Building a docker container on top of another image… "permission denied"?

August 18, 2022

I am trying to build an extension of an existing image with FROM and then apt install additional packages on top and do own customizations. I get permission denied and "are you root" messages. Specifically, this is the image I want to extend:

https://hub.docker.com/r/makarius/isabelle

My Dockerfile:

FROM makarius/isabelle:latest
SHELL ["/bin/bash", "-c"]


# Add dependencies
RUN apt-get update && \
    apt-get install --yes build-essential && \
    apt-get install --yes openjdk-8-jdk && \
    apt-get install --yes xterm && \
    apt-get install --yes iputils-ping && \
    apt-get install --yes vim && \
    apt-get install --yes net-tools && \
    apt-get -y install xauth && \
    apt-get clean   

# user
RUN useradd -m foo && (echo foo:foo | chpasswd)
USER foo

# Setup FOO repository
WORKDIR /home/foo

# ... some commands

ENTRYPOINT ["/bin/bash"]

Building it it seems I can’t get the ability to install anything. There is no sudo in the image.

root@ub18:/home/x/foo/bar# sudo docker build -t i8:01 -f Dockerfile .
Sending build context to Docker daemon  408.7MB
Step 1/9 : FROM makarius/isabelle:latest
 ---> da948b0dd494
Step 2/9 : SHELL ["/bin/bash", "-c"]
 ---> Using cache
 ---> 64f897ae98ea
Step 3/9 : RUN apt-get update &&    apt-get install --yes build-essential &&    apt-get install --yes openjdk-8-jdk &&  apt-get install --yes xterm &&  apt-get install --yes iputils-ping &&   apt-get install --yes vim &&    apt-get install --yes net-tools &&  apt-get -y install xauth &&     apt-get clean
 ---> Running in 9ec12ecb98e8
Reading package lists...
E: Could not open lock file /var/lib/apt/lists/lock - open (13: Permission denied)
E: Unable to lock directory /var/lib/apt/lists/
The command '/bin/bash -c apt-get update &&     apt-get install --yes build-essential &&    apt-get install --yes openjdk-8-jdk &&  apt-get install --yes xterm &&  apt-get install --yes iputils-ping &&   apt-get install --yes vim &&    apt-get install --yes net-tools &&  apt-get -y install xauth &&     apt-get clean' returned a non-zero code: 100

I expect to be able to build the extended image from the existing one, with two users defined and all packages installed. I can get by with a single user as well if have to.

>Solution :

The parent image markarius/isabelle switched user to isabelle, you gotta switch it back to root to run apt-get with additional line USER root before that line in your docker file. There’s no need to use sudo in docker images since by default you already have root access.