To use a non-default URL for downloading base cloud images, use the environment variable DIB_CLOUD_IMAGES

To download a non-default release of cloud images, use the environment variable DIB_RELEASE

Alternatively, set DIB_LOCAL_IMAGE to the local path of a qcow2 cloud image. This is useful in that you can use a customized or previously built cloud image from diskimage-builder as input. The cloud image does not have to have been built by diskimage-builder. It should be a full disk image, not just a filesystem image.