Given:
apt-get install ssh)Problem: each when I start container I hav
This is quite an old question, but for the sake of others finding it, I think the correct way to do it would follow docker's instructions to dockerizing the ssh service.
And in correlation to the specific question, the following lines added at the end of the dockerfile will achieve what you were looking for:
EXPOSE 22
CMD ["/usr/sbin/sshd", "-D"]
Dockerize a SSHD service