How to access to a docker container via SSH using IP address? - docker

Question

I'm using NVIDIA Docker in a Linux machine (Ubuntu 20.04). I've created a container named user1 using nvidia/cuda:11.0-base image as follows:
docker run --gpus all --name user1 -dit nvidia/cuda:11.0-base /bin/bash
And, here is what I see if I run docker ps -a:
admin#my_desktop:~$ docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
a365362840de nvidia/cuda:11.0-base "/bin/bash" 3 seconds ago Up 2 seconds user1
I want to access to that container via ssh using its unique IP address from a totally different machine (other than my_desktop, which is the host). First of all, is it possible to grant each container a unique IP address? If so, how can I do it? Thanks in advance.

Answer 1

In case you want to access to your container with ssh from an external VM, you need to do the following
Install the ssh daemon for your container
Run the container and expose its ssh port
I would propose the following Dockerfile, which builds from nvidia/cuda:11.0-base and creates an image with the ssh daemon inside
Dockerfile
# Instruction for Dockerfile to create a new image on top of the base image (nvidia/cuda:11.0-base)
FROM nvidia/cuda:11.0-base
ARG root_password
RUN apt-get update || echo "OK" && apt-get install -y openssh-server
RUN mkdir /var/run/sshd
RUN echo "root:${root_password}" | chpasswd
RUN sed -i 's/#PermitRootLogin prohibit-password/PermitRootLogin yes/' /etc/ssh/sshd_config
RUN sed -i 's/#PasswordAuthentication yes/PasswordAuthentication yes/' /etc/ssh/sshd_config
EXPOSE 22
CMD ["/usr/sbin/sshd", "-D"]
Build the image from the Dockerfile
docker image build --build-arg root_password=password --tag nvidia/cuda:11.0-base-ssh .
Create the container
docker container run -d -P --name ssh nvidia/cuda:11.0-base-ssh
Run docker ps to see the container port
Finally, access the container
ssh -p 49157 root#<VM_IP>
EDIT: As David Maze correctly pointed out. You should be aware that the root password will be visible in the image history. Also this way overwrites the original container process.
This process, if it is to be adopted it needs to be modified in case you need it for production use. This serves as a starting point for someone who wishes to add ssh to his container.