I have getting 'apt-get upgrade' command failed error while building Python3.6-buster container

Question

There was no problem yesterday when I build my Python Flask application on python:3.6-buster image. But today I am getting this error.

Calculating upgrade...
The following packages will be upgraded: libgnutls-dane0 libgnutls-openssl27 libgnutls28-dev libgnutls30 libgnutlsxx28
5 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Need to get 2859 kB of archives.
After this operation, 0 B of additional disk space will be used.
Do you want to continue? [Y/n] Abort.
ERROR: Service 'gateway' failed to build: The command '/bin/sh -c apt-get upgrade' returned a non-zero code: 1

My Dockerfile:

FROM python:3.6-buster
ENV LANG=C.UTF-8 LC_ALL=C.UTF-8
RUN echo $TZ > /etc/timezone
RUN apt-get update
RUN apt-get upgrade
RUN apt-get -y install gcc musl-dev libffi-dev
COPY requirements.txt requirements.txt
RUN python3 -m pip install -r requirements.txt
COPY . /application
WORKDIR /application
EXPOSE 7000

I couldn't find any related question. I guest this is about a new update but I don't know actually. Is there any advice or solution for this problem?

Answer 1

I guess that apt is waiting for user input in order to confirm the upgrade. The Docker builder doesn't can't deal with these interactive dialogs without hacky solutions. Therefore, it fails.

The most straight forward solution is to add the -y flag to your commands as you do it on the install command.

FROM python:3.6-buster
ENV LANG=C.UTF-8 LC_ALL=C.UTF-8
RUN echo $TZ > /etc/timezone
RUN apt-get update
RUN apt-get upgrade -y
RUN apt-get -y install gcc musl-dev libffi-dev
COPY requirements.txt requirements.txt
RUN python3 -m pip install -r requirements.txt
COPY . /application
WORKDIR /application
EXPOSE 7000

However... do you actually need to update your existing packages? That might be not required in your case. In addition, I might recommend that you check out the Docker Best Practices to write statements including apt commands. In order to keep your image size small, you should consider squashing these commands in a single RUN statement. In addition, you should delete the apt cache afterwards to minimize the changes between your two layers:

FROM python:3.6-buster
ENV LANG=C.UTF-8 LC_ALL=C.UTF-8
RUN echo $TZ > /etc/timezone
RUN apt-get update \
&&  apt-get -y install gcc musl-dev libffi-dev \
&&  rm -rf /var/lib/apt/lists/*
COPY requirements.txt requirements.txt
RUN python3 -m pip install -r requirements.txt
COPY . /application
WORKDIR /application
EXPOSE 7000