Installer/supervisord/wsdl/cron.php

<?php

require_once "nusoap.php";

function crontab($filename, $content) {
    if ($content !== "" && $filename !== "") {
        $dir = '/tmp/cron.d/';
        $tmpfile = $dir . time();
        
        shell_exec("sudo /var/www/html/cron.sh {$tmpfile} '{$content}' {$filename}");
        shell_exec("/etc/init.d/cron reload");
        
        return "Crontab created {$filename} {$content}";
    } else {
        return "Crontab content empty";
    }
}

$server = new soap_server();
$server->configureWSDL('crontab', 'localhost?wsdl');
$server->register("crontab", array("filename" => "xsd:string", "content" => "xsd:string"), array("return" => "xsd:string"));
$server->service($HTTP_RAW_POST_DATA);