Drupal - Get an image from an article/entity
Didn't see this before.
The shortest way to get the referenced entity for a single-value field is this:
$node->field_image->entity->url()
You can also specify the delta explicitly:
$node->field_image[0]->entity->url()
This works with a lot of ArrayAccess and __get() magic.
See also the great cheat sheet at http://wizzlern.nl/drupal/drupal-8-entity-cheat-sheet. and https://www.drupal.org/node/1795854 and the other documentation pages there for more information (still very much work in progress).
What ended up working for me in D8 is:
$imageUrl = $node->get('field_image')->entity->uri->value;
Using kint($node->get('field_image')->entity)
and looking through the array was very helpful
Then in my twig file I used:
<img class="top-article-image" src="{{ file_url(imageUrl) }}" />