My Spark set up is a cluster on top of mesos using docker containers.
I want to pull the docker images from a private repository (currently gcr.io),
and I can't get the authentication to work.

I know how to generate a .dockercfg file  (running on GCE, using gcloud docker -a).
My problem is that as far as I understand I need this file in the root directory of the executor dir and I can't find a way to make spark executor to pull this file (not without changing spark code).

Am I missing something?
It seems that spark do support mesos+docker so I wonder what other people with this setup are doing?