Microservices Patterns Demo

A demo project showcasing core microservices patterns using Spring Boot, Spring Cloud, Redis, and Resilience4j. This project includes service discovery, API gateway routing, Redis-backed rate limiting, and circuit breaker handling.

Project Structure

microservices-patterns-demo/
── discovery-server # Eureka service registry
── api-gateway # Spring Cloud Gateway with rate limiting and routing
── user-service # Sample user service
── order-service # Sample order service with circuit breaker protection
── README.md #Project documentation

Services Overview

discovery-server:8761 -> Eureka Server for service registration and discovery | api-gateway: 8080 -> Entry point for routing, rate limiting, and circuit breaker | user-service: 8082 -> Exposes user-related endpoints | order-service:8081 -> Exposes order-related endpoints with circuit breaker |

Tech Stack

• Java 17
• Spring Boot 3.x
• Spring Cloud (Eureka, Gateway)
• Spring WebFlux
• Redis (for rate limiting)
• Resilience4j (Circuit Breaker)

Microservice Patterns Implemented

Service Discovery (Eureka)

• discovery-server runs on port 8761
• All other services register themselves with Eureka
• api-gateway uses load-balanced URLs (lb://service-name) to route

API Gateway with Rate Limiting

• api-gateway routes requests to microservices
• Rate limiting is configured using RequestRateLimiter filter with Redis
• Limits defined per client IP (via KeyResolver)
• Example config:

  filters:
    - name: RequestRateLimiter
      args:
        redis-rate-limiter.replenishRate: 5
        redis-rate-limiter.burstCapacity: 10
        key-resolver: "#{@ipKeyResolver}"

Circuit Breaker with Resilience4j

1. Implemented in order-service to handle failures from user-service
2. Uses @CircuitBreaker annotation
3. Fallback methods provide graceful degradation

Run the Services

You can start each service individually or use IntelliJ's multi-module run config:

1. start redis-server
2. discovery-service
3. api-gateway
4. user-service
5. order-service

Testing the System

1. Service Registry Access http://localhost:8761 to see registered services
2. Rate Limiting Send repeated requests to: http://localhost:8080/order/hello Exceeding limit should return 429 Too Many Requests