The issue is that boot2docker doesn’t support

-v /Users/mattes/project1:/data/project1 out of the box since it doesn’t include VirtualBox Guest Additions. It’s still unclear to me, if the VirtualBox Guest Additions will make it into boot2docker any time soon/ ever.

“we’re making boot2docker as simple and small as possible — so at this point, adding tools that are not relevant to all usecases (bare HW, vbox, vagrant, hyper-v, vmware, kvm, etc) is not on the plan. This may change in future, but we havn’t completed our original feature set yet.”

SvenDowideit (boot2docker repo owner) commented on May 30 (link)

Though, there is a pull request to include VB guest additions, see https://github.com/boot2docker/boot2docker/pull/284

So I tried to built my own custom boot2docker.iso following the steps from the pull request above. I ran into a lot of issues and problems, so I thought it would be nice to document the steps that worked out for me.

Prerequisites: The following assumes you already have boot2docker installed. If not, follow http://docs.docker.com/installation/mac and use the Docker OSX Installer. Or use brew: