Excessive AWS Config Costs from Spot Instances

Abdeldjallil Koutchoukali

Service Category

Other

Cloud Provider

AWS

Service Name

AWS Config

Inefficiency Type

Over-Recording of Ephemeral Resources

Explanation

Spot Instances are designed to be short-lived, with frequent interruptions and replacements. 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.

Relevant Billing Model

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.

Detection

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

Remediation

Use tag-based exclusions to prevent AWS Config from recording ephemeral Spot Instances and other transient resources
Apply standardized tagging (e.g., `finops:config-exclude:true`) and configure AWS Config to filter them out
If some visibility is required, switch Config from continuous to periodic recording to reduce event volume
Maintain full Config tracking for long-lived production resources while limiting or excluding transient workloads

Relevant Documentation

AWS Config Pricing | Selecting Resources to Record

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