Services or capabilities described in Amazon Web Services documentation might vary by Region. To see the differences applicable to the China Regions, see Getting Started with Amazon Web Services in China (PDF).

Create a target tracking scaling policy using the Amazon CLI

You can create a target tracking scaling policy for Application Auto Scaling by using the Amazon CLI for the following configuration tasks.

For brevity, the examples in this topic illustrate CLI commands for an Amazon EC2 Spot Fleet. To specify a different scalable target, specify its namespace in --service-namespace, its scalable dimension in --scalable-dimension, and its resource ID in --resource-id. For more information and examples for each service, see the topics in Amazon services that you can use with Application Auto Scaling.

When using the Amazon CLI, remember that your commands run in the Amazon Web Services Region configured for your profile. If you want to run the commands in a different Region, either change the default Region for your profile, or use the --region parameter with the command.

Register a scalable target

If you haven't already done so, register the scalable target. Use the register-scalable-target command to register a specific resource in the target service as a scalable target. The following example registers a Spot Fleet request with Application Auto Scaling. Application Auto Scaling can scale the number of instances in the Spot Fleet at a minimum of 2 instances and a maximum of 10.

Linux, macOS, or Unix

aws application-autoscaling register-scalable-target --service-namespace ec2 \
  --scalable-dimension ec2:spot-fleet-request:TargetCapacity \
  --resource-id spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE \
  --min-capacity 2 --max-capacity 10

Windows

aws application-autoscaling register-scalable-target --service-namespace ec2 --scalable-dimension ec2:spot-fleet-request:TargetCapacity --resource-id spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE --min-capacity 2 --max-capacity 10

If successful, this command returns the ARN of the scalable target.

{
    "ScalableTargetARN": "arn:aws-cn:application-autoscaling:region:account-id:scalable-target/1234abcd56ab78cd901ef1234567890ab123"
}

Create a target tracking scaling policy

Example: target tracking configuration file

The following is an example target tracking configuration that keeps the average CPU utilization at 40 percent. Save this configuration in a file named config.json.

{
  "TargetValue": 40.0,
  "PredefinedMetricSpecification": 
    {
      "PredefinedMetricType": "EC2SpotFleetRequestAverageCPUUtilization"
    }
}

For more information, see PredefinedMetricSpecification in the Application Auto Scaling API Reference.

Alternatively, you can use a custom metric for scaling by creating a customized metric specification and adding values for each parameter from CloudWatch. The following is an example target tracking configuration that keeps the average utilization of the specified metric at 40 percent.

{
   "TargetValue":40.0,
   "CustomizedMetricSpecification":{
      "MetricName":"MyUtilizationMetric",
      "Namespace":"MyNamespace",
      "Dimensions":[
         {
            "Name":"MyOptionalMetricDimensionName",
            "Value":"MyOptionalMetricDimensionValue"
         }
      ],
      "Statistic":"Average",
      "Unit":"Percent"
   }
}

For more information, see CustomizedMetricSpecification in the Application Auto Scaling API Reference.

Example: cpu40-target-tracking-scaling-policy

Use the following put-scaling-policy command, along with the config.json file you created, to create a scaling policy named cpu40-target-tracking-scaling-policy.

Linux, macOS, or Unix

aws application-autoscaling put-scaling-policy --service-namespace ec2 \
  --scalable-dimension ec2:spot-fleet-request:TargetCapacity \
  --resource-id spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE \
  --policy-name cpu40-target-tracking-scaling-policy --policy-type TargetTrackingScaling \
  --target-tracking-scaling-policy-configuration file://config.json

Windows

aws application-autoscaling put-scaling-policy --service-namespace ec2 --scalable-dimension ec2:spot-fleet-request:TargetCapacity --resource-id spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE --policy-name cpu40-target-tracking-scaling-policy --policy-type TargetTrackingScaling --target-tracking-scaling-policy-configuration file://config.json

If successful, this command returns the ARNs and names of the two CloudWatch alarms created on your behalf.

{
    "PolicyARN": "arn:aws-cn:autoscaling:region:account-id:scalingPolicy:policy-id:resource/ec2/spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE:policyName/cpu40-target-tracking-scaling-policy",
    "Alarms": [
        {
            "AlarmARN": "arn:aws-cn:cloudwatch:region:account-id:alarm:TargetTracking-spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE-AlarmHigh-d4f0770c-b46e-434a-a60f-3b36d653feca",
            "AlarmName": "TargetTracking-spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE-AlarmHigh-d4f0770c-b46e-434a-a60f-3b36d653feca"
        },
        {
            "AlarmARN": "arn:aws-cn:cloudwatch:region:account-id:alarm:TargetTracking-spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE-AlarmLow-1b437334-d19b-4a63-a812-6c67aaf2910d",
            "AlarmName": "TargetTracking-spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE-AlarmLow-1b437334-d19b-4a63-a812-6c67aaf2910d"
        }
    ]
}

Describe target tracking scaling policies

You can describe all scaling policies for the specified service namespace using the following describe-scaling-policies command.

aws application-autoscaling describe-scaling-policies --service-namespace ec2

You can filter the results to just the target tracking scaling policies using the --query parameter. For more information about the syntax for query, see Controlling command output from the Amazon CLI in the Amazon Command Line Interface User Guide.

Linux, macOS, or Unix

aws application-autoscaling describe-scaling-policies --service-namespace ec2 \
  --query 'ScalingPolicies[?PolicyType==`TargetTrackingScaling`]'

Windows

aws application-autoscaling describe-scaling-policies --service-namespace ec2 --query "ScalingPolicies[?PolicyType==`TargetTrackingScaling`]"

The following is example output.

[
    {
        "PolicyARN": "PolicyARN",
        "TargetTrackingScalingPolicyConfiguration": {
            "PredefinedMetricSpecification": {
                "PredefinedMetricType": "EC2SpotFleetRequestAverageCPUUtilization"
            },
            "TargetValue": 40.0
        },
        "PolicyName": "cpu40-target-tracking-scaling-policy",
        "ScalableDimension": "ec2:spot-fleet-request:TargetCapacity",
        "ServiceNamespace": "ec2",
        "PolicyType": "TargetTrackingScaling",
        "ResourceId": "spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE",
        "Alarms": [
            {
                "AlarmARN": "arn:aws-cn:cloudwatch:region:account-id:alarm:TargetTracking-spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE-AlarmHigh-d4f0770c-b46e-434a-a60f-3b36d653feca",
                "AlarmName": "TargetTracking-spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE-AlarmHigh-d4f0770c-b46e-434a-a60f-3b36d653feca"
            },
            {
                "AlarmARN": "arn:aws-cn:cloudwatch:region:account-id:alarm:TargetTracking-spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE-AlarmLow-1b437334-d19b-4a63-a812-6c67aaf2910d",
                "AlarmName": "TargetTracking-spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE-AlarmLow-1b437334-d19b-4a63-a812-6c67aaf2910d"
            }
        ],
        "CreationTime": 1515021724.807
    }
]

Delete a target tracking scaling policy

When you are finished with a target tracking scaling policy, you can delete it using the delete-scaling-policy command.

The following command deletes the specified target tracking scaling policy for the specified Spot Fleet request. It also deletes the CloudWatch alarms that Application Auto Scaling created on your behalf.

Linux, macOS, or Unix

aws application-autoscaling delete-scaling-policy --service-namespace ec2 \
  --scalable-dimension ec2:spot-fleet-request:TargetCapacity \
  --resource-id spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE \
  --policy-name cpu40-target-tracking-scaling-policy

Windows

aws application-autoscaling delete-scaling-policy --service-namespace ec2 --scalable-dimension ec2:spot-fleet-request:TargetCapacity --resource-id spot-fleet-request/sfr-73fbd2ce-aa30-494c-8788-1cee4EXAMPLE --policy-name cpu40-target-tracking-scaling-policy