I would like to create a glance image from a running nova instance, and am able to do so with
nova image-create instance-id new-image-name
However, the created image is huge. It appears to be the same size as the disk from the instance's flavor (~150gb) instead of close to the size of the instance's original image (2-3gb).
I found some documentation that seems to have a warning about creating images without associated kernel and ramdisk images not being resizable on boot, but I'm not sure how to I would go about creating an image from and existing instance that has associated kernel and ramdisk images.