Dockerfile

FROM alpine AS build
LABEL maintainer="Kazushi (Jam) Marukawa <jam@pobox.com>"

ENV KINDLEGEN=kindlegen_linux_2.6_i386_v2_9.tar.gz
ENV KINDLEGEN_SHA256="9828db5a2c8970d487ada2caa91a3b6403210d5d183a7e3849b1b206ff042296"

RUN apk --update add ca-certificates curl tar && rm -rf /var/cache/apk/*

RUN curl -L http://kindlegen.s3.amazonaws.com/${KINDLEGEN} -o ${KINDLEGEN} && \
    echo "${KINDLEGEN_SHA256}  ${KINDLEGEN}" | sha256sum -c - && \
    mkdir -p /opt/kindlegen && \
    tar zxf ${KINDLEGEN} -C /opt/kindlegen && \
    rm ${KINDLEGEN}

RUN touch /tmp/passwd /tmp/group

FROM scratch

COPY --from=build /tmp/passwd /etc/passwd
COPY --from=build /tmp/group /etc/group
COPY --from=build /opt/kindlegen/kindlegen /opt/kindlegen/kindlegen

WORKDIR /work
ENTRYPOINT ["/opt/kindlegen/kindlegen"]