Registering a Scalable Target

You can apply a scaling policy based on either a predefined or custom metric. To do so, you can use the AWS CLI or the Application Auto Scaling API. The first step is to register your ElastiCache (Redis OSS) replication group with ElastiCache (Redis OSS) auto scaling.

Before you can use ElastiCache (Redis OSS) auto scaling with an ElastiCache (Redis OSS) cluster, you register your cluster with ElastiCache (Redis OSS) auto scaling. You do so to define the scaling dimension and limits to be applied to that cluster. ElastiCache (Redis OSS) auto scaling dynamically scales the ElastiCache (Redis OSS) cluster along the elasticache:replication-group:Replicas scalable dimension, which represents the number of cluster replicas per shard.

Using the CLI

To register your ElastiCache cluster, use the register-scalable-target command with the following parameters:

• --service-namespace – Set this value to elasticache.

• --resource-id – The resource identifier for the ElastiCache cluster. For this parameter, the resource type is ReplicationGroup and the unique identifier is the name of the ElastiCache (Redis OSS) cluster, for example replication-group/myscalablecluster.

• --scalable-dimension – Set this value to elasticache:replication-group:Replicas.

• --min-capacity – The minimum number of replicas to be managed by ElastiCache (Redis OSS) auto scaling. For information about the relationship between --min-capacity, --max-capacity, and the number of replicas in your cluster, see Minimum and maximum capacity.

• --max-capacity – The maximum number of replicas to be managed by ElastiCache (Redis OSS) auto scaling. For information about the relationship between --min-capacity, --max-capacity, and the number of replicas in your cluster, see Minimum and maximum capacity.

In the following example, you register an ElastiCache (Redis OSS) cluster named myscalablecluster. The registration indicates that the cluster should be dynamically scaled to have from one to 5 replicas.

For Linux, macOS, or Unix:

aws application-autoscaling register-scalable-target \
    --service-namespace elasticache \
    --resource-id replication-group/myscalablecluster \
    --scalable-dimension elasticache:replication-group:Replicas \
    --min-capacity 1 \
    --max-capacity 5 \

For Windows:

aws application-autoscaling register-scalable-target ^
    --service-namespace elasticache ^
    --resource-id replication-group/myscalablecluster ^
    --scalable-dimension elasticache:replication-group:Replicas ^
    --min-capacity 1 ^
    --max-capacity 5 ^

Using the API

To register your ElastiCache cluster, use the register-scalable-target command with the following parameters:

• ServiceNamespace – Set this value to elasticache.

• ResourceID – The resource identifier for the ElastiCache cluster. For this parameter, the resource type is ReplicationGroup and the unique identifier is the name of the ElastiCache (Redis OSS) cluster, for example replication-group/myscalablecluster.

• ScalableDimension – Set this value to elasticache:replication-group:Replicas.

• MinCapacity – The minimum number of replicas to be managed by ElastiCache (Redis OSS) auto scaling. For information about the relationship between --min-capacity, --max-capacity, and the number of replicas in your cluster, see Minimum and maximum capacity.

• MaxCapacity – The maximum number of replicas to be managed by ElastiCache (Redis OSS) auto scaling. For information about the relationship between --min-capacity, --max-capacity, and the number of replicas in your cluster, see Minimum and maximum capacity.

In the following example, you register an ElastiCache (Redis OSS) cluster named myscalablecluster with the Application Auto Scaling API. This registration indicates that the cluster should be dynamically scaled to have from one to 5 replicas.

POST / HTTP/1.1
Host: autoscaling.us-east-2.amazonaws.com
Accept-Encoding: identity
Content-Length: 219
X-Amz-Target: AnyScaleFrontendService.RegisterScalableTarget
X-Amz-Date: 20160506T182145Z
User-Agent: aws-cli/1.10.23 Python/2.7.11 Darwin/15.4.0 botocore/1.4.8
Content-Type: application/x-amz-json-1.1
Authorization: AUTHPARAMS
{
    "ServiceNamespace": "elasticache",
    "ResourceId": "replication-group/myscalablecluster",
    "ScalableDimension": "elasticache:replication-group:Replicas",
    "MinCapacity": 1,
    "MaxCapacity": 5
}