cloud image

Hi there
Thanks for the Video... https://www.youtube.com/watch?v=ey3sKdOmPa8

I have a question that how can i make a Linux Distro with Buildroot for cloud image (like openstack) because i can't use the output of buildroot in the openstack as an image! 
Please let me know if there is a way to do that?
is there a step i missed

Please let me know

Thanks
Best regards