CloudWatchFormatter for Monolog

CloudWatchFormatter.php

<?php

namespace YourBundle\OwnNamespace\Monolog\Formatter;

use Monolog\Formatter\NormalizerFormatter;

/**
 * Class CloudWatchFormatter
 * @author Chris Bednarczyk <bordeux>
 * @package YourBundle\OwnNamespace\Monolog\Formatter
 */
class CloudWatchFormatter extends NormalizerFormatter
{
    /**
     * @var string the name of the system for the Logstash log message, used to fill the source field
     */
    protected $systemName;

    /**
     * @var string an application name for the Logstash log message, used to fill the type field
     */
    protected $applicationName;

    /**
     * @var string a prefix for 'extra' fields from the Monolog record (optional)
     */
    protected $extraPrefix;

    /**
     * @var string a prefix for 'context' fields from the Monolog record (optional)
     */
    protected $contextPrefix;


    /**
     * CloudWatchFormatter constructor.
     * @param $applicationName
     * @param null $systemName
     * @param null $extraPrefix
     */
    public function __construct(
        $applicationName,
        $systemName = null,
        $extraPrefix = null,
        $contextPrefix = 'ctxt_'
    )
    {
        parent::__construct('Y-m-d\TH:i:s.uP');

        $this->systemName = $systemName ?: gethostname();
        $this->applicationName = $applicationName;
        $this->extraPrefix = $extraPrefix;
        $this->contextPrefix = $contextPrefix;
    }


    /**
     * {@inheritdoc}
     */
    public function format(array $record)
    {
        $message = $this->formatToJson(
            parent::format($record)
        );

        return $message['timestamp'].' '.$this->toJson($message) . "\n";
    }


    /**
     * @param mixed[] $record
     * @return mixed[]
     * @author Chris Bednarczyk <chris@tourradar.com>
     */
    protected function formatToJson(array $record)
    {
        if (empty($record['datetime'])) {
            $record['datetime'] = gmdate('c');
        }
        $message = array(
            'timestamp' => $record['datetime'],
            'source' => $this->systemName,
            'fields' => array(),
        );
        if (isset($record['message'])) {
            $message['message'] = $record['message'];
        }
        if (isset($record['channel'])) {
            $message['tags'] = array($record['channel']);
            $message['fields']['channel'] = $record['channel'];
        }
        if (isset($record['level'])) {
            $message['fields']['level'] = $record['level'];
        }
        if ($this->applicationName) {
            $message['type'] = $this->applicationName;
        }
        if (isset($record['extra']['server'])) {
            $message['source_host'] = $record['extra']['server'];
        }
        if (isset($record['extra']['url'])) {
            $message['source_path'] = $record['extra']['url'];
        }
        if (!empty($record['extra'])) {
            foreach ($record['extra'] as $key => $val) {
                $message['fields'][$this->extraPrefix . $key] = $val;
            }
        }
        if (!empty($record['context'])) {
            foreach ($record['context'] as $key => $val) {
                $message['fields'][$this->contextPrefix . $key] = $val;
            }
        }

        return $message;
    }

}