using .env files and basic rewrite with the built-in php server

.env

# add your env variables
DATABASE_HOST='127.0.0.1'
DATABASE_USER='root'
DATABASE_PASS='root'
DATABASE_NAME='database_name'

.router

# place this in your /public folder
if (!isset($_SERVER['DATABASE_HOST'])) {
    $lines = file("../.env");
    foreach ($lines as $line) {
        if (strpos($line, "#") === false && strpos($line, "=") !== false) {
            $vars = explode("=",$line);
            $_SERVER[$vars[0]] = preg_replace("/'/", '', trim($vars[1]));
        }
    }
}

if (file_exists(__DIR__ . '/' . parse_url($_SERVER["REQUEST_URI"], PHP_URL_PATH))) {
    return false;
} else {
    include_once 'index.php';
}

server.sh

#!/bin/bash

# place this in your project root
# running `server` in the termial fires things up
pushd public > /dev/null
  php -d variables_order=EGPCS -S localhost:9000 .router
popd