How I use Linux distributions on my Mac, with a single command

As mentioned in a previous article, I use aliases to ease my (CLI) life. In addition to day-to-day actions, they allow me to automate “boring” stuff, which requires me to remember multiple commands, launch them the same way over and over again. A good example of this is Docker.

For me, Docker is a great tool for local development. If I need to test something in a specific distribution or context, it’s easy to download an image and use it. To cover my needs on GNU/Linux, I prefer Podman. I can use it with the same command but no sudo. Under macOS, I use Docker Desktop.

Most of the time, once installed, I just want to access an image quickly, do my stuff and exit. For that, I need to pull it, create and start a container and run. But I found an easier way to do all that adding a function in my ~/.zshrc file and use it as an alias (it works with bash or fish too):

dssh() {
  local container_name=$1
  local image_name=$2
  local prefix="dock"
  local docker_command="docker"
  local launch_command=$([[ "${image_name}" == *alpine* ]] && \
    echo "/bin/sh" || echo "/bin/bash")

  if ! command -v ${docker_command} &> /dev/null; then
    echo "Error: Docker is not installed"
    return
  fi

  container_exists=$(docker ps -a --format '{{.Names}}' | \
    grep -q "^${container_name}$" && echo "yes" || echo "no")

  if [ "$#" -eq 1 ]; then
    if [ "${container_exists}" = "no" ]; then
      echo "Container ${container_name} does not exist"
      return
    fi
  elif [ "$#" -eq 2 ]; then
    if [ "${container_exists}" = "no" ]; then
      echo "Creating container ${container_name} with image ${image_name}..."
      ${docker_command} run -dit --hostname "${prefix}_${container_name}" \
      --name "${container_name}" "${image_name}" ${launch_command}
    fi
  else
    echo "Usage: $0 <CONTAINER_NAME> [IMAGE]"
    return
  fi

  if [ "$(docker inspect -f '{{.State.Running}}' "${container_name}")" = "false" ]; then
    echo "Starting container ${container_name}..."
    ${docker_command} start "${container_name}"
  fi

  echo "Executing '${launch_command}' in container ${container_name}..."
  ${docker_command} exec -it "${container_name}" ${launch_command}
}

What it does is check whether docker (or another command you can define) is available. If so, you can use it to access an existing container by name or create one from an image and access it.

I always use /bin/bash as the start command unless I’m requesting an Alpine image where /bin/sh is the default Shell. This could be done better, with an optional variable for example, but it fits my needs as is for now.

I usually don’t use this function directly as an alias, rather from other aliases. For example on a Mac, based on an Apple Silicon aarch64 SoC:

alias exherbo="dssh exherbo exherbo/exherbo-aarch64-unknown-linux-gnueabi-gcc-base"
alias ubuntu="dssh ubuntu ubuntu:latest"

Thus, I can access an already configured Ubuntu whenever I want simply with the ubuntu command, or do the same with exherbo.

And if I want to access another distribution:

dssh alpine alpine:latest # To get latest Alpine
dssh debian debian:latest # To get latest Debian stable
dssh debslim debian:unstable-slim # To get next Debian in slim version