AppExtension.php

<?php

class AppExtension extends CompilerExtension
{
    public function loadConfiguration()
        {
            $builder = $this->getContainerBuilder();
            $builder->addDefinition('service.routerFactory')
                ->setClass('Modules\RouterFactory') // YOUR ROUTER FACTORY CLASS
                ->addTag(Flame\Modules\ModulesExtension::TAG_ROUTER); // DONT FORGET TO ADD THE TAG!
        }
}