Cluster routing and awareness
Introduced 1.0
To control the distribution of search or HTTP traffic, you can use the weights per awareness attribute to control the distribution of search or HTTP traffic across zones. This is commonly used for zonal deployments, heterogeneous instances, and routing traffic away from zones during zonal failure.
Path and HTTP methods
PUT /_cluster/routing/awareness/<attribute>/weights
GET /_cluster/routing/awareness/<attribute>/weights?local
GET /_cluster/routing/awareness/<attribute>/weights
Path parameters
| Parameter | Type | Description |
|---|---|---|
| attribute | String | The name of the awareness attribute, usually zone. The attribute name must match the values listed in the request body when assigning weights to zones. |
Request body fields
| Parameter | Type | Description |
|---|---|---|
| weights | JSON object | Assigns weights to attributes within the request body of the PUT request. Weights can be set in any ratio, for example, 2:3:5. In a 2:3:5 ratio with 3 zones, for every 100 requests sent to the cluster, each zone would receive either 20, 30, or 50 search requests in a random order. When assigned a weight of 0, the zone does not receive any search traffic. |
| _version | String | Implements optimistic concurrency control (OCC) through versioning. The parameter uses simple versioning, such as 1, and increments upward based on each subsequent modification. This allows any servers from which a request originates to validate whether or not a zone has been modified. |
In the following example request body, zone_1 and zone_2 receive 50 requests each, whereas zone_3 is prevented from receiving requests:
{
"weights":
{
"zone_1": "5",
"zone_2": "5",
"zone_3": "0"
}
"_version" : 1
}
Example requests
Weighted round robin search
The following example request creates a round robin shard allocation for search traffic by using an undefined ratio:
PUT /_cluster/routing/awareness/zone/weights
{
"weights":
{
"zone_1": "1",
"zone_2": "1",
"zone_3": "0"
}
"_version" : 1
}
Getting weights for all zones
The following example request gets weights for all zones.
GET /_cluster/routing/awareness/zone/weights
Deleting weights
You can remove your weight ratio for each zone using the DELETE method:
DELETE /_cluster/routing/awareness/zone/weights
Example responses
OpenSearch typically responds with the following when successfully allocating shards:
{
"acknowledged": true
}
Getting weights for all zone
OpenSearch responds with the weight of each zone:
```json { “weights”: {
"zone_1": "1.0",
"zone_2": "1.0",
"zone_3": "0.0"
},
"_version":1 }
Next steps
- For more information about zone commissioning, see Cluster decommission.
- For more information about allocation awareness, see Cluster formation.