So far I only has little experience of using foreman to build a VMWare VM using iso image to build from
Deploy a VM(VMWare/OpenStack) starting from loading iso image is slow compare with pre-built VM template.
Can foreman build a VM using template to save build time ?
Expected outcome:
Be able to use pre-built VM template to save VM deployment time.
Yes, for VMware you have to create your template in VMware, then go to the Compute Resource in Foreman and register the template in Foreman which assigns it to a Operating System, then in the Create Host dialog you can chose the Template when selecting template-based installation.
Also have a look at the Provisioning guide for using cloud init and user data.
Openstack I have not used in Foreman, so no practical experience or tips for this compute resource, but it should in general be the same.