Where is /var/lib/docker on Mac/OS X
As mentioned in the above answers, you will find it in:screen ~/Library/Containers/com.docker.docker/Data/vms/0/tty
Once you get the tty running you can navigate to /var/lib/docker
The other answers here are outdated if you're using Docker for Mac.
Here's how I was able to get into the VM. Run the command:
screen ~/Library/Containers/com.docker.docker/Data/vms/0/tty
This is the default path, but you may need to first do:cd ~/Library/Containers/com.docker.docker/Data/vms
and then ls to see which directory your VM is in and replace the "0" accordingly.
When you're in, you might just see a blank screen. Hit your "Enter" key.
This page explains that to exit from the VM you need to "Ctrl-a" then "d"
See this answer
When using Docker for Mac Application, it appears that the containers are stored within the VM located at:
~/Library/Containers/com.docker.docker/Data/com.docker.driver.amd64-linux/Docker.qcow2