本文属于机器翻译版本。若本译文内容与英语原文存在差异，则一律以英文原文为准。

# 将 CloudFormation 用于 Auto Scaling 策略
<a name="AutoScaling-with-Cloudformation-Shards"></a>

此代码段演示如何使用 [AWS::ApplicationAutoScaling::ScalableTarget](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-applicationautoscaling-scalabletarget.html) 资源创建目标跟踪策略并将其应用于 [AWS::ElastiCache::ReplicationGroup](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-elasticache-replicationgroup.html) 资源。此示例利用 [Fn::Join](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference-join.html) 和 [Ref](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference-ref.html) 内置函数，使用在同一模板中指定的 `AWS::ElastiCache::ReplicationGroup` 资源的逻辑名称来构建 `ResourceId` 属性。

```
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
```