Dockerfile

FROM ubuntu:16.04

# Set correct environment variables.
ENV HOME /root
ENV PORT 2222
ENV HOSTNAME pair.dasapp.co

RUN apt update &&  apt install -y software-properties-common

# Use libssh 0.7 https://github.com/tmate-io/tmate/issues/82#issuecomment-216165761
RUN add-apt-repository -u ppa:kedazo/libssh-0.7.x
RUN add-apt-repository -u ppa:tmate.io/archive
RUN add-apt-repository -u ppa:evarlast/experimental

RUN apt -y install tmate-slave  && \
    apt-get clean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*

# impl in progress

CMD ["./tmate-get-fingerprints.sh"]

message.sh

#!/bin/sh

DSA=`ssh-keygen -l -f /opt/tmate-slave/keys/ssh_host_dsa_key 2>&1 | cut -d\  -f 2`
RSA=`ssh-keygen -l -f /opt/tmate-slave/keys/ssh_host_rsa_key 2>&1 | cut -d\  -f 2`
ECDSA=`ssh-keygen -l -f /opt/tmate-slave/keys/ssh_host_ecdsa_key 2>&1 | cut -d\  -f 2`
echo Add this to your ~/.tmate.conf file
echo set -g tmate-server-host \"$HOSTNAME\"
echo set -g tmate-server-port \"$PORT\"
echo set -g tmate-server-rsa-fingerprint   \"$RSA\"
echo set -g tmate-server-dsa-fingerprint   \"$DSA\"
echo set -g tmate-server-ecdsa-fingerprint   \"$ECDSA\"
echo set -g tmate-identity \"\"              # Can be specified to use a different SSH key.

/opt/tmate-slave/tmate-slave -h $HOSTNAME -p $PORT