Constructing the JSON for custom metrics - Amazon EC2 Auto Scaling
Example predictive scaling policy with custom load and scaling metrics (AWS CLI)

Constructing the JSON for custom metrics

The following section contains examples for how to configure predictive scaling to query data from CloudWatch. There are two different methods to configure this option, and the method that you choose affects which format you use to construct the JSON for your predictive scaling policy. When you use metric math, the format of the JSON varies further based on the metric math being performed.

  1. To create a policy that gets data directly from other CloudWatch metrics provided by AWS or metrics that you publish to CloudWatch, see Example predictive scaling policy with custom load and scaling metrics (AWS CLI).

  2. To create a policy that can query multiple CloudWatch metrics and use math expressions to create new time series based on these metrics, see Use metric math expressions.

Example predictive scaling policy with custom load and scaling metrics (AWS CLI)

To create a predictive scaling policy with custom load and scaling metrics with the AWS CLI, store the arguments for --predictive-scaling-configuration in a JSON file named config.json.

You start adding custom metrics by replacing the replaceable values in the following example with those of your metrics and your target utilization.

{
  "MetricSpecifications": [
    {
      "TargetValue": 50,
      "CustomizedScalingMetricSpecification": {
        "MetricDataQueries": [
          {
            "Id": "scaling_metric",
            "MetricStat": {
              "Metric": {
                "MetricName": "MyUtilizationMetric",
                "Namespace": "MyNameSpace",
                "Dimensions": [
                  {
                    "Name": "MyOptionalMetricDimensionName",
                    "Value": "MyOptionalMetricDimensionValue"
                  }
                ]
              },
              "Stat": "Average"
            }
          }
        ]
      },
      "CustomizedLoadMetricSpecification": {
        "MetricDataQueries": [
          {
            "Id": "load_metric",
            "MetricStat": {
              "Metric": {
                "MetricName": "MyLoadMetric",
                "Namespace": "MyNameSpace",
                "Dimensions": [
                  {
                    "Name": "MyOptionalMetricDimensionName",
                    "Value": "MyOptionalMetricDimensionValue"
                  }
                ]
              },
              "Stat": "Sum"
            }
          }
        ]
      }
    }
  ]
}

For more information, see MetricDataQuery in the Amazon EC2 Auto Scaling API Reference.

Note

Following are some additional resources that can help you find metric names, namespaces, dimensions, and statistics for CloudWatch metrics:

  • For information about the available metrics for AWS services, see AWS services that publish CloudWatch metrics in the Amazon CloudWatch User Guide.

  • To get the exact metric name, namespace, and dimensions (if applicable) for a CloudWatch metric with the AWS CLI, see list-metrics.

To create this policy, run the put-scaling-policy command using the JSON file as input, as demonstrated in the following example.

aws autoscaling put-scaling-policy --policy-name my-predictive-scaling-policy \
  --auto-scaling-group-name my-asg --policy-type PredictiveScaling \
  --predictive-scaling-configuration file://config.json

If successful, this command returns the policy's Amazon Resource Name (ARN).

{
  "PolicyARN": "arn:aws:autoscaling:region:account-id:scalingPolicy:2f4f5048-d8a8-4d14-b13a-d1905620f345:autoScalingGroupName/my-asg:policyName/my-predictive-scaling-policy",
  "Alarms": []
}