How can I run ENTRYPOINT as root user?

Question

This is a part of my dockerfile:

COPY ./startup.sh /root/startup.sh
RUN chmod +x /root/startup.sh

ENTRYPOINT ["/root/startup.sh"]

EXPOSE 3306
CMD ["/usr/bin/mysqld_safe"]

USER jenkins

I have to switch in the end to USER jenkins and i have to run the container as jenkins.

My Question is now how can I run the startup.sh as root user when the container starts?

Answer 1

Delete the USER jenkins line in your Dockefile.

Change the user at the end of your entrypoint script (/root/startup.sh).

by adding: su - jenkins man su

Example:

Dockerfile

FROM debian:8

RUN useradd -ms /bin/bash exemple

COPY entrypoint.sh /root/entrypoint.sh

ENTRYPOINT "/root/entrypoint.sh"

entrypoint.sh

#!/bin/bash

echo "I am root" && id

su - exemple

# needed to run parameters CMD
$@

Now you can run

$ docker build -t so-test .
$ docker run --rm -it so-test bash
I am root
uid=0(root) gid=0(root) groups=0(root)
exemple@37b01e316a95:~$ id
uid=1000(exemple) gid=1000(exemple) groups=1000(exemple)

It's just a simple example, you can also use the su -c option to run command with changing user.