AWS OpsWorks app layer: environment variables not accessible from PHP app

I love the services AWS is offering. I'm using OpsWorks to deploy my PHP apps, but I can't access any environment variables from the php app, to securely connecting to the databases. Neither with genenv and not with $_SERVER.

I've found the following question about this topic: Set environment variables with AWS Opsworks, but I can't imagine this is the way to go..

Can anybody tell me how I can access those environment variables?

Thanks in advance.

Cheers.