CloudWatch automatic AlarmLow "Do Not Delete" generating charges

Question

I'm using the AWS free tier to develop a web app. I'm occasionally getting small charges from CloudWatch alarms that AWS set up automatically. Example: TargetTracking-table/[tablename]-AlarmLow-[random string of characters]. These AlarmLow alarms apparently have to do with my dynamodb tables being set to auto-scaling. The tables are set to Provisioned with a minimum capacity of 1 (which is the minimum value), and auto-scaling is On. I would expect alarms if my usage goes above my max capacity units, but why am I getting alarms for going too low when my minimum is set to 1? The alarm descriptions say "DO NOT EDIT OR DELETE", but I don't want to be getting charged on my free tier account just because my tables go a while without being called. Is there any way to have auto-scaling turned On without having a CloudWatch alarm that cares if my usage drops below the threshold for 1 capacity unit?

Answer

Hi There,

Those Alarms (TargetTracking-table/xxxx) are created when you configure a DynameDB table with Autoscaling.

While you can use them to monitor and have alerts on spending, the main purpose for those alarm is technical. They are used to trigger scaling up and down of DynamoDB capacity.

If you don't want to incur in CloudWatch cost, and you know the load on the table, you can consider not setting auto-scaling in the table.

Cheers.

CloudWatch automatic AlarmLow "Do Not Delete" generating charges

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