installing `lightdm` in Dockerfile raises interactive keyboard layout menu

This should work:

DEBIAN_FRONTEND=noninteractive apt-get install lightdm -y

I had the same problem installing CUDA and this fixed it.

1. copy a working /etc/default/keyboard file to the directory that contains the Dockerfile

2. Add the following line to your Dockerfile before installing xdm or lightdm

   COPY ./keyboard /etc/default/keyboard

Example keyboard file:

# Check /usr/share/doc/keyboard-configuration/README.Debian for# documentation on what to do after having modified this file.# The following variables describe your keyboard and can have the same# values as the XkbModel, XkbLayout, XkbVariant and XkbOptions options# in /etc/X11/xorg.conf.XKBMODEL="pc105"XKBLAYOUT="us"XKBVARIANT="intl"XKBOPTIONS=""# If you don't want to use the XKB layout on the console, you can# specify an alternative keymap.  Make sure it will be accessible# before /usr is mounted.# KMAP=/etc/console-setup/defkeymap.kmap.gzBACKSPACE="guess"

Try setting a TERM environment variable before running the install:ENV TERM xtermin order to get rid of that error, although I'm not sure how you would specify the keyboard option.