Hello,
After cloning virtual machines, I want to reconfigure packages in a
fully automated fashion. In short, I've tried using
"debian-set-selections" followed by "dpkg-reconfigure -f
noninteractive", but it isn't actually changing the configuration.
Here's a concrete example.
Suppose I have installed postfix, preseeded in a particular way, then I
want to reconfigure it for a new hostname. If I do the following
interactively:
dpkg-reconfigure -p high postfix
then everything is fine: I get prompted with dialogs for the new mail
server configuration type and mailname, and then the relevant files get
updated and written out.
root@foo1:~# dpkg-reconfigure -p high postfix
* changing /etc/mailname to foo2.lxd**
** setting myorigin**
** setting relayhost:**
** setting inet_interfaces: all*
*Postfix is now set up with the changes above.* If you need to make
changes, edit
/etc/postfix/main.cf (and others) as needed. To view Postfix
configuration
values, see postconf(1).
...
Now I want to do this in a non-interactive script. So I try:
root@foo1:~# debconf-set-selections <<EOS
> postfix postfix/mailname string foo3.lxd
> EOS
root@foo1:~# dpkg-reconfigure -f noninteractive postfix
* Postfix configuration was untouched.* If you need to make changes,
edit
/etc/postfix/main.cf (and others) as needed. To view Postfix
configuration
values, see postconf(1).
...
Nothing is updated. I have tried tracing the code through and I've got
stuck. I can see these messages come from
/var/lib/dpkg/info/postfix.postinst. It does some magic to check if a
particular attribute has changed (e.g. "db_fget postfix/mailname
changed"). The db_fget and db_fset functions are from
/usr/share/debconf/confmodule which is doing some very low-level _db_cmd
stuff. It seems to be talking over FD 3 to set or test which attributes
have changed.
My best guess is: the noninteractive frontend is saying "nope, this
setting has not been changed".
What I'm trying to avoid is duplicating all the config generation logic
from the postinst script. Whereas with postfix it would be a relatively
simple job of writing out /etc/mailname and running "postconf" for a few
settings, with other packages it's much more tricky (e.g.
request-tracker4 is another one I'm working on)
So in summary: is there a general way for an already-installed package,
to tell debconf either that specific setting(s) should be considered
changed, or to reconfigure the package from scratch as if it were a new
installation?
Thanks,
Brian.
P.S. The authoritative documentation I found was:
https://manpages.debian.org/testing/debconf-doc/debconf.7.en.html
https://manpages.debian.org/testing/debconf/dpkg-reconfigure.8.en.html
https://manpages.debian.org/testing/debconf-doc/debconf-devel.7.en.html
The latter mentions flags (FSET/FGET), and the "seen" flag in
particular, but not the "changed" flag.
