count should be moved to group, not be in template

Templates is not a real key in the final config, all the names defined in templates get expanded before analyzing the config. Ex:

templates:
  mycfengine: 
    version: 3.27.0

groups:
  - myhub:
      role: hub
      cfengine: mycfengine

Gets turned into:

groups:
  - myhub:
      role: hub
      cfengine: 
        version: 3.27.0

Also, I believe it makes sense to have "count" inside "spawn", Ex:

groups:
 - client1:
      role: client
      source:
        count: 4
        mode: spawn
        spawn:
          provider: vagrant
          vagrant:
            box: ubuntu/focal64
 
  - client2:
      role: client
      source:
        # count: 4. Here count doesn't make sense, because we have saved hosts
        mode: save
        hosts: [ 8.8.8.8 ]

Okay, but:

1. You say that templates are not "real" keys, but I still think we should show examples that make sense to us and are useful for users. Thus, can you adjust the example to where you use a template to specify the provider and and box name, but you don't specify count inside the template, instead the normal case would be to specify this in the group.
2. In your first example there, what decides that mycfengine should be expanded as a template? Is it just based on the fact that the string happens to be matching the name of a template?
3. I agree that it doesn't make sense to include count there when you have hosts. count should always be the length of hosts in that case.

In your first example there, what decides that mycfengine should be expanded as a template? Is it just based on the fact that the string happens to be matching the name of a template?

Yes, exactly. We iterate through all the defined groups, and check if values match with one of the defined template name. If they do match, the value is replaced with the template

Unused function?

It is not used for now but it will be used later. It's a getattr that doesn't throw an exception if one of the keys is missing. Ex: rgetattr(obj, "source.spawn.provider")