Yeah, this is my favourite:
screen ~/Library/Containers/com.docker.docker/Data/com.docker.driver.amd64-linux/tty
Oh you can just login as passwordless root to the VM, then you know, access the mounted fs which is your root fs. Insane.
/ # uname -a
Linux moby 4.9.4-moby #1 SMP Wed Jan 18 17:04:43 UTC 2017 x86_64 Linux
/ # mount | grep osxfs
osxfs on /Users type fuse.osxfs (rw,nosuid,nodev,relatime,user_id=0,group_id=0,allow_other,max_read=1048576)
osxfs on /Volumes type fuse.osxfs (rw,nosuid,nodev,relatime,user_id=0,group_id=0,allow_other,max_read=1048576)
osxfs on /tmp type fuse.osxfs (rw,nosuid,nodev,relatime,user_id=0,group_id=0,allow_other,max_read=1048576)
osxfs on /private type fuse.osxfs (rw,nosuid,nodev,relatime,user_id=0,group_id=0,allow_other,max_read=1048576)
osxfs on /host_docker_app type fuse.osxfs (rw,nosuid,nodev,relatime,user_id=0,group_id=0,allow_other,max_read=1048576)
