Jenkins + Docker: How to control docker user when using Image.inside command

Question

Dear Stackoverflow Community,

I am trying to setup a Jenkins CI pipeline using docker images as containers for my build processes. I am defining a Jenkinsfile to have a

Answer 1

I found you can actually change user by adding args like following. Although -u 1000:1000 will still be there in the docker run, you will an additional -u [your user] after 1000:1000. Docker will acutally use latest -u parameter

agent {
  docker {
    image 'your image'
    args '-u root --privileged'
  }
}

Answer 2

As you can see here or here is hardcoded the fact of append the uid and gid of the user that is running Jenkins (in your case, the Jenkins user created inside the oficial docker image).

You can change the user that runs the processes inside your Jenkins image passing the --user (or -u) argument to the docker run command. Maybe this can minimize your problems.

Edited

how can I change this behavior? Is there a switch where I can turn the -u 1000:1000 off?

You can't change this behaviour in the actual version because the whoami is hardcoded.

Is this even a bug?

In this pull request seems that they are working on it.

However, is there another simple way to get to my goal if the Docker Plugin is not usable?

The new pipeline plugin version that comes with Jenkins also use the docker-workflow-plugin to run the containers. I don't know another plugin to run that in a simple way. To workaround this, you can run your Jenkins as root but is a very ugly solution.