simple_silex_config.php

<?php
class Config
{
    /**
     * @var string
     */
    private $root;
    public function __construct(string $root)
    {
        $this->root = $root;
    }
    public function configure(\ArrayAccess $app, string $env = null)
    {
        if (empty($env)) {
            $env = getenv('APP_ENV') ?: 'prod';
        }
        $config = array_merge(
            $this->getDefaultConfig(),
            $this->getConfig($env)
        );
        $secure_json = $config['secure_json'];
        if ($secure_json && file_exists($secure_json)) {
            $config = array_replace_recursive(
                $config,
                json_decode(file_get_contents($secure_json), true)
            );
        }
        $app['config'] = $config;
        $app['env'] = $env;
        foreach ($config['application'] as $key => $val) {
            $app[$key] = $val;
        }
        array_map(
            function (string $service) use ($app) {
                include $service;
            },
            $config['services']
        );
    }
    protected function getConfig(string $env): array
    {
        $path = "{$this->root}/{$env}.php";
        if (file_exists($path)) {
            return include $path;
        }
        throw new \InvalidArgumentException("Nonexistent environment: $env");
    }
    protected function getDefaultConfig(): array
    {
        return [
            'secure_json' => false,
            'services'    => [],
            'application' => [],
        ];
    }
}