workflows/build-ci-container: Add an arm64 container (#120828)

This also changes the container version numbers in the tag from unix
timestamps to the abbreviated commit hash for the workflow. This ensures
that the amd64 and arm64 containers have the same tag.

For amd64 we now generate 4 tags:

* ghcr.io/llvm/ci-ubuntu-22.04:latest
* ghcr.io/llvm/ci-ubuntu-22.04:$GITHUB_SHA
* ghcr.io/llvm/amd64/ci-ubuntu-22.04:latest
* ghcr.io/llvm/amd64/ci-ubuntu-22.04:$GITHUB_SHA

For arm64 we generate 2 tags:

* ghcr.io/tstellar/arm64v8/ci-ubuntu-22.04:latest
* ghcr.io/tstellar/arm64v8/ci-ubuntu-22.04:$GITHUB_SHA

Author: tstellar

.github/workflows/build-ci-container.yml

@@ -20,24 +20,31 @@ on:
 jobs:
   build-ci-container:
     if: github.repository_owner == 'llvm'
-    runs-on: depot-ubuntu-22.04-16
-    outputs:
-      container-name: ${{ steps.vars.outputs.container-name }}
-      container-name-agent: ${{ steps.vars.outputs.container-name-agent }}
-      container-name-tag: ${{ steps.vars.outputs.container-name-tag }}
-      container-name-agent-tag: ${{ steps.vars.outputs.container-name-agent-tag }}
-      container-filename: ${{ steps.vars.outputs.container-filename }}
-      container-agent-filename: ${{ steps.vars.outputs.container-agent-filename }}
+    runs-on: ${{ matrix.runs-on }}
+    strategy:
+      matrix:
+        include:
+          # The arch names should match the names used on dockerhub.
+          # See https://github.com/docker-library/official-images#architectures-other-than-amd64
+          - arch: amd64
+            runs-on: depot-ubuntu-22.04-16
+          - arch: arm64v8
+            runs-on: depot-ubuntu-22.04-arm-16
     steps:
       - name: Checkout LLVM
         uses: actions/checkout@v4
         with:
           sparse-checkout: .github/workflows/containers/github-action-ci/
+      # podman is not installed by default on the ARM64 images.
+      - name: Install Podman
+        if: runner.arch == 'ARM64'
+        run: |
+          sudo apt-get install podman
       - name: Write Variables
         id: vars
         run: |
-          tag=`date +%s`
-          container_name="ghcr.io/$GITHUB_REPOSITORY_OWNER/ci-ubuntu-22.04"
+          tag=$(git rev-parse --short=12 HEAD)
+          container_name="ghcr.io/$GITHUB_REPOSITORY_OWNER/${{ matrix.arch }}/ci-ubuntu-22.04"
           echo "container-name=$container_name" >> $GITHUB_OUTPUT
           echo "container-name-agent=$container_name-agent" >> $GITHUB_OUTPUT
           echo "container-name-tag=$container_name:$tag" >> $GITHUB_OUTPUT
@@ -61,7 +68,7 @@ jobs:
       - name: Upload container image
         uses: actions/upload-artifact@v4
         with:
-          name: container
+          name: container-${{ matrix.arch }}
           path: "*.tar"
           retention-days: 14
 
@@ -84,18 +91,29 @@ jobs:
     steps:
       - name: Download container
         uses: actions/download-artifact@v4
-        with:
-          name: container
 
       - name: Push Container
         run: |
-          podman load -i ${{ needs.build-ci-container.outputs.container-filename }}
-          podman tag ${{ needs.build-ci-container.outputs.container-name-tag }} ${{ needs.build-ci-container.outputs.container-name }}:latest
+          function push_container {
+            image_name=$1
+            latest_name=$(echo $image_name | sed 's/:[.0-9]\+$/:latest/g')
+            podman tag $image_name $latest_name
+            echo "Pushing $image_name ..."
+            podman push $image_name
+            echo "Pushing $latest_name ..."
+            podman push $latest_name
+          }
+
           podman login -u ${{ github.actor }} -p $GITHUB_TOKEN ghcr.io
-          podman push ${{ needs.build-ci-container.outputs.container-name-tag }}
-          podman push ${{ needs.build-ci-container.outputs.container-name }}:latest
+          for f in $(find . -iname *.tar); do
+            image_name=$(podman load -q -i $f | sed 's/Loaded image: //g')
+            push_container $image_name
 
-          podman load -i ${{ needs.build-ci-container.outputs.container-agent-filename }}
-          podman tag ${{ needs.build-ci-container.outputs.container-name-agent-tag }} ${{ needs.build-ci-container.outputs.container-name-agent }}:latest
-          podman push ${{ needs.build-ci-container.outputs.container-name-agent-tag }}
-          podman push ${{ needs.build-ci-container.outputs.container-name-agent }}:latest
+            if echo $image_name | grep '/amd64/'; then
+              # For amd64, create an alias with the arch component removed.
+              # This matches the convention used on dockerhub.
+              default_image_name=$(echo $(dirname $(dirname $image_name))/$(basename $image_name))
+              podman tag $image_name $default_image_name
+              push_container $default_image_name
+            fi
+          done