File: vendor/symfony/symfony/src/Symfony/Bundle/FrameworkBundle/Resources/config/esi.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="esi.class">Symfony\Component\HttpKernel\HttpCache\Esi</parameter>
        <parameter key="esi_listener.class">Symfony\Component\HttpKernel\EventListener\SurrogateListener</parameter>
    </parameters>

    <services>
        <service id="esi" class="%esi.class%" />

        <service id="esi_listener" class="%esi_listener.class%">
            <tag name="kernel.event_subscriber" />
            <argument type="service" id="esi" on-invalid="ignore" />
        </service>
    </services>
</container>