Cluster Health

The cluster health API allows to get a very simple status on the health of the cluster.

$ curl -XGET 'http://localhost:9200/_cluster/health?pretty=true'
{
  "cluster_name" : "testcluster",
  "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,
  "delayed_unassigned_shards": 0,
  "number_of_pending_tasks" : 0,
  "number_of_in_flight_fetch": 0,
  "task_max_waiting_in_queue_millis": 0,
  "active_shards_percent_as_number": 100
}

The API can also be executed against one or more indices to get just the specified indices health:

$ curl -XGET 'http://localhost:9200/_cluster/health/test1,test2'

The cluster health status is: green, yellow or red. On the shard level, a red status indicates that the specific shard is not allocated in the cluster, yellow means that the primary shard is allocated but replicas are not, and green means that all shards are allocated. The index level status is controlled by the worst shard status. The cluster status is controlled by the worst index status.

One of the main benefits of the API is the ability to wait until the cluster reaches a certain high water-mark health level. For example, the following will wait for 50 seconds for the cluster to reach the yellow level (if it reaches the green or yellow status before 50 seconds elapse, it will return at that point):

$ curl -XGET 'http://localhost:9200/_cluster/health?wait_for_status=yellow&timeout=50s'

The cluster health API accepts the following request parameters:

The following is an example of getting the cluster health at the shards level:

$ curl -XGET 'http://localhost:9200/_cluster/health/twitter?level=shards'