Add chown configuration parameter to set groupId and userId for files.

[coollog]

NOT READY

Regards #727

Add a configuration to jib-maven-plugin/jib-gradle-plugin that can define the userid/groupid to set for the files we build into the container, similar to how Dockerfile's COPY --chown works. The container configuration User field should also be set accordingly.

chown can either be a single uid or a string of the form uid:gid.

So, for example, in your case, the configuration could look something like:

Maven:

<configuration>
  ...
  <container>
    <chown>10:11</chown>
  </container>
</configuration>

Gradle:

jib.container.chown = 10000

Tasks:

• Add OwnerGroup to represent a pair of user id and group id (group id defaults to user id if not given).
• Add User field to ContainerConfigurationTemplate.
• Add OwnerGroup to BuildConfiguration.
• Use OwnerGroup to build the layer files.
• Add jib-maven-plugin chown parameter.
• Add jib-gradle-plugin chown parameter.

[coollog]

Closing unless found necessary again.

[chanseokoh]

Just FTR: files are already readable and possibly executable for any, so it doesn't seem necessary to set user and group IDs. At least we don't see a use case for it for now.