return nil, fmt.Errorf("could not unmarshal Node: %w", err)
				}
				meta, err := model.ParseMetadata(node.Metadata)
				if err != nil || meta.ProxyConfig == nil {
					// Skip non-sidecars (e.g. istioctl queries)
					continue
				}
				pi = append(pi, istioVersion.ProxyInfo{
					ID:           node.Id,
					IstioVersion: getIstioVersionFromXdsMetadata(node.Metadata),
				})

func registerEnvironment[T env.Parseable](name string, defaultValue T, usage string) {
	envName := strings.Replace(strings.ToUpper(name), "-", "_", -1)
	// Note: we do not rely on istio env package to retrieve configuration. We relies on viper.
	// This is just to make sure the reference doc tool can generate doc with these vars as env variable at istio.io.
	env.Register(envName, defaultValue, usage)
	bindViper(name)
}