AWS CloudWatch unused custom metrics retention and pricing - 2018

Question

It looks like custom metrics will be kept for 15 months, if I understand it correctly, since they get aggregated to higher resolution, according to https://aws.amazon.com/cloudwatch/faqs. Does it mean we have to pay for at least 15 months once we create a custom metric?

I have CloudWatch agent installed to collect various metrics using user_data. It creates new metrics for every new instances. After running many tests, I have more than 6,000 custom metrics, but most of them are unused. Since there is no way to delete custom metrics, do I get charged for those unused metrics until they expire (15 months)? I hope I'm wrong on this :]

Please clarify how we get charged for unused custom metrics.

Answer 1

we have the same issue to resolve. waiting for clearification from aws

Answer 2

You will not get charged for those. You will get charged for the metric for the duration you publish data onto them. It's not very clear on the CloudWatch pricing page but they hint it in the [original pricing reduction blogpost]{https://aws.amazon.com/blogs/aws/aws-price-reduction-cloudwatch-custom-metrics/).

You will get charged though on the retrieval of those (API costs).