# Architecture Overview - Microservices

This document serves as a comprehensive guide to the microservices architecture, enabling rapid understanding of service boundaries, communication patterns, and system design.

## 1. Project Structure

```
[Project Root]/
├── services/                   # Microservices
│   ├── api-gateway/           # Entry point for all requests
│   ├── user-service/          # User management
│   ├── [service-name]/        # Additional services
│   └── shared/                # Shared libraries
├── infrastructure/            # Infrastructure as code
│   ├── k8s/                  # Kubernetes manifests
│   └── terraform/            # Terraform configs
├── docs/                     # Documentation
└── scripts/                  # DevOps scripts
```

## 2. High-Level System Diagram

```
[API Gateway] <--> [Service Mesh/Load Balancer]
                            |
        +-------------------+-------------------+
        |                   |                   |
    [Service 1]        [Service 2]         [Service 3]
        |                   |                   |
    [Database 1]       [Database 2]        [Database 3]
        |                                       |
        +-------------[Message Queue]-----------+
```

## 3. Core Components

### 3.1. API Gateway

**Name:** [e.g., Kong, AWS API Gateway, Custom Gateway]

**Description:** Routes requests, handles authentication, rate limiting, and request aggregation

**Technologies:** [e.g., Kong, Express Gateway, Spring Cloud Gateway]

**Deployment:** [e.g., Kubernetes, AWS]

### 3.2. Microservices

#### 3.2.1. [Service Name]

**Name:** [e.g., User Service, Order Service]

**Description:** [Service responsibility and domain]

**Technologies:** [Language and framework]

**API Endpoints:** [Key endpoints this service exposes]

**Dependencies:** [Other services it calls]

**Database:** [Dedicated database if any]

**Deployment:** [Container registry, orchestration]

### 3.3. Service Mesh

**Name:** [e.g., Istio, Linkerd, Consul]

**Description:** Handles service-to-service communication, observability, and security

**Key Features:** [Traffic management, circuit breaking, etc.]

## 4. Data Stores

### 4.1. Service-Specific Databases

Each microservice has its own database following the database-per-service pattern.

#### [Service Name] Database

**Type:** [PostgreSQL, MongoDB, etc.]

**Purpose:** [Data domain this service owns]

**Key Schemas:** [Main tables/collections]

### 4.2. Shared Data Stores

**Name:** [e.g., Redis Cache, Message Queue]

**Type:** [Redis, RabbitMQ, Kafka]

**Purpose:** [Cross-service caching or messaging]

## 5. External Integrations / APIs

**Service Name:** [e.g., Payment Gateway, Email Service]

**Purpose:** [Functionality]

**Integration Method:** [REST, gRPC, Message Queue]

**Owning Service:** [Which microservice handles this integration]

## 6. Deployment & Infrastructure

**Cloud Provider:** [AWS, GCP, Azure]

**Orchestration:** [Kubernetes, Docker Swarm, ECS]

**Service Discovery:** [Consul, Eureka, Kubernetes DNS]

**CI/CD Pipeline:** [Jenkins, GitLab CI, GitHub Actions]

**Container Registry:** [Docker Hub, ECR, GCR]

**Monitoring & Logging:** [Prometheus, Grafana, ELK, Jaeger for tracing]

**Configuration Management:** [Consul, etcd, ConfigMap]

## 7. Security Considerations

**Authentication:** [OAuth2, JWT at API Gateway]

**Authorization:** [Service-level RBAC, mutual TLS]

**Service-to-Service Security:** [mTLS, API keys, service mesh policies]

**Data Encryption:** [TLS in transit, encrypted at rest]

**Secrets Management:** [Vault, AWS Secrets Manager, Kubernetes Secrets]

## 8. Development & Testing Environment

**Local Setup Instructions:** [Docker Compose, Minikube, or Skaffold]

**Testing Strategy:**
- Unit Tests: [Per service]
- Integration Tests: [Between services]
- Contract Tests: [API contracts]
- E2E Tests: [Full system tests]

**Testing Frameworks:** [Service-specific frameworks]

## 9. Future Considerations / Roadmap

- [e.g., Implement event sourcing for specific services]
- [e.g., Add service mesh for better observability]
- [e.g., Break down Service X into smaller services]
- [e.g., Implement CQRS pattern]

## 10. Project Identification

**Project Name:** [Microservices System Name]

**Repository URL:** [Monorepo or organization URL]

**Primary Contact/Team:** [Platform Team]

**Date of Last Update:** [YYYY-MM-DD]

**Service Catalog:** [Link to service registry/documentation]

## 11. Glossary / Acronyms

**API Gateway:** Entry point for all external requests

**Service Mesh:** Infrastructure layer for service-to-service communication

**Circuit Breaker:** Pattern to prevent cascading failures

**CQRS:** Command Query Responsibility Segregation

**Event Sourcing:** Storing state changes as events

**[Add domain-specific terms]**