Using sudo inside a docker container

Normally, docker containers are run using the user root. I’d like to use a different user, which is no problem using docker’s USER directive. But this user should be able to use sudo inside the container. This command is missing.

Here’s a simple Dockerfile for this purpose:

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  • FROM ubuntu:12.04
    RUN useradd docker && echo "docker:docker" | chpasswd
    RUN mkdir -p /home/docker && chown -R docker:docker /home/docker
    USER docker
    CMD /bin/bash

    Running this container, I get logged in with user ‘docker’. When I try to use sudo, the command isn’t found. So I tried to install the sudo package inside my Dockerfile using

    RUN apt-get install sudo

    This results in Unable to locate package sudo

    I’ve no idea how to manage this. Any suggestions? Thx a lot!

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  • One Solution collect form web for “Using sudo inside a docker container”

    Just got it. As regan pointed out, I had to add the user to the sudoers group. But the main reason was I’d forgotten to update the repositories cache, so apt-get couldn’t find the sudo package. It’s working now. Here’s the completed code:

    FROM ubuntu:12.04
    RUN apt-get update && \
          apt-get -y install sudo
    RUN useradd -m docker && echo "docker:docker" | chpasswd && adduser docker sudo
    USER docker
    CMD /bin/bash
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