The purpose of coordinating_only role

OpenSearch
1

Versions (relevant - OpenSearch/Dashboard/Server OS/Browser): OpenSearch

Describe the issue:

Hi, I am testing OpenSearch configuration.

I know that I should config the roles of node as blank list for building coordinating node.

By the way, I found that there is “coorinating_only” role in OpenSearch.
When I config “coordinating_only” role in OpenSearch node, It works as same as blank role.

Then, I wonder why “coordinating_only” role exists in OpenSearch although we can create coordinating role with blank role.

Thanks in advance

Configuration:

Relevant Logs or Screenshots:

2

This would be a perfect issue and/or comment in the github repo for the core opensearch component. The developers are usually able to justify their decision making with great precision.

If I were to wager a guess, I would say it would be to prevent accidental replication and segmentation in case a node gets brought up on accident. If a node were to get brought up as a data node and start acting as a replica and/or start hosting segments of an index, it may not be intended and might even degrade the performance of a cluster. Setting the default role to coordinating only might be a safety measure.

Just a guess though. It’s a perfect question to put into an issue for the OpenSearch Core Repo on Github

And welcome back! I know your last post was several months ago.

3

@huckebein79 Please have a look at this GitHub commit. It explains the existence of the coordinating_only role.