code: func (db *SnapshotDB) IsInternalService(c context.Context, hostname string) (bool, error) {
  	if db.internalServices == nil {
  		return false, nil
  	}
  	return db.internalServices.MatchString(hostname), nil
  }
docs: // IsInternalService returns true if the given hostname belongs to a service
  // that is a part of the current LUCI deployment.
  //
  // What hosts are internal is controlled by 'internal_service_regexp' setting
  // in security.cfg in the Auth Service configs.