Whiteout files not supported about imagebuilder HOT 7 CLOSED

Different storage drivers have different ways to handle removal of contents that were present in a lower layer. What's the intended result of creating a .wh.foo.repo file instead of just deleting foo.repo?

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Fair point, it seemed like a hack anyway.

Deleting a file (let's assume with RUN rm file) requires that the current USER have permission to delete the file, so it's not a simple inverse of ADD. In our case we're wanting to automate the addition of a yum repo file at the beginning of the Dockerfile and then removing it at the end (to supply a build repo written on the fly). This means we have to determine what the USER is supposed to be at the end and switch it like so:

USER root
RUN rm /etc/yum.repos.d/foo.repo
USER previous_user

And that assumes rm is even present -- if your base image is scratch that will break (so would using yum, but this is automation, it doesn't know if the repo will be needed or not).

As an alternative, we can ADD an empty file to overwrite it at the end, but then you have a useless empty file to confuse people. Ideally, we could mount the file as a volume during the build so it's never present in the container; but the repo file is generated in a container fs, so mounting it into the build container is complicated.

It would be great if there were a REMOVE instruction or ADD --remove option for removing files, or some other way for imagebuilder to facilitate this.

But if nothing else, this issue just serves as notice that the whiteout file hack works differently here.

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I think docker actually standardizes on the whiteout format inside the tar. The question is whether we can safely do that via the invocation of the command. You'd get into some interesting cases where whiteout doesn't have the same behavior.

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@openshift-bot: Closing this issue.

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