Redis Pub/Sub Message Queue Setup for Web Application

Redis Pub/Sub and Streams Message Queue Setup

Redis provides two mechanisms for asynchronous messaging: Pub/Sub — simple fire-and-forget without persistence, and Streams — persistent queue with consumer groups, similar to lightweight Kafka.

Redis Pub/Sub

Suitable for real-time notifications within application. Messages are not persisted — if subscriber is disconnected, message is lost.

// Laravel: publish via Redis Pub/Sub
use Illuminate\Support\Facades\Redis;

// Publisher
Redis::publish('user-notifications', json_encode([
    'user_id' => $userId,
    'type'    => 'order.shipped',
    'message' => 'Your order has been shipped',
]));

// Subscriber (console command)
class RedisSubscribeCommand extends Command
{
    protected $signature = 'redis:subscribe';

    public function handle(): void
    {
        Redis::subscribe(['user-notifications'], function (string $message) {
            $data = json_decode($message, true);
            broadcast(new UserNotificationEvent($data));  // → WebSocket
        });
    }
}

Redis Streams

Streams — the right choice for task queue on Redis. Messages are stored in the stream, consumer groups track progress, pending entries — unprocessed messages.

# Create stream and add message
XADD emails * user_id 123 email [email protected] template welcome

# Create consumer group
XGROUP CREATE emails email-workers $ MKSTREAM

# Read new messages (worker 1)
XREADGROUP GROUP email-workers worker-1 COUNT 10 BLOCK 5000 STREAMS emails >

# Acknowledge processing
XACK emails email-workers <message-id>

PHP: Redis Streams worker

use Illuminate\Support\Facades\Redis;

class RedisStreamWorker
{
    private string $stream = 'emails';
    private string $group = 'email-workers';
    private string $consumer;

    public function __construct()
    {
        $this->consumer = gethostname() . ':' . getmypid();
        $this->ensureGroup();
    }

    private function ensureGroup(): void
    {
        try {
            Redis::xgroup('CREATE', $this->stream, $this->group, '$', true);
        } catch (\Throwable) {
            // Group already exists
        }
    }

    public function run(): void
    {
        while (true) {
            // First process pending (unacknowledged from previous run)
            $pending = Redis::xreadgroup(
                $this->group, $this->consumer,
                [$this->stream => '0'],  // '0' = pending messages
                10
            );
            $this->processMessages($pending);

            // Then new messages
            $messages = Redis::xreadgroup(
                $this->group, $this->consumer,
                [$this->stream => '>'],  // '>' = only new
                10,
                5000  // block 5 seconds
            );
            $this->processMessages($messages);
        }
    }

    private function processMessages(?array $streams): void
    {
        if (!$streams) return;

        foreach ($streams[$this->stream] ?? [] as [$id, $fields]) {
            try {
                $this->handleEmail($fields);
                Redis::xack($this->stream, $this->group, $id);
            } catch (\Throwable $e) {
                Log::error('Stream message failed', ['id' => $id, 'error' => $e->getMessage()]);
                // Message remains in pending — will be reread on next run
            }
        }
    }

    private function handleEmail(array $fields): void
    {
        Mail::to($fields['email'])->send(new TemplateMail($fields['template'], $fields));
    }
}

Node.js: ioredis Streams

import Redis from 'ioredis';

const redis = new Redis({ host: 'redis', port: 6379 });
const STREAM = 'emails';
const GROUP = 'email-workers';
const CONSUMER = `worker-${process.pid}`;

async function startWorker(): Promise<void> {
  // Create group if doesn't exist
  try {
    await redis.xgroup('CREATE', STREAM, GROUP, '$', 'MKSTREAM');
  } catch { /* group exists */ }

  while (true) {
    const messages = await redis.xreadgroup(
      'GROUP', GROUP, CONSUMER,
      'COUNT', '10',
      'BLOCK', '5000',
      'STREAMS', STREAM, '>'
    ) as [string, [string, string[]][]][] | null;

    if (!messages) continue;

    for (const [, entries] of messages) {
      for (const [id, fields] of entries) {
        const data = Object.fromEntries(
          fields.reduce((acc, val, i) => (i % 2 === 0 ? acc.push([val, fields[i+1]]) : acc, acc), [] as [string,string][])
        );

        try {
          await sendEmail(data);
          await redis.xack(STREAM, GROUP, id);
        } catch (err) {
          console.error('Email failed:', id, err);
        }
      }
    }
  }
}

Stream trimming and cleanup

# Trim stream to last 10000 messages
XTRIM emails MAXLEN ~ 10000

# Auto-trim on add
XADD emails MAXLEN ~ 100000 * user_id 123 template welcome

Redis mechanisms comparison

Implementation timeline

Redis Streams worker for typical PHP/Node.js application (email, notifications): 1–2 days. With pending messages monitoring and alerts: 2–3 days.