AWS Cost Anomaly Detection: automatically detect unusual spending

No more bill surprises

AWS Cost Anomaly Detection uses machine learning to continuously monitor your cloud spending and alert you when something unusual happens. An EC2 instance forgotten in a test environment, an unexpected data transfer or a configuration error that generates excessive costs are detected automatically. The service is free and takes a few minutes to configure.

Why AWS bills surprise

AWS bills surprise for three main reasons. The first is pricing complexity: hundreds of services with different billing models make cost estimation difficult. The second is forgotten resources: a test environment that was never deleted, an unattached EBS volume or an unused NAT Gateway generate silent costs. The third is configuration errors: a Lambda function stuck in a loop, an unplanned cross-region data transfer or a CloudWatch log group that grows without limit.

How to configure Cost Anomaly Detection

Configuration takes less than 5 minutes. In the AWS Cost Management console, create a cost monitor. Choose the monitoring scope: all AWS services, a specific service, an account or a cost tag. Define an alert threshold (for example, alert when the anomaly exceeds €50). Configure notifications by email or through Amazon SNS.

The service starts learning your spending patterns immediately. The first relevant alerts arrive after a few days of learning. The more history the service accumulates, the more accurate the detection becomes.

Types of anomalies detected

Cost Anomaly Detection identifies several types of anomalies. Sudden spikes are detected when a service’s spending rises sharply compared to normal. Gradual increases are detected when spending slowly drifts above the usual pattern. New costs are flagged when a service that generated no costs starts to generate them.

Each alert includes the service concerned, the amount of the anomaly, the probable cause and a link to Cost Explorer to investigate. This context lets you react quickly without hunting for the information.

Complementarity with AWS Budgets

AWS Budgets and Cost Anomaly Detection are complementary. Budgets monitors absolute thresholds: “alert if monthly spending exceeds €5,000”. Cost Anomaly Detection monitors relative deviations: “alert if today’s spending is abnormally high compared to previous days”.

Use both together. Budgets protects you against overruns of your overall budget. Cost Anomaly Detection alerts you to one-off anomalies that could slip under the radar of the monthly budget.

LCMH configures AWS cost monitoring for businesses in Alsace.

For optimization levers, read our article on the 7 levers for optimizing AWS costs.

Sources

1. AWS, AWS Cost Anomaly Detection. aws.amazon.com/aws-cost-management/aws-cost-anomaly-detection
2. AWS, Cost Anomaly Detection User Guide. docs.aws.amazon.com/cost-management/latest/userguide/manage-ad.html
3. AWS, AWS Budgets. aws.amazon.com/aws-cost-management/aws-budgets