# Microservices Platform PRD

**Complexity Tier:** Complex (10+ files, multiple services, external integrations)

## Overview

A multi-service e-commerce platform with independent microservices communicating via message queues. Includes user management, product catalog, order processing, payment handling, and notification delivery. Deployed on Kubernetes with monitoring and observability.

## Services

### User Service
- Registration and authentication (OAuth2 + JWT)
- User profile management
- Role-based access control (admin, seller, buyer)
- Rate limiting on auth endpoints

### Product Service
- CRUD operations for products
- Category and tag management
- Full-text search with Elasticsearch
- Image upload to S3-compatible storage
- Inventory tracking with optimistic locking

### Order Service
- Shopping cart management (Redis-backed)
- Order creation with inventory reservation
- Order status tracking (created, paid, shipped, delivered, cancelled)
- Saga pattern for distributed transactions

### Payment Service
- Stripe integration for payment processing
- Webhook handling for payment events
- Refund processing
- Payment status reconciliation

### Notification Service
- Email notifications (order confirmation, shipping updates)
- Event-driven via message queue consumption
- Template-based email rendering
- Delivery status tracking

## Architecture

### Communication
- Synchronous: REST APIs between services (via API gateway)
- Asynchronous: RabbitMQ message queues for event-driven flows
- Events: OrderCreated, PaymentCompleted, OrderShipped, UserRegistered

### Data Storage
- PostgreSQL per service (database-per-service pattern)
- Redis for session storage and shopping cart
- Elasticsearch for product search
- S3-compatible object storage for images

### Infrastructure
- Docker containers for all services
- Kubernetes manifests (Deployment, Service, Ingress, ConfigMap, Secret)
- Helm chart for parameterized deployment
- Health check endpoints per service (`/health`, `/ready`)
- Horizontal Pod Autoscaler based on CPU/request metrics

## Tech Stack

- **Services:** Node.js with TypeScript, Express
- **Database:** PostgreSQL with Prisma ORM
- **Cache:** Redis
- **Search:** Elasticsearch
- **Queue:** RabbitMQ
- **Payments:** Stripe SDK
- **Container:** Docker
- **Orchestration:** Kubernetes
- **Monitoring:** Prometheus metrics endpoints, Grafana dashboards

## Non-Functional Requirements

- Service response time < 200ms (p99)
- Message queue processing latency < 500ms
- 99.9% uptime target
- Zero-downtime deployments (rolling updates)
- Unit test coverage > 80% per service
- Integration tests for cross-service flows
- E2E test for complete purchase flow
- Security: OWASP Top 10, secret management via K8s Secrets, network policies

## Success Criteria

- All 5 services start and pass health checks
- User can register, browse products, add to cart, and place an order
- Payment webhook processes correctly (requires Stripe test keys)
- Notifications are queued and sent on order events
- Kubernetes manifests deploy all services
- Prometheus endpoints expose metrics
- All unit and integration tests pass
- No Critical or High security findings

## Notes

- Stripe integration requires a test API key (`STRIPE_TEST_KEY`). Mark as "requires provider API key" if not available.
- Elasticsearch and RabbitMQ require running instances. Docker Compose is provided for local development.
- Kubernetes deployment requires a cluster (minikube, kind, or cloud provider).
