def METHOD_NAME(service_name, instance_name):
    smartstack_yaml = "/nail/etc/services/%s/smartstack.yaml" % service_name
    proxy_port = None
    if os.path.exists(smartstack_yaml):
        with open(smartstack_yaml, "r") as stream:
            data = yaml.safe_load(stream)
            if instance_name in data:
                proxy_port = data[instance_name].get("proxy_port", None)
    return proxy_port