Fat-Free Framework + Environment Variables in configuration files

config.ini

[globals]
foo=bar
baz={{@foo}}
ENV_VALUE={{ getenv('ENV_VALUE') }}

test.php

<?php

require_once __DIR__ . '/../../fatfree-core/base.php';

$f3 = Base::instance();
$f3->config('config.ini', true);

$t = new Test;

$t->expect('bar' === $f3->foo, "Static value");
$t->expect('bar' === $f3->baz, "Dynamic value based on a static value");
$t->expect(123 === $f3->ENV_VALUE, "Environment value");

foreach ($t->results() as $result) {
    printf('Test "%s": %s' . "\n", $result['text'], $result['status'] ? 'PASS' : 'FAIL');
}

test.sh

ENV_VALUE=123 php test.php