---
layout: default
title: Cluster health
nav_order: 16
---

# Cluster health
Introduced 1.0
{: .label .label-purple }

The most basic cluster health request returns a simple status of the health of your cluster. OpenSearch expresses cluster health in three colors: green, yellow, and red. A green status means all primary shards and their replicas are allocated to nodes. A yellow status means all primary shards are allocated to nodes, but some replicas aren't. A red status means at least one primary shard is not allocated to any node.

To get the status of a specific index, provide the index name.

## Example

This request waits 50 seconds for the cluster to reach the yellow status or better:

```
GET _cluster/health?wait_for_status=yellow&timeout=50s
```

If the cluster health becomes yellow or green before 50 seconds elapse, it returns a response immediately. Otherwise it returns a response as soon as it exceeds the timeout.

## Path and HTTP methods

```
GET _cluster/health
GET _cluster/health/<index>
```

## Query parameters

The following table lists the available query parameters. All query parameters are optional.

Parameter | Type | Description
:--- | :--- | :---
expand_wildcards | Enum | Expands wildcard expressions to concrete indexes. Combine multiple values with commas. Supported values are `all`, `open`, `closed`, `hidden`, and `none`. Default is `open`.
level | Enum | The level of detail for returned health information. Supported values are `cluster`, `indices`, and `shards`. Default is `cluster`.
local | Boolean | Whether to return information from the local node only instead of from the cluster manager node. Default is false.
cluster_manager_timeout | Time | The amount of time to wait for a connection to the cluster manager node. Default is 30 seconds.
timeout | Time | The amount of time to wait for a response. If the timeout expires, the request fails. Default is 30 seconds.
wait_for_active_shards | String | Wait until the specified number of shards is active before returning a response. `all` for all shards. Default is `0`.
wait_for_nodes | String | Wait for N number of nodes. Use `12` for exact match, `>12` and `<12` for range.
wait_for_events | Enum | Wait until all currently queued events with the given priority are processed. Supported values are `immediate`, `urgent`, `high`, `normal`, `low`, and `languid`.
wait_for_no_relocating_shards | Boolean | Whether to wait until there are no relocating shards in the cluster. Default is false.
wait_for_no_initializing_shards | Boolean | Whether to wait until there are no initializing shards in the cluster. Default is false.
wait_for_status | Enum | Wait until the cluster health reaches the specified status or better. Supported values are `green`, `yellow`, and `red`.

#### Sample request

The following sample request retrieves cluster health for all indexes in the cluster:

```json
GET _cluster/health
```

#### Sample response

The response contains cluster health information:

```json
{
  "cluster_name" : "opensearch-cluster",
  "status" : "green",
  "timed_out" : false,
  "number_of_nodes" : 2,
  "number_of_data_nodes" : 2,
  "discovered_master" : true,
  "active_primary_shards" : 6,
  "active_shards" : 12,
  "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
}
```

## Response fields

The following table lists all response fields.

|Field |Data type |Description |
|:---	|:---	|:---	|
|cluster_name | String | The name of the cluster. |
|status	| String | The cluster health status, which represents the state of shard allocation in the cluster. May be `green`, `yellow`, or `red`. |
|number_of_nodes | Integer | The number of nodes in the cluster. |
|number_of_data_nodes | Integer | The number of data nodes in the cluster. |
|discovered_cluster_manager | Boolean | Specifies whether the cluster manager is discovered. |
|active_primary_shards | Integer |  The number of active primary shards. |
|active_shards | Integer | The total number of active shards, including primary and replica shards. |
|relocating_shards | Integer | The number of relocating shards. |
|initializing_shards | Integer | The number of intializing shards. |
|unassigned_shards | Integer | The number of unassigned shards. |
|delayed_unassigned_shards | Integer | The number of delayed unassigned shards. |
|number_of_pending_tasks | Integer | The number of pending tasks in the cluster. |
|number_of_in_flight_fetch | Integer | The number of unfinished fetches. |
|task_max_waiting_in_queue_millis | Integer | The maximum wait time for all tasks waiting to be performed, in milliseconds. |
|active_shards_percent_as_number | Double | The percentage of active shards in the cluster. |

## Required permissions

If you use the security plugin, make sure you have the appropriate permissions:
`cluster:monitor/health`.