     else
       Mix.raise "Docker provider expected artifact to exist at #{tar_file}"
     end
-  end
-
-  def shell(_pkg) do
-
   end
 
   defp build_paths(pkg) do

    end
  end

  defp docker_image_create do
    cmd = "docker"
    args = ["build", "--label", @label, "--tag", "nerves_system_br:latest", @dockerfile]
    Nerves.Utils.Shell.info "Docker provider needs to create the image."
    if Mix.shell.yes?("Continue?") do
      case Mix.Nerves.Utils.shell(cmd, args) do

    end
  end

  defp container_ensure_started(name) do
    cmd = "docker"
    args = ["start", name]
    case System.cmd(cmd, args) do
      {_, 0} -> :noop
      {error, _} -> Mix.raise """
        Could not start Docker container #{name}
        Reason: #{error}
        """
    end
  end

  defp container_stop(name) do
    cmd = "docker"
    args = ["stop", name]
    case System.cmd(cmd, args) do
      {_, 0} -> :noop
      {error, _} -> Mix.raise """
        Could not stop Docker container #{name}
        Reason: #{error}
        """
    end
  end

  defp error_not_installed do
    Mix.raise """
    Docker is not installed on your machine.
