Proxying ES traffic through nginx with, say, basic auth enabled is one way of handling this (but use HTTPS to protect the credentials). Even without basic auth in your proxy rules, you might, for instance, restrict access to various endpoints to specific users or from specific IP addresses.
What we do in one of our environments is to use Docker. Docker containers are only accessible to the world AND/OR other Docker containers if you explicitly define them as such. By default, they are blind.
In our docker-compose setup, we have the following containers defined:
nginx - Handles all web requests, serves up static files and proxies API queries to a container named 'middleware'
middleware - A Java server that handles and authenticates all API requests. It interacts with the following three containers, each of which is exposed only to middleware:
- redis
- mongodb
- elasticsearch
The net effect of this arrangement is the access to elasticsearch can only be through the middleware piece, which ensures authentication, roles and permissions are correctly handled before any queries are sent through.
A full docker environment is more work to setup than a simple nginx proxy, but the end result is something that is more flexible, scalable and secure.