Considerations for custom metrics in a predictive scaling policy - Application Auto Scaling

Considerations for custom metrics in a predictive scaling policy

If an issue occurs while using custom metrics, we recommend that you do the following:

  • If an error message is provided, read the message and resolve the issue it reports, if possible.

  • If you did not validate an expression in advance, the put-scaling-policy command validates it when you create your scaling policy. However, there is a possibility that this command might fail to identify the exact cause of the detected errors. To fix the issues, troubleshoot the errors that you receive in a response from a request to the get-metric-data command. You can also troubleshoot the expression from the CloudWatch console.

  • You must specify false for ReturnData if MetricDataQueries specifies the SEARCH() function on its own without a math function like SUM(). This is because search expressions might return multiple time series, and a metric specification based on an expression can return only one time series.

  • All metrics involved in a search expression should be of the same resolution.

Limitations

The following limitations apply.

  • You can query data points of up to 10 metrics in one metric specification.

  • For the purposes of this limit, one expression counts as one metric.