Rate Limiter (Spring Boot)

A lightweight request-rate limiter built with Spring Boot. It uses a Spring Security filter to intercept incoming requests, tracks request frequency per IP, and stores counters in Redis. The limiter blocks clients that exceed a configured threshold within a one-minute window.

Features

• Intercepts requests via a Spring Security filter
• Tracks request counts per IP
• Uses Redis for fast in-memory storage
• Simple per-minute rate limiting
• Maven-based build
• Easy to configure through application properties

How It Works

1. Each request passes through a custom security filter.
2. The filter identifies the client IP and increments its request counter in Redis.
3. If the IP exceeds the request-limit-per-minute value, the request is rejected.
4. Counters expire automatically after one minute.

Configuration

application.yml example:

server:
  port: 12345

spring:
  data:
    redis:
      host: localhost
      port: 6379

request-limit-per-minute: 5

Requirements

• Java 17+ (or your project’s target)
• Maven
• Redis server

Running the Service

1. Start Redis:

   redis-server

2. Build the project:

   mvn clean package

3. Run the application:

   mvn spring-boot:run

Project Structure

• Filter layer: Handles request interception and rate checks
• Redis service: Manages counters and TTL
• Configuration: Exposes the per-minute limit as a property

Customization

You can adjust or extend:

• Different rate windows (e.g., per-second, per-hour)
• Keying strategies (API key, user ID, etc.)
• Enforcement behavior (headers, custom responses, logging)

License

MIT or your chosen license.