Spring-Kotlin-Redis-DynamicConfig-JedisPubSub is a Java client library for Redis. JedisPubSub is an abstract class in Jedis that provides a convenient way to implement Redis Publish/Subscribe (Pub/Sub) messaging in Java applications.

What Redis Pub/Sub Does

Redis Pub/Sub allows applications to communicate using channels:

• Publisher sends messages to a channel.
• Subscriber listens to that channel and receives messages in real time.

This is useful for:

• Event-driven systems
• Notifications
• Cache invalidation
• Chat applications
• Distributed communication

What JedisPubSub Provides

JedisPubSub defines callback methods that are invoked automatically when Pub/Sub events occur.

JedisPubSub works by combining three pieces:

1. A connection to Redis
2. A listener object that extends JedisPubSub
3. A blocking subscription loop that waits for messages

🚦 Getting Started

Run Redis Cluster locally (or use Docker):

version: '3.7'  
services:  
  redis-cluster:  
    build:  
      context: https://github.com/senocak/redis-single-node-cluster.git#main:build  
      args:  
        \- REDIS\_BASE\_IMAGE=redis:7.2-alpine  
    environment:  
      \- REDIS\_CONFIG\_CLUSTER\_ANNOUNCE\_IP=127.0.0.1  
    ports:  
      \- "6379:6379"  
    networks:  
      \- ops  
networks:  
  ops:

docker-compose up -d

Make sure you enabled Redis keyspace notifications by running the following command in your Redis CLI:

redis-cli config set notify-keyspace-events KEA

Configure Redis in application.yml

spring:  
  data:  
    redis:  
      cluster:  
        nodes: localhost:6379  \# Update with your Redis server address  
      database: 0  
      timeout: 60000

Configuration default values:

The application can be configured through the application.yml file:

# Using redis-cli

redis-cli SET "redis-pub-sub-config:ping" "Hello, Dynamic World!"

Start the app and test:

The application includes a simple endpoint to test dynamic configuration:

# Using curl

curl http://localhost:8082/ping

Hello, Dynamic World!

The response will show the current value of the ping configuration.

How It Works

1. The application scans all Spring beans for fields annotated with @RedisConfig
2. It registers these fields in a registry with their default values
3. It subscribes to Redis keyspace notifications for the configured keys
4. When a key changes in Redis, the application receives a notification
5. The field value is updated with the new value from Redis

Spring-Kotlin-Redis-DynamicConfig-JedisPubSub