How to Implement Interface Rate Limiting with Sentinel in Spring Cloud Alibaba

Sentinel, described as the "distributed system traffic guardian", provides flow control and circuit breaking for service stability, and is a recommended alternative to Hystrix in Spring Cloud Alibaba.

Deploy Sentinel Dashboard

Download the matching version of sentinel-dashboard-1.4.0.jar and start it with java -jar sentinel-dashboard-1.4.0.jar. The dashboard runs on port 8080 by default and can be accessed at http://localhost:8080.

Integrate Sentinel into a Spring Cloud application

Step 1: Add the spring-cloud-starter-alibaba-sentinel dependency (and optional Lombok) to the project's pom.xml.

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
    </dependency>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <version>1.18.2</version>
        <optional>true</optional>
    </dependency>
</dependencies>

Step 2: Configure the dashboard address in application.properties (e.g., spring.cloud.sentinel.transport.dashboard=localhost:8080) and set the service name.

Step 3: Create a Spring Boot main class and a simple REST controller exposing /hello that returns a string.

@SpringBootApplication
public class TestApplication {
    public static void main(String[] args) {
        SpringApplication.run(TestApplication.class, args);
    }
}

@RestController
class TestController {
    @GetMapping("/hello")
    public String hello() {
        return "didispace.com";
    }
}

Step 4: Run the application (e.g., on port 8001) and verify the endpoint works with curl http://localhost:8001/hello. The request appears in the Sentinel Dashboard.

Configure a flow‑control rule

In the dashboard, select the service alibaba-sentinel-rate-limiting, open the “Flow Control” tab, add a new rule for the /hello resource, choose QPS as the threshold type, and set the limit to 2 requests per second.

After saving, the rule is listed under “Flow Control Rules”.

Validate the rule

Calling the endpoint three times quickly shows the third request blocked with the message “Blocked by Sentinel (flow limiting)”.

$ curl http://localhost:8001/hello
didispace.com
$ curl http://localhost:8001/hello
didispace.com
$ curl http://localhost:8001/hello
Blocked by Sentinel (flow limiting)