monolog-gdpr-filter/docs/symfony-integration.md

Symfony Integration Guide

This guide explains how to integrate the Monolog GDPR Filter with Symfony applications.

Installation

composer require ivuorinen/monolog-gdpr-filter

Basic Service Configuration

Add the GDPR processor as a service in config/services.yaml:

services:
    App\Logging\GdprProcessor:
        class: Ivuorinen\MonologGdprFilter\GdprProcessor
        arguments:
            $patterns: '%gdpr.patterns%'
            $fieldPaths: '%gdpr.field_paths%'
            $customCallbacks: []
            $auditLogger: null
            $maxDepth: 100
            $dataTypeMasks: []
            $conditionalRules: []

Parameters Configuration

Define GDPR patterns in config/services.yaml or a dedicated parameters file:

parameters:
    gdpr.patterns:
        '/\b\d{3}-\d{2}-\d{4}\b/': '***-**-****'        # US SSN
        '/\b[A-Z]{2}\d{2}[A-Z0-9]{4}\d{7}([A-Z0-9]?){0,16}\b/': '****'  # IBAN
        '/[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}/': '[email]'   # Email
        '/\b\d{4}[\s-]?\d{4}[\s-]?\d{4}[\s-]?\d{4}\b/': '****-****-****-****'  # Credit Card

    gdpr.field_paths:
        'user.password': '***REMOVED***'
        'user.ssn': '***-**-****'
        'payment.card_number': '****-****-****-****'

Monolog Handler Configuration

Configure Monolog to use the GDPR processor in config/packages/monolog.yaml:

monolog:
    handlers:
        main:
            type: stream
            path: "%kernel.logs_dir%/%kernel.environment%.log"
            level: debug
            channels: ["!event"]
            formatter: monolog.formatter.json
            processor: ['@App\Logging\GdprProcessor']

        # For production with file rotation
        production:
            type: rotating_file
            path: "%kernel.logs_dir%/%kernel.environment%.log"
            level: info
            max_files: 14
            processor: ['@App\Logging\GdprProcessor']

Environment-Specific Configuration

Create environment-specific configurations:

config/packages/dev/monolog.yaml

monolog:
    handlers:
        main:
            type: stream
            path: "%kernel.logs_dir%/%kernel.environment%.log"
            level: debug
            # In dev, you might want less aggressive masking

config/packages/prod/monolog.yaml

monolog:
    handlers:
        main:
            type: fingers_crossed
            action_level: error
            handler: nested
            excluded_http_codes: [404, 405]
            buffer_size: 50

        nested:
            type: rotating_file
            path: "%kernel.logs_dir%/%kernel.environment%.log"
            level: info
            max_files: 14
            processor: ['@App\Logging\GdprProcessor']

Advanced Configuration with Audit Logging

Enable audit logging for compliance tracking:

services:
    App\Logging\AuditLogger:
        class: Ivuorinen\MonologGdprFilter\RateLimitedAuditLogger
        arguments:
            $auditLogger: '@App\Logging\AuditCallback'
            $maxRequestsPerMinute: 100
            $windowSeconds: 60

    App\Logging\AuditCallback:
        class: Closure
        factory: ['App\Logging\AuditCallbackFactory', 'create']
        arguments:
            $logger: '@monolog.logger.audit'

    App\Logging\GdprProcessor:
        class: Ivuorinen\MonologGdprFilter\GdprProcessor
        arguments:
            $patterns: '%gdpr.patterns%'
            $fieldPaths: '%gdpr.field_paths%'
            $auditLogger: '@App\Logging\AuditLogger'

Create the factory class:

<?php
// src/Logging/AuditCallbackFactory.php

namespace App\Logging;

use Psr\Log\LoggerInterface;

class AuditCallbackFactory
{
    public static function create(LoggerInterface $logger): callable
    {
        return function (string $path, mixed $original, mixed $masked) use ($logger): void {
            $logger->info('GDPR masking applied', [
                'path' => $path,
                'original_type' => gettype($original),
                'masked_preview' => substr((string) $masked, 0, 20) . '...',
            ]);
        };
    }
}

Conditional Masking by Environment

Apply different masking rules based on log level or channel:

services:
    App\Logging\ConditionalRuleFactory:
        class: App\Logging\ConditionalRuleFactory

    App\Logging\GdprProcessor:
        class: Ivuorinen\MonologGdprFilter\GdprProcessor
        arguments:
            $conditionalRules:
                error_only: '@=service("App\\Logging\\ConditionalRuleFactory").createErrorOnlyRule()'

<?php
// src/Logging/ConditionalRuleFactory.php

namespace App\Logging;

use Monolog\Level;
use Monolog\LogRecord;

class ConditionalRuleFactory
{
    public function createErrorOnlyRule(): callable
    {
        return fn(LogRecord $record): bool =>
            $record->level->value >= Level::Error->value;
    }

    public function createChannelRule(array $channels): callable
    {
        return fn(LogRecord $record): bool =>
            in_array($record->channel, $channels, true);
    }
}

Testing in Symfony

Create a test to verify GDPR filtering works:

<?php
// tests/Logging/GdprProcessorTest.php

namespace App\Tests\Logging;

use Ivuorinen\MonologGdprFilter\GdprProcessor;
use Monolog\Level;
use Monolog\LogRecord;
use PHPUnit\Framework\TestCase;
use DateTimeImmutable;

class GdprProcessorTest extends TestCase
{
    public function testEmailMasking(): void
    {
        $processor = new GdprProcessor([
            '/[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}/' => '[email]',
        ]);

        $record = new LogRecord(
            datetime: new DateTimeImmutable(),
            channel: 'test',
            level: Level::Info,
            message: 'User logged in: user@example.com',
            context: []
        );

        $result = $processor($record);

        $this->assertStringContainsString('[email]', $result->message);
        $this->assertStringNotContainsString('user@example.com', $result->message);
    }
}

Troubleshooting

Patterns Not Matching

1. Verify regex patterns are valid: preg_match('/your-pattern/', 'test-string')
2. Check pattern escaping in YAML (may need quotes)
3. Enable debug mode to see which patterns are applied

Performance Issues

1. Use the rate-limited audit logger
2. Consider caching pattern validation results
3. Profile with Symfony profiler

Memory Issues

1. Set appropriate maxDepth to prevent deep recursion
2. Monitor rate limiter statistics
3. Use cleanup intervals for long-running processes

See Also

• PSR-3 Decorator Guide
• Framework Examples
• Docker Development