omidp · September 24, 2023 18:10 · Sep 24, 2023
diff --git a/RateLimiterConfig.java b/RateLimiterConfig.java
@@ -0,0 +1,21 @@
+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;
+    }
+}
diff --git a/RateLimiterServlet.java b/RateLimiterServlet.java
@@ -0,0 +1,35 @@
+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);
+    }
+
+}
diff --git a/pom.xml b/pom.xml
@@ -0,0 +1,10 @@
+ <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>