AWS Well-Architected Cost Optimization pillar review for Terraform

Last reviewed: 2026-05-27

5+ years AWS engineering · Open-source contributor

Last reviewed: 2026-05-27

The AWS Well-Architected Cost Optimization pillar covers five design areas: implementing cloud financial management, adopting a consumption model, measuring overall efficiency, stopping spending on undifferentiated heavy lifting, and analyzing and attributing expenditure. This guide maps each area to Terraform patterns and explains what ArchGuard evaluates in your HCL.

The Cost Optimization pillar design principles, as Terraform-aware checks

Five things ArchGuard flags most often in the Cost Optimization pillar

·NAT Gateways in every AZ without traffic analysis (use a single NAT or VPC endpoints for AWS services)
·EC2 instances without instance type cost modelling (no evidence of right-sizing review)
·S3 buckets with no lifecycle rules — all objects remain in S3 Standard indefinitely
·CloudWatch Logs log groups with no retention period set (unbounded storage cost)
·No resource tagging strategy enforced in Terraform — cost allocation is opaque

AWS Well-Architected Cost Optimization pillar review for Terraform

The Cost Optimization pillar design principles, as Terraform-aware checks

Five things ArchGuard flags most often in the Cost Optimization pillar

Further reading

Get a Cost Optimization pillar review of your Terraform