RateLimiterServlet

pom.xml

 <dependency>
            <groupId>io.github.resilience4j</groupId>
            <artifactId>resilience4j-all</artifactId>
            <version>2.1.0</version>
        </dependency>
        <dependency>
            <groupId>io.github.resilience4j</groupId>
            <artifactId>resilience4j-vavr</artifactId>
            <version>2.1.0</version>
        </dependency>

RateLimiterConfig.java

import io.github.resilience4j.ratelimiter.RateLimiter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import java.time.Duration;

@Configuration
public class RateLimiterConfig {

    @Bean
    public RateLimiter rateLimiter(){
        //2 request per second
        io.github.resilience4j.ratelimiter.RateLimiterConfig config = io.github.resilience4j.ratelimiter.RateLimiterConfig.custom()
                .timeoutDuration(Duration.ofSeconds(0))
                .limitRefreshPeriod(Duration.ofSeconds(1))
                .limitForPeriod(2)
                .build();
        RateLimiter rateLimiter = RateLimiter.of("backendName", config);
        return rateLimiter;
    }
}

RateLimiterServlet.java

import io.github.resilience4j.ratelimiter.RateLimiter;
import io.github.resilience4j.ratelimiter.RequestNotPermitted;
import io.vavr.control.Try;
import jakarta.servlet.*;
import jakarta.servlet.http.HttpServletResponse;
import lombok.RequiredArgsConstructor;
import lombok.SneakyThrows;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;

import java.io.IOException;

@RequiredArgsConstructor
@Component
@Slf4j
public class RateLimiterServlet implements Filter {

    private final RateLimiter rateLimiter;

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        try {
            Try.runRunnable(() -> RateLimiter.decorateConsumer(rateLimiter, 1, unused -> chain(servletRequest, servletResponse, filterChain)).accept(null)).get();
        } catch (RequestNotPermitted rnp) {
            log.info("2 requests per second is allowed");
            ((HttpServletResponse) servletResponse).setStatus(429);
        }
    }

    @SneakyThrows
    private void chain(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) {
        filterChain.doFilter(servletRequest, servletResponse);
    }

}