[Github][CI] Add separate container for code-format premerge job

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

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+name: Build CI Container
+
+permissions:
+  contents: read
+
+on:
+  push:
+    branches:
+      - main
+    paths:
+      - .github/workflows/build-ci-container-tooling.yml
+      - '.github/workflows/containers/github-action-ci-tooling/**'
+      - llvm/utils/git/requirements_formatting.txt
+      - llvm/utils/git/requirements_linting.txt
+  pull_request:
+    paths:
+      - .github/workflows/build-ci-container-tooling.yml
+      - '.github/workflows/containers/github-action-ci-tooling/**'
+      - llvm/utils/git/requirements_formatting.txt
+      - llvm/utils/git/requirements_linting.txt
+
+jobs:
+  build-ci-container-tooling:
+    if: github.repository_owner == 'llvm'
+    runs-on: depot-ubuntu-24.04-16
+    strategy:
+      matrix:
+        target: [ci-container-code-format, ci-container-code-lint]
+        include:
+          - target: ci-container-code-format
+            container_name: code-format
+            check_line: clang-format --version | grep version
+          - target: ci-container-code-lint
+            container_name: code-lint
+            check_line: clang-tidy --version | grep version
+    steps:
+      - name: Checkout LLVM
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+        with:
+          sparse-checkout: |
+            .github/workflows/containers/github-action-ci-tooling/
+            llvm/utils/git/requirements_formatting.txt
+            llvm/utils/git/requirements_linting.txt
+            clang-tools-extra/clang-tidy/tool/clang-tidy-diff.py
+
+      - name: Write Variables
+        id: vars
+        run: |
+          tag=$(git rev-parse --short=12 HEAD)
+          container_name="ghcr.io/$GITHUB_REPOSITORY_OWNER/amd64/ci-ubuntu-24.04-${{ matrix.container_name }}"
+          echo "container-name=$container_name" >> $GITHUB_OUTPUT
+          echo "container-name-tag=$container_name:$tag" >> $GITHUB_OUTPUT
+          echo "container-filename=$(echo $container_name:$tag  | sed -e 's/\//-/g' -e 's/:/-/g').tar" >> $GITHUB_OUTPUT
+      - name: Build container
+        run: |
+          podman build --target ${{ matrix.target }} \
+          -f .github/workflows/containers/github-action-ci-tooling/Dockerfile \
+          -t ${{ steps.vars.outputs.container-name-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 }}  >  ${{ steps.vars.outputs.container-filename }}
+
+      - name: Upload container image
+        uses: actions/upload-artifact@65c4c4a1ddee5b72f698fdd19549f0f0fb45cf08 # v4.6.0
+        with:
+          name: container-amd64-${{ matrix.container_name }}
+          path: "*.tar"
+          retention-days: 14
+
+      - name: Test Container
+        run: |
+          for image in ${{ steps.vars.outputs.container-name-tag }}; do
+            # Use --pull=never to ensure we are testing the just built image.
+            podman run --pull=never --rm -it $image /usr/bin/bash -x -c 'cd $HOME && ${{ matrix.check_line }}'
+          done
+
+  push-ci-container:
+    if: github.event_name == 'push'
+    needs:
+      - build-ci-container-tooling
+    permissions:
+      packages: write
+    runs-on: ubuntu-24.04
+    env:
+      GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+    steps:
+      - name: Download container
+        uses: actions/download-artifact@634f93cb2916e3fdff6788551b99b062d0335ce0 # v5.0.0
+
+      - name: Push Container
+        run: |
+          function push_container {
+            image_name=$1
+            latest_name=$(echo $image_name | sed 's/:[a-f0-9]\+$/: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
+          for f in $(find . -iname *.tar); do
+            image_name=$(podman load -q -i $f | sed 's/Loaded image: //g')
+            push_container $image_name
+
+            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

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

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+FROM docker.io/library/ubuntu:24.04 AS llvm-downloader
+
+ENV LLVM_VERSION=21.1.1
+
+RUN apt-get update && \
+    apt-get install -y wget xz-utils && \
+    wget --progress=bar:force -O llvm.tar.xz https://github.com/llvm/llvm-project/releases/download/llvmorg-${LLVM_VERSION}/LLVM-${LLVM_VERSION}-Linux-X64.tar.xz && \
+    mkdir -p /llvm-extract && \
+    tar -xvJf llvm.tar.xz -C /llvm-extract LLVM-${LLVM_VERSION}-Linux-X64/bin/ && \
+    rm llvm.tar.xz
+
+
+FROM docker.io/library/ubuntu:24.04 AS base
+
+ENV LLVM_SYSROOT=/opt/llvm
+ENV LLVM_VERSION=21.1.1
+
+# Need nodejs for some of the GitHub actions.
+# Need git for git-clang-format.
+RUN apt-get update && \
+    DEBIAN_FRONTEND=noninteractive apt-get install -y \
+    git \
+    nodejs \
+    sudo \
+    # These are needed by the premerge pipeline.
+    # Pip and venv are used to install dependent python packages.
+    python3-pip \
+    python3-venv \
+    python-is-python3 && \
+    apt-get clean && \
+    rm -rf /var/lib/apt/lists/*
+
+
+# Create a new user to avoid test failures related to a lack of expected
+# permissions issues in some tests. Set the user id to 1001 as that is the
+# user id that Github Actions uses to perform the checkout action.
+RUN useradd gha -u 1001 -m -s /bin/bash
+
+# Also add the user to passwordless sudoers so that we can install software
+# later on without having to rebuild the container.
+RUN adduser gha sudo
+RUN echo '%sudo ALL=(ALL) NOPASSWD:ALL' >> /etc/sudoers
+
+USER gha
+WORKDIR /home/gha
+
+
+FROM base AS ci-container-code-format
+
+COPY --from=llvm-downloader /llvm-extract/LLVM-${LLVM_VERSION}-Linux-X64/bin/clang-format ${LLVM_SYSROOT}/bin/clang-format
+
+ENV PATH=${LLVM_SYSROOT}/bin:${PATH}
+
+# Install dependencies for 'pr-code-format.yml' job
+COPY llvm/utils/git/requirements_formatting.txt /home/gha/requirements_formatting.txt
+RUN python -m venv venv && \
+    venv/bin/pip install -r /home/gha/requirements_formatting.txt && \
+    rm /home/gha/requirements_formatting.txt
+
+
+FROM base AS ci-container-code-lint
+
+COPY --from=llvm-downloader /llvm-extract/LLVM-${LLVM_VERSION}-Linux-X64/bin/clang-tidy ${LLVM_SYSROOT}/bin/
+COPY clang-tools-extra/clang-tidy/tool/clang-tidy-diff.py ${LLVM_SYSROOT}/bin/clang-tidy-diff.py
+
+ENV PATH=${LLVM_SYSROOT}/bin:${PATH}
+
+# Install dependencies for 'pr-code-lint.yml' job
+COPY llvm/utils/git/requirements_linting.txt /home/gha/requirements_linting.txt
+RUN python -m venv venv && \
+    venv/bin/pip install -r /home/gha/requirements_linting.txt && \
+    rm /home/gha/requirements_linting.txt