While the installation experience of Docker for Mac is very good, the unfortunate downfall of the project is they try to hide what is really going on. You are running a VM and through a series of very clever tricks and fancy technology they attempt to make the VM hidden as though you are running Docker local (like in Linux). This has the side effect of odd behaviors. As a result in my own projects we struggle to support Docker for Mac also.
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)
