Alert via Slack

Send SLA breach and recovery notifications to a Slack channel with one incoming-webhook URL. No packages needed beyond Laravel's HTTP client.

1. Create a Slack incoming webhook

1. In Slack: Apps → Incoming Webhooks → Add to Slack
2. Pick a channel (e.g. #queue-alerts)
3. Copy the webhook URL

2. Store the URL

.env:

QUEUE_ALERTS_SLACK_WEBHOOK=https://hooks.slack.com/services/T00/B00/xxx

config/services.php:

'queue_alerts' => [
    'slack_webhook' => env('QUEUE_ALERTS_SLACK_WEBHOOK'),
],

3. The listener

app/Listeners/NotifyQueueSlack.php:

<?php

namespace App\Listeners;

use Cbox\LaravelQueueAutoscale\Alerting\AlertRateLimiter;
use Cbox\LaravelQueueAutoscale\Events\SlaBreached;
use Cbox\LaravelQueueAutoscale\Events\SlaRecovered;
use Illuminate\Support\Facades\Http;
use Illuminate\Support\Facades\Log;

class NotifyQueueSlack
{
    public function __construct(private AlertRateLimiter $limiter) {}

    public function onBreach(SlaBreached $event): void
    {
        if (! $this->limiter->allow("slack:breach:{$event->connection}:{$event->queue}")) {
            return;
        }

        $this->post(sprintf(
            ":rotating_light: *SLA breach on `%s:%s`* — oldest job %ds (target %ds), %d pending, %d workers",
            $event->connection,
            $event->queue,
            $event->oldestJobAge,
            $event->slaTarget,
            $event->pending,
            $event->activeWorkers,
        ));
    }

    public function onRecovery(SlaRecovered $event): void
    {
        // No rate-limit needed: SlaRecovered only fires on state transition.
        $this->post(sprintf(
            ":white_check_mark: *SLA recovered on `%s:%s`* — pickup back under %ds",
            $event->connection,
            $event->queue,
            $event->slaTarget,
        ));
    }

    private function post(string $text): void
    {
        $url = (string) config('services.queue_alerts.slack_webhook');

        if ($url === '') {
            return;
        }

        try {
            Http::timeout(5)->post($url, ['text' => $text]);
        } catch (\Throwable $e) {
            // Never let alerting crash the manager — log and move on.
            Log::warning('Slack alert failed', ['error' => $e->getMessage()]);
        }
    }
}

4. Register it

app/Providers/EventServiceProvider.php:

use Cbox\LaravelQueueAutoscale\Events\SlaBreached;
use Cbox\LaravelQueueAutoscale\Events\SlaRecovered;
use App\Listeners\NotifyQueueSlack;

protected $listen = [
    SlaBreached::class => [NotifyQueueSlack::class.'@onBreach'],
    SlaRecovered::class => [NotifyQueueSlack::class.'@onRecovery'],
];

Done

Force a breach in a local test to verify:

# Shovel 50 slow jobs (1s each) into the default queue, then watch Slack.
# Run this in tinker; the queued-closure approach avoids needing a job class.
php artisan tinker
>>> for ($i = 0; $i < 50; $i++) { dispatch(function () { sleep(1); }); }

Tuning

• Default rate-limit is 5 minutes per connection:queue. Change via QUEUE_AUTOSCALE_ALERT_COOLDOWN or queue-autoscale.alerting.cooldown_seconds.
• For multi-channel routing (e.g. #critical-alerts for payments, #queue-noise for everything else), add a match on $event->queue and use different webhook URLs.
• Swap the raw webhook for laravel/slack-notification-channel if you prefer the Notification abstraction — same rate-limiter pattern, different sender.
• Running into Slack rate limits from the webhook itself? That's an upstream concern — our rate limiter dedupes at the event source, but bursts across many queues can still hit Slack's ingest. Consider batching or a dedicated # per severity tier.