/ledger

IaC Cost Estimation

Purpose: Methods for estimating cloud costs from IaC code and a tool integration guide. Read when: Assessing the cost impact of Terraform/CloudFormation/Pulumi changes.

Infracost Integration

Basic Workflow

# Estimate cost from a Terraform plan
infracost breakdown --path .

# Compare cost across a PR diff
infracost diff --path . --compare-to infracost-base.json

# CI/CD pipeline integration (GitHub Actions)
infracost comment --path . --format github-comment --behavior update

CI/CD Cost Gate

# GitHub Actions example
- name: Infracost
  run: |
    infracost diff --path . --compare-to /tmp/infracost-base.json --format json --out-file /tmp/infracost.json
    DIFF=$(jq -r '.diffTotalMonthlyCost' /tmp/infracost.json)
    if (( $(echo "$DIFF > 100" | bc -l) )); then
      echo "::warning::Monthly cost increase exceeds $100 threshold"
    fi

Threshold Configuration

Pricing API Reference

AWS Pricing

GCP Pricing

Azure Pricing

High-Cost Resource Flags

The following resources have a large cost impact, so always flag them at creation time:

Cost Estimation Report Template

## Cost Estimation Report

### Summary
- **Estimated monthly cost (before):** $X,XXX
- **Estimated monthly cost (after):** $Y,YYY
- **Monthly delta:** +/- $ZZZ (+/- N%)
- **Confidence level:** High / Medium / Low

### Assumptions
1. [Usage assumption 1]
2. [Data transfer assumption]
3. [Pricing tier assumption]

### Resource Breakdown
| Resource | Type | Monthly Cost | Notes |
|----------|------|-------------|-------|
| ... | ... | ... | ... |

### High-Cost Warnings
- [Warning 1]
- [Warning 2]

### Data Transfer Costs
- Intra-region: $X
- Cross-region: $Y
- Internet egress: $Z

### Recommendations
1. [Cost optimization recommendation]
2. [Alternative architecture suggestion]

Data Transfer Cost Matrix

Note: Pricing changes frequently. Check each cloud provider's pricing page for current prices.