Here it is stated that the master node should not be a coordinating node.
Dedicated master-eligible nodes only have the
masterrole, allowing them to focus on managing the cluster. While master nodes can also behave as coordinating nodes and route search and indexing requests from clients to data nodes, it is better not to use dedicated master nodes for this purpose.
However, we then state that every node is implicitly a coordinating node, and suggest that cannot be disabled:
Every node is implicitly a coordinating node. This means that a node that has all three
falsewill only act as a coordinating node, which cannot be disabled.
Is it possible to turn off coordinating node responsibilities? Or is it acceptable to have master nodes also be coordinating nodes?