Cloud Cost Engineering and Open Source FinOps
Notes from the team building C3X. Cost estimation for Terraform, the economics of cloud infrastructure, and how to ship FinOps tooling without a SaaS gate.
EKS vs ECS: total cost comparison
The honest cost comparison between EKS and ECS, including control plane fees, Fargate vs EC2 trade-offs, and when each platform makes financial sense. With concrete numbers from a 10-service production fleet.
Reserved Instances vs Savings Plans: which to buy
Compute Savings Plans, EC2 Instance Savings Plans, Standard and Convertible Reserved Instances. The actual discount math, what each one covers, and a decision framework for which commitment to buy.
AWS Spot instances: when do they actually save money?
Spot instances offer 50-90% discounts but can be reclaimed with 2 minutes notice. Here's when they're worth it, how to handle interruptions gracefully, and how to combine Spot with Savings Plans for the lowest total cost.
Budget guardrails in CI: blocking PRs that exceed cost limits
Cost regressions are a category of bug that production-quality teams catch automatically. Here's how to add a budget gate to GitHub Actions, GitLab CI, Bitbucket, Atlantis, and Spacelift in five minutes.
CloudFormation cost estimation: the missing piece
How to estimate the monthly cost of a CloudFormation template before deploying. SAM templates, CDK output, nested stacks, and the patterns that work for migrating an existing CloudFormation workflow.
Air-gapped Terraform cost estimation for regulated environments
Federal, defense, and regulated industries can't use SaaS-based cost tools. Here's how to set up fully offline Terraform cost estimation for IL5/IL6, GovCloud, and classified environments.
AWS NAT Gateway costs: 3 alternatives that actually save money
NAT Gateway is the second-most-expensive AWS resource for many production workloads. Here's how to cut its cost by 60-90% using free VPC Gateway Endpoints, paid Interface Endpoints, and NAT instances.
How to estimate AWS costs from Terraform before deploying
From a single CLI command to PR comments in CI that block over-budget merges, this is the practical guide to Terraform cost estimation. No AWS credentials, no terraform plan, no SaaS account.
When gp2 to gp3 actually saves money (and when it doesn't)
gp3 is 20% cheaper than gp2 with better baseline performance. The migration is in-place with no downtime. Here's exactly when it saves money, when it doesn't, and how to migrate safely at scale.
Infracost Alternative: Open Source Cloud Cost Estimation Without a SaaS
Honest comparison of C3X vs Infracost for Terraform cost estimation. Where each tool wins, full feature matrix, and a migration guide for teams switching off Infracost.