dbal_service_single_connection.xml

<?xml version="1.0" ?>

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

    <config>
        <dbal default-connection="mysql">
            <connection
                name="mysql"
                dbname="mysql_db"
                user="mysql_user"
                password="mysql_s3cr3t"
                unix-socket="/path/to/mysqld.sock" /><!--  -->
        </dbal>
    </config>
</srv:container>