How We Cut Cloud Costs 40% with Terraform & FinOps

Cost Is an Architecture Decision

By the time a bill looks alarming, most of it has already been designed in. The 40% reduction came from changing how modules were written and reviewed, not from hunting individual resources after the fact.

The Changes That Moved the Number

Roughly three quarters of the saving came from five decisions, all of them enforceable in code review.

• Right-sizing from observed p95 usage instead of launch-day estimates
• Replacing always-on non-production environments with scheduled shutdowns
• Moving stable workloads onto savings plans once usage was predictable
• Deleting cross-AZ data transfer by co-locating dependent services
• Setting lifecycle rules on every bucket at the moment it is created

Governance We Put in Place

Savings decay without guardrails, so the rules had to become part of the pipeline rather than a monthly report.

• Mandatory cost tags enforced by a policy check in the plan stage
• Per-workspace budget alarms owned by the team that created it
• A monthly diff of the Terraform plan reviewed for cost, not just risk
• An anomaly alert that pages before a weekend of runaway spend
• A shared dashboard where every team sees its own line item