/**
  * Returns an array of the instances assigned to a cluster
  *
  * @param int|string $clusterId The cluster ID
  *
  * @return array
  */
 public function getInstances($clusterId)
 {
     $_cluster = $this->_findCluster($clusterId);
     $_rows = Instance::byClusterId($_cluster->id)->get(['id', 'instance_name_text']);
     $_response = [];
     /** @type Instance $_instance */
     foreach ($_rows as $_instance) {
         $_response[] = ['id' => $_instance->id, 'name' => $_instance->instance_name_text];
     }
     //$this->debug('found ' . count($_response) . ' instance(s)');
     usort($_response, function ($a, $b) {
         return strcasecmp($a['name'], $b['name']);
     });
     return $_response;
 }