Docker - Setting Daemon user fails - not in right order

[nightwolfzor]

I'm trying to create a Docker image, I have a simple build.sbt file;

enablePlugins(JavaAppPackaging)

enablePlugins(DockerPlugin)

maintainer in Docker := "Blah <blah@blah.com>"

daemonUser in Docker := "chotbi"

dockerExposedPorts := Seq(4800)

dockerExposedVolumes := Seq("/opt/docker/logs")

However the docker build fails (using docker v1.5, sbt 0.13.8, packager 1.0.0-RC1) with

[info] Step 4 : RUN chown -R chotbi:chotbi .
[info]  ---> Running in 663be3a5e5f3
[info] chown: invalid user: 'chotbi:chotbi'

Its not to hard to see why looking at the resulting docker file;

FROM dockerfile/java:latest
MAINTAINER Blah <blah@blah.com>
WORKDIR /opt/docker
ADD opt /opt
RUN ["chown", "-R", "chotbi:chotbi", "."]
EXPOSE 4800
RUN ["mkdir", "-p", "/opt/docker/logs"]
RUN ["chown", "-R", "chotbi:chotbi", "/opt/docker/logs"]
VOLUME ["/opt/docker/logs"]
USER chotbi
ENTRYPOINT ["bin/report-server"]
CMD []

[muuki88]

Hm. Problem is you can't chown something if you aren't root. The user has to be created, that's what is missing.

[muuki88]

We default to the daemon user, which should be present on most (all?) linux systems. We may need to add this to the docs.

Why do you want to change the user running inside docker?

[nightwolfzor]

The user ID and user name are needed for underlying authentication with the host os for some services with volume mounts. So we need to be able to create a custom user. It seems weird to have daemonUser in Docker := ... only support preexisting accounts.

[muuki88]

I'm not sure what the best practice in this case is. Options coming in mind for me are

• Create the user on the machine you are building the docker image
• Create the user within the dockerfile. (you can extend the dockerCommands setting)

cc @fiadliel