# Use CloudFormation for Auto Scaling policies
<a name="AutoScaling-with-Cloudformation-Shards"></a>

This snippet shows how to create a target tracking policy and apply it to an [AWS::ElastiCache::ReplicationGroup](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-elasticache-replicationgroup.html) resource using the [AWS::ApplicationAutoScaling::ScalableTarget](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-applicationautoscaling-scalabletarget.html) resource. It uses the [Fn::Join](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference-join.html) and [Ref](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference-ref.html) intrinsic functions to construct the `ResourceId` property with the logical name of the `AWS::ElastiCache::ReplicationGroup` resource that is specified in the same template. 

```
ScalingTarget:
   Type: 'AWS::ApplicationAutoScaling::ScalableTarget'
   Properties:
     MaxCapacity: 3
     MinCapacity: 1
     ResourceId: !Sub replication-group/${logicalName}
     ScalableDimension: 'elasticache:replication-group:NodeGroups'
     ServiceNamespace: elasticache
     RoleARN: !Sub "arn:aws:iam::${AWS::AccountId}:role/aws-service-role/elasticache.application-autoscaling.amazonaws.com/AWSServiceRoleForApplicationAutoScaling_ElastiCacheRG"

  ScalingPolicy:
    Type: "AWS::ApplicationAutoScaling::ScalingPolicy"
    Properties:
      ScalingTargetId: !Ref ScalingTarget
      ServiceNamespace: elasticache
      PolicyName: testpolicy
      PolicyType: TargetTrackingScaling
      ScalableDimension: 'elasticache:replication-group:NodeGroups'
      TargetTrackingScalingPolicyConfiguration:
        PredefinedMetricSpecification:
          PredefinedMetricType: ElastiCachePrimaryEngineCPUUtilization
        TargetValue: 40
```