Spring boot tutorial

Spring boot API Rate limiting is a strategy using Bucket4j

Project Folder Structure :

At first, We have created Maven based Spring boot application. Folder structure is below :

Maven pom.xml :

Project dependencies. Nothing special here, just some Spring Boot dependencies.

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.1.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.ruhulmus</groupId>
    <artifactId>spring-boot-bucket4j</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>spring-boot-bucket4j</name>
    <description>Spring boot Bucket4j Example</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>


    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

Add bucker4j + cache Dependancy into pom.xml

    <dependency>
        <groupId>com.giffing.bucket4j.spring.boot.starter</groupId>
        <artifactId>bucket4j-spring-boot-starter</artifactId>
        <version>0.2.0</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-cache</artifactId>
    </dependency>
    <dependency>
        <groupId>org.ehcache</groupId>
        <artifactId>ehcache</artifactId>
    </dependency>

application.properties file :

Define application server port 8089

server.port=8089

Now Configure bucket4j

# enable/disable bucket4j support
 bucket4j.enabled=true
 # the name of the cache key
 bucket4j.filters[0].cache-name=buckets
# the json response which should be added to the body
bucket4j.filters[0].http-response-body={ "message": "Too many requests" }
# a regular expression
 bucket4j.filters[0].url=.*
 bucket4j.filters[0].metrics.enabled=true
 #rate limit
 bucket4j.filters[0].rate-limits[0].bandwidths[0].capacity=2
 #rate per seconds
 bucket4j.filters[0].rate-limits[0].bandwidths[0].time=1
 bucket4j.filters[0].rate-limits[0].bandwidths[0].unit=seconds

Here capacity=2 , time=1 and unit=seconds that means maximum 2 api call in 1 second duration

create a file name ehcache.xml under resource directory and configure accordingly. Add bucket file location into application.properties

spring.cache.jcache.config=classpath:ehcache.xml

ehcache.xml File look like :

<?xml version="1.0" encoding="UTF-8"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xmlns:jsr107="http://www.ehcache.org/v3/jsr107"
        xmlns='http://www.ehcache.org/v3'
        xsi:schemaLocation="http://www.ehcache.org/v3 http://www.ehcache.org/schema/ehcache-core-3.0.xsd
							http://www.ehcache.org/v3/jsr107 http://www.ehcache.org/schema/ehcache-107-ext-3.0.xsd">
    <cache alias="buckets">
        <expiry>
            <tti unit="seconds">3600</tti>
        </expiry>
        <heap unit="entries">1000000</heap>
        <jsr107:mbeans enable-statistics="true"/>
    </cache>
</config>

Configure @SpringBootApplication Class :

@SpringBootApplication to start everything.

package com.ruhulmus;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@EnableCaching
@SpringBootApplication
public class SpringBootBucket4j {
    public static void main(String[] args) {
        SpringApplication.run(SpringBootDocker.class, args);
    }
}

Create a test controller HelloController and a api endpoint for /testuri

package com.ruhulmus.controller;

import org.springframework.web.bind.annotation.CrossOrigin;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@CrossOrigin()
public class HelloController {
    @RequestMapping({"/testuri"})
    public String hello() {
        return "Hello World !! Rest Controller is working ...";
    }
}

Springboot Run

Now Run the below commands :

$ cd spring-boot-bucket4j
$ mvn clean install

It will build a jar spring-boot-bucket4j-0.0.1-SNAPSHOT.jar file under the target Location

Now run another command to run our jar file.

$ java -jar target/spring-boot-bucket4j-0.0.1-SNAPSHOT.jar

It will run the jar file into 8089 Port (as we set the server.port=8089 on application.properties file). The Output should be look like in your terminal :

2021-04-15 16:32:34.107  INFO 5297 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8089 (http)
2021-04-15 16:32:34.137  INFO 5297 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2021-04-15 16:32:34.137  INFO 5297 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.27]
2021-04-15 16:32:34.287  INFO 5297 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2021-04-15 16:32:34.287  INFO 5297 --- [           main] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 1907 ms
2021-04-15 16:32:34.554  INFO 5297 --- [           main] o.s.s.concurrent.ThreadPoolTaskExecutor  : Initializing ExecutorService 'applicationTaskExecutor'
2021-04-15 16:32:34.848  INFO 5297 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8089 (http) with context path ''
2021-04-15 16:32:34.852  INFO 5297 --- [           main] com.ruhulmus.SpringBootBucket4j            : Started SpringBootDocker in 4.027 seconds (JVM running for 5.352)

Now we can try to check our rest api. Here we used postman as a rest client. You can use your preferred one.

So that means our spring boot application, rest api is working fine with 8089 port.

Now try to hit the same API more than 2 times within 1 sec. We will get status code 429 means Too Many Requests. The API response screenshot is below: