How to view ElasticSearch cluster health using curl

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To view the cluster health of your ElasticSearch cluster use

curl -X GET "http://localhost:9200/_cluster/health?pretty=true"

If your ElasticSearch is not running on localhost, replace localhost by the hostname or IP address ElasticSearch is running on.

Example output:
{
  "cluster_name" : "docker-cluster",
  "status" : "green",
  "timed_out" : false,
  "number_of_nodes" : 1,
  "number_of_data_nodes" : 1,
  "active_primary_shards" : 0,
  "active_shards" : 0,
  "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" : 100.0
}

The most important information from this is:

  • "cluster_name" : "docker-cluster" The name you assigned to your cluster. You should verify that you are connecting to the correct cluster. All ElasticSearch nodes from that cluster must have the same cluster name, or they won’t connect!
  • "number_of_nodes" : 1 The number of nodes currently in the cluster. Sometimes some nodes take longer to start up, so if there are some nodes missing, wait a minute and retry
  • "status" : "green" The status or cluster health of your cluster.

The cluster health can take three values:

  • green: Everything is OK with your cluster (like in our example)
  • yellow: Your cluster is mostly OK, but some shards couldn’t be replicated. This is often the case with cluster consisting of one node only (in that case, note that a data loss on the one node can not be recovered)
  • red: Something is wrong with the cluster. Usually that’s some configuration issue, so be sure to check the logs.

Also see the official reference on cluster health

If you are looking for help on how to setup your ElasticSearch cluster using docker and docker-compose, you can generate your config file using our generator at ElasticSearch docker-compose.yml and systemd service generator.