Telegram Bot as a centOS server monitor

I'm trying to mount a bot telegram to manage my centOS server.

I follow the example shown in this blog

https://blog.angelinux-slack.net/2017/01/28/usar-un-bot-de-telegram-como-monitor-de-servidores-linux/

I indicate to the telegram api where the server.php file is found

https://api.telegram.org/bot<token>/setwebhook?url=https://<url>.php

I give permissions in / etc / sudoers to give permission to the user where you put the bot (/ var / www / html).

apache ALL = NOPASSWD: /usr/sbin/csf
apache ALL = NOPASSWD: /scripts/cphulkdwhitelist
apache ALL = NOPASSWD: /bin/grep
apache ALL = NOPASSWD: /bin/ls
apache ALL = NOPASSWD: /bin/ping
apache ALL = NOPASSWD: /usr/bin/top
apache ALL = NOPASSWD: /usr/bin/whois

I add the file xxx.php to the path / var / www / html

<?php
# author          Horacio Romero Mendez (angelos)
# License         Copyleft 2017
# since           28 de enero de 2017 12:36:09
# version         1.0

define('BOT_TOKEN', '561737869:AAGaCcAri...');
define('API_URL', 'https://api.telegram.org/bot'.BOT_TOKEN.'/');

//OBTENER INFORMACION
$content = file_get_contents("php://input");
$update = json_decode($content, true);
$chatID = $update["message"]["chat"]["id"];
$text = $update['message']['text'];
$file = "$chatID/$chatID.txt";

if ($text == "")
    die();


//CREAR DIRECTORIO PARA ESTADOS
if (!file_exists($chatID)) :
    mkdir($chatID, 0700, true);
    fopen($file, 'w');
endif;


//COMANDOS
switch ($text):

    case "/apacheerrorlog":
        file_put_contents($file, '');
        $msg = shell_exec("tail /var/log/httpd/error_log");
    break;

    case "/eximsendmaillog":
        file_put_contents($file, '');
        $msg = shell_exec("/usr/bin/sudo grep cwd /var/log/exim_mainlog | grep -v /var/spool | awk -F\"cwd=\" '{print $2}' | awk '{print $1}' | sort | uniq -c | sort -n");
    break;

    case "/firewall":
        $status = "$text,0";
        file_put_contents($file, $status);
        $msg = "Escribe la ip que se pondrá en lista blanca";
    break;  

    case "/free":
        file_put_contents($file, '');
        $msg = shell_exec("free -m");
    break;

    case "/last":
        file_put_contents($file, '');
        $msg = shell_exec("last -20");
    break;

    case "/ls":
        $status = "$text,0";
        file_put_contents($file, $status);
        $msg = "Escribe la ruta a listar";
    break;  

    case "/ping":
        $status = "$text,0";
        file_put_contents($file, $status);
        $msg = "Escribe el dominio o IP";
    break;      

    case "/ps":
        $status = "$text,0";
        file_put_contents($file, $status);
        $msg = "Escribe el texto a filtrar en los procesos";
    break;  

    case "/start" : 
        file_put_contents($file, '');
        $msg = "Bienvenido a Linux Server Monitor";
    break;

    case "/top" : 
        file_put_contents($file, '');
        $msg = shell_exec("/usr/bin/sudo top -b -n 1 | head -n 15");
    break;

    case "/uptime":
        file_put_contents($file, '');
        $msg = shell_exec("uptime");
    break;

    case "/versions":
        file_put_contents($file, '');
        $cen = shell_exec("cat /etc/redhat-release");
        $des = shell_exec("ls -lct --time-style=+\"%F %T\" / | tail -1 | awk '{print $6, $7}'");
        $apa = shell_exec("/usr/sbin/apachectl -v | grep 'Server version:'");
        $php = phpversion();
        $mys = shell_exec("mysql -V");
        $msg = "S.O.: $cen $des";
        $msg.= "Apache: $apa";
        $msg.= "PHP: $php";
        $msg.= "\nMySQL: $mys";
    break;

    case "/w":
        file_put_contents($file, '');
        $msg = shell_exec("w");
    break;

    case "/whois":
        $status = "$text,0";
        file_put_contents($file, $status);
        $msg = "Escribe el dominio a buscar";
    break;

    default:
        //SI YA SE ESTÁ EJECUTANDO UN COMANDO
        $st = explode(",", file_get_contents($file));

        switch ($st[0]):

            case "/firewall":
                $ip = $text;
                if (!filter_var($ip, FILTER_VALIDATE_IP) === false) :
                    $csf = shell_exec("/usr/bin/sudo /usr/sbin/csf -a $ip Bot consoluciones");
                    $hulk = shell_exec("/usr/bin/sudo /scripts/cphulkdwhitelist $ip");
                    $msg = "CSF: $csf\n";
                    $msg.= "CPHulk: $hulk";
                else :
                    $msg = "$ip no es una IP válida";
                endif;
                $msg.= "\nPuede escribir otra IP";
            break;

            case "/ls":
                $msg = shell_exec("/usr/bin/sudo ls -lh $text");
                $msg.= "\nPuede escribir otra ruta a listar";
            break;

            case "/ping":
                $msg = shell_exec("/usr/bin/sudo ping $text -c 4");
                $msg.= "\nPuede escribir otro dominio o IP";
            break;

            case "/ps":
                $msg = shell_exec("ps aux | grep $text");
                $msg.= "\nPuede escribir otra palabra para filtrar";
            break;

            case "/whois":
                $msg = shell_exec("/usr/bin/sudo whois $text");
                $msg.= "\nPuede escribir otro dominio a buscar";
            break;
        endswitch;

    break;
endswitch;

$sendto =API_URL."sendmessage?chat_id=".$chatID."&text=".urlencode($msg);
file_get_contents($sendto);
?>

When I make any request in telegram I do not get any response from the server. Any idea that it may be wrong.

How could I verify that the bot is actually connecting to my centOS server? Some example hello world.