"sudo dpkg --force-confdef --force-confold --configure -a" shows dialog

Question

I am trying to run this unattended but I keep getting presented with this dialog by unattended-upgrades:

I can see this in ps:

$ ps aux | grep -i frontend
root      348793  0.0  0.1  24992 19644 pts/2    S+   14:12   0:00 /usr/bin/perl -w /usr/share/debconf/frontend /var/lib/dpkg/info/unattended-upgrades.postinst configure 2.3ubuntu0.1

This is despite running this which should force the old config:

$ dpkg --force-confdef --force-confold --configure -a

My versions are:

$ dpkg --version
Debian 'dpkg' package management program version 1.19.7 (amd64).
$ apt-get --version
apt 2.0.9 (amd64)
$ lsb_release -d
Description:    Ubuntu 20.04.5 LTS

Any ideas how to get the above to run unattended?

Answer 1

Oh, it seems I need to also pass an environment variable, the full command being:

sudo DEBIAN_FRONTEND=noninteractive dpkg --force-confdef --force-confnew #{args}