provider/coredns.go
func newTLSConfig(certPath, keyPath, caPath, serverName string, insecure bool) (*tls.Config, error) {
	if certPath != "" && keyPath == "" || certPath == "" && keyPath != "" {
		return nil, errors.New("either both cert and key or none must be provided")
	}
	var certificates []tls.Certificate
	if certPath != "" {
		cert, err := tls.LoadX509KeyPair(certPath, keyPath)
		if err != nil {
			return nil, fmt.Errorf("could not load TLS cert: %s", err)
		}
		certificates = append(certificates, cert)
	}
	roots, err := loadRoots(caPath)
	if err != nil {
		return nil, err
	}

	return &tls.Config{
		Certificates:       certificates,
		RootCAs:            roots,
		InsecureSkipVerify: insecure,
		ServerName:         serverName,
	}, nil
}
func newTLSConfig(certPath, keyPath, caPath, serverName string, insecure bool) (*tls.Config, error) {
	if certPath != "" && keyPath == "" || certPath == "" && keyPath != "" {
		return nil, errors.New("either both cert and key or none must be provided")
	}
	var certificates []tls.Certificate
	if certPath != "" {
		cert, err := tls.LoadX509KeyPair(certPath, keyPath)
		if err != nil {
			return nil, fmt.Errorf("could not load TLS cert: %s", err)
		}
		certificates = append(certificates, cert)
	}
	roots, err := loadRoots(caPath)
	if err != nil {
		return nil, err
	}

	return &tls.Config{
		Certificates:       certificates,
		RootCAs:            roots,
		InsecureSkipVerify: insecure,
		ServerName:         serverName,
	}, nil
}
// loads TLS artifacts and builds tls.Clonfig object