code: func DefaultCertificate() (*tls.Certificate, error) {
  	randomBytes := make([]byte, 100)
  	_, err := rand.Read(randomBytes)
  	if err != nil {
  		return nil, err
  	}
  	zBytes := sha256.Sum256(randomBytes)
  	z := hex.EncodeToString(zBytes[:sha256.Size])
  	domain := fmt.Sprintf("%s.%s.traefik.default", z[:32], z[32:])
  
  	certPEM, keyPEM, err := KeyPair(domain, time.Time{})
  	if err != nil {
  		return nil, err
  	}
  
  	certificate, err := tls.X509KeyPair(certPEM, keyPEM)
  	if err != nil {
  		return nil, err
  	}
  
  	return &certificate, nil
  }
docs: // DefaultCertificate generates random TLS certificates