FROM ghcr.io/linuxserver/baseimage-alpine:3.18

# Install SSH client
RUN \
  apk add --no-cache \
    openssh-client


# Set volume for ssh key
VOLUME /root/.ssh/id_rsa

# Set default values for SSH tunnel configuration
ENV SSH_HOSTNAME=server.example.com
ENV SSH_USERNAME=username
ENV SSH_DESTINATION=destination
ENV SSH_DESTINATION_PORT=12345
ENV SSH_LOCAL_PORT=12345

ENTRYPOINT ssh \
  -N -4 \
  -L *:$SSH_LOCAL_PORT:$SSH_DESTINATION:$SSH_DESTINATION_PORT \
  -l $SSH_USERNAME \
  -o "StrictHostKeyChecking no" \
  -o "UserKnownHostsFile /dev/null" \
  $SSH_HOSTNAME