• легко настраиваться
• писать логи в несколько мест одновременно

<?php
namespace Logger;

use Psr\Log\AbstractLogger;
use Psr\Log\LoggerInterface;

/**
 * Class Logger
 */
class Logger extends AbstractLogger implements LoggerInterface
{
	/**
	 * @inheritdoc
	 */
	public function log($level, $message, array $context = [])
	{
		//тут мы будем логировать
	}
}

<?php
namespace Logger;

use Psr\Log\AbstractLogger;
use Psr\Log\LoggerInterface;

/**
 * Class Route
 */
abstract class Route extends AbstractLogger implements LoggerInterface
{
	/**
	 * @var bool Включен ли роут
	 */
	public $isEnable = true;
}

<?php
namespace Logger\Routes;

use Logger\Route;

/**
 * Class FileRoute
 */
class FileRoute extends Route
{
	/**
	 * @var string Путь к файлу
	 */
	public $filePath;
	/**
	 * @var string Шаблон сообщения
	 */
	public $template = "{date} {level} {message} {context}";

	/**
	 * @inheritdoc
	 */
	public function __construct(array $attributes = [])
	{
		parent::__construct($attributes);

		if (!file_exists($this->filePath))
		{
			touch($this->filePath);
		}
	}

	/**
	 * @inheritdoc
	 */
	public function log($level, $message, array $context = [])
	{
		file_put_contents($this->filePath, trim(strtr($this->template, [
			'{date}' => $this->getDate(),
			'{level}' => $level,
			'{message}' => $message,
			'{context}' => $this->contextStringify($context),
		])) . PHP_EOL, FILE_APPEND);
	}
}

<?php
namespace Logger\Routes;

use PDO;
use Logger\Route;

/**
 * Class DatabaseRoute
 *
 * Создание таблицы:
 *
 * CREATE TABLE default_log (
 *      id integer PRIMARY KEY,
 *      date date,
 *      level varchar(16),
 *      message text,
 *      context text
 * );
 */
class DatabaseRoute extends Route
{
	/**
	 * @var string Data Source Name
	 * @see http://php.net/manual/en/pdo.construct.php
	 */
	public $dsn;
	/**
	 * @var string Имя пользователя БД
	 */
	public $username;
	/**
	 * @var string Пароль пользователя БД
	 */
	public $password;
	/**
	 * @var string Имя таблицы
	 */
	public $table;

	/**
	 * @var PDO Подключение к БД
	 */
	private $connection;

	/**
	 * @inheritdoc
	 */
	public function __construct(array $attributes = [])
	{
		parent::__construct($attributes);
		$this->connection = new PDO($this->dsn, $this->username, $this->password);
	}

	/**
	 * @inheritdoc
	 */
	public function log($level, $message, array $context = [])
	{
		$statement = $this->connection->prepare(
			'INSERT INTO ' . $this->table . ' (date, level, message, context) ' .
			'VALUES (:date, :level, :message, :context)'
		);
		$statement->bindParam(':date', $this->getDate());
		$statement->bindParam(':level', $level);
		$statement->bindParam(':message', $message);
		$statement->bindParam(':context', $this->contextStringify($context));
		$statement->execute();
	}
}

<?php
namespace Logger\Routes;

use Logger\Route;
use Psr\Log\LogLevel;

/**
 * Class SyslogRoute
 */
class SyslogRoute extends Route
{
	/**
	 * @var string Шаблон сообщения
	 */
	public $template = "{message} {context}";

	/**
	 * @inheritdoc
	 */
	public function log($level, $message, array $context = [])
	{
		$level = $this->resolveLevel($level);
		if ($level === null)
		{
			return;
		}

		syslog($level, trim(strtr($this->template, [
			'{message}' => $message,
			'{context}' => $this->contextStringify($context),
		])));
	}
	/**
	 * Преобразование уровня логов в формат подходящий для syslog()
	 *
	 * @see http://php.net/manual/en/function.syslog.php
	 * @param $level
	 * @return string
	 */
	private function resolveLevel($level)
	{
		$map = [
			LogLevel::EMERGENCY => LOG_EMERG,
			LogLevel::ALERT => LOG_ALERT,
			LogLevel::CRITICAL => LOG_CRIT,
			LogLevel::ERROR => LOG_ERR,
			LogLevel::WARNING => LOG_WARNING,
			LogLevel::NOTICE => LOG_NOTICE,
			LogLevel::INFO => LOG_INFO,
			LogLevel::DEBUG => LOG_DEBUG,
		];
		return isset($map[$level]) ? $map[$level] : null;
	}
}

<?php
namespace Logger;

use DateTime;
use Psr\Log\AbstractLogger;
use Psr\Log\LoggerInterface;

/**
 * Class Route
 */
abstract class Route extends AbstractLogger implements LoggerInterface
{
	/**
	 * @var bool Включен ли роут
	 */
	public $isEnable = true;
	/**
	 * @var string Формат даты логов
	 */
	public $dateFormat = DateTime::RFC2822;

	/**
	 * Текущая дата
	 *
	 * @return string
	 */
	public function getDate()
	{
		return (new DateTime())->format($this->dateFormat);
	}

	/**
	 * Преобразование $context в строку
	 *
	 * @param array $context
	 * @return string
	 */
	public function contextStringify(array $context = [])
	{
		return !empty($context) ? json_encode($context) : null;
	}
}

<?php
namespace Logger;

use SplObjectStorage;
use Psr\Log\AbstractLogger;
use Psr\Log\LoggerInterface;

/**
 * Class Logger
 */
class Logger extends AbstractLogger implements LoggerInterface
{
	/**
	 * @var SplObjectStorage Список роутов
	 */
	public $routes;

	/**
	 * Конструктор
	 */
	public function __construct()
	{
		$this->routes = new SplObjectStorage();
	}

	/**
	 * @inheritdoc
	 */
	public function log($level, $message, array $context = [])
	{
		foreach ($this->routes as $route)
		{
			if (!$route instanceof Route)
			{
				continue;
			}
			if (!$route->isEnable)
			{
				continue;
			}
			$route->log($level, $message, $context);
		}
	}
}

$logger = new Logger\Logger();

$logger->routes->attach(new Logger\Routes\FileRoute([
	'isEnable' => true,
	'filePath' => 'data/default.log',
]));
$logger->routes->attach(new Logger\Routes\DatabaseRoute([
	'isEnable' => true,
	'dsn' => 'sqlite:data/default.sqlite',
	'table' => 'default_log',
]));
$logger->routes->attach(new Logger\Routes\SyslogRoute([
	'isEnable' => true,
]));

$logger->info("Info message");
$logger->alert("Alert message");
$logger->error("Error message");
$logger->debug("Debug message");
$logger->notice("Notice message");
$logger->warning("Warning message");
$logger->critical("Critical message");
$logger->emergency("Emergency message");

<?php
namespace Logger;

use DateTime;
use Psr\Log\AbstractLogger;
use Psr\Log\LoggerInterface;

/**
 * Class Route
 */
abstract class Route extends AbstractLogger implements LoggerInterface
{
	/**
	 * @var bool Включен ли роут
	 */
	public $isEnable = true;
	/**
	 * @var string Формат даты логов
	 */
	public $dateFormat = DateTime::RFC2822;

	/**
	 * Конструктор
	 *
	 * @param array $attributes Атрибуты роута
	 */
	public function __construct(array $attributes = [])
	{
		foreach ($attributes as $attribute => $value)
		{
			if (property_exists($this, $attribute))
			{
				$this->{$attribute} = $value;
			}
		}
	}

	/**
	 * Текущая дата
	 *
	 * @return string
	 */
	public function getDate()
	{
		return (new DateTime())->format($this->dateFormat);
	}

	/**
	 * Преобразование $context в строку
	 *
	 * @param array $context
	 * @return string
	 */
	public function contextStringify(array $context = [])
	{
		return !empty($context) ? json_encode($context) : null;
	}
}