code: func CreateTLSConfiguration(certFile, keyFile string, cipherSuites []uint16) (*tls.Config, error) {
  	config := TLSConfig(cipherSuites)
  
  	if _, err := os.Stat(certFile); err != nil {
  		return nil, trace.BadParameter("certificate is not accessible by '%v'", certFile)
  	}
  	if _, err := os.Stat(keyFile); err != nil {
  		return nil, trace.BadParameter("certificate is not accessible by '%v'", certFile)
  	}
  
  	cert, err := tls.LoadX509KeyPair(certFile, keyFile)
  	if err != nil {
  		return nil, trace.Wrap(err)
  	}
  	config.Certificates = []tls.Certificate{cert}
  
  	return config, nil
  }
docs: // CreateTLSConfiguration sets up default TLS configuration