Serve Remote Assets WP Function

remote_assets_advanced.php

add_filter('upload_dir', 'set_upload_folder', 999);

function set_upload_folder( $upload_data ) {
  // absolute dir path, must be writable by wordpress
  $upload_data['basedir'] = trailingslashit(ABSPATH). '/wp-content/uploads';
  $upload_data['baseurl'] = 'http://example.com/wp-content/uploads';
  $subdir = $upload_data['subdir'];
  $upload_data['path'] = $upload_data['basedir'] . $subdir;
  $upload_data['url'] = $upload_data['baseurl'] . $subdir;
  return wp_parse_args($upload_data, $upload_data);
}

remote_assets_basic.php

// Serve Remote Uploads
function remote_uploads() {
  return 'http://example.com/app/uploads';
}
add_filter( 'pre_option_upload_url_path', 'remote_uploads' );