ARG BASEIMAGE=debian:testing-slim
FROM ${BASEIMAGE}
RUN apt-get update && \
    DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
        netcat-openbsd \
        openssh-server \
    && \
    rm -f /etc/ssh/ssh_host_* && \
    echo > /etc/ssh/sshd_config && \
    rm -rf /tmp/* /var/tmp/* /var/lib/apt/lists/* /var/cache/apt/archives/*
COPY entrypoint /entrypoint
EXPOSE 22
ENTRYPOINT ["/entrypoint"]
HEALTHCHECK --start-period=5m CMD echo | nc localhost 22 | grep -q 'SSH-2.0-OpenSSH'
ENV SSHD_ARGS="-De -o 'PermitRootLogin no' -o 'PasswordAuthentication no' -o 'ChallengeResponseAuthentication no' -o 'PrintMotd no' -o 'PidFile none' -o 'Subsystem sftp /usr/lib/openssh/sftp-server'"
ENV EXTRA_SSHD_ARGS=""
CMD ["/usr/sbin/sshd", "$SSHD_ARGS", "$EXTRAS_SSHD_ARGS"]