code: func (kl *Kubelet) GeneratePodHostNameAndDomain(pod *v1.Pod) (string, string, error) {
  	clusterDomain := kl.dnsConfigurer.ClusterDomain
  
  	hostname := pod.Name
  	if len(pod.Spec.Hostname) > 0 {
  		if msgs := utilvalidation.IsDNS1123Label(pod.Spec.Hostname); len(msgs) != 0 {
  			return "", "", fmt.Errorf("Pod Hostname %q is not a valid DNS label: %s", pod.Spec.Hostname, strings.Join(msgs, ";"))
  		}
  		hostname = pod.Spec.Hostname
  	}
  
  	hostname, err := truncatePodHostnameIfNeeded(pod.Name, hostname)
  	if err != nil {
  		return "", "", err
  	}
  
  	hostDomain := ""
  	if len(pod.Spec.Subdomain) > 0 {
  		if msgs := utilvalidation.IsDNS1123Label(pod.Spec.Subdomain); len(msgs) != 0 {
  			return "", "", fmt.Errorf("Pod Subdomain %q is not a valid DNS label: %s", pod.Spec.Subdomain, strings.Join(msgs, ";"))
  		}
  		hostDomain = fmt.Sprintf("%s.%s.svc.%s", pod.Spec.Subdomain, pod.Namespace, clusterDomain)
  	}
  
  	return hostname, hostDomain, nil
  }
docs: // GeneratePodHostNameAndDomain creates a hostname and domain name for a pod,
  // given that pod's spec and annotations or returns an error.