc:23.11-devel-cuda_multi-ubuntu22.04' }
+            - { name: 'gpu', runner: 'ubuntu-22.04-arm', base_image: 'nvcr.io/nvidia/nvhpc:23.11-devel-cuda_multi-ubuntu22.04' }
     runs-on: ${{ matrix.config.runner }}
     outputs:
       tag: ${{ steps.clone.outputs.tag }}
@@ -45,16 +48,19 @@ jobs:
       - name: Setup Buildx
         uses: docker/setup-buildx-action@v3
 
-      - name: Setup QEMU
-        uses: docker/setup-qemu-action@v3
-
       - name: Clone
         id: clone
         run: |
-          TAG="${{ github.event.inputs.tag || github.ref_name }}"
+          if [ "${{ github.event_name }}" = "schedule" ]; then
+            BRANCH="master"
+            TAG="nightly"
+          else
+            BRANCH="${{ github.event.inputs.tag || github.ref_name }}"
+            TAG="$BRANCH"
+          fi
           echo "tag=$TAG" >> $GITHUB_OUTPUT
           echo "TAG=$TAG" >> $GITHUB_ENV
-          git clone --branch "$TAG" --depth 1 ${{ github.server_url }}/${{ github.repository }}.git mfc
+          git clone --branch "$BRANCH" --depth 1 ${{ github.server_url }}/${{ github.repository }}.git mfc
 
       - name: Stage
         run: |
@@ -71,16 +77,13 @@ jobs:
           cp -r mfc/.git /mnt/share/.git
           cp mfc/.github/Dockerfile /mnt/share/
           cp mfc/.github/.dockerignore /mnt/share/
-          docker buildx create --name mfcbuilder --driver docker-container --use
 
       - name: Build and push image (cpu)
         if: ${{ matrix.config.name == 'cpu' }}
         uses: docker/build-push-action@v6
         with:
-          builder: mfcbuilder
           context: /mnt/share
           file: /mnt/share/Dockerfile
-          platforms: linux/amd64,linux/arm64
           build-args: |
             BASE_IMAGE=${{ matrix.config.base_image }}
             TARGET=${{ matrix.config.name }}
@@ -89,12 +92,12 @@ jobs:
             FC_COMPILER=${{ 'gfortran' }}
             COMPILER_PATH=${{ '/usr/bin' }}
             COMPILER_LD_LIBRARY_PATH=${{ '/usr/lib' }}
-          tags: ${{ secrets.DOCKERHUB_USERNAME }}/mfc:${{ env.TAG }}-${{ matrix.config.name }}
+          tags: ${{ secrets.DOCKERHUB_USERNAME }}/mfc:${{ env.TAG }}-${{ matrix.config.name }}-${{ matrix.config.runner }}
           push: true
 
       - name: Build and push image (gpu)
         if: ${{ matrix.config.name == 'gpu' }}
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         with:
           builder: default
           context: /mnt/share
@@ -120,13 +123,15 @@ jobs:
           username: ${{ secrets.DOCKERHUB_USERNAME }}
           password: ${{ secrets.DOCKERHUB_PASSWORD }}
 
+      - name: Setup Buildx
+        uses: docker/setup-buildx-action@v3
+
       - name: Create and Push Manifest Lists
         env:
           TAG: ${{ needs.Container.outputs.tag }}
           REGISTRY: ${{ secrets.DOCKERHUB_USERNAME }}/mfc
         run: |
-          docker buildx imagetools create -t $REGISTRY:latest-cpu $REGISTRY:$TAG-cpu
-          docker manifest create $REGISTRY:$TAG-gpu $REGISTRY:$TAG-gpu-ubuntu-22.04 $REGISTRY:$TAG-gpu-ubuntu-22.04-arm
-          docker manifest create $REGISTRY:latest-gpu $REGISTRY:$TAG-gpu-ubuntu-22.04 $REGISTRY:$TAG-gpu-ubuntu-22.04-arm
-          docker manifest push $REGISTRY:$TAG-gpu
-          docker manifest push $REGISTRY:latest-gpu
+          docker buildx imagetools create -t $REGISTRY:$TAG-cpu  $REGISTRY:$TAG-cpu-ubuntu-22.04 $REGISTRY:$TAG-cpu-ubuntu-22.04-arm
+          docker buildx imagetools create -t $REGISTRY:latest-cpu $REGISTRY:$TAG-cpu-ubuntu-22.04 $REGISTRY:$TAG-cpu-ubuntu-22.04-arm
+          docker buildx imagetools create -t $REGISTRY:$TAG-gpu  $REGISTRY:$TAG-gpu-ubuntu-22.04 $REGISTRY:$TAG-gpu-ubuntu-22.04-arm
+          docker buildx imagetools create -t $REGISTRY:latest-gpu $REGISTRY:$TAG-gpu-ubuntu-22.04 $REGISTRY:$TAG-gpu-ubuntu-22.04-arm