The SSH key is sent to CloudStack by API. When a VM is launched, CloudStack will push the public key to the virtual router. When the VM boots, it will pull the key from the virtual router and place it in /root/.ssh/authorized_keys. Note, that like the password management script, there's also a script that needs to be installed on the template that will pull the SSH key from the virtual router. See the SSH KeyGen Script section of the download page - http://www.cloudstack.org/download.html

There's also a fairly good blog about this here: http://chriskleban-internet.blogspot.com/2012/03/build-cloud-cloudstack-instance.html

Edited by: davidnol on Jul 18, 2012 8:25 PM