FROM centos:7 AS centos-devtoolset

ARG DEVTOOLSET

# Install required dependencies.
RUN yum groupinstall -y 'Development Tools' && \
    yum install -y epel-release && \
    yum update -y && \
    yum -y install centos-release-scl-rh && \
    yum install -y \
        # required by libbpf, Clang
        centos-release-scl \
        # required by Clang/LLVM
        cmake3 \
        # required by libbpf and Clang
        ${DEVTOOLSET}-gcc* \
        # required by libbpf
        ${DEVTOOLSET}-make \
        # required by libbpf
        elfutils-libelf-devel \
        # required by libbpf
        elfutils-libelf-devel-static \
        git \
        # required by libbpf, Clang
        scl-utils \
        # required by libbpf
        zlib-devel \
        # required by libbpf
        zlib-static && \
    yum clean all

# Use just created devtool image with newer GCC and Cmake
FROM centos-devtoolset as clang10

ARG DEVTOOLSET

# Compile Clang 10.0.1 from source. It is needed to create BPF files.
# Centos 7 doesn't provide it as a package unfortunately.
# LLVM_INCLUDE_BENCHMARKS must be off, otherwise compilation fails,
# CLANG_BUILD_TOOLS must be on, it builds clang binary,
# LLVM_BUILD_TOOLS must be on, it builds llvm-strip binary.
# the rest is disabled to speedup the compilation.
RUN git clone --branch llvmorg-10.0.1 --depth=1 https://github.com/llvm/llvm-project.git && \
    cd llvm-project/ && \
    mkdir build && cd build/ && \
    scl enable ${DEVTOOLSET} 'bash -c "cmake3 \
    -DCLANG_BUILD_TOOLS=ON \
    -DCLANG_ENABLE_ARCMT=OFF \
    -DCLANG_ENABLE_STATIC_ANALYZER=OFF \
    -DCMAKE_BUILD_TYPE=Release \
    -DCMAKE_INSTALL_PREFIX=/opt/llvm \
    -DLLVM_BUILD_TOOLS=ON \
    -DLLVM_BUILD_UTILS=OFF \
    -DLLVM_ENABLE_BINDINGS=OFF \
    -DLLVM_ENABLE_PROJECTS=clang \
    -DLLVM_INCLUDE_BENCHMARKS=OFF \
    -DLLVM_INCLUDE_GO_TESTS=OFF \
    -DLLVM_INCLUDE_TESTS=OFF \
    -DLLVM_TOOL_LLI_BUILD=OFF \
    -G \"Unix Makefiles\" ../llvm && \
    make -j$(grep -c processor /proc/cpuinfo) &&  \
    make install"' && \
    cd ../.. && \
    rm -rf llvm-project

# Create the final image with Clang only. We're using this Docker image as a tar.gz mainly
# because we want to keep our artifacts on GitHub, and GH doesn't support blobs, only Docker images.
FROM scratch AS buildbox-centos7-assets

# Copy Clang into the final image.
COPY --from=clang10 /opt/llvm /opt/llvm/