Lots of extra testing reveals the following:
I am basically following the procedure described here: How-to: Samba Homes and Shares - Basics
I have an NFS share on a member server created via domain/shares, exporting for both Samba and NFS. Both are also visible and usable manually, for read and write access.
I then put /home/[username] (/home/testuser in this case) into the /user/account/posix section of the user account data (#1 from the top post), select the NFS share created above from the drop-down menu for the home share (#2) and add testuser into the (relative) home-share path (#3).
But it just doesn’t work as expected.
When I log in (putty session or just a plain su - testuser from a member server), a matching (name and ownership) directory is created on the NFS share for a new user added and the home directory is created and filled with some basic config data, while the NFS directory remains empty.
Evidently the two simply aren’t tied together, the NFS isn’t mounted where #1 is pointing. I can (as root) manually mount the NFS share to that home directory, effectivaly hiding the auto-created profile data within it, but it’s not happening at login.
I have no idea if it’s some race condition (NFS export is synchronous, if anyone should wonder), or a logic issue in the /usr/sbin/univention-mount-homedir which seems to be responsible for the magic under the roof.
I have a CS master, but I started IT 45 years ago and never got around programming in Python: I’d have to see full traces or debug to understand what’s going wrong, the code and logs alone aren’t geving me enough information and I can’t see any trace of any outright failure.
But I did notice, that while #1 (the home directory) isn’t allowed to be empty when home share and home path are used, its actual content seems to be ignored or overrriden elsewhere.
I had mounted the NFS share on /roam and then put /roam/jdoe into home directory (#1) to see if it made any difference, only to have /home/jdoe created on the member server…
At this point I no longer think I am doing anything wrong, but that there is either an outride bug or same odd side effect at play.
Testing is made a bit more confusing by (unconfirmed) fact that just changing the various paths in user configuration and deleting the created directories doesn’t seem to trigger their recreation. Some data seems to be cached somewhere which means I really have to create a new user for very debugging attempt…
What’s really needed is some theory of operation documentation, which explains how those fields correlate and what is supposed to happen there in the background. Or a bug fix…