I have been trying to preseed config files for a set of servers we have
just bought. Since I do not want either the root password (even hashed)
in the config file or any user-interaction on these (headless) machines,
I would like to disable both the root password and not create a user.
Access is enabled by late_command which installs an ssh public key to
/root/.ssh/authorized_keys.

The documentation (at
http://www.debian.org/releases/stable/i386/apbs04.html.en) says:

   "The passwd/root-password-crypted and passwd/user-password-crypted
   variables can also be preseeded with ?!? as their value. In that
   case, the corresponding account is disabled. This may be convenient
   for the root account, provided of course that an alternative method
   is setup to allow administrative activities or root login (for
   instance by using SSH key authentication or sudo)"

However, a preseed file containing:
   d-i passwd/make-user boolean false
   d-i passwd/root-password-crypted string !
or:
   d-i passwd/make-user boolean false
   d-i passwd/root-login boolean false

still prompts for either the root password or creation of a user. This
would appear to be deliberate because user-setup-ask contains:

      db_get passwd/root-login
      if [ "$RET" = false ]; then
         # always make non-root user; this user will be able
         # to sudo to root
         db_set passwd/make-user true

and

         db_get passwd/root-password-crypted || true
         if ! test "$RET" || [ "x$RET" = "x!" ]; then
            # No preseed of the root password hash
            # we will prompt the user

This, however, is not what the documentation claims or what would be
useful in this case.

I have currently solved the problem by using the following preseed:

   d-i passwd/make-user boolean false
   d-i passwd/root-password-crypted string !!

but it would better if the actual implementation matched the
documentation and if the situation I would like were supported.

As an additional wishlist item; user-setup could do the preseeding of
ssh public keys for users or root itself and therefore explicitly
support this case. No patch yet; maybe if I have time.

Matt

creating i386 live-system with live-helper results in system with no user
account and locked root account.

During startup the script user-setup-apply gives the message
" chpasswd: invalid option -- 'e' "

it is working with
36c36,37
< 	$chroot $ROOT chpasswd $OPTS <<EOF
---

Hi,

So has anybody ever found a solution to this? I'm still in the same boat 7
years later with 1.48 of user-setup on ubuntu 14.04. The work-around using
!! kind of works but means that the emergency recovery mode in Ubuntu
mistakenly thinks that root has a password set and prompts for one which
makes it rather useless in an emergency.

Cheers,
Seb

Quoting Sebastian Unger (sebunger44@gmail.com):

Thanks for bringing back this issue.

I suspect that actually nobody felt like implementing this (which would
indeed require another pressedable variable) mostly because
(speculation here) we consider this to be a corner case that can be
solved by alternative methods.

And then the issue fell under the radar of everybody (the installer
team desperately needs people to help triaging bugs)

The documentation is indeed unclear more than wrong: it lets you think
that you can preseed the locked root password *and* not have a regular
user created,; which is not the case. Your (interesting) workaround
could however be documented in the installation manual, though.