'DEBIAN_FRONTEND=noninteractive' not working inside shell script with apt-get - docker

Question

I'm buildinga a docker image using a Dockerfile to build it. I have put ARG DEBIAN_FRONTEND=noninteractive in the beginning of the Dockerfile to avoid debconf warnings while building.
The warnings does not show up when using apt-get install inside the Dockerfile. However when executing a sh script (install_dependencies.sh) from the Dockerfile that contains apt-get install commands, the warnings show up again. I also tried to set DEBIAN_FRONTEND=noninteractive inside the sh script itself.
I can solve this by adding echo 'debconf debconf/frontend select Noninteractive' | sudo debconf-set-selections in the sh script before the apt-get install commands but I would want to avoid that, since any fail in the script would leave debconf select to Noninteractive.
Dockerfile:
FROM ubuntu:18.04
# Avoid warnings by switching to noninteractive
ARG DEBIAN_FRONTEND=noninteractive
WORKDIR /tmp
# Configure APT --> HERE THE WARNINGS 'debconf: unable to initialize frontend: Dialog' ARE NOT DISPLAYED
RUN apt-get update \
&& apt-get -y upgrade \
&& apt-get install -y \
apt-utils \
dialog \
fakeroot \
software-properties-common \
2>&1
# Install APT packages --> HERE THE WARNINGS 'debconf: unable to initialize frontend: Dialog' ARE NOT DISPLAYED
RUN apt-get update && apt-get install -y \
#
# System packages
iproute2 \
procps \
lsb-release \
sudo \
unattended-upgrades \
dnsutils \
iputils-ping \
xauth \
openssl \
tar \
zip \
#
# Helpers
&& apt-get install -y \
ca-certificates \
curl \
wget \
lsof \
gconf2 \
gconf-service \
#
# Clean up
&& apt-get autoremove -y \
&& apt-get clean -y \
&& rm -rf /var/lib/apt/lists/*
# Install LTE stack dependencies --> HERE THE WARNINGS 'debconf: unable to initialize frontend: Dialog' ARE DISPLAYED
RUN chmod +x install_dependencies.sh \
&& export DEBIAN_FRONTEND=noninteractive; ./install_dependencies.sh
install_dependencies.sh:
#!/bin/sh
export DEBIAN_FRONTEND=noninteractive
APT_PACKAGES="lib32z1 \
python-setuptools \
libmysqlclient-dev \
ninja-build"
install_apt_packages() {
sudo apt-get install -y tzdata \
build-essential \
git
for package in $APT_PACKAGES;
do
sudo apt-get -y install "$package";
done
}
main() {
sudo apt-get update && sudo apt-get upgrade -y
install_apt_packages
}
main
EDIT: Thanks to #arkadiusz-drabczyk for telling me to remove sudo from the apt-get commands, it makes perfect sense what he says, that the environment variables drop before executing the command.

Answer 1

Drop sudo in your script, there is point to use it if you're running as root. This is also the reason that DEBIAN_FRONTEND has no effect - sudo drops your current user's environment for security reasons, you'd have to use with -E option to make it work.