A new Salt Autosign via Grains procedure has been implemented and was already merged for Foreman Salt (https://github.com/theforeman/foreman_salt/pull/136) and Smart Proxy Salt (https://github.com/theforeman/foreman_salt/pull/136).

To enable the new procedure, changes to the Provisioning Template Snippet are necessary which includes calling the

@host.derive_salt_grains()

method to get the grains which shall be added to the minion configuration.