PHP to delete EBS snapshots in a rolling window

gistfile1.php

<?php
date_default_timezone_set('UCT');

require '/usr/share/pear/AWSSDKforPHP/aws.phar';

use Aws\Ec2\Ec2Client;

$daysToSave = 14; // set this to the number of days to keep

$zone = '<zone>';

$aws_creds = array(
    'key' => '<key>',
    'secret' => '<secret>',
    'region' => $zone
);

$client = Ec2Client::factory($aws_creds);

$result = $client->describeSnapshots(array(
    'DryRun' => false,
    'Filters' => array(
        array(
            'Name' => 'description',
            'Values' => array('auto-*'), //search for any snapshot starting with auto-
        )
        
    )
));

$snapshots = $result->get('Snapshots');

foreach ($snapshots as $snapshot){
        $snaptime = strtotime($snapshot['StartTime']);
        $delete_time = time() - ($daysToSave * 24 * 3600);
        if ($snaptime >= $delete_time) {   
            echo "keep " . $snapshot['SnapshotId'] . "\n";;
        } else {
            $result = $client->deleteSnapshot(array(
                'DryRun' => false,
                'SnapshotId' => $snapshot['SnapshotId'],
            ));
            echo "delete " . $snapshot['SnapshotId'] . "\n";

        }
}

See also creating automated snapshots:
https://gist.github.com/chrissiefken/bdda397583416cd59547