Unable to set root password with clear text using preseed/early_command

[Glen Huang <heyhgl@gmail.com>]

Hi,

I want to set the root password to a random string. this is the preseed I use:

d-i preseed/early_command string \
    pw="$(tr -dc A-Za-z0-9 </dev/urandom | head -c 24)"; \
    debconf-set passwd/root-password "$pw"; \
    debconf-set passwd/root-password-again "$pw"

However, the installer still prompts me for the root password.

Setting the crypted password works though:

d-i preseed/early_command string \
    debconf-set passwd/root-password-crypted '<crypted-string>'

Directly setting the password also works:

d-i passwd/root-password password r00tme
d-i passwd/root-password-again password r00tme

>From https://sources.debian.org/src/user-setup/1.88/user-setup-ask/#L36,
it seems the installer will ask for the root password if
root-password-crypted is empty or !. My guess is that in the direct
version, somehow root-password-crypted gets a corresponding value when
only root-password and root-password-again are set, but I couldn't
find the code responsible for that.

I'd be grateful if anyone could shed some light.