FROM linuxkit/alpine:a120ad6aead3fe583eaa20e9b75a05ac1b3487da AS kernel-build
RUN apk add \
    argp-standalone \
    build-base \
    curl \
    diffutils \
    ncurses-dev \
    tar \
    xz

ARG KERNEL_VERSIONS

# There is no simple way to copy directories with wild cards as needed
# for patches-*. Copy the entire dir instead.
COPY / /

# Unpack kernels (download if not present)
RUN set -e && for VERSION in ${KERNEL_VERSIONS}; do \
        echo "Downloading/Unpacking $VERSION" && \
        KERNEL_SOURCE=https://www.kernel.org/pub/linux/kernel/v4.x/linux-${VERSION}.tar.xz && \
        [ -f sources/linux-${VERSION}.tar.xz ] || curl -fSLo sources/linux-${VERSION}.tar.xz ${KERNEL_SOURCE} && \
        tar xf sources/linux-${VERSION}.tar.xz; \
    done

# Apply patches to all kernels and move config files into place
RUN for VERSION in ${KERNEL_VERSIONS}; do \
        SERIES=${VERSION%.*}.x && \
        echo "Patching $VERSION" && \
        cd /linux-${VERSION} && \
        set -e && for patch in /patches-${SERIES}/*.patch; do \
            echo "Applying $patch" && \
            patch -p1 < "$patch"; \
        done && \
        mv /kernel_config-${SERIES}-x86_64 arch/x86/configs/x86_64_defconfig && \
        mv /kernel_config-${SERIES}-aarch64 arch/arm64/configs/defconfig; \
    done

ENTRYPOINT ["/bin/sh"]