Implementing Redis Pub/Sub with .NET Aspire: A Simple Guide

Overview

What is Redis Pub/Sub?

Redis Pub/Sub (Publish/Subscribe) is a messaging pattern where:

Publishers send messages to channels
Subscribers listen to specific channels
Publishers and subscribers are decoupled
Messages are delivered in real-time

First, let's look at the AppHost configuration:

App Host:

var builder = DistributedApplication.CreateBuilder(args);
var redis = builder.AddRedis("redis");
builder.AddProject<Projects.Api>("api")
    .WithReference(redis)
    .WithReplicas(1);
builder.AddProject<Projects.Worker>("worker")
    .WithReference(redis);
await builder.Build().RunAsync();

In this configuration, we set up Redis. You need to install the Aspire.Hosting.Redis package.

The application consists of an API service for publishing messages and a background worker for reading them. The API service sends the message to Redis channel:

Api/Program.cs

// ... (initialization code)
builder.AddRedisDistributedCache("redis");

As you can see, we need to add Redis to the API service first. For this, you need to install the Aspire.StackExchange.Redis.DistributedCaching package.

app.MapPost("/send-message", async ([FromBody] SendMessageRequest request, IConnectionMultiplexer connectionMultiplexer) =>
{
    await connectionMultiplexer.GetSubscriber().PublishAsync(Constants.DefaultChannel, request.Message);
    return Results.Ok();
});

The background worker then gets the messages from Redis channel and writes a log message:

using RedisPubSub.ServiceDefaults;
using StackExchange.Redis;

namespace Worker;

public class Worker(ILogger<Worker> logger, IConnectionMultiplexer connectionMultiplexer) : BackgroundService
{
    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        while (!stoppingToken.IsCancellationRequested)
        {
            await connectionMultiplexer.GetSubscriber().SubscribeAsync(Constants.DefaultChannel, (channel, message) =>
            {
                logger.LogWarning("Here is the message: {Message} from channel: {ChannelName}", message, Constants.DefaultChannel);
            });
            await Task.Delay(5000, stoppingToken);
        }
    }
}

Here are screenshots from testing:

Conclusion

With .NET Aspire, implementing Redis Pub/Sub becomes straightforward. This pattern is excellent for building scalable, real-time applications with decoupled components. As you explore further, you'll find even more ways to leverage Redis and .NET Aspire in your cloud-native applications.

For the complete source code of this example, you can visit: aspire-samples