Rewrite Wordpress uploads to lorempixel (Nginx)

gistfile1.txt

  # if you're requesting anything within '/wp-content/uploads' or '/files'
  location ~ (/wp-content/uploads|files) {
      # and it doesn't exist
      if (!-e $document_root$uri) {
          # try and match the dimensions from the filename
          rewrite (\d+)(?:x)(\d+)(?:\.(?:[^\.]+)$) http://lorempixel.com/$1/$2 break;
          # otherwise just use a default size
          rewrite .* http://lorempixel.com/800/600 break;
      }
  }