AWS Cost Optimizer

Purpose

This skill provides patterns for cost-aware AWS interactions, ongoing cost optimization, and financial governance. Use it to understand costs, identify savings opportunities, and implement cost controls.

When to Use

•Planning resources with cost considerations
•Analyzing current spending
•Identifying optimization opportunities
•Implementing cost controls and budgets
•Reviewing reserved capacity options

When NOT to Use

•Billing account configuration changes
•AWS Marketplace purchases
•Enterprise agreement negotiations

Cost Visibility

Cost Explorer Queries

bash

# Monthly cost by service (last 3 months)
aws ce get-cost-and-usage \
  --time-period Start=2024-01-01,End=2024-04-01 \
  --granularity MONTHLY \
  --metrics UnblendedCost \
  --group-by Type=DIMENSION,Key=SERVICE \
  --profile {profile}

# Daily cost for current month
aws ce get-cost-and-usage \
  --time-period Start=$(date -d "$(date +%Y-%m-01)" +%Y-%m-%d),End=$(date +%Y-%m-%d) \
  --granularity DAILY \
  --metrics UnblendedCost \
  --profile {profile}

# Cost by tag (e.g., Environment)
aws ce get-cost-and-usage \
  --time-period Start=2024-01-01,End=2024-02-01 \
  --granularity MONTHLY \
  --metrics UnblendedCost \
  --group-by Type=TAG,Key=Environment \
  --profile {profile}

# Cost by account (for Organizations)
aws ce get-cost-and-usage \
  --time-period Start=2024-01-01,End=2024-02-01 \
  --granularity MONTHLY \
  --metrics UnblendedCost \
  --group-by Type=DIMENSION,Key=LINKED_ACCOUNT \
  --profile {profile}

Cost Forecast

bash

# 3-month forecast
aws ce get-cost-forecast \
  --time-period Start=$(date +%Y-%m-%d),End=$(date -d "+3 months" +%Y-%m-%d) \
  --granularity MONTHLY \
  --metric UNBLENDED_COST \
  --profile {profile}

Budgets

Budget Configuration

bash

# Create monthly budget with alert
aws budgets create-budget \
  --account-id {account-id} \
  --budget '{
    "BudgetName": "monthly-total",
    "BudgetLimit": {"Amount": "10000", "Unit": "USD"},
    "TimeUnit": "MONTHLY",
    "BudgetType": "COST"
  }' \
  --notifications-with-subscribers '[
    {
      "Notification": {
        "NotificationType": "ACTUAL",
        "ComparisonOperator": "GREATER_THAN",
        "Threshold": 80,
        "ThresholdType": "PERCENTAGE"
      },
      "Subscribers": [
        {"SubscriptionType": "EMAIL", "Address": "alerts@example.com"}
      ]
    }
  ]' \
  --profile {profile}

Budget Types

Type	Use Case
Cost Budget	Overall or service-specific spending
Usage Budget	Resource usage limits (e.g., EC2 hours)
RI Utilization	Reserved Instance coverage
Savings Plans Utilization	Savings Plans coverage

Budget Strategy

markdown

## Recommended Budgets

### Account Level
- Total monthly budget with 80%, 100%, 120% alerts
- Per-service budgets for top 3-5 services

### Environment Level
- Production budget (track actual vs expected)
- Development budget (cap to prevent waste)
- Sandbox budget (strict limit)

### Team Level
- Cost allocation by CostCenter tag
- Alerts to team owners

Right-Sizing

EC2 Right-Sizing

bash

# Get right-sizing recommendations
aws ce get-rightsizing-recommendation \
  --service EC2 \
  --configuration '{
    "RecommendationTarget": "SAME_INSTANCE_FAMILY",
    "BenefitsConsidered": true
  }' \
  --profile {profile}

# Detailed instance utilization
aws cloudwatch get-metric-statistics \
  --namespace AWS/EC2 \
  --metric-name CPUUtilization \
  --dimensions Name=InstanceId,Value=i-xxxxxxxxx \
  --start-time $(date -d "7 days ago" -u +%Y-%m-%dT%H:%M:%SZ) \
  --end-time $(date -u +%Y-%m-%dT%H:%M:%SZ) \
  --period 3600 \
  --statistics Average Maximum \
  --profile {profile} \
  --region {region}

Right-Sizing Guidelines

Utilization	Action
< 20% average CPU	Consider smaller instance
20-60% average CPU	Likely right-sized
> 80% average CPU	Consider larger instance
Spiky usage	Consider auto-scaling

RDS Right-Sizing

bash

# RDS utilization check
aws cloudwatch get-metric-statistics \
  --namespace AWS/RDS \
  --metric-name CPUUtilization \
  --dimensions Name=DBInstanceIdentifier,Value={db-id} \
  --start-time $(date -d "7 days ago" -u +%Y-%m-%dT%H:%M:%SZ) \
  --end-time $(date -u +%Y-%m-%dT%H:%M:%SZ) \
  --period 3600 \
  --statistics Average Maximum \
  --profile {profile} \
  --region {region}

Reserved Capacity

Savings Plans

bash

# Get Savings Plans recommendations
aws ce get-savings-plans-purchase-recommendation \
  --savings-plans-type COMPUTE_SP \
  --term-in-years ONE_YEAR \
  --payment-option NO_UPFRONT \
  --lookback-period-in-days THIRTY_DAYS \
  --profile {profile}

# Current Savings Plans utilization
aws ce get-savings-plans-utilization \
  --time-period Start=2024-01-01,End=2024-02-01 \
  --granularity MONTHLY \
  --profile {profile}

Reserved Instances

bash

# Get RI recommendations
aws ce get-reservation-purchase-recommendation \
  --service EC2 \
  --term-in-years ONE_YEAR \
  --payment-option NO_UPFRONT \
  --lookback-period-in-days THIRTY_DAYS \
  --profile {profile}

# Current RI utilization
aws ce get-reservation-utilization \
  --time-period Start=2024-01-01,End=2024-02-01 \
  --granularity MONTHLY \
  --profile {profile}

Commitment Strategy

markdown

## Commitment Decision Framework

### Savings Plans (Preferred)
- Compute Savings Plans: Most flexible, covers EC2, Lambda, Fargate
- EC2 Instance Savings Plans: Larger discount, specific instance family

### Reserved Instances (When Needed)
- Use for RDS, ElastiCache, Redshift
- Use when RI-specific features needed (capacity reservation)

### Commitment Levels
| Commitment | Best For |
|------------|----------|
| 1-year No Upfront | Moderate confidence, cash flow preference |
| 1-year All Upfront | High confidence, maximum savings |
| 3-year | Very stable workloads, largest discount |

Idle Resources

Finding Idle Resources

bash

# Unattached EBS volumes
aws ec2 describe-volumes \
  --filters Name=status,Values=available \
  --query 'Volumes[*].[VolumeId,Size,CreateTime]' \
  --output table \
  --profile {profile} \
  --region {region}

# Unassociated Elastic IPs
aws ec2 describe-addresses \
  --filters Name=association-id,Values="" \
  --query 'Addresses[*].[PublicIp,AllocationId]' \
  --output table \
  --profile {profile} \
  --region {region}

# Unused NAT Gateways (check connections)
aws ec2 describe-nat-gateways \
  --filter Name=state,Values=available \
  --profile {profile} \
  --region {region}

# Old snapshots (> 90 days)
aws ec2 describe-snapshots \
  --owner-ids self \
  --query 'Snapshots[?StartTime<=`2024-01-01`].[SnapshotId,VolumeSize,StartTime,Description]' \
  --output table \
  --profile {profile} \
  --region {region}

Cleanup Actions

bash

# Delete unattached volume (DESTRUCTIVE - ensure backup)
aws ec2 delete-volume \
  --volume-id vol-xxxxxxxxx \
  --profile {profile} \
  --region {region}

# Release Elastic IP
aws ec2 release-address \
  --allocation-id eipalloc-xxxxxxxxx \
  --profile {profile} \
  --region {region}

# Delete old snapshot
aws ec2 delete-snapshot \
  --snapshot-id snap-xxxxxxxxx \
  --profile {profile} \
  --region {region}

Cost-Aware Architecture

Service Selection

Use Case	Cost-Effective Choice
Variable compute	Lambda or Fargate Spot
Steady-state compute	Reserved EC2 or Savings Plans
Data storage	S3 with lifecycle policies
Database reads	ElastiCache or read replicas
Batch processing	Spot instances

Data Transfer Optimization

markdown

## Data Transfer Cost Reduction

### Within AWS
- Use VPC endpoints for AWS services
- Keep resources in same AZ when possible
- Use private IPs instead of public

### To Internet
- Use CloudFront for static content
- Compress data before transfer
- Cache at edge when possible

### Cross-Region
- Minimize cross-region replication
- Use S3 Transfer Acceleration for large uploads
- Consider regional consolidation

Storage Optimization

bash

# S3 storage analysis
aws s3api list-buckets --query 'Buckets[*].Name' --output text | \
  xargs -I {} sh -c 'echo "Bucket: {}"; aws s3api get-bucket-location --bucket {} 2>/dev/null'

# Enable S3 Intelligent Tiering
aws s3api put-bucket-lifecycle-configuration \
  --bucket {bucket} \
  --lifecycle-configuration '{
    "Rules": [{
      "ID": "IntelligentTiering",
      "Status": "Enabled",
      "Filter": {},
      "Transitions": [{
        "Days": 0,
        "StorageClass": "INTELLIGENT_TIERING"
      }]
    }]
  }' \
  --profile {profile}

Cost Tags

Tagging Strategy

markdown

## Required Cost Tags

| Tag | Purpose | Example |
|-----|---------|---------|
| Environment | Environment allocation | production, development |
| CostCenter | Chargeback/showback | CC-1234 |
| Owner | Responsibility | platform-team |
| Project | Project allocation | project-phoenix |

## Tag Enforcement
- Use AWS Organizations SCP to require tags
- Use AWS Config rules to detect untagged resources
- Regular tag compliance reports

Tag Compliance Check

bash

# Find untagged EC2 instances
aws ec2 describe-instances \
  --query 'Reservations[*].Instances[?!not_null(Tags[?Key==`CostCenter`].Value)].[InstanceId,State.Name]' \
  --output table \
  --profile {profile} \
  --region {region}

Cost Optimization Checklist

markdown

## Monthly Cost Review Checklist

### Visibility
- [ ] Review Cost Explorer trends
- [ ] Check budget alerts
- [ ] Analyze cost by tag/team
- [ ] Identify anomalies

### Right-Sizing
- [ ] Review EC2 utilization
- [ ] Review RDS utilization
- [ ] Check right-sizing recommendations
- [ ] Implement approved changes

### Idle Resources
- [ ] Identify unattached volumes
- [ ] Check unused Elastic IPs
- [ ] Review old snapshots
- [ ] Clean up approved resources

### Reserved Capacity
- [ ] Review RI/SP utilization
- [ ] Check for new recommendations
- [ ] Plan upcoming purchases
- [ ] Adjust coverage as needed

### Architecture
- [ ] Review data transfer costs
- [ ] Check S3 storage classes
- [ ] Evaluate serverless options
- [ ] Consider Spot for suitable workloads

Cost Estimation for Planning

When planning new resources:

markdown

## Cost Estimate Template

### Resource: {Resource Type}

| Component | Quantity | Unit Cost | Monthly Cost |
|-----------|----------|-----------|--------------|
| EC2 (m5.large) | 2 | $0.096/hr | $140 |
| EBS (gp3, 100GB) | 2 | $0.08/GB | $16 |
| Data Transfer | 100GB | $0.09/GB | $9 |
| **Total** | | | **$165** |

### With Optimization
| Option | Savings | New Monthly |
|--------|---------|-------------|
| 1yr Savings Plan | 30% | $115 |
| Spot (if suitable) | 60-70% | ~$60 |

### Recommendation
{Which option and why}

Related Skills

•aws-cli-playbook — CLI patterns for cost commands
•aws-well-architected — Cost optimization pillar
•aws-governance-guardrails — Cost policies
•aws-observability-setup — Cost of monitoring