protected function loadExternalConfig()
    {
        $config = new Repository(static::getDefaultConfig());
        $filesystem = new Filesystem();

        foreach ($this->getConfigFiles($filesystem) as $filename) {

            $this->output->writeln("<info>Reading config from <path>{$filename}</path></info>");

            if ($filesystem->extension($filename) == 'php') {
                $configValues = $filesystem->getRequire($filename);
            } else {
                $configValues = Yaml::parse($filesystem->get($filename));
            }

            $config->set(array_dot($configValues));
        }

        $this->container->instance('config', $config);
    }