code: protected function getServices($config)
      {
          $services       = array();
          $travisServices = isset($config['services']) && is_array($config['services']) ? $config['services'] : array();
  
          foreach ($travisServices as $service) {
              if (isset($this->servicesMapping[$service])) {
                  $services[] = new Service(
                      $service,
                      $this->servicesMapping[$service]['repository'],
                      $this->servicesMapping[$service]['tag'],
                      $this->servicesMapping[$service]['config']
                  );
              }
          }
  
          return $services;
      }
docs: Get services list from travis ci configuration file
  
  @param $config
  
  @return Service[]