http://slides.liip.ch/static/2011-05-31_assetic/#14
Configuration options
assetic: debug: %kernel.debug% use_controller: false read_from: %kernel.root_dir%/../web write_to: %kernel.root_dir%/../web filters: lessphp: apply_to: "\.less$" file: %kernel.root_dir%/../vendor/lessphp/lessc.inc.php
use_controller:true in config_dev.yml
Different read and write for content distribution network (CND) apply_to to automatically apply filter to files