code: public function register(Application $app)
      {
          if (is_null($this->filename)) {
              throw new \RuntimeException('You must provide a valid config filename');
          }
          if (!file_exists($this->filename)) {
              throw new \RuntimeException(sprintf('Config path \'%s\' is not valid', $this->filename));
          }
          if (!is_readable($this->filename)) {
              throw new \RuntimeException(sprintf('Config path \'%s\' is not readable', $this->filename));
          }
          $parser = new YamlParser();
          $config = $parser->parse(file_get_contents($this->filename));
          if (is_array($config) && !empty($config)) {
              if (isset($app['config']) && is_array($app['config'])) {
                  $config = array_replace_recursive($app['config'], $config);
              }
              $app['config'] = $config;
          }
      }
docs: Register this provider.
  
  @param Silex\Application $app
  
  @author Ronan Chilvers <ronan@d3r.com>