API Gateway
Problem
Design an API Gateway that acts as the single entry point for all client requests to a microservices backend.
Functional Requirements
- Route requests to appropriate backend services
- Authentication & Authorization
- Rate limiting per client
- Request/Response transformation
- Load balancing
Non-Functional Requirements
- Low latency (< 10ms overhead)
- High availability (99.99%)
- Horizontally scalable
High-Level Design
Client → DNS → Load Balancer → API Gateway Cluster → Microservices
↓
Auth Service
Rate Limiter
Cache (Redis)
Key Responsibilities
| Concern | Implementation |
|---|---|
| Routing | Path-based or header-based rules |
| Auth | JWT validation, OAuth2, API keys |
| Rate Limiting | Token bucket per client/endpoint |
| Caching | Redis for GET responses |
| Observability | Request logging, distributed tracing |
| Circuit Breaking | Fail fast when downstream is unhealthy |
Relevance to Your Work
The Go API orchestration layer you're building IS an API Gateway wrapping Python/LangChain services. Same patterns apply.