Avoiding user interaction with tzdata when installing certbot in a docker container

Question

I want to install certbot in a docker environment with an Ubuntu 16.04 image:

For example:

docker run -it ubuntu:16.04 /bin/bash

When I'm inside the container, the most straightforward way to install certbot does not work as it requires user intervention:

apt-get update && \
apt-get install -y software-properties-common && \
add-apt-repository -y -u ppa:certbot/certbot && \
apt-get install -y certbot

The problem is tzdata, which stops with this interactive dialog:

Extracting templates from packages: 100%
Preconfiguring packages ...
Configuring tzdata
------------------

Please select the geographic area in which you live. Subsequent configuration
questions will narrow this down by presenting a list of cities, representing
the time zones in which they are located.

 1. Africa      4. Australia  7. Atlantic  10. Pacific  13. Etc
 2. America     5. Arctic     8. Europe    11. SystemV
 3. Antarctica  6. Asia       9. Indian    12. US
Geographic area: 

Strangely enough, it works when I install tzdata before adding the ppa:

apt-get update && \
apt-get install -y tzdata && \
apt-get install -y software-properties-common && \
add-apt-repository -y -u ppa:certbot/certbot && \
apt-get install -y certbot

Questions:

• Why makes it a difference whether I install tzdata before or after adding the ppa?
• Is there a better approach for avoiding the interactive dialog when installing certbot?

Answer 1

To run dpkg (behind other tools like Apt) without interactive dialogue, you can set one environment variable as

DEBIAN_FRONTEND=noninteractive

For example, you can set it in Dockerfile using ARG:

ARG DEBIAN_FRONTEND=noninteractive

Answer 2

On Ubuntu 18.04 I did that Dockerfile:

ENV TZ=Europe/Minsk
RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ > /etc/timezone
RUN apt update && apt instal....

Answer 3

TL&DR: Within your DockerFile

ENV DEBIAN_FRONTEND=noninteractive 

Reason:

Certain Installers make 'installations' easier by having a nice front-end. While this is great when you have a manual install, this becomes an issue during automated installations.

You can over ride the interactive installation by placing the following in your environment string.

Cheers

Answer 4

You can set DEBIAN_FRONTEND=noninteractive before your command to avoid ENV DEBIAN_FRONTEND=noninteractive affects commands after or child image:

RUN apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
        tzdata \
    && rm -rf /var/lib/apt/lists/*

Answer 5

You should just set your timezone BEFORE installing of tzdata:

# Set timezone:
RUN ln -snf /usr/share/zoneinfo/$CONTAINER_TIMEZONE /etc/localtime && echo $CONTAINER_TIMEZONE > /etc/timezone

# Install dependencies:
RUN apt-get update && apt-get install -y tzdata