The cluster state API allows to get a comprehensive state information of the whole cluster.

$ curl -XGET 'http://localhost:9200/_cluster/state'

It is possible to filter the cluster state response using the following REST parameters:

• filter_nodes: Set to true to filter out the nodes part of the response.
• filter_routing_table: Set to true to filter out the routing_table part of the response.
• filter_metadata: Set to true to filter out the metadata part of the response.
• filter_indices: When not filtering metadata, a comma separated list of indices to include in the response.

Example follows:

$ curl -XGET 'http://localhost:9200/_cluster/state?filter_nodes=true'