In the Understanding clusters, replication, and sharding recipe in Chapter 1, Getting Started, we discussed the ElasticSearch cluster and how to manage red and yellow states.
ElasticSearch provides a convenient way to manage cluster state, which is one of the first things to check in case of problems.
To control cluster health, we will perform the following steps:
To view cluster health, the HTTP method is GET and the curl command is:
curl -XGET 'http://localhost:9200/_cluster/health?pretty'
The result will be:
{ "cluster_name" : "elasticsearch", "status" : "green", "timed_out" : false, "number_of_nodes" : 2, "number_of_data_nodes" : 2, "active_primary_shards" : 5, "active_shards" : 10, "relocating_shards" : 0, "initializing_shards" : 0, "unassigned_shards" : 0 }