While installing Openstack on Ubuntu using http://docs.openstack.org/juno/install-guide/install/apt/content/sahara-install.html (http://docs.openstack.org/juno/instal...) ,I read this warning. So which all packages do I need to install?

You need to install the required packages. For now, sahara doesn't have packages for Ubuntu. Documentation will be updated once the packages are available. The rest of this document assumes that you have the sahara service packages installed on the system.