In this tutorial I am going to look at the possibility of using Drupal 7 as a content management system that powers another high performance application. To illustrate the latter, I will use the Silex PHP microframework and Elasticsearch as the data source. The goal is to create a proof of concept, demonstrating using these three technologies together. [...] The tutorial will be split into two pieces, because there is quite a lot of ground to cover. In this part, we’ll set up Elasticsearch on the server and integrate it with Drupal by creating a small, custom module that will insert, update, and delete Drupal nodes into Elasticsearch.
They assume you already have an Elasticsearch install set up and ready to go but do offer some suggestions on how to configure it to be a little bit more secure. Then, in your Drupal application (again, already installed) they show you how to use the Elasticsearch module to connect to the ES instance and, once connected, insert, update and delete data for the data in your nodes.