Sets the format of the backing image file for a given drive.
The value of this configuration key is usually passed verbatim to image creation commands. It's worth noticing that QEMU has support for many formats, while Avocado-VT currently plays really well only with qcow2 and raw.
You can also use vmdk, but it's considered 'not supported', at least on image conversion tests.
To set the default image format:
image_format = qcow2
To set the image format for another image:
# Tests
variants:
- block_hotplug: install setup image_copy unattended_install.cdrom
images += " stg"
image_format_stg = raw
No other documentation currently references this configuration key.