My dg7.module implementation of hook_islandora_multi_importer_remote_file_get to retrive content from a mounted file system when "local*" option is selected.

My Implementation of hook_islandora_multi_importer_remote_file_get

/**
 * Implements hook_islandora_multi_importer_remote_file_get for https://digital.grinnell.edu. and
 *   https://dgadmin.grinnell.edu
 *
 * @param $url
 *   Path to the file to be fetched.  Default behavior strips the 'basename' from $url and looks
 *   for that file somewhere in $target.
 * @return array
 *   On error or failure an empty array is returned.
 *   On success, a single array element LOCAL path like /mnt/storage/exmample.xml
 *
 * Important!  This function requires that your target directory of files be mounted to
 *   the HOST server, or your Apache container in the case of ISLE, as $target (see below).
 *   The mount statement should look something like this:
 *
 *  sudo mount -t cifs -o username=mcfatem //storage.grinnell.edu/LIBRARY/mcfatem/PHPP_Content /mnt/storage
 *
 * And in an ISLE environment, you need an additonal Volume/bind-mount statement in your
 *   docker-compose.yml, or a suitable override, like so:
 *
 *   apache:
 *     volumes:
 *       - /host/path/to/object/files:/mnt/storage
 *
 *   See https://static.grinnell.edu/blogs/McFateM/posts/046-dg-fedora-a-portable-object-repository/ for more detail.
 *
 */
function dg7_islandora_multi_importer_remote_file_get($url) {
  if ($url === '') { return array(); }  // return an empty array if $url is blank
  $parsed_url = parse_url($url);

  // Assumes the file is somewhere in the /mnt/storage path
  $target = "/mnt/storage";

  $basename = drupal_basename($parsed_url['path']);
  $pattern = "/" . preg_quote($basename) . "/";
  $options['key'] = 'filename';
  $file = file_scan_directory($target, $pattern, $options);

  $msg = "IMI hook " . __FUNCTION__ . " was invoked ";

  // Nothing found...report and return an empty array.

  if (empty($file)) {
    $msg .= "and was unable to find a file matching '$basename' in '$target' for ingest. ";
    $msg .= "Make sure that you have mounted your files as '$target', and that they can be read by 'www-data'! ";
    $msg .= "See https://github.com/DigitalGrinnell/dg7/blob/master/README.md for additional details.";
    drupal_set_message($msg, 'warning');
    watchdog('Islandora Multi Importer', $msg);
    return array();
  }

  // File found!  Report and send back the URI in an array.

  else {
    $uri = $file[$basename]->uri;
    $msg .= "and found file '$uri' in '$target' for ingest.";
    drupal_set_message($msg, 'status');
    return array($uri);
  }
}