Spring-boot with Bucket4j and Redis Demo

The aim of this demo is to demonstrate rate-limiting by using Bucket4j and the In-Memory Data Grid Redis.

To do that, we will run two instances of the same application, they share the same bucket which is stored in Redis. When a request from the same Ip hit any of the two instances the shared bucket is decremented.

The result is immediately visible to any instance.

Pre requisite

1. Redis server running on port 6379

Demo

1. Run the first instance : mvn spring-boot:run -Dserver.port=8081

2. Run the second instance : mvn spring-boot:run -Dserver.port=8082

3. You can also run a third instance if you want.

Testing

When calling any of the two instances, say we run the following command curl -s -D - localhost:8081, the response looks like :

 HTTP/1.1 200
 X-Rate-Limit-Remaining: 9
 Content-Type: text/plain;charset=UTF-8
 Content-Length: 13
 Date: Thu, 29 Jun 2017 21:25:00 GMT
 
 Hello World !

Notice the X-Rate-Limit-Remaining that indicates the remaining requests.

In this sample we configured the bucket with a capacity of 10 requests every minute as the following code shows.

Bucket4j.configurationBuilder()
               .addLimit(Bandwidth.simple(10, Duration.ofMinutes(1)))
               .buildConfiguration();

Run alternatively the following commands :

1. Request the instance one : curl -s -D - localhost:8081

2. Request the instance two : curl -s -D - localhost:8082

You will see the value of X-Rate-Limit-Remaining header decrementing until it equals 0 the subsequent request gives a 429 HTTP status code along with message too many requests.

 HTTP/1.1 429
 Content-Type: text/plain;charset=ISO-8859-1
 Content-Length: 17
 Date: Thu, 29 Jun 2017 21:36:11 GMT
 
 Too many requests

Note :

It is possible to not see the X-Rate-Limit-Remaining decrementing or on contrary incrementing, especially if you take a long time to execute the queries, this is because bucket4j regenerates tokens immediately (for more detailed information read the documentation of Refill.java )