Elasticsearch - how to disable client access on data node?

Question

I am fairly new to Elasticsearch and was watching some tutorials that are somewhat outdated.

In the tutorial, they said that if one has dedicated data nodes, it is recommended to disable client access on them so they won't be serving queries and instead focus on indexing data. They used the setting node.client: false to disable client access, but I have come to learn that this setting has since been deprecated and removed.

The reasoning behind removing the node.client setting was that it was redundant and by setting node.master and node.data to false, the node became a dedicated client node. What does this mean if they aren't both set to false? is the client role always on? can it be turned off?

Answer 1

finally found my answer in the documentation. apparently, client nodes are now called coordinating node..

Requests like search requests or bulk-indexing requests may involve data held on different data nodes. A search request, for example, is executed in two phases which are coordinated by the node which receives the client request — the coordinating node. ...Every node is implicitly a coordinating node. This means that a node that has all three node.master, node.data and node.ingest set to false will only act as a coordinating node, which cannot be disabled. As a result, such a node needs to have enough memory and CPU in order to deal with the gather phase.