Privileges in an Ubuntu Docker container after USER statement in Dockerfile

Question

I created a Dockerfile

FROM       ubuntu:latest

as the parent image.

Later the Dockerfile creates a new group and user without sudo privileges via

RUN groupadd -r myappuser -g 433
RUN useradd -u 431 -r -g myappuser -d /opt/myapp -s /bin/false -c "my app user" myappuser

Before executing the application I switch to this new

USER       myappuser

Question: Does this setting make it possible to gain root privileges again once the image is build and the container is running (with e.g. docker exec -it)?

just a though, can you add the user to sudoers or is that not what you are looking for? — Greg, Feb 20 '15 at 13:53
Since this user is dedicated for running the main application it should not have full privileges .. — Jens Piegsa, Feb 20 '15 at 16:20

score 3 · Accepted Answer · answered Feb 20 '15 at 19:55

If you don't want to use sudo, you could have a Dockerfile without USER (so it runs the command as root) and CMD pointing to a script that does the user switching, that way a docker exec would run as root.

Other way is to set the root password and use su. An example of doing that is in the tutum images

https://github.com/tutumcloud/tutum-centos/blob/master/set_root_pw.sh

Privileges in an Ubuntu Docker container after USER statement in Dockerfile

1 Answers1