FROM alpine:3.21

RUN apk add --no-cache openssh-server

COPY sshd_config /etc/ssh/sshd_config
COPY entrypoint.sh /usr/local/bin/tunnel-entrypoint
RUN chmod 0755 /usr/local/bin/tunnel-entrypoint

EXPOSE 22 22000-22099
VOLUME ["/data"]

HEALTHCHECK --interval=15s --timeout=3s --start-period=5s --retries=3 \
  CMD ssh-keyscan -T 2 -p 22 127.0.0.1 >/dev/null 2>&1 || exit 1

ENTRYPOINT ["/usr/local/bin/tunnel-entrypoint"]