🌊 Topic 12: Statelessness Doctrine

Your server must be killable at any moment. Design for failure.

🔴 The Problem: State Stored Locally

✅ The Solution: Stateless Architecture

📋 The Statelessness Checklist

⚙️ Making Laravel Stateless (Step by Step)

1. Move Sessions to Redis

# .env
SESSION_DRIVER=redis
SESSION_CONNECTION=default

# config/session.php (already configured for Redis)

2. Move Cache to Redis

# .env
CACHE_DRIVER=redis

# config/cache.php
'default' => env('CACHE_DRIVER', 'redis'),

3. Move Files to S3

# .env
FILESYSTEM_DRIVER=s3
AWS_ACCESS_KEY_ID=your-key
AWS_SECRET_ACCESS_KEY=your-secret
AWS_DEFAULT_REGION=us-east-1
AWS_BUCKET=your-bucket

# In your code
$path = Storage::disk('s3')->put('avatars', $request->file('avatar'));
$url = Storage::disk('s3')->url($path);

4. Move Logs to Centralized Service

# config/logging.php
'channels' => [
    'cloudwatch' => [
        'driver' => 'custom',
        'via' => \App\Logging\CloudWatchLogger::class,
    ],
],

# .env
LOG_CHANNEL=cloudwatch

5. Ensure Config is Cached

# After every deployment
php artisan config:cache

# Never use env() outside config files
// Wrong: env('APP_NAME')
// Right: config('app.name')

6. Handle Scheduled Tasks with Mutex

// app/Console/Kernel.php
protected function schedule(Schedule $schedule)
{
    // With onOneServer(), tasks run only once across all servers
    $schedule->command('reports:generate')
        ->daily()
        ->onOneServer();  // ← Uses Redis/Cache for mutex
    
    $schedule->command('emails:send')
        ->hourly()
        ->onOneServer();
}

// For Laravel 8+, you need to set:
// config/schedule.php
'schedule_cache_driver' => 'redis',

🔄 Horizontal Scaling: Adding More Servers

# Forge recipe for stateless servers
- 1 GB swap (no session files)
- Nginx + PHP-FPM
- .env with Redis/S3 credentials
- Deployment script:
    git pull
    composer install --no-dev --optimize-autoloader
    php artisan migrate --force
    php artisan config:cache
    php artisan route:cache
    php artisan view:cache
    php artisan queue:restart
    sudo systemctl reload php8.2-fpm

⚠️ The Downsides of Statelessness

🔍 How to Check If Your App Is Stateless

Automated statelessness audit:

#!/bin/bash
# audit-statelessness.sh

echo "Checking for stateful patterns..."

# Check session driver
grep "SESSION_DRIVER=file" .env && echo "❌ Sessions in files! Use Redis."

# Check cache driver
grep "CACHE_DRIVER=file" .env && echo "❌ Cache in files! Use Redis."

# Check filesystem
grep "FILESYSTEM_DRIVER=local" .env && echo "❌ Files on local disk! Use S3."

# Check for env() in app code (outside config)
grep -r "env(" --include="*.php" --exclude-dir=vendor \
  --exclude-dir=config | grep -v "config/" && \
  echo "❌ env() found outside config/! Use config()."

# Check for hardcoded paths
grep -r "storage/app/public" --include="*.php" --exclude-dir=vendor && \
  echo "❌ Hardcoded storage path! Use Storage facade."

echo "Audit complete."

📝 Topic 12 Summary: Statelessness Doctrine