muzich/vendor/bundles/Symfony/Bundle/AsseticBundle/Resources/config/filters/sprockets.xml

<?xml version="1.0" ?>

<container xmlns="http://symfony.com/schema/dic/services"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">

    <parameters>
        <parameter key="assetic.filter.sprockets.class">Assetic\Filter\SprocketsFilter</parameter>
        <parameter key="assetic.filter.sprockets.lib">null</parameter>
        <parameter key="assetic.filter.sprockets.ruby">%assetic.ruby.bin%</parameter>
        <parameter key="assetic.filter.sprockets.asset_root">%assetic.write_to%</parameter>
        <parameter key="assetic.filter.sprockets.include_dirs" type="collection" />
    </parameters>

    <services>
        <service id="assetic.filter.sprockets" class="%assetic.filter.sprockets.class%">
            <tag name="assetic.filter" alias="sprockets" />
            <argument>%assetic.filter.sprockets.lib%</argument>
            <argument>%assetic.filter.sprockets.ruby%</argument>
            <call method="setAssetRoot"><argument>%assetic.filter.sprockets.asset_root%</argument></call>
        </service>
    </services>
</container>