vagrant/plugins/providers/docker/action/pull.rb

module VagrantPlugins
  module DockerProvider
    module Action
      class Pull
        def initialize(app, env)
          @app = app
        end

        def call(env)
          @env             = env
          @machine         = env[:machine]
          @provider_config = @machine.provider_config
          @driver          = @machine.provider.driver

          # Skip pulling if the image is built
          return @app.call(env) if @env[:create_image] || !@provider_config.pull

          image = @provider_config.image
          env[:ui].output(I18n.t("docker_provider.pull", image: image))
          @driver.pull(image)

          @app.call(env)
        end
      end
    end
  end
end