t.Errorf("unable to write public key to file %q: [%v]", filename, err)
			}
		case *rsa.PrivateKey:
			privateKey, err := keyutil.MarshalPrivateKeyToPEM(body)
			if err != nil {
				t.Errorf("unable to write private key to file %q: [%v]", filename, err)
			}
			if err := keyutil.WriteKey(filepath.Join(dir, filename), privateKey); err != nil {

		},
		NotAfter: notAfter,
	}
	cert, key, err := pkiutil.NewCertAndKey(caCert, caKey, cfg)
	if err != nil {
		t.Fatalf("couldn't generate certificate: %v", err)
	}

	encodedClientKey, err := keyutil.MarshalPrivateKeyToPEM(key)
	if err != nil {
		t.Fatalf("failed to marshal private key to PEM: %v", err)
	}

	certificateAuthorityData := pkiutil.EncodeCertPEM(caCert)

	config := kubeconfigutil.CreateWithCerts(

	if rw.kubeConfig == nil {
		return errors.Errorf("failed to Write kubeConfig file with renewed certs. It is necessary to call Read before Write")
	}

	// encodes the new key
	encodedClientKey, err := keyutil.MarshalPrivateKeyToPEM(newKey)
	if err != nil {
		return errors.Wrapf(err, "failed to marshal private key to PEM")
	}

	// Update the embedded CA in the kubeconfig file.