Docker – When building from Dockerfile, Debian/Ubuntu package install debconf Noninteractive install not allowed

docker

I've set the following environment so that no question/dialog is asked during apt-get install:

ENV DEBIAN_FRONTEND noninteractive    # export DEBIAN_FRONTEND="noninteractive"

Which is equivalent to:

export DEBIAN_FRONTEND="noninteractive"

Yet, when building an image from a Dockerfile, at the end of one specific Debian/Ubuntu package install (using apt-get install), package configuration debconf says:

debconf: unable to initialize frontend: Noninteractive    # export DEBIAN_FRONTEND="noninteractive"
debconf: (Bareword "Debconf::FrontEnd::Noninteractive" not allowed while "strict subs" in use at (eval 35) line 3, <> line 1.)
debconf: falling back to frontend: Noninteractive
Subroutine BEGIN redefined at (eval 36) line 2, <> line 1.

Best Answer

It should be actively discouraged to set the DEBIAN_FRONTEND to noninteractive via ENV. The reason is that the environment variable persists after the build, e.g. when you run docker exec -it ... bash. The setting would not make sense here.

There are two other possible ways:

Set it via ARG as this only is available during build:

ARG DEBIAN_FRONTEND=noninteractive
RUN apt-get -qq install {your-package}

Set it on-the-fly when required.

RUN apt-get update && \
    DEBIAN_FRONTEND=noninteractive apt-get -qq install {your-package}

Related Solutions

Ubuntu – How to set locale when building an Ubuntu Docker image with Packer

I haven't tried it, but according to the documentation, you should be able to do this using the docker-import post-processor: https://www.packer.io/docs/post-processors/docker-import.html

Example:

{
  "type": "docker-import",
  "repository": "local/ubuntu",
  "tag": "latest",
  "changes": [
    "ENV LC_ALL en_GB.UTF-8"
  ]
}

Docker Install on Debian 10.2 – AUFS-DKMS Error Fix

I did a complete reinstall of Debian 10. Following might be the reason that I could not purge the aufs-dkms package in an earlier attempt. The default $PATH for root did not include /sbin and /usr/sbin. So I update the $PATH temporarily:

export PATH=$PATH:/sbin:/usr/sbin

In my second installation I was than able to properly purge aufs-dkms using aptitude (I now learned to prefer aptitude over apt-get):

aptitude purge aufs-dkms

Now the apt pipeline is clean and Docker is running. Unfortunately, that does not explain why there was a problem in the first place.

Update:

The missing $PATH was not set correctly because I was using su from a normal user login (not sure why this is different from a root login). Setting $PATH correctly would not make a difference.

But, when I logged in as root directly into tty1, I could run the apt install docker-ce without the aufs-dkms errors!