การค้นพบบริการและเกตเวย์ API

In a microservice system, instances start, stop, and move between hosts. Hardcoding IP addresses breaks quickly. Service discovery lets services locate each other dynamically.

A service registry is a database of available services and their network locations. Popular options include Consul, etcd, and Eureka.

On startup, a service registers itself with the registry, including a health-check endpoint so the registry can drop it if it dies.

In client-side discovery, the calling service queries the registry for healthy instances and picks one itself.

In server-side discovery, the client calls a load balancer or gateway, which consults the registry and forwards the request. The client stays simple.

An API gateway is a single entry point that routes incoming requests to the right backend service. It hides internal topology from clients.

Beyond routing, a gateway often handles cross-cutting concerns:

• Authentication and authorization
• Rate limiting
• Request/response transformation
• Aggregating multiple service calls

You can build a basic gateway in Clojure by matching the path and proxying to the discovered service.

Centralizing auth at the gateway means individual services trust the gateway and avoid duplicating login logic.

The gateway is the natural place to throttle abusive clients before requests reach your services.

A production setup: services self-register in a registry with health checks, and a gateway discovers them, enforces auth and rate limits, then routes. This keeps clients decoupled from internal changes.

Test your discovery knowledge.

You learned how services discover each other and how a gateway unifies access.

• Registries like Consul track instances via health checks
• Discovery can be client-side or server-side
• Gateways centralize routing, auth, and rate limiting