/**
  * @return OpenStackNovaInstance[]
  */
 function getInstances()
 {
     $instancesarr = array();
     $ret = $this->restCall('compute', '/servers/detail', 'GET');
     $instances = self::_get_property($ret['body'], 'servers');
     if (!$instances) {
         return $instancesarr;
     }
     foreach ($instances as $instance) {
         $instance = new OpenStackNovaInstance($instance, $this->getRegion(), true);
         $id = $instance->getInstanceOSId();
         $instancesarr[$id] = $instance;
     }
     return $instancesarr;
 }