Using a block with parameter_filter I discover that it is executed through Foreman::ParameterFilter::Context. However, none of the variants I’ve tried so far had any impact, :host_aliases_attributes stayed unpermitted.
With the latest revelations I found Compute resource plugin: Network compute attributes not passed, where @jbm wanted to do something very similar seven years ago. @iNecas explained how the remote execution Foreman plugin (rex) had to be updated regarding the :execution parameter on Nic::Interface. As for @jbm, applying the same solution to my situation made no difference, probably because :host_aliases_attributes isn’t a mere scalar parameter?
# ForemanCnames::Engine
Foreman::Plugin.register :foreman_cnames do
requires_foreman '>= 3.5.0'
parameter_filter ::Nic::Interface do |context|
context.permit(host_aliases_attributes: [])
end
end