Explanation
Why the waste happens and who it affects.
When AWS Config continuously records every lifecycle change for these instances, it produces a large number of CIRs. This drives costs significantly higher without delivering meaningful compliance insight, since Spot Instances are typically stateless and non-critical. In environments with heavy Spot usage, Config costs can balloon and exceed the value of tracking these transient resources.
Billing model
The pricing dimensions that drive this cost.
AWS Config charges per CIR. Ephemeral resources like Spot Instances can generate extremely high CIR volumes because each interruption and replacement is recorded as a new resource event. This creates cost disproportionate to governance value.
How to detect
4 checks to find it in your estate.
- Review AWS Config cost trends and correlate spikes with increased Spot Instance usage
- Assess the number of configuration items recorded for EC2 instances relative to the count of long-lived resources
- Identify whether Spot Instances are generating repeated records due to interruptions and replacements
- Confirm whether tracking ephemeral Spot resources is required for compliance or governance purposes
How to fix
4 ways to remove the waste.
- Exclude high-churn resource types used by Spot and other ephemeral workloads (for example AWS::EC2::Instance, AWS::EC2::NetworkInterface, and AWS::EC2::Volume) from recording in accounts dominated by transient workloads, using the recording strategy that records all resource types with exclusions
- Because the recorder scopes by resource type and cannot exclude individual resources by tag, consider running Spot and other ephemeral workloads in a separate account where AWS Config is turned off or has a narrower recording scope
- If some visibility is required, test daily recording (billed as periodic recording) for the EC2 resource types only. Daily recording produces at most one configuration item per resource per day, but each periodic configuration item costs four times as much as a continuous one, so savings can be small or negative for short-lived Spot Instances
- Maintain full Config tracking for long-lived production resources while limiting or excluding transient workloads
Documentation
Vendor references for pricing and configuration.