Cloud Cost Optimization — Fundamentals

The Four Pillars of Cloud Cost Optimization

1. RIGHT-SIZING:    Match resource size to actual usage
2. PRICING MODEL:   Choose On-Demand vs Savings Plans vs Spot
3. WASTE REMOVAL:   Delete unused resources
4. ARCHITECTURE:    Design for cost efficiency from the start

AWS Cost Tools

bash

# AWS Cost Explorer — visualize spend
aws ce get-cost-and-usage \
    --time-period Start=2024-01-01,End=2024-01-31 \
    --granularity MONTHLY \
    --metrics BlendedCost \
    --group-by Type=DIMENSION,Key=SERVICE

# Find biggest spenders
aws ce get-cost-and-usage \
    --time-period Start=2024-01-01,End=2024-01-31 \
    --granularity MONTHLY \
    --metrics BlendedCost \
    --group-by Type=DIMENSION,Key=SERVICE \
    --query 'ResultsByTime[].Groups[] | sort_by(@, &Metrics.BlendedCost.Amount) | reverse(@) | [:10]'

# AWS Compute Optimizer — right-sizing recommendations
aws compute-optimizer get-ec2-instance-recommendations \
    --filters name=Finding,values=OVER_PROVISIONED

# Trusted Advisor checks (Cost Optimization category)
aws support describe-trusted-advisor-checks --language en \
    --query 'checks[?category==`cost_optimizing`].[id,name]'

Quick Wins (Find and Delete Waste)

bash

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

# Old snapshots (older than 90 days)
aws ec2 describe-snapshots --owner-ids self \
    --query "Snapshots[?StartTime<='$(date -u -d '90 days ago' +%Y-%m-%dT%H:%M:%SZ)'].[SnapshotId,VolumeSize,StartTime]"

# Unassociated Elastic IPs ($0.005/hr each when not attached)
aws ec2 describe-addresses --query 'Addresses[?AssociationId==null].[AllocationId,PublicIp]'

# Idle Load Balancers (no requests for 7 days)
aws cloudwatch get-metric-statistics \
    --namespace AWS/ApplicationELB \
    --metric-name RequestCount \
    --dimensions Name=LoadBalancer,Value=app/my-alb/xxx \
    --start-time $(date -u -d '7 days ago' +%Y-%m-%dT%H:%M:%SZ) \
    --end-time $(date -u +%Y-%m-%dT%H:%M:%SZ) \
    --period 604800 --statistics Sum

# NAT Gateway idle data processing
aws cloudwatch get-metric-statistics \
    --namespace AWS/NATGateway \
    --metric-name BytesOutToDestination \
    --dimensions Name=NatGatewayId,Value=nat-xxx ...

Savings Plans vs Reserved Instances

On-Demand:      No commitment, highest price ($1.00/hr example)
Reserved (1yr): 30-40% off, commit to specific instance type
Reserved (3yr): 50-60% off, longer commit
Savings Plans:  Like RI but flexible — commit $ per hour, any instance

Compute Savings Plan (most flexible):
  Commit: $0.50/hr of compute
  Covers: EC2, Lambda, Fargate — any type, any region
  Discount: 54-66% vs on-demand

EC2 Instance Savings Plan:
  Commit to specific instance family (e.g., m5 in us-east-1)
  Discount: up to 72% vs on-demand

Spot Instances:
  Up to 90% off — but can be interrupted with 2-min notice
  Use for: batch jobs, ML training, CI/CD, rendering
  NOT for: production web servers without interruption handling