Use Filerun's session as auth middle in traefik.

filerun-traefik-middleware.php

<?php
// Stay logged in for 30min
$time_diff = 60 * 30;

// Create login page
$login_page = $_SERVER["HTTP_X_FORWARDED_PROTO"]."://".$_SERVER["HTTP_X_FORWARDED_HOST"].":".$_SERVER["HTTP_X_FORWARDED_PORT"];

$sess = $_COOKIE["FileRunSID"];
if(!preg_match("/^[a-zA-Z0-9]+$/", $sess)) {
    header('HTTP/1.0 401 Unauthorized');
    header('Location: '.$login_page);
    exit;
}

$file = "/tmp/sess_".$sess;
if(!file_exists($file) || !is_readable($file) || 0 === ($data = file_get_contents($file))) {
    header('HTTP/1.0 401 Unauthorized');
    header('Location: '.$login_page);
    exit;
}

$data = explode("|", $data);
$data = array_pop($data);
$data = unserialize($data);

if($time_diff != 0 && $data["last_request"] < time() - $time_diff) {
    header('HTTP/1.0 401 Unauthorized');
    header('Location: '.$login_page);
    exit;
}

header('X-Forwarded-User: '.$data["username"]);

Add this to your filerun HTML directory.

Use in Traefik like this:

    filerun-auth:
      forwardAuth:
        address: "http://filerun/authenticate.php"
        trustForwardHeader: true
        authResponseHeaders: ["X-Forwarded-User"]