We are migrating a big website to Varnish (putting Varnish in front of Apache), but we would like to use ESI tags even without Varnish (in local development setups, for example).
Does exists an Apache module for that?
I haven't found nothing useful or clear on the internet.
There are frameworks with ESI support. The one I know by hand is the PHP framework Symfony2 but I have seen it in some other framework as well (unsure if that was even PHP).
But to get a good local environment for testing it would be better to get a proper vagrant setup - in which you just write provisioning for varnish as well. Once the provisioning is done it's just one simple command to get the whole development environment up. Use Chef or Puppet for provisioning and you have apache, varnish etc almost ready for usage.