func STSEnabled(value bool) Instance {
	return newOption("sts", value)
}

func DiscoveryHost(value string) Instance {
	return newOption("discovery_host", value)
}

func MetadataDiscovery(value bool) Instance {
	return newOption("metadata_discovery", value)
}

func MetricsLocalhostAccessOnly(proxyMetadata map[string]string) Instance {
	value, ok := proxyMetadata["METRICS_LOCALHOST_ACCESS_ONLY"]
	if ok && value == "true" {

		ProxyNamespace:              PodNamespaceVar.Get(),
		ProxyDomain:                 proxy.DNSDomain,
		IstiodSAN:                   istiodSAN.Get(),
		UseExternalWorkloadSDS:      useExternalWorkloadSDSEnv,
		MetadataDiscovery:           enableWDSEnv,
		SDSFactory:                  sds,
	}
	extractXDSHeadersFromEnv(o)
	return o
}

// Simplified extraction of gRPC headers from environment.