Initial attempt with CI

.github/workflows/ghcr-push.yml

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+name: Deploy to GHCR
+
+# only run most recent workflow in branch
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+on:
+  push:
+    branches: [ "master" ]
+
+jobs:
+  build-16:
+    name: Build + Publish 16
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+
+    steps:
+    - uses: actions/checkout@v4
+      name: Checkout
+
+    - name: Build
+      run: |
+        docker build -f clang-format-16.dockerfile -t ghcr.io/cwpearson/clang-format-16:latest .
+
+    - name: Publish to GHCR
+      run: |
+        echo '${{secrets.GHCR_TOKEN}}' | docker login ghcr.io -u cwpearson --password-stdin
+        docker push ghcr.io/cwpearson/clang-format-16:latest
+  build-8:
+    name: Build + Publish 8
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+
+    steps:
+    - uses: actions/checkout@v4
+      name: Checkout
+
+    - name: Build
+      run: |
+        docker build -f clang-format-8.dockerfile -t ghcr.io/cwpearson/clang-format-8:latest .
+
+    - name: Publish to GHCR
+      run: |
+        echo '${{secrets.GHCR_TOKEN}}' | docker login ghcr.io -u cwpearson --password-stdin
+        docker push ghcr.io/cwpearson/clang-format-8:latest

README.md

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+# 
+
+```bash
+podman build -f clang-format-16.dockerfile -t clang-format-16:latest
+podman build -f clang-format-8.dockerfile -t clang-format-8:latest
+```
+
+## Deploy
+
+1. Create a "personal access token (classic)" with `write:packages`
+  * account > settings > developer settings > personal access tokens
+2. Put that personal access token as the repository secret `GHCR_TOKEN`.

clang-format-16.dockerfile

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+# Stage 1: Build environment
+FROM docker.io/redhat/ubi8 AS builder
+
+LABEL org.opencontainers.image.source https://github.com/cwpearson/clang-format
+
+RUN dnf install -y \
+    cmake \
+    gcc \
+    gcc-c++ \
+    python3 \
+    wget \
+    xz \
+    && dnf clean all
+
+RUN wget -q https://github.com/llvm/llvm-project/releases/download/llvmorg-16.0.6/llvm-project-16.0.6.src.tar.xz \
+    && tar -xf llvm-project-16.0.6.src.tar.xz
+RUN cmake -S llvm-project-16.0.6.src/llvm -B build \
+  -DLLVM_ENABLE_PROJECTS='clang' \
+  -DCMAKE_BUILD_TYPE=MinSizeRel \
+  -DLLVM_TARGETS_TO_BUILD=""
+RUN make -C build -j$(nproc) install
+
+# base final image off ubi8-micro
+FROM docker.io/redhat/ubi8-micro
+
+# clang-format-16 links this
+COPY --from=builder /lib64/libstdc++.so.6 /lib64/libstdc++.so.6
+# keep clang-format binary only
+COPY --from=builder /usr/local/bin/clang-format /usr/local/bin/clang-format
+# also provide clang-format-16
+RUN ln -s /usr/local/bin/clang-format /usr/local/bin/clang-format-16
+
+# expect caller to map $PWD into /src with -v flag
+WORKDIR /src

clang-format-8.dockerfile

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+# Stage 1: Build environment
+FROM docker.io/redhat/ubi8 AS builder
+
+LABEL org.opencontainers.image.source https://github.com/cwpearson/clang-format
+
+RUN dnf install -y \
+    cmake \
+    gcc \
+    gcc-c++ \
+    python3 \
+    wget \
+    xz \
+    && dnf clean all
+
+RUN wget -q https://github.com/llvm/llvm-project/releases/download/llvmorg-8.0.1/llvm-8.0.1.src.tar.xz \
+    && tar -xf llvm-8.0.1.src.tar.xz --no-same-owner
+RUN wget -q https://github.com/llvm/llvm-project/releases/download/llvmorg-8.0.1/cfe-8.0.1.src.tar.xz \
+    && tar -xf cfe-8.0.1.src.tar.xz --no-same-owner
+RUN mv cfe-8.0.1.src clang
+RUN cmake -S llvm-8.0.1.src -B build \
+  -DLLVM_ENABLE_PROJECTS='clang' \
+  -DCMAKE_BUILD_TYPE=MinSizeRel \
+  -DLLVM_TARGETS_TO_BUILD=""
+RUN make -C build -j$(nproc) install
+
+# base final image off ubi8-micro
+FROM docker.io/redhat/ubi8-micro
+
+# clang-format-16 links this
+COPY --from=builder /lib64/libstdc++.so.6 /lib64/libstdc++.so.6
+# keep clang-format binary only
+COPY --from=builder /usr/local/bin/clang-format /usr/local/bin/clang-format
+# also provide clang-format-8
+RUN ln -s /usr/local/bin/clang-format /usr/local/bin/clang-format-8
+
+# expect caller to map $PWD into /src with -v flag
+WORKDIR /src