Monolog handler for Slack's (new?) incoming webooks

MonologSlackHandler.php

class MonologSlackHandler extends \Monolog\Handler\MailHandler {
    protected $hook_url;
    protected $channel;
    protected $username;
    protected $icon;

    /**
    * @param string $hook_url  The URL of your incoming web hook (e.g.
    *                          https://hooks.slack.com/services/$token)
    * @param string $channel   Slack channel to post in (with leading # sign)
    * @param string $username  Username you'd like to display message as
    * @param string $icon      URL to custom icon
    */
    public function __construct(
        $hook_url, $channel, $username, $icon,
        $level = \Monolog\Logger::ERROR, $bubble = true)
    {
        parent::__construct($level, $bubble);
        $this->hook_url = $hook_url;
        $this->channel = $channel;
        $this->username = $username;
        $this->icon = $icon;
    }

    /**
    * Post the message to Slack using CURL
    */
    protected function send($content, array $records) {
        $ch = curl_init();
        curl_setopt($ch, CURLOPT_URL, $this->hook_url);
        curl_setopt($ch, CURLOPT_HEADER, 0);
        $payload = json_encode(
            array(
                "channel" => $this->channel,
                "username" => $this->username,
                "text" => $content,
                "icon_emoji" => $this->icon
            )
        );
        curl_setopt($ch, CURLOPT_POSTFIELDS, $payload);
        // supress output
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch, CURLOPT_VERBOSE, 0);
        curl_exec($ch);
        curl_close($ch);
    }
}