I want to make a fancy environment for testing out CI/CD methods, but don’t want a larger cloud bill next month. SO I fired up an ancient linux server old desktop. to begin with I want to do stuff with jenkins ssh slave, so I need an ssh server, this worked out of the box.

# The password is ``screencast``.

Dockerize an SSH service

Estimated reading time: 2 minutes

Build an eg_sshd image

The following Dockerfile sets up an SSHd service in a container that you can use to connect to and inspect other container’s volumes, or to get quick access to a test container.

FROM ubuntu:16.04

RUN apt-get update && apt-get install -y openssh-server
RUN mkdir /var/run/sshd
RUN echo 'root:screencast' | chpasswd
RUN sed -i 's/PermitRootLogin prohibit-password/PermitRootLogin yes/' /etc/ssh/sshd_config

# SSH login fix. Otherwise user is kicked off after login
RUN sed 's@session\s*required\s*pam_loginuid.so@session optional pam_loginuid.so@g' -i /etc/pam.d/sshd

ENV NOTVISIBLE "in users profile"
RUN echo "export VISIBLE=now" >> /etc/profile

EXPOSE 22
CMD ["/usr/sbin/sshd", "-D"]

Build the image using:

$ docker build -t eg_sshd .

Run a test_sshd container

Then run it. You can then use docker port to find out what host port the container’s port 22 is mapped to:

$ docker run -d -P --name test_sshd eg_sshd
$ docker port test_sshd 22

0.0.0.0:49154

And now you can ssh as root on the container’s IP address (you can find it with docker inspect) or on port 49154 of the Docker daemon’s host IP address (ip address or ifconfig can tell you that) or localhost if on the Docker daemon host:

$ ssh root@192.168.1.2 -p 49154
# The password is ``screencast``.
root@f38c87f2a42d:/#

Environment variables

Using the sshd daemon to spawn shells makes it complicated to pass environment variables to the user’s shell via the normal Docker mechanisms, as sshd scrubs the environment before it starts the shell.

If you’re setting values in the Dockerfile using ENV, you need to push them to a shell initialization file like the /etc/profileexample in the Dockerfile above.

If you need to passdocker run -e ENV=value values, you need to write a short script to do the same before you start sshd -Dand then replace the CMD with that script.

Source: Dockerize an SSH service | Docker Documentation