During Pike upstream, we made some enhancements to how you can pre-configure the agents on pre-provisioned nodes in TripleO. Those changes are documented in this upstream patch: https://review.openstack.org/#/c/481339/ We need to update the director docs as well with these changes. *However*, that should be done only if we have sufficient time to QE these changes, which is why this doc bog is blocked by the bug tracking the QE effort.
Discussed this with James in late Jan. He recommended this feature remain undocumented due to a lack of testing. In addition, this feature is not used for OSP14+ due to the switch to config-download.