---

name: ops-cost-optimization description: | Structured workflow for cloud cost analysis and optimization including rightsizing, reserved capacity planning, and FinOps practices.

trigger: |

• Monthly/quarterly cost reviews
• Cost anomaly investigation
• Budget overrun alerts
• Reserved instance planning

skip_when: |

• Capacity planning focus -> use ops-capacity-planning
• One-time cost question -> direct query
• Application performance -> use ring-dev-team specialists

related: similar: [ops-capacity-planning] uses: [cloud-cost-optimizer]

Cost Optimization Workflow

This skill defines the structured process for cloud cost optimization. Use it for systematic cost analysis and data-driven optimization.

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Cost Optimization Phases

Phase	Focus	Output
1. Cost Visibility	Understand current spend	Cost breakdown
2. Anomaly Detection	Identify unusual spend	Anomaly report
3. Optimization Analysis	Find savings opportunities	Opportunities list
4. Risk Assessment	Evaluate optimization risks	Risk matrix
5. Implementation	Execute optimizations	Cost reduction
6. Monitoring	Track savings	Savings report

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Phase 1: Cost Visibility

Cost Breakdown Dimensions

Analyze costs across multiple dimensions:

Dimension	Purpose	Tool
Service	Which AWS services cost most	Cost Explorer
Account	Which accounts spend most	Cost Explorer
Tag	Cost by team/project/environment	Cost Allocation Tags
Resource	Individual resource costs	Cost Explorer
Time	Cost trends over time	Cost Explorer

Cost Visibility Template

## Cost Visibility Report

**Period:** [Month YYYY]
**Total Spend:** $XX,XXX
**Budget:** $XX,XXX
**Variance:** [+/-X%]

### Cost by Service

| Service | Cost | % of Total | MoM Change |
|---------|------|------------|------------|
| EC2 | $X,XXX | XX% | +X% |
| RDS | $X,XXX | XX% | +X% |
| S3 | $X,XXX | XX% | +X% |
| Data Transfer | $X,XXX | XX% | +X% |
| Other | $X,XXX | XX% | +X% |

### Cost by Environment

| Environment | Cost | % of Total |
|-------------|------|------------|
| Production | $X,XXX | XX% |
| Staging | $X,XXX | XX% |
| Development | $X,XXX | XX% |

### Cost by Team

| Team | Cost | % of Total |
|------|------|------------|
| Platform | $X,XXX | XX% |
| API | $X,XXX | XX% |
| Data | $X,XXX | XX% |

Tagging Requirements

Minimum required tags for cost allocation:

Tag	Purpose	Example
Environment	Env separation	prod, staging, dev
Team	Cost ownership	platform, api, data
Service	Service identification	api-gateway, auth
CostCenter	Financial allocation	CC-1234

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Phase 2: Anomaly Detection

Anomaly Detection Rules

Rule	Threshold	Alert
Daily spend spike	>20% vs 7-day avg	Warning
Service cost jump	>50% vs last month	Critical
New service appears	Any new service >$100/day	Info
Tag coverage drop	<95% coverage	Warning

Anomaly Investigation

When anomaly detected:

1. Identify the spike:

   • Which service/resource?
   • When did it start?
   • What changed?

2. Check common causes:

   • New deployment
   • Traffic increase
   • Data growth
   • Misconfiguration
   • Forgotten resources

3. Validate intentionality:

   • Expected growth?
   • Approved change?
   • One-time vs recurring?

Anomaly Report Template

## Cost Anomaly Report

**Detected:** YYYY-MM-DD HH:MM
**Severity:** [Critical/Warning/Info]

### Anomaly Details

| Metric | Expected | Actual | Delta |
|--------|----------|--------|-------|
| Daily spend | $X,XXX | $X,XXX | +XX% |

### Investigation

**Root Cause:** [description]

**Contributing Factors:**
1. [Factor 1]
2. [Factor 2]

**Intentional:** [Yes/No]

### Action Required

- [ ] [Action if remediation needed]
- [ ] [Update budget if expected]

---

Phase 3: Optimization Analysis

Optimization Categories

Category	Typical Savings	Effort	Risk
Rightsizing	20-40%	Low	Low
Reserved Capacity	30-70%	Medium	Low-Medium
Spot Instances	60-90%	Medium	Medium
Storage Tiering	20-50%	Low	Low
Idle Resources	100%	Low	None
Data Transfer	10-30%	Medium	Low

Rightsizing Analysis

## Rightsizing Opportunities

### Underutilized Instances

| Instance | Type | Avg CPU | Avg Mem | Recommendation | Savings |
|----------|------|---------|---------|----------------|---------|
| api-prod-1 | m5.xlarge | 15% | 25% | m5.large | $70/mo |
| worker-2 | c5.2xlarge | 30% | 20% | c5.xlarge | $140/mo |

### Criteria Used

- CPU avg <40% over 14 days -> downsize candidate
- Memory avg <50% over 14 days -> downsize candidate
- Excluded: ASG instances (handled by ASG sizing)

Reserved Instance Analysis

## Reserved Instance Coverage

### Current Coverage

| Service | On-Demand | Reserved | Coverage |
|---------|-----------|----------|----------|
| EC2 | $5,000 | $3,000 | 38% |
| RDS | $2,000 | $0 | 0% |
| ElastiCache | $500 | $500 | 50% |

### RI Recommendations

| Resource Type | Term | Payment | Monthly Savings | Break-even |
|---------------|------|---------|-----------------|------------|
| 10x m5.large | 1 year | No upfront | $350 | 0 months |
| db.r5.xlarge | 1 year | Partial | $180 | 4 months |

### RI Purchase Criteria

- Stable workload for >80% of term
- Usage predictable for commitment period
- Consider convertible RIs for flexibility

Idle Resource Detection

## Idle Resources

### Unattached EBS Volumes

| Volume ID | Size | Cost/Month | Last Attached |
|-----------|------|------------|---------------|
| vol-xxx | 100GB | $10 | 90 days ago |
| vol-yyy | 500GB | $50 | Never |

### Unused Elastic IPs

| IP | Allocation ID | Associated | Cost/Month |
|----|---------------|------------|------------|
| x.x.x.x | eipalloc-xxx | No | $3.60 |

### Idle Load Balancers

| LB Name | Target Groups | Requests/Day | Cost/Month |
|---------|---------------|--------------|------------|
| old-api | 0 | 0 | $16.50 |

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Phase 4: Risk Assessment

Optimization Risk Matrix

Optimization	Risk Level	Potential Impact	Mitigation
Downsize instance	Low	Performance degradation	Monitor, quick rollback
Purchase RI	Low-Medium	Unused commitment	Convertible RIs
Spot instances	Medium	Instance interruption	Diversify, checkpointing
Delete idle	None-Low	Lost data (if EBS)	Snapshot first
Storage tiering	Low	Retrieval latency	Test access patterns

Risk Assessment Checklist

• Rollback plan documented
• Performance baseline captured
• Monitoring in place
• Stakeholders informed
• Timeline appropriate (not during peak)

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Phase 5: Implementation

Implementation Priority

Priority	Criteria	Examples
Quick Wins	Low effort, no risk, immediate savings	Delete idle resources
High Impact	Significant savings, manageable risk	RI purchases
Medium Impact	Moderate savings, requires planning	Rightsizing
Long-term	Architectural changes	Spot migration

Implementation Checklist

• Change request approved
• Scheduled during low-traffic period
• Rollback plan ready
• Monitoring dashboards open
• Communication sent to stakeholders

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Phase 6: Monitoring

Savings Tracking

## Savings Report

**Period:** [Month YYYY]
**Target Savings:** $X,XXX
**Actual Savings:** $X,XXX
**Achievement:** XX%

### Savings by Category

| Category | Target | Actual | Status |
|----------|--------|--------|--------|
| Rightsizing | $500 | $450 | 90% |
| Reserved Instances | $2,000 | $2,100 | 105% |
| Idle Resources | $200 | $200 | 100% |

### Monthly Trend

| Month | Spend | Savings | Cumulative |
|-------|-------|---------|------------|
| Jan | $50,000 | $0 | $0 |
| Feb | $48,000 | $2,000 | $2,000 |
| Mar | $47,500 | $2,500 | $4,500 |

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Anti-Rationalization Table

Rationalization	Why It's WRONG	Required Action
"Small savings not worth it"	Small savings compound	Evaluate ALL opportunities
"RIs are too risky"	RI risk is manageable	Analyze stable workloads
"Dev doesn't need optimization"	Dev is often 30%+ of cost	Optimize ALL environments
"Can't predict future usage"	Historical data helps	Use data-driven forecasting
"Optimization takes too much time"	ROI on optimization is high	Invest in systematic process

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Pressure Resistance

User Says	Your Response
"Just cut costs by 30%"	"Cannot proceed without analysis. Blind cuts cause outages. Will provide data-driven recommendations."
"Skip the analysis, buy RIs"	"RI purchases require usage analysis. Wrong RIs waste money. Analysis required first."
"Dev environment is fine as-is"	"Dev costs are significant. Optimization applies to all environments."

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Dispatch Specialist

For cost optimization tasks, dispatch:

Task tool:
  subagent_type: "cloud-cost-optimizer"
  model: "opus"
  prompt: |
    COST ANALYSIS REQUEST
    Scope: [accounts/services to analyze]
    Period: [time range]
    Focus: [rightsizing/RI/general optimization]
    Constraints: [budget targets, risk tolerance]