Docker Container as a Shell

Most of my work is done either on a Macbook Pro, or my Linux desktop. As much as macOS is a Unix, with supporting tools like MacPorts, Linux is still richer as far as commandline utilities go.

Prior to native Docker support on macOS/OSX, you would resort to running Linux in a virtual machine, and having a share directory.

With Docker, we basically emulate the same, but obviously, native Docker on the Mac, or Windows 10 for that matter, is far more lightweight than a VM. Note that this is not a very container’ey use of Docker where everything you need is ready to deploy right from the image.

The approach I’m taking for this use case is basically to treat a Docker container as a lightweight VM, with adhoc tooling installed — essentially a rolling-release style VM, occasionally taking snapshots, and pushing up to the docker registry so it’s shareable across machines.

The overall approach is:

Pull down an existing container, I went with ubuntu
Tag it as your own and push to your docker registry. Follow instructions here on this step.
Pull down your tagged image
Create a script that will mount your home directory as a volume. Thereby providing you with a live workspace to execute your container utilities against. I have nearly all my work in my home directory, so this mount makes sense, but it’s simply a regular mount.
Create a user in the container, so you don’t constantly log in as root.
Commit and push the container’s changes as needed.

Your data is still in your host’s home, while the utilities are installed in the container.

Running docker commands is a pain if you do the above workflow often. Here I’m providing the scripts and utilities I wrote. Replace with your custom values as needed.

My Docker utility run script. Note that it’s already using my tagged ubuntu image. So the tagging and pushing step is a prerequisite.

#
# ubuntu-docker-start.sh
#

HOST_HOME=/Users/xdyme
CONTAINER_HOME=/home/xdyme/data
TZ=Australia/Melbourne
HOSTNAME=ubuntu-container
CONTAINER_NAME=ubuntu
IMAGE="kva1966/ubuntu:latest"

docker run -dt \
  --name ${CONTAINER_NAME} \
  -h ${HOSTNAME} \
  -e ${TZ} \
  --volume ${HOST_HOME}:${CONTAINER_HOME} \
  ${IMAGE}

I also added a bunch of utility aliases for common container tasks in ~/.bashrc:

#### Local Shell Container ####

alias d=docker
alias ubuntu-deploy-container='~/projects/checkouts/desktop-scripts/ubuntu-docker-start.sh'
alias ubuntu-commit='d commit ubuntu kva1966/ubuntu:latest'
alias ubuntu-push='d push kva1966/ubuntu:latest'
alias ubuntu-stop='d stop ubuntu'
alias ubuntu-start='d start ubuntu'
alias ubuntu-run='ubuntu-stop; d rm ubuntu; ~/projects/checkouts/desktop-scripts/ubuntu-docker-start.sh'
alias ubuntu-delete-container='ubuntu-stop; d rm ubuntu'

ubuntu-login-user() {
  username=$1
  homedir=/home/$username
  if [ -z $username ]; then
    username=root
    homedir=/root
  fi
  
  d exec -it -u $username ubuntu bash -c "cd $homedir; exec ${SHELL} --login"
}

alias ubuntu-login='ubuntu-login-user xdyme'
alias ubuntu-login-root='ubuntu-login-user'

#### END Local Shell Container ####

Some very basic .bashrc and .profile can be found when you login to the xdyme user on my container. Mainly git completion, and a nicer looking default shell.

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Docker Container as a Shell