code: func TLSConfigFromCertPath(path string) (*tls.Config, error) {
  	cert, err := ioutil.ReadFile(filepath.Join(path, "cert.pem"))
  	if err != nil {
  		return nil, err
  	}
  	key, err := ioutil.ReadFile(filepath.Join(path, "key.pem"))
  	if err != nil {
  		return nil, err
  	}
  	ca, err := ioutil.ReadFile(filepath.Join(path, "ca.pem"))
  	if err != nil {
  		return nil, err
  	}
  	tlsCert, err := tls.X509KeyPair(cert, key)
  	if err != nil {
  		return nil, err
  	}
  	tlsConfig := &tls.Config{Certificates: []tls.Certificate{tlsCert}}
  	tlsConfig.RootCAs = x509.NewCertPool()
  	if !tlsConfig.RootCAs.AppendCertsFromPEM(ca) {
  		return nil, errors.New("Could not add RootCA pem")
  	}
  	return tlsConfig, nil
  }
docs: // TLSConfigFromCertPath returns a configuration based on PEM files in the directory
  //
  // path is usually what is set by the environment variable `DOCKER_CERT_PATH`,
  // or `$HOME/.docker`.