Set the default size for new Docker for Mac disk images
UPDATE: The instructions here are no longer necessary! Resizing the disk image is now possible right from the UI since Docker for Mac Version 17.12.0-ce-mac49 (21995).
If you are getting the error:
No space left on device
Configuring the qcow2 size cap is possible in the current versions:
# my disk is currently 64GiB