Introduction
In cloud and microservices architectures, API Gateways and Load Balancers serve distinct but essential roles. This guide clarifies their differences with practical AWS examples.
API Gateway vs Load Balancer — Key Differences
| Aspect | API Gateway | Load Balancer |
|---|---|---|
| Primary Purpose | Manages and controls API requests. | Distributes traffic evenly across servers. |
| Layer | Operates at the application layer (Layer 7). | Works at Layer 4 (Transport) or Layer 7 (Application). |
| Key Functions | - API Routing - Authentication & Authorization - Rate Limiting - Protocol Transformation (e.g., REST to gRPC) - Metrics & Logging |
- Traffic Distribution - SSL Termination - Health Checks - Session Persistence |
| Use Case | Managing microservices APIs, enforcing security policies, versioning APIs. | Balancing incoming traffic across multiple servers or services. |
| Examples | AWS API Gateway, Kong, Apigee, Azure API Management | AWS Elastic Load Balancer (ALB/NLB), NGINX, HAProxy, GCP Load Balancer |
| Security | Advanced API-level security: OAuth, JWT, API keys. | SSL Termination, Basic Routing |
AWS Examples
API Gateway (REST API example)
Resources:
MyApiGateway:
Type: AWS::ApiGateway::RestApi
Properties:
Name: "MyDemoAPI"
Load Balancer (Application Load Balancer example)
Resources:
MyLoadBalancer:
Type: AWS::ElasticLoadBalancingV2::LoadBalancer
Properties:
Name: "MyALB"
Scheme: internet-facing
Subnets:
- subnet-0123456789abcdef0
- subnet-0fedcba9876543210
When to Use Which?
- API Gateway: Managing and securing APIs, enforcing auth (e.g., OAuth/JWT), rate limiting.
- Load Balancer: Spreading web/app traffic across servers, providing redundancy.
Conclusion
API Gateway and Load Balancer both ensure scalability and availability but are used in different layers and contexts. Combining them often results in a robust cloud architecture.
Feel free to reach out for deeper architecture discussions!