Phase 1: Controller Skeleton & Prometheus Integration

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Goal

Build the basic controller infrastructure that can query Lumina (RFC-0002) metrics from Prometheus.

Deliverables

• Kubernetes controller with leader election
• Prometheus client configuration
• Query RFC-0002 metrics: savings_plan_remaining_capacity, ec2_reserved_instance
• Health checks and readiness endpoints (/healthz, /readyz)
• Structured logging (zap or logrus)
• Basic controller reconciliation loop
• ConfigMap-based configuration (Prometheus URL, reconciliation intervals)

Technology Stack

• Go with kubebuilder/controller-runtime
• Prometheus client (prometheus/client_golang)
• Follow Lumina's project structure patterns

Success Criteria

• Controller successfully queries Prometheus metrics
• Logs show SP/RI capacity data every 5 minutes
• Leader election working with 2 replicas
• Health endpoints return 200 OK
• No errors in logs during normal operation

Dependencies

• RFC-0002 (Lumina) Phase 3 completed (metrics available)
• Access to Prometheus with Lumina metrics

Testing Requirements

• Unit tests for Prometheus client
• Integration tests with mock Prometheus
• Leader election tests
• 100% code coverage required

References

• RFC-0003: Lines 760-777
• Lumina: https://github.com/Nextdoor/lumina

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Closed by #8