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:
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.
level | Enum | The level of detail for returned health information. Supported values are `cluster`, `indices`, `shards`, and `awareness_attributes`. Default is `cluster`.
awareness_attribute | String | The name of the awareness attribute, for which to return cluster health (for example, `zone`). Applicable only if `level` is set to `awareness_attributes`.
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_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.
|awareness_attributes | Object | Contains cluster health information for each awareness attribute. |
## Returning cluster health by awareness attribute
To check cluster health by awareness attribute (for example, zone or rack), specify `awareness_attributes` in the `level` query parameter:
```json
GET _cluster/health?level=awareness_attributes
```
The response contains cluster health metrics partitioned by awareness attribute:
```json
{
"cluster_name": "runTask",
"status": "green",
"timed_out": false,
"number_of_nodes": 3,
"number_of_data_nodes": 3,
"discovered_master": true,
"discovered_cluster_manager": true,
"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,
"awareness_attributes": {
"zone": {
"zone-3": {
"active_shards": 0,
"initializing_shards": 0,
"relocating_shards": 0,
"unassigned_shards": 0,
"data_nodes": 1,
"weight": 1
},
"zone-1": {
"active_shards": 0,
"initializing_shards": 0,
"relocating_shards": 0,
"unassigned_shards": 0,
"data_nodes": 1,
"weight": 1
},
"zone-2": {
"active_shards": 0,
"initializing_shards": 0,
"relocating_shards": 0,
"unassigned_shards": 0,
"data_nodes": 1,
"weight": 1
}
},
"rack": {
"rack-3": {
"active_shards": 0,
"initializing_shards": 0,
"relocating_shards": 0,
"unassigned_shards": 0,
"data_nodes": 1,
"weight": 1
},
"rack-1": {
"active_shards": 0,
"initializing_shards": 0,
"relocating_shards": 0,
"unassigned_shards": 0,
"data_nodes": 1,
"weight": 1
},
"rack-2": {
"active_shards": 0,
"initializing_shards": 0,
"relocating_shards": 0,
"unassigned_shards": 0,
"data_nodes": 1,
"weight": 1
}
}
}
}
```
If you're interested in a particular awareness attribute, you can include the name of the awareness attribute as a query parameter:
```json
GET _cluster/health?level=awareness_attributes&awareness_attribute=zone
```
In response to the preceding request, OpenSearch returns cluster health information only for the `zone` awareness attribute.
The unassigned shard information will be accurate only if you [enable replica count enforcement]({{site.url}}{{site.baseurl}}/opensearch/cluster#forced-replica-count-enforcement) and [configure forced awareness]({{site.url}}{{site.baseurl}}/opensearch/cluster#forced-awareness) for the awareness attribute either before cluster start or after cluster start but before any indexing requests. If you enable replica enforcement after the cluster receives indexing requests, the unassigned shard information may be inaccurate. If you don't configure replica count enforcement and forced awareness, the `unassigned_shards` field will contain -1.
