RFE: Specify user to run a container (as docker run --user name:group)

[tashoyan]

We use Docker slaves, and inside the image we create a user jenkins:

RUN useradd jenkins -m -d /build

We also use a volume for cached dependencies downloaded by Groovy Grapes. Without this volume, each new Docker slave would download all dependencies, making the build much slower. This leads to a problem: all downloaded and cached dependencies belong to some irrelevant user, that by chance has the same uid as the user jenkins in the container:

drwxrwxr-x.  3 itinvent itinvent 4096 Apr 11 15:26 aopalliance                                                                                                                                                     
drwxrwxr-x.  3 itinvent itinvent 4096 Apr 11 15:27 com.clearspring.analytics
...

With console docker client, we could fix this problem by running the container as user jenkins:

docker run --user jenkins my_image

However, there is no such option in the Docker Plugin configuration. A workaround is to create user jenkins on the host machine running Docker containers with the same uid and gid as within the container. With many images and many host machines, this workaround seems poor.

Jenkins 2.164.2 Docker Plugin 1.1.6 Docker Commons Plugin 1.14

[pjdarton]

Well, it looks like the underlying docker-java library probably supports a user argument, so it shouldn't be too tricky to implement. If you create a PR, I'd be happy to review it.