"portage" image produce huge I/O every time

[anonymous09]

Good day. I am using Gentoo images in Continuous Integration (Gitlab CI). I run docker via commands:

docker create -v /usr/portage --name portage gentoo/portage
docker run --volumes-from portage --name gentoo gentoo/stage3-amd64 -c "foo bar"

And every time first command produce huge I/O because all content from /usr/portage copying from image to container "portage".
How I can prevent it?

Can you create image without "VOLUME /usr/portage" keyword?

[simonvanderveldt]

@anonymous09 There's not a whole lot you can do. Docker is basically extracting the volume image at that point. That obviously needs to happen, so afaik there's nothing you can do about it.

[oxr463]

See also: presslabs/gitfs#319, presslabs/gitfs#305

[ajakk]

Yeah, not much we can do as the Docker downstream, unless we see a good replacement for the way we currently recommend using the repository. Users might try fiddling with different storage backends or see if podman can handle things any better.

[tianon]

Oh, I think BuildKit's ability to mount content directly from another image might be useful here?

# syntax=docker/dockerfile:1
FROM gentoo/stage3
RUN --mount=type=bind,from=gentoo/portage,source=/var/db/repos/gentoo,target=/var/db/repos/gentoo \
        emerge app-misc/hello
CMD ["hello"]

(Then built with docker buildx build)