Cloud Gateway

This project implements a Cloud Gateway using Spring Cloud Gateway, integrated with Eureka for service discovery and Resilience4j for fault tolerance. It serves as the entry point for client requests in a microservices architecture, providing features like retry mechanisms, rate limiting, and circuit breakers to enhance reliability and manage load effectively.

Features

• Service Discovery: Utilizes Eureka for discovering and routing to microservices.
• Retry Mechanism: Automatically retries failed requests to improve success rates.
• Rate Limiting: Controls the number of requests to prevent overloading services.
• Circuit Breaker: Prevents cascading failures by halting requests to unhealthy services.
• Spring Cloud Gateway: Routes requests based on defined rules and filters.

Prerequisites

• Java 17 or later
• Maven for dependency management
• Spring Boot 3.x
• A running downstream service for testing (e.g., a simple REST API)

Installation

1. Clone the repository:

   git clone https://github.com/Prasannajaga/cloud-gateway.git

2. Navigate to the project directory:

   cd cloud-gateway

3. Build the project using Maven:

   mvn clean install

4. Run the application:

   mvn spring-boot:run

Configuration

The project is configured via the application.yml file. Key configurations include:

• Redis: Host and port for rate limiting (default: localhost:6379).
• Circuit Breaker: Settings like sliding window size (5), failure rate threshold (50%), wait duration in open state (10s), and permitted calls in half-open state (3).
• Rate Limiter: Replenish rate (10), burst capacity (20), and requested tokens (1).
• Retry: Number of retries (3), first backoff (50ms), and max backoff (500ms).
• Routes: Definitions for routing to different services.
• Server Port: The gateway runs on port 8090.

For detailed configuration, refer to the application.yml file in the project.

Resilience Features

Retry

• Configuration: Up to 3 retries with exponential backoff starting at 50ms.
• Purpose: Automatically retries failed requests to handle transient failures.

Rate Limiter

• Configuration: Allows 10 requests per second with a burst capacity of 20.
• Purpose: Prevents system overload by limiting the request rate.

Circuit Breaker

• Configuration: Opens if 50% of the last 5 requests fail, waits 10 seconds before attempting recovery.
• Purpose: Protects the system by stopping requests to failing services and providing fallback responses.

Usage

1. Ensure a downstream service is running (e.g., a REST API).
2. Access the gateway by sending requests to http://localhost:8090/api/endpoint.
3. In case of failures, the gateway will attempt retries, apply rate limiting, or trigger circuit breakers as configured.

Testing

Retry Testing

• Simulate a failure in the downstream service and observe the gateway retrying the request up to 3 times.

Rate Limiter Testing

• Send more than 10 requests per second to see the rate limiter in action, returning 429 Too Many Requests.

Circuit Breaker Testing

• Cause repeated failures in the downstream service to trigger the circuit breaker, which will then route to the fallback endpoint.

Dependencies

Key dependencies include:

• spring-cloud-starter-gateway
• resilience4j spring-boot3
• spring-boot-starter-data-redis

These are managed via Maven in the pom.xml file.