FROM alpine:3.22@sha256:4bcff63911fcb4448bd4fdacec207030997caf25e9bea4045fa6c8c44de311d1 AS rootfs
RUN apk --no-cache add alpine-base tzdata
RUN rc-update add devfs sysinit && \
    rc-update add dmesg sysinit && \
    rc-update add mdev sysinit && \
    rc-update add cgroups sysinit && \
    rc-update add sysctl boot && \
    rc-update add hostname boot && \
    rc-update add bootmisc boot && \
    rc-update add syslog boot && \
    rc-update add mount-ro shutdown && \
    rc-update add killprocs shutdown && \
    rc-update add savecache shutdown && \
    ln -s /sbin/init /init && \
    echo 'root:root' | chpasswd && \
    echo 'sprout' > /etc/hostname && \
    echo '' > /etc/motd && \
    ln -s /usr/share/zoneinfo/UTC /etc/localtime && \
    echo 'hvc0::respawn:/sbin/getty -L hvc0 115200 vt100' >> /etc/inittab

FROM alpine:3.22@sha256:4bcff63911fcb4448bd4fdacec207030997caf25e9bea4045fa6c8c44de311d1 AS build
COPY --from=rootfs / /rootfs
WORKDIR /rootfs
RUN find . | cpio -R 0:0 --ignore-devno --renumber-inodes -o -H newc --quiet > /initramfs

FROM scratch AS final
COPY --from=build /initramfs /initramfs