log in as root without specifying password on Openstack instance?

When I did some KVM testing, I could set up ssh so that I didn't have to enter the password. Is there something like that I could do for these Openstack instances? I suppose if I never delete the instances then I could do the same thing, but I don't think that's the normal use-case scenario for openstack instances - is it?

I've created an image that has some software on it that I need to run as root. The root user has a password.

I'm able to launch an instance based on this image but when I specify the keypair file on the ssh command, it still asks me for root's password. Is there a way to get around this?

I thought using the keypair was supposed to allow for password-less login to the instance.

I just saw on this site that it says I need to use cloud-init(?). That's not mentioned in the getting started guide. It also says not to specify the keypair if an image has a static password for root.

Any pointers are appreciated,
Dave