The cluster health API returns a simple status on the health of the cluster Added in 1.3.0

GET /_cluster/health

You can also use the API to get the health status of only specified data streams and indices. For data streams, the API retrieves the health status of the stream’s backing indices. 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.

Query parameters

  • expand_wildcards string | array[string]

    Whether to expand wildcard expression to concrete indices that are open, closed or both.

  • level string

    Can be one of cluster, indices or shards. Controls the details level of the health information returned.

    Values are cluster, indices, or shards.

  • local boolean

    If true, the request retrieves information from the local node only. Defaults to false, which means information is retrieved from the master node.

  • master_timeout string

    Period to wait for a connection to the master node. If no response is received before the timeout expires, the request fails and returns an error.

  • timeout string

    Period to wait for a response. If no response is received before the timeout expires, the request fails and returns an error.

  • wait_for_active_shards number | string

    A number controlling to how many active shards to wait for, all to wait for all shards in the cluster to be active, or 0 to not wait.

  • wait_for_events string

    Can be one of immediate, urgent, high, normal, low, languid. Wait until all currently queued events with the given priority are processed.

    Values are immediate, urgent, high, normal, low, or languid.

  • wait_for_nodes string | number

    The request waits until the specified number N of nodes is available. It also accepts >=N, <=N, >N and <N. Alternatively, it is possible to use ge(N), le(N), gt(N) and lt(N) notation.

  • wait_for_no_initializing_shards boolean

    A boolean value which controls whether to wait (until the timeout provided) for the cluster to have no shard initializations. Defaults to false, which means it will not wait for initializing shards.

  • wait_for_no_relocating_shards boolean

    A boolean value which controls whether to wait (until the timeout provided) for the cluster to have no shard relocations. Defaults to false, which means it will not wait for relocating shards.

  • wait_for_status string

    One of green, yellow or red. Will wait (until the timeout provided) until the status of the cluster changes to the one provided or better, i.e. green > yellow > red. By default, will not wait for any status.

    Values are green, GREEN, yellow, YELLOW, red, or RED.

Responses

GET /_cluster/health 
curl \
 -X GET http://api.example.com/_cluster/health
Response examples (200)
This is the API response in case of a quiet single node cluster with a single index with one shard and one replica. 
{
  "cluster_name" : "testcluster",
  "status" : "yellow",
  "timed_out" : false,
  "number_of_nodes" : 1,
  "number_of_data_nodes" : 1,
  "active_primary_shards" : 1,
  "active_shards" : 1,
  "relocating_shards" : 0,
  "initializing_shards" : 0,
  "unassigned_shards" : 1,
  "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": 50.0
}