Cloud Watch - Custom Metric - Pricing / Deleting

Question

I have a system that is using two custom metrics to track API requests.  The two metrics are a call to the API, and the duration of that call.  I added to the metrics the dimensions of which API was being called, as well as the URL that was using the endpoint.  This caused the "metrics" on our account to balloon to over 12,000 metrics (the two metrics with thousands of combinations of URLs and endpoints).  At the time of adding this too the system, I didn't realize that the dimensions would cause unique metrics, especially for cost purposes.

From what I can tell I added something that would add and addition $3000 or so per month to our account.

I found in the pricing information on the AWS website the following: "All custom metrics charges are prorated by the hour and metered only when you send metrics to CloudWatch."  This would suggest that if I stopped sending the metrics with the crazy ballooning dimension (namely URL), that I wouldn't be charged moving forward.  Can anyone confirm that this is an accurate interpretation of this?

If not, and I am stuck with the $0.30 / metric / month for all 12,000 ish metrics, is there a way to remove them from the system?  Or do I just have to wait the year for them to age out?

Thank you for your help.

Accepted Answer

Hi,
as indicated in the previous answer, no fee is charged when no new data is sent to the metrics, so yes if you stop sending the metrics with ballooning dimension, you will not be charged for those dimensions moving forward. Your interpretation is accurate: CloudWatch metrics only get charged at the time you send data, and you don't pay anything for the metric retention and ageing process.

If you want to estimate the impact of ballooning the number of metrics for a given number of hours in a month, you can get a sense of how prorating works by looking at the example 25 on the [CloudWatch Pricing page](https://aws.amazon.com/cloudwatch/pricing/). Although the example is referring to alarms, you can apply the same kind of estimation for metrics charges prorating. You should also be able to check the measured impact in the cost explorer, or reach out to support.

I'd like to add that if you stop sending ballooning dimensions:
- you will see the metrics with ballooning dimensions for 15 days in the console and list metrics API
- after 15 days, if you haven't sent any data to some dimensions, the dimensions that have not received any data in 15 days will disappear from the console and list APIs, but you will still be able to query those dimensions for the timerange you sent data to them using the GetMetricData API (until the 15 month retention limit).

Answer

Metrics will not be deleted until they expire as described in the following document.  
> CloudWatch does not support metric deletion. Metrics expire based on the retention schedules described above.

https://aws.amazon.com/cloudwatch/faqs/?nc1=h_ls

> Metrics exist only in the Region in which they are created. Metrics cannot be deleted, but they automatically expire after 15 months if no new data is published to them. Data points older than 15 months expire on a rolling basis; as new data points come in, data older than 15 months is dropped.

https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/cloudwatch_concepts.html#Metric

No fee is charged if no new data is sent to the metrics.

Cloud Watch - Custom Metric - Pricing / Deleting

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