[Github] Add Agent Container Image (llvm#123486)

This patch adds an agent container image on top of the normal CI
container image. They are the exact same except that the agent container
image also contains Github Runner binaries. I've split it into a
separate container as only one user of these images (the new premerge)
needs this binary installed, and it bloats the container image size
significantly (900MB->1.3GB or so).

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

@@ -36,19 +36,22 @@ jobs:
           tag=`date +%s`
           container_name="ghcr.io/$GITHUB_REPOSITORY_OWNER/ci-ubuntu-22.04"
           echo "container-name=$container_name" >> $GITHUB_OUTPUT
+          echo "container-name-agent=$container_name-agent" >> $GITHUB_OUTPUT
           echo "container-name-tag=$container_name:$tag" >> $GITHUB_OUTPUT
+          echo "container-name-agent-tag=$container_name-agent:$tag" >> $GITHUB_OUTPUT
           echo "container-filename=$(echo $container_name:$tag  | sed -e 's/\//-/g' -e 's/:/-/g').tar" >> $GITHUB_OUTPUT
       - name: Build container
         working-directory: ./.github/workflows/containers/github-action-ci/
         run: |
-          podman build -t ${{ steps.vars.outputs.container-name-tag }} .
+          podman build --target ci-container -t ${{ steps.vars.outputs.container-name-tag }} .
+          podman build --target ci-container-agent -t ${{ steps.vars.outputs.container-name-agent-tag }} .
 
       # Save the container so we have it in case the push fails.  This also
       # allows us to separate the push step into a different job so we can
       # maintain minimal permissions while building the container.
       - name: Save container image
         run: |
-          podman save  ${{ steps.vars.outputs.container-name-tag }} >  ${{ steps.vars.outputs.container-filename }}
+          podman save  ${{ steps.vars.outputs.container-name-tag }} ${{ steps.vars.outputs.container-name-agent-tag }} >  ${{ steps.vars.outputs.container-filename }}
 
       - name: Upload container image
         uses: actions/upload-artifact@v4
@@ -86,3 +89,7 @@ jobs:
           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
+
+          podman tag ${{ needs.build-ci-container.outpus.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

.github/workflows/containers/github-action-ci/Dockerfile

@@ -39,7 +39,7 @@ RUN cmake -B ./build -G Ninja ./llvm \
 
 RUN ninja -C ./build stage2-clang-bolt stage2-install-distribution && ninja -C ./build install-distribution
 
-FROM base
+FROM base as ci-container
 
 COPY --from=stage1-toolchain $LLVM_SYSROOT $LLVM_SYSROOT
 
@@ -92,4 +92,15 @@ RUN adduser gha sudo
 RUN echo '%sudo ALL=(ALL) NOPASSWD:ALL' >> /etc/sudoers
 
 USER gha
+WORKDIR /home/gha
+
+FROM ci-container as ci-container-agent
+
+ENV GITHUB_RUNNER_VERSION=2.321.0
+
+RUN mkdir actions-runner && \
+    cd actions-runner && \
+    curl -O -L https://github.com/actions/runner/releases/download/v$GITHUB_RUNNER_VERSION/actions-runner-linux-x64-$GITHUB_RUNNER_VERSION.tar.gz && \
+    tar xzf ./actions-runner-linux-x64-$GITHUB_RUNNER_VERSION.tar.gz && \
+    rm ./actions-runner-linux-x64-$GITHUB_RUNNER_VERSION.tar.gz