discovery.seed_hosts: ["host1", "host2"]

This line of code is an example of a configuration setting in the Elasticsearch cluster.

Specifically, this line sets the list of initial seed hosts for the Elasticsearch discovery process. The discovery process is responsible for finding and connecting all nodes in the cluster. The seed hosts are the initial nodes that are used to start the discovery process, allowing the other nodes to join the cluster.

In this example, the seed hosts are specified as "host1" and "host2". These could be the hostnames or IP addresses of two nodes in the Elasticsearch cluster. When a new node starts up and looks for other nodes to join, it will use these seed hosts as a starting point to discover the other nodes in the cluster.