Accessing Data Reactively with Redis

This guide walks you through the process of creating a functional reactive application that uses Spring Data to interact with Redis using the non-blocking Lettuce driver.

What You Will Build

You’ll build a Spring application that uses Spring Data Redis and Project Reactor to interact with a Redis data store reactively, storing and retrieving Coffee objects without blocking. This application uses Reactor’s Publisher implementations based upon the Reactive Streams specification, namely Mono (for a Publisher returning 0 or 1 value) and Flux (for a Publisher returning 0 to n values).

What You Need

How to complete this guide

Like most Spring Getting Started guides, you can start from scratch and complete each step or you can bypass basic setup steps that are already familiar to you. Either way, you end up with working code.

To start from scratch, move on to Starting with Spring Initializr.

To skip the basics, do the following:

When you finish, you can check your results against the code in gs-spring-data-reactive-redis/complete.

Starting with Spring Initializr

You can use this pre-initialized project and click Generate to download a ZIP file. This project is configured to fit the examples in this tutorial.

To manually initialize the project:

  1. Navigate to This service pulls in all the dependencies you need for an application and does most of the setup for you.

  2. Choose either Gradle or Maven and the language you want to use. This guide assumes that you chose Java.

  3. Click Dependencies and select Spring Reactive Web, Spring Data Reactive Redis, and Lombok.

  4. Click Generate.

  5. Download the resulting ZIP file, which is an archive of a web application that is configured with your choices.

If your IDE has the Spring Initializr integration, you can complete this process from your IDE.
You can also fork the project from Github and open it in your IDE or other editor.

Standing up a Redis Server

Before you can build a messaging application, you need to set up the server that will handle receiving and sending messages.

Redis is an open source, BSD-licensed, key-value data store that also comes with a messaging system. The server is freely available at You can download it manually, or, if you use a Mac, with Homebrew, by running the following command in a terminal window:

brew install redis

Once you unpack Redis, you can launch it with its default settings by running the following command:


You should see a message similar to the following:

[35142] 01 May 14:36:28.939 # Warning: no config file specified, using the default config. In order to specify a config file use redis-server /path/to/redis.conf
[35142] 01 May 14:36:28.940 * Max number of open files set to 10032
              _.-``__ ''-._
        _.-``    `.  `_.  ''-._           Redis 2.6.12 (00000000/0) 64 bit
    .-`` .-```.  ```\/    _.,_ ''-._
  (    '      ,       .-`  | `,    )     Running in stand alone mode
  |`-._`-...-` __...-.``-._|'` _.-'|     Port: 6379
  |    `-._   `._    /     _.-'    |     PID: 35142
    `-._    `-._  `-./  _.-'    _.-'
  |`-._`-._    `-.__.-'    _.-'_.-'|
  |    `-._`-._        _.-'_.-'    | 
    `-._    `-._`-.__.-'_.-'    _.-'
  |`-._`-._    `-.__.-'    _.-'_.-'|
  |    `-._`-._        _.-'_.-'    |
    `-._    `-._`-.__.-'_.-'    _.-'
        `-._    `-.__.-'    _.-'
            `-._        _.-'

[35142] 01 May 14:36:28.941 # Server started, Redis version 2.6.12
[35142] 01 May 14:36:28.941 * The server is now ready to accept connections on port 6379

Create a Domain Class

Create a class representing a type of coffee we wish to stock in our coffee catalog:


package com.example.demo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

public class Coffee {
  private String id;
  private String name;
I use Lombok in this example to eliminate the boilerplate code for constructors and so-called "data class" methods ( accessors/mutators, equals(), toString(), & hashCode()).

Create a Configuration Class

Create a class that includes Spring Beans that support reactive Redis operations:


package com.example.demo;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

public class CoffeeConfiguration {
  ReactiveRedisOperations<String, Coffee> redisOperations(ReactiveRedisConnectionFactory factory) {
    Jackson2JsonRedisSerializer<Coffee> serializer = new Jackson2JsonRedisSerializer<>(Coffee.class);

    RedisSerializationContext.RedisSerializationContextBuilder<String, Coffee> builder =
        RedisSerializationContext.newSerializationContext(new StringRedisSerializer());

    RedisSerializationContext<String, Coffee> context = builder.value(serializer).build();

    return new ReactiveRedisTemplate<>(factory, context);


Create a Spring Bean to Load Data

Create a Spring Bean to load sample data for our application when we start it:

Since we may (re)start our application multiple times, we should first remove any data that may still exist from previous executions. We do this with a flushAll() (Redis) server command. Once we’ve flushed any existing data, we create a small Flux, map each coffee name to a Coffee object, and save it to the reactive Redis repository. We then query the repo for all values and display them.


package com.example.demo;

import org.springframework.stereotype.Component;
import reactor.core.publisher.Flux;

import jakarta.annotation.PostConstruct;
import java.util.UUID;

public class CoffeeLoader {
  private final ReactiveRedisConnectionFactory factory;
  private final ReactiveRedisOperations<String, Coffee> coffeeOps;

  public CoffeeLoader(ReactiveRedisConnectionFactory factory, ReactiveRedisOperations<String, Coffee> coffeeOps) {
    this.factory = factory;
    this.coffeeOps = coffeeOps;

  public void loadData() {
        Flux.just("Jet Black Redis", "Darth Redis", "Black Alert Redis")
            .map(name -> new Coffee(UUID.randomUUID().toString(), name))
            .flatMap(coffee -> coffeeOps.opsForValue().set(coffee.getId(), coffee)))

Create a RestController

Create a RestController to provide an external interface for our application:


package com.example.demo;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import reactor.core.publisher.Flux;

public class CoffeeController {
  private final ReactiveRedisOperations<String, Coffee> coffeeOps;

  CoffeeController(ReactiveRedisOperations<String, Coffee> coffeeOps) {
    this.coffeeOps = coffeeOps;

  public Flux<Coffee> all() {
    return coffeeOps.keys("*")

Make the Application Executable

Although you can package this service as a traditional WAR file for deployment to an external application server, the simpler approach shown here creates a standalone application. You package everything in a single, executable JAR file, driven by a good old Java main() method. Along the way, you use Spring’s support for embedding the Netty an asynchronous "container" as the HTTP runtime instead of deploying to an external instance.


package com.example.demo;

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

public class DemoApplication {

  public static void main(String[] args) {, args);

@SpringBootApplication is a convenience annotation that adds all of the following:

  • @Configuration: Tags the class as a source of bean definitions for the application context.

  • @EnableAutoConfiguration: Tells Spring Boot to start adding beans based on classpath settings, other beans, and various property settings. For example, if spring-webmvc is on the classpath, this annotation flags the application as a web application and activates key behaviors, such as setting up a DispatcherServlet.

  • @ComponentScan: Tells Spring to look for other components, configurations, and services in the hello package, letting it find the controllers.

The main() method uses Spring Boot’s method to launch an application. Did you notice that there was not a single line of XML? There is no web.xml file, either. This web application is 100% pure Java and you did not have to deal with configuring any plumbing or infrastructure.

Build an executable JAR

You can run the application from the command line with Gradle or Maven. You can also build a single executable JAR file that contains all the necessary dependencies, classes, and resources and run that. Building an executable jar makes it easy to ship, version, and deploy the service as an application throughout the development lifecycle, across different environments, and so forth.

If you use Gradle, you can run the application by using ./gradlew bootRun. Alternatively, you can build the JAR file by using ./gradlew build and then run the JAR file, as follows:

java -jar build/libs/gs-spring-data-reactive-redis-0.1.0.jar

If you use Maven, you can run the application by using ./mvnw spring-boot:run. Alternatively, you can build the JAR file with ./mvnw clean package and then run the JAR file, as follows:

java -jar target/gs-spring-data-reactive-redis-0.1.0.jar
The steps described here create a runnable JAR. You can also build a classic WAR file.

Test the application

Now that the application is running, you can test it by accessing http://localhost:8080/coffees from HTTPie, curl, or your favorite browser.


Congratulations! You have developed a Spring application that uses Spring Data and Redis for fully reactive, non-blocking database access!

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