Node roles

Every instance of Elasticsearch server is called a node. A collection of connected nodes is called a cluster. All nodes know about all the other nodes in the cluster and can forward client requests to the appropriate node. Besides that, each node serves one or more purpose:

• Master-eligible node - A node that has node.master set to true (default), which makes it eligible to be elected as the master node, which controls the cluster
• Data node - A node that has node.data set to true (default). Data nodes hold data and perform data related operations such as CRUD, search, and aggregations
• Client node - A client node has both node.master and node.data set to false. It can neither hold data nor become the master node. It behaves as a “smart router” and is used to forward cluster-level requests to the master node and data-related requests (such as search) to the appropriate data nodes
• Tribe node - A tribe node, configured via the tribe.* settings, is a special type of client node that can connect to multiple clusters and perform search and other operations across all connected clusters.