Unable to set up remote interperter on docker

Hi

I have the latest Idea (2017.1.5) and I've installed the docker plugin and php docker plugin.

I've tried to set up CLI iterpeter but it fails, when I look at the examples and documentation, there seems to be an option to set up mapping, which I don't have for some reason (?)

I've checked the docker that was lunched by Idea and seems the IDE adds a mapping from the root folder to '/opt/project', however, I need a different location and I don't know how I can configure it.

It also causes a failure in the detection since I have a php_prepend which obviously now isn't even mapped into the container

Thanks