FROM ubuntu:16.04

RUN mkdir -p /root/.ssh
ADD id_rsa /root/.ssh/id_rsa
RUN chmod -R 600 /root/.ssh
RUN chmod 600 /root/.ssh/id_rsa

RUN apt-get update && apt-get -y install ssh git

RUN ssh-keyscan github.com >> /root/.ssh/known_hosts

RUN mkdir -p /home/yo/repo
RUN git clone git@github.com:username/yo.git /home/yo/repo

------------------------

Cloning into '/home/yo/repo'...
Warning: Permanently added the RSA host key for IP address 'xxx.xx.xx.xxx' to the list of known hosts.
Permission denied (publickey).
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.