Loyen / php-fastcgi-xdebug-test

Test $_SERVER vs filter_input discrepancy

Test $_SERVER vs filter_input discrepancy

This repository was created to show that $_SERVER and filter_input() (or filter_input_array) with type INPUT_SERVER differs when xdebug is enabled.

The test is setup using docker and docker compose. Once you have it installed, you can run run.sh and it will start two containers:

1. app: A PHP container with FPM and xdebug (image built will be found as local/php:8-fpm-xdebug)
2. loadbalancer: An nginx container which always forwards the header FOO=BAR

The test then sends a request to a page that simply outputs the value of $_SERVER['FOO'] and filter_input(INPUT_SERVER, 'FOO') in JSON format, once where xdebug.mode=off and another where xdebug.mode=develop.

When xdebug.mode=off you should see the output of both lines match:

{
    "$_SERVER": "BAR",
    "filter_input": "BAR"
}

However when xdebug.mode=develop you will see filter_input return null:

{
    "$_SERVER": "BAR",
    "filter_input": null
}