Docker-Machine Lazy Loading

Like many, I use docker-machine (installed via Docker Toolbox) to develop Docker images on OSX. I am terrible about remembering to launch the docker-machine VM ahead of time, and I don’t like having STDERR output or delays from launching new shell tabs, so I wrote a quick lazy-load function inspired by Spacemacs.

I use ZSH but this may work on Bash as well, and my VM is named dev. This will intercept the first command that begins with docker during a given shell session, and ensure that the VM has been booted and that the shell variables DOCKER_HOST and DOCKER_CERT_PATH are set appropriately. It won’t try to boot the machine or update the shell environment until the first time a docker command is attempted.

docker() {
  unset -f docker
  # docker-machine create -d virtualbox dev
  # VBoxManage list runningvms | grep -E "^\"dev\"" >/dev/null 2>/dev/null || docker-machine start dev
  # docker-machine create -d vmwarefusion dev
  vmrun list | grep -E ".docker\/machine\/machines\/dev\/dev.vmx$" 2>&1 >/dev/null || docker-machine start dev
  eval "$(docker-machine env dev)"
  docker "$@"
}