# System Design

## Overview

GoodGo Microservices Platform is built using a microservices architecture pattern with the following principles:

- **Service Independence**: Each service has its own database and can be deployed independently
- **API Gateway**: Traefik handles routing, load balancing, and cross-cutting concerns
- **Shared Libraries**: Common functionality is extracted into shared packages
- **Infrastructure as Code**: All infrastructure configurations are versioned
- **Observability**: Full monitoring, logging, and tracing capabilities

## Architecture Diagram

```
┌─────────────┐     ┌─────────────┐
│   Web App   │     │ Mobile App  │
│  (Next.js)  │     │ (React Native)
└──────┬──────┘     └──────┬──────┘
       │                   │
       └──────────┬────────┘
                  │
         ┌────────▼────────┐
         │   Traefik       │
         │  (API Gateway)   │
         └────────┬─────────┘
                  │
    ┌─────────────┼─────────────┐
    │             │             │
┌───▼────┐   ┌───▼────┐   ┌───▼────┐
│ Auth  │   │ Future │   │ Future │
│Service │   │Service │   │Service │
└───┬────┘   └───┬────┘   └───┬────┘
    │            │            │
    └────────────┼────────────┘
                 │
    ┌────────────┼────────────┐
    │            │            │
┌───▼────┐  ┌───▼────┐  ┌───▼────┐
│Postgres│  │ Redis  │  │Prometheus│
└────────┘  └────────┘  └─────────┘
```

## Components

### Frontend Layer
- **Web App**: Next.js application with App Router
- **Mobile App**: React Native application

### API Gateway
- **Traefik**: Reverse proxy, load balancer, SSL termination

### Services Layer
- **Auth Service**: Authentication and authorization
- **Future Services**: Payment, Order, Notification, etc.

### Infrastructure Layer
- **PostgreSQL**: Primary database
- **Redis**: Caching and session storage
- **Prometheus**: Metrics collection
- **Grafana**: Metrics visualization
- **Loki**: Log aggregation

## Communication Patterns

- **Synchronous**: HTTP/REST for request-response patterns
- **Asynchronous**: Message queues (future implementation)
- **Service Discovery**: Docker networking and Kubernetes DNS

## Data Management

- **Database per Service**: Each service owns its data
- **API Composition**: Services expose APIs for data access
- **Event Sourcing**: Future consideration for audit trails

## Security

- **Authentication**: JWT tokens with refresh token rotation
- **Authorization**: Role-based access control (RBAC)
- **Network Security**: TLS/SSL, rate limiting, CORS
- **Secrets Management**: Environment variables, Kubernetes secrets