finops-cost-optimization

What this skill does

# OCI FinOps - Expert Knowledge

## 🏗️ Use OCI Landing Zone Terraform Modules

**Don't reinvent the wheel.** Use [oracle-terraform-modules/landing-zone](https://github.com/oracle-terraform-modules/terraform-oci-landing-zones) for cost-optimized infrastructure.

**Landing Zone solves:**
- ❌ Bad Practice #3: Internet breakout from spoke networks (Egress cost waste $3k-5k/month; Landing Zone uses hub-spoke with centralized NAT/Firewall)
- ❌ Bad Practice #8: Creating your own Terraform modules (Maintenance cost; Landing Zone is Oracle-maintained, CIS-certified, no technical debt)
- ❌ Bad Practice #10: No monitoring (Blind spending; Landing Zone auto-configures budget alerts, usage notifications, and cost tracking)

**This skill provides**: Cost optimization strategies, hidden cost traps, and savings calculations for resources deployed WITHIN a Landing Zone.

---

## ⚠️ OCI CLI/API Knowledge Gap

**You don't know OCI CLI commands or OCI API structure.**

Your training data has limited and outdated knowledge of:
- OCI CLI syntax and parameters (updates monthly)
- OCI API endpoints and request/response formats
- Cost Management CLI operations (`oci usage-api`)
- Current OCI pricing (changes frequently)
- Universal Credits consumption rates and SKUs

**When OCI operations are needed:**
1. Use exact CLI commands from skill references
2. Do NOT guess OCI CLI syntax or parameters
3. Do NOT assume current pricing - always verify
4. Reference official Oracle pricing calculator

**What you DO know:**
- General cloud cost optimization principles
- FinOps frameworks and methodologies
- Resource right-sizing concepts

This skill bridges the gap by providing current OCI-specific cost traps and optimization patterns.

---

You are an OCI cost optimization expert. This skill provides knowledge Claude lacks: hidden cost traps, Universal Credits gotchas, exact savings calculations, free tier maximization, and OCI-specific billing nuances.

## NEVER Do This

❌ **NEVER ignore orphaned boot volumes (silent cost drain)**
```
# Default OCI behavior: Boot volumes PRESERVED after instance termination
oci compute instance terminate --instance-id <ocid> --force
# Instance deleted, but boot volume remains (charges continue!)

Cost trap:
- Boot volume: 50 GB × $0.025/GB/mo = $1.25/month per instance
- 20 terminated test instances = $25/month wasted
- Over 1 year: $300 wasted on deleted instances

# RIGHT - explicitly delete boot volume
oci compute instance terminate \
  --instance-id <ocid> \
  --preserve-boot-volume false  # Critical flag!

# Or in Terraform:
resource "oci_core_instance" "dev" {
  preserve_boot_volume = false  # Must set explicitly
}
```

**Cleanup strategy**: Monthly audit for unattached boot volumes older than 7 days

❌ **NEVER forget reserved public IPs cost money when unattached**
```
Cost: $0.01/hour = $7.30/month per IP

# Common mistake: Reserve IP, detach from instance, forget to release
oci network public-ip create --lifetime RESERVED
# Later: delete instance but IP remains reserved (charges continue)

Wasted cost example:
- 5 old reserved IPs from deleted instances
- 5 × $7.30/month = $36.50/month waste
- Over 1 year: $438 wasted

# RIGHT - use ephemeral IPs for temporary resources
oci network public-ip create --lifetime EPHEMERAL
# Auto-deleted when instance terminated

# Or release reserved IPs explicitly
oci network public-ip delete --public-ip-id <ocid>
```

**Detection**: List reserved IPs without instance attachment

❌ **NEVER assume stopped resources = zero cost**
```
Stopped Autonomous Database:
✓ Compute: Zero cost (stopped)
✗ Storage: $0.025/GB/mo continues
✗ Backups: Retention charges continue

Example: 1 TB ADB stopped for 30 days
Storage: 1000 GB × $0.025 = $25/month (charged!)

Stopped Compute Instance:
✓ Compute: Zero cost
✗ Boot volume: $0.025/GB/mo continues
✗ Block volumes: $0.025/GB/mo continues
✗ Reserved IP (if attached): $7.30/month continues

# Better for long-term idle (>30 days): TERMINATE + backup
# Restore from backup when needed
```

**Rule**: Stopped = compute paused, storage still charged

❌ **NEVER ignore data egress costs (surprise bills)**
```
OCI egress pricing:
- First 10 TB/month: FREE
- 10-50 TB: $0.0085/GB
- 50+ TB: Contact sales for discount

# Common mistake: Large data export
oci os object bulk-download --bucket-name backups --download-dir /local
# Downloading 15 TB = 5 TB chargeable × $0.0085/GB = $42,500 surprise!

# Cheaper alternatives:
1. Use OCI FastConnect (fixed cost, unlimited egress)
2. Download within same region (free between OCI services)
3. Export to another OCI region first (inter-region = free)

Cost comparison (15 TB export):
- Internet egress: $42,500
- FastConnect (1 Gbps): $1,100/month flat rate
- Breakeven: 130 GB/month egress
```

**Gotcha**: Egress is FREE between OCI regions (intra-Oracle network)

❌ **NEVER enable NAT Gateway without understanding costs**
```
NAT Gateway pricing:
- Gateway itself: $0.01/hour = $7.30/month
- Data processed: $0.01/GB

# Mistake: Use NAT Gateway for high-traffic apps
Example: Application with 5 TB/month outbound traffic
- Gateway: $7.30/month
- Data: 5000 GB × $0.01 = $50/month
- Total: $57.30/month

# Cheaper alternative: Public IP on instance (ephemeral IP = free)
Cost: $0/month for egress <10 TB

When NAT Gateway makes sense:
- Private subnets with <100 GB/month egress
- Security requirement (no public IPs on instances)

When to avoid:
- High-traffic egress (use public IPs instead)
- Low-security dev/test environments
```

❌ **NEVER over-commit with Universal Credits**
```
Universal Credits gotcha:
- Credits are NON-TRANSFERABLE between service categories
  * Compute credits → can only pay for compute
  * Database credits → can only pay for database
  * Cannot move credits between categories

# Mistake: Commit to $10k/month compute credits
# Reality: Only use $6k/month compute
# Cannot use $4k surplus for database spending
# Result: Waste $4k/month ($48k/year)

# RIGHT - commit conservatively based on baseline usage
Analyze 3-6 months historical usage
Commit to 70-80% of baseline (not peak)

Expiration gotcha:
- Monthly credits expire end of month
- Cannot roll over to next month
- Use-it-or-lose-it model
```

❌ **NEVER trust forecast budgets (30-40% error rate)**
```
OCI Budget types:
1. ACTUAL: Alerts on actual spending (accurate)
2. FORECAST: Alerts on projected spending (often wrong)

# Problem: Forecast uses simple linear projection
Example:
- Week 1: $100 spend
- Forecast for month: $100 × 4 = $400
- Reality: Week 1 included one-time data migration
- Actual month: $150 total
- Forecast error: 167% over-prediction

# WRONG - rely on forecast alerts
Alert at 80% forecast → fires prematurely

# RIGHT - use actual spend alerts at multiple thresholds
Alert at 50% actual, 75% actual, 90% actual, 100% actual
```

**Best practice**: Use FORECAST for trends, ACTUAL for budgeting

## Cost Optimization Strategies

### Shape Migration Savings (Exact Calculations)

**Fixed → Flex Shape Migration**

```
Legacy fixed shape:
VM.Standard2.4: 4 OCPUs, 60 GB RAM (fixed ratio 1:15)
Cost: $0.06/hr × 4 = $0.24/hr = $175/month

Flex shape (right-sized):
VM.Standard.E4.Flex: 4 OCPUs, 16 GB RAM (custom ratio)
Cost: ($0.02/OCPU-hr × 4) + ($0.0015/GB-hr × 16) = $0.104/hr = $76/month

Savings: $99/month per instance (56% reduction)

Migration path:
1. Create flex instance with same OCPU count
2. Test with minimal RAM (4 GB per OCPU)
3. Increase RAM only if needed
4. Delete fixed instance
```

**AMD → Arm Migration**

```
AMD instance:
VM.Standard.E4.Flex: 4 OCPUs, 16 GB RAM
Cost: $0.02/OCPU-hr × 4 × 730 = $58.40/month

Arm instance (same workload):
VM.Standard.A1.Flex: 4 OCPUs, 16 GB RAM
Cost: $0.01/OCPU-hr × 4 × 730 = $29.20/month

Savings: $29.20/month per instance (50% reduction)

Gotcha: ARM64 architecture (not all apps compatible)
Check: Docker images available for ARM64?
```

### Free Tier Maximization

**Exact cost avoidance** (what you DON'T pay):

```
Always-Free ti