Validating AWS Pricing

MANDATORY validation step that catches pricing errors before they reach the user.

Why This Matters

Common errors this skill catches:

•CloudWatch Logs: Confusing $0.50/GB ingestion with $0.03/GB storage
•Savings exceeding actual service spend (impossible)
•Wrong multipliers or formulas
•Missing cost components

Purpose

This skill validates pricing for significant findings using live AWS Pricing API. Smaller findings use fallback estimates to avoid unnecessary API calls.

Quick Start

bash

# Validate with default $100 threshold (queries API only for >$100 findings)
python skills/validating-aws-pricing/scripts/validate_pricing.py findings.json --profile ctm

# Lower threshold to validate more findings
python skills/validating-aws-pricing/scripts/validate_pricing.py findings.json --profile ctm --threshold 50

# Works with any AWS auth method (SSO, access keys, IAM role)
python skills/validating-aws-pricing/scripts/validate_pricing.py findings.json  # uses default credentials

What Gets Updated

For findings above threshold (default $100):

•Queries real AWS Pricing API for EC2, RDS, EBS
•Updates monthly_savings with validated value
•Marks api_validated: true in metadata

For findings below threshold:

•Uses fallback estimates (fast, no API calls)
•Marks api_validated: false in metadata

All findings get pricing_validated metadata showing the source.

Pricing Calculation by Finding Type

Idle Resources (EC2-001, etc.)

Savings = Full monthly cost of the resource

python

savings = hourly_rate * 730  # Resource should be terminated

Unattached Storage (EC2-012, EBS-001)

Savings = Storage cost per month

python

savings = size_gb * price_per_gb  # e.g., 100GB * $0.08 = $8.00

Over-provisioned (RDS-002, LAMBDA-001)

Savings = Difference between current and recommended size

python

current_cost = current_hourly * 730
recommended_cost = recommended_hourly * 730
savings = current_cost - recommended_cost

No RI Coverage (RDS-005)

Savings = On-Demand cost - Reserved Instance cost

python

on_demand_monthly = hourly_rate * 730
ri_monthly = ri_upfront / 12 + ri_hourly * 730
savings = on_demand_monthly - ri_monthly  # ~40-60% typically

CloudWatch Logs (SEC-001)

Savings = Storage cost that can be avoided with retention policy

python

savings = stored_gb * 0.03  # $0.03 per GB-month

AWS Pricing Reference

Current pricing (us-east-1):

Resource	Price	Unit	Monthly (730 hrs)
t2.nano	$0.0058	/hour	$4.23
t3.nano	$0.0052	/hour	$3.80
gp3 storage	$0.08	/GB-month	-
db.r5.xlarge	$0.50	/hour	$365.00
cache.t3.small (Valkey)	$0.0272	/hour	$19.86
CloudWatch Logs	$0.03	/GB-month	-

For complete pricing, see PRICING_REFERENCE.md.

Output

The script updates findings.json in place:

json

{
  "check_id": "EC2-001",
  "monthly_savings": 4.23,
  "pricing_validated": {
    "source": "AWS Pricing API",
    "validated_at": "2026-01-19T10:00:00Z",
    "hourly_rate": 0.0058,
    "calculation": "0.0058 * 730 hours"
  }
}

Workflow

•Load findings.json
•
For each finding:
- •Identify resource type from check_id and details
- •Query AWS Pricing API (or use cached known prices)
- •Calculate correct savings based on finding category
- •Update monthly_savings field
- •Add pricing_validated metadata
•Recalculate total_monthly_savings in metadata
•Save updated findings.json

Task Checklist

code

- [ ] Load findings.json
- [ ] Get actual billing from Cost Explorer (by service AND usage type)
- [ ] For EACH finding:
  - [ ] Verify formula matches finding type
  - [ ] Check savings <= service spend (sanity check)
  - [ ] Query AWS Pricing API if > $100
  - [ ] Recalculate if errors found
  - [ ] Add calculation breakdown to details
- [ ] Flag any corrected findings with pricing_corrected: true
- [ ] Recalculate total savings in metadata
- [ ] Save corrected findings.json
- [ ] Regenerate report with accurate prices

CRITICAL: Sanity Check Rules

Rule 1: Savings Cannot Exceed Service Spend

python

assert finding.monthly_savings <= service_monthly_spend, \
    f"Finding {finding.check_id} claims ${finding.monthly_savings} but service only costs ${service_monthly_spend}"

Example Failure:

•Finding: CloudWatch Logs retention saves $594/mo
•Billing: CloudWatch total spend = $159/mo
•INVALID - immediately flag and recalculate

Rule 2: Use Correct Cost Component

Many AWS services have MULTIPLE cost components:

Service	Components	What Retention Affects
CloudWatch Logs	Ingestion ($0.50/GB) + Storage ($0.03/GB)	Storage ONLY
S3	Storage + Requests + Transfer	Storage + old versions
EBS	Storage + IOPS + Throughput	Storage ONLY
RDS	Compute + Storage + I/O	Depends on finding

Rule 3: Verify With Usage Type Breakdown

For any finding > $100, get usage-type breakdown:

bash

aws ce get-cost-and-usage --profile {profile} \
  --time-period Start=2025-12-01,End=2026-01-01 \
  --granularity MONTHLY \
  --metrics UnblendedCost \
  --filter '{"Dimensions": {"Key": "SERVICE", "Values": ["AmazonCloudWatch"]}}' \
  --group-by Type=DIMENSION,Key=USAGE_TYPE

This shows:

•DataProcessing-Bytes: Log ingestion ($0.50/GB)
•TimedStorage-ByteHrs: Log storage ($0.03/GB)

Only storage can be reduced by retention policy!

Common Pricing Mistakes & Corrections

CloudWatch Logs Retention

WRONG:

python

savings = stored_gb * 0.50  # Using ingestion price!
# 221 GB * $0.50 = $110.50  # WRONG!

CORRECT:

python

savings = stored_gb * 0.03  # Storage price
# 221 GB * $0.03 = $6.63    # CORRECT!

Even more correct (check what % is older than retention):

python

# If setting 90-day retention, only logs older than 90 days are deleted
# Estimate 50% of stored data is older than 90 days
savings = stored_gb * 0.03 * 0.5

Unattached EBS Volume

CORRECT:

python

savings = size_gb * price_per_gb
# gp3: 100 GB * $0.08 = $8.00
# gp2: 100 GB * $0.10 = $10.00

Over-provisioned RDS

CORRECT:

python

current_cost = current_hourly * 730
recommended_cost = recommended_hourly * 730
savings = current_cost - recommended_cost

# db.r5.xlarge -> db.r5.large
# $0.50 * 730 - $0.25 * 730 = $365 - $182.50 = $182.50

Validation Output Format

After validation, each finding should include:

json

{
  "check_id": "LOG-001",
  "monthly_savings": 6.64,
  "pricing_validated": {
    "validated_at": "2026-01-19T12:00:00Z",
    "original_estimate": 594.34,
    "corrected": true,
    "correction_reason": "Used storage price ($0.03/GB) instead of ingestion price ($0.50/GB)",
    "calculation": "221.4 GB × $0.03/GB = $6.64",
    "sanity_check": {
      "service": "AmazonCloudWatch",
      "service_spend": 159.13,
      "finding_savings": 6.64,
      "passed": true
    }
  }
}