What are the components of ovirt api for creating the VM

Question

I am using the oVirt API, I am checking into the ovirt documentation,

It has the following as payload,

<vm>
  <name>myvm</name>
  <template>
    <name>Blank</name>
  </template>
  <cluster>
    <name>mycluster</name>
  </cluster>
</vm>

1) What is the difference between template and cluster?

I can understand that template - It is a configuration which we can set and apply for multiple vm's but What is cluster?

2) Is it necessary to use the template and cluster in using createVM rest API in ovirt?

3) Can't we create a vm without specifying the template and cluster?

Answer 1

Template is the template this VM has been derived from. You can take a working VM, save it as a template and then create new VMs based on this one - the new VMs will be clones or snapshots of the template, with the same properties. For new VMs the template is called "Blank" since they aren't based on any template.

Cluster is the host cluster/migration domain the VM belongs to, it can only run on the hosts that belong to the same cluster and can only migrate between the hosts in the same cluster.

IIRC template isn't necessary, blank will be selected unless you specify otherwise. Cluster is required, for the system to know where to place the VM.