vagrant/plugins/provisioners/docker/installer.rb

module VagrantPlugins
  module DockerProvisioner
    class Installer
      def initialize(machine)
        @machine = machine
      end

      # This handles verifying the Docker installation, installing it if it was
      # requested, and so on. This method will raise exceptions if things are
      # wrong.
      # @return [Boolean] - false if docker cannot be detected on machine, else
      #                     true if docker installs correctly or is installed
      def ensure_installed
        if !@machine.guest.capability?(:docker_installed)
          @machine.ui.warn(I18n.t("vagrant.docker_cant_detect"))
          return false
        end

        if !@machine.guest.capability(:docker_installed)
          @machine.ui.detail(I18n.t("vagrant.docker_installing"))
          @machine.guest.capability(:docker_install)
        end

        if !@machine.guest.capability(:docker_installed)
          raise DockerError, :install_failed
        end

        if @machine.guest.capability?(:docker_configure_vagrant_user)
          @machine.guest.capability(:docker_configure_vagrant_user)
        end

        true
      end
    end
  end
end