metrics.php

<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**
 * Publicly accessible endpoint for displaying metrics
 *
 * @package     local_prometheus
 * @copyright   2023 University of Essex
 * @author      John Maydew <jdmayd@essex.ac.uk>
 * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

use local_prometheus\gatherer;

// phpcs:ignore moodle.Files.RequireLogin.Missing
require_once(__DIR__ . '/../../config.php');
require_once(__DIR__ . '/locallib.php');

global $DB, $CFG, $SITE;

$authtoken = get_config('local_prometheus', 'token');
$tokenauthenabled = !empty($authtoken);

$token = $tokenauthenabled
    ? optional_param('token', '', PARAM_BASE64)
    : required_param('token', PARAM_BASE64);

$timeframe = optional_param('timeframe', 60 * 5, PARAM_INT);

$cutoff = time() - $timeframe;

if ($tokenauthenabled && $token !== $authtoken) {
    http_response_code(403);
    exit;
}

header('Content-Type: text/plain');

$gatherer = new gatherer();

echo $gatherer->output($cutoff);