link

 $options = ['absolute' => TRUE];
 $url = Url::fromRoute('entity.node.canonical', ['node' => 1], $options);
//$url = $url->toString();
$link = Link::fromTextAndUrl("Node 1", $url);
 $link = $link->toRenderable();
 $link['#attributes'] = array('class' => array('internal'));
$outlink = render($link);