Linode Kernel version alerting.

kernel-checker.php

<?php
/*
 * Linode Kernel Version alerter. 
 * 
 * Fetches a list of the available Linode kernels and alerts you if
 * your currently running version is out of date.
 *
 * Crontab: * 23 * * php /path/to/this/script
 * @author Gareth Jones
*/

$kernels = new LinodeKernelList();
$thisKernel = php_uname('r');
$thisArch   = php_uname('m');

if ("x86_64" == $thisArch) {
    $latestKernel = $kernels->getLatest64Bit();
} else {
    $latestKernel = $kernels->getLatest32Bit();
}

if (!strstr($thisKernel, 'linode')) {
    echo "You don't appear to be running a Linode Kernel: " . $thisKernel . PHP_EOL;
    exit(1);
}
if (!strstr($thisKernel, $latestKernel)) {
    echo 'Your Kernel appears to be out of date' . PHP_EOL;
    echo 'Current: ' . $thisKernel .   PHP_EOL;
    echo 'Latest:  '  . $latestKernel . PHP_EOL;
}



class LinodeKernelList
{
    private $kernels;
    private $latest32bit;
    private $latest64bit;
    private $rawFeed;

    public function __construct($feedUrl = "http://www.linode.com/kernels/rss.xml")
    {
        $this->kernels = array();
        $this->rawFeed = @file_get_contents($feedUrl);
        if ($this->rawFeed == false) {
            throw new \Exception('Unable to get the Linode Kernels RSS feed.');
        }
        $this->parseFeed();
    }

    public function getLatest32Bit()
    {
        return $this->latest32bit;
    }

    public function getLatest64Bit()
    {
        return $this->latest64bit;
    }

    public function getAll()
    {
        return $this->kernels;
    }

    private function parseFeed()
    {
        $xml = simplexml_load_string($this->rawFeed);
        foreach ($xml->channel->item as $item) {
            $title = (string) $item->title;
            if (strstr($title, 'Latest 32')) {
                $title = $this->parseLatest($title);
                $this->latest32bit = $title;
            } elseif (strstr($title, 'Latest 64') ) {
                $title = $this->parseLatest($title);
                $this->latest64bit = $title;
            }
            if (strstr($title,'x86_64')) {
                $this->kernels['64 bit'][] = $title;
            } else {
                $this->kernels['32 bit'][] = $title;
            }
        }
    }

    // Latest kernels are listed as:
    // "Latest 32 bit (3.6.5-linode47)"
    // "Latest 64 bit (3.6.5-x86_64-linode28)"
    private function parseLatest($title)
    {
        $res = preg_match('/(?<=\()(.+)(?=\))/is', $title, $matches);

        return $matches[0];
    }
}