Currently, if using parameterized classes with theforeman, you can't modify the params at the "domain" or "os" level.

I'd love to see foreman support overriding class parameters at each of the places where you can override global params, as it's currently inconsistent.

In our current setup, we use hostgroups, and apply classes to the hostgroups. We then override the params at the "domain" level, which allows it to effectively apply for all hosts within a specific datacenter for things like NTP servers. Currently, this isn't possible unless we rewrite the module to support global params instead of parameterized classes.