Dockerizing an SSH daemon service
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.
# sshd # # VERSION 0.0.2 FROM ubuntu:14.04 MAINTAINER Sven Dowideit <SvenDowideit@docker.com> 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 without-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``. $$
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’ll need to push them to a shell initialization file like the /etc/profile
example in the Dockerfile
above.
If you need to passdocker run -e ENV=value
values, you will need to write a short script to do the same before you start sshd -D
and then replace the CMD
with that script.
Clean up
Finally, clean up after your test by stopping and removing the container, and then removing the image.
$ docker stop test_sshd $ docker rm test_sshd $ docker rmi eg_sshd
Please login to continue.