composer require monolog/monolog

use Monolog\Logger;
use Monolog\Handler\RotatingFileHandler;
use Monolog\Formatter\JsonFormatter;

$log = new Logger('app');

$handler = new RotatingFileHandler(
    __DIR__ . '/logs/application.log',
    maxFiles: 30,
    level: Logger::INFO
);

$handler->setFormatter(new JsonFormatter());
$log->pushHandler($handler);

class CorrelationIdProcessor implements ProcessorInterface
{
    private string $correlationId;

    public function __construct()
    {
        $this->correlationId = $_SERVER['HTTP_X_CORRELATION_ID']
            ?? bin2hex(random_bytes(16));

        header('X-Correlation-ID: ' . $this->correlationId);
    }

    public function __invoke(array $record): array
    {
        $record['extra']['correlation_id'] = $this->correlationId;
        return $record;
    }
}

$log->pushProcessor(new CorrelationIdProcessor());

$handler = new RotatingFileHandler(
    filename: __DIR__ . '/logs/app.log',
    maxFiles: 30,
    level: Logger::WARNING,
);

# /etc/logrotate.d/php-app
/var/www/app/logs/*.log {
    daily
    rotate 30
    compress
    missingok
    size 100M
}

use Monolog\Handler\BufferHandler;

$bufferHandler = new BufferHandler(
    handler: new StreamHandler('logs/app.log'),
    bufferSize: 100,
    flushOnOverflow: true
);

$log->pushHandler($bufferHandler);

use Monolog\Handler\GelfHandler;
use Gelf\Publisher;
use Gelf\Transport\UdpTransport;

$publisher = new Publisher(
    new UdpTransport('logstash.example.com', 12201)
);

$log->pushHandler(new GelfHandler($publisher));

$data = [
    'name' => '  John  ',
    'address' => [
        'city' => '  Berlin  ',
        'zip'  => '  10115  ',
    ],
];

array_walk_recursive($data, function (&$value) {
    if (is_string($value)) {
        $value = trim($value);
    }
});

// Все строки на любом уровне вложенности — обрезаны

php
$data = [0, '', null, false, 'hello', 42, [], 'world'];

$result = array_filter($data);

// ['hello', 42, 'world']