app/Core/Log/File.php

<?php

namespace Kanboard\Core\Log;

use RuntimeException;

/**
 * File Logger
 *
 * @package Kanboard\Core\Log
 * @author  Frédéric Guillot
 */
class File extends Base
{
    /**
     * Filename
     *
     * @access protected
     * @var string
     */
    protected $filename = '';

    /**
     * Setup logger configuration
     *
     * @param string $filename Output file
     */
    public function __construct($filename)
    {
        $this->filename = $filename;
    }

    /**
     * Logs with an arbitrary level.
     *
     * @param mixed  $level
     * @param string $message
     * @param array  $context
     */
    public function log($level, $message, array $context = array())
    {
        $line = $this->formatMessage($level, $message, $context);

        if (file_put_contents($this->filename, $line, FILE_APPEND | LOCK_EX) === false) {
            throw new RuntimeException('Unable to write to the log file.');
        }
    }
}