Building a Docker image for GitLab-CI

["Ludovic Courtès" <ludovic.courtes@inria.fr>]

Hello Guix!

Has anyone succeeded in building a Docker image suitable for use in
GitLab-CI?  I haven’t.  Here’s what I tried.

Initially, I built an image with ‘guix system image -t docker …’ but
that doesn’t work because then the image’s “entry point” is shepherd,
but shepherd never returns.  Thus, GitLab-CI would spawn the image and
eventually time out.

So I tried this instead:

  guix pack guix bash-minimal coreutils-minimal grep net-base \
    --save-provenance -S /bin=bin -S /share=share -S /etc=etc \
    -f docker --max-layers=100

… with ‘.gitlab-ci.yml’ doing something like this:

--8<---------------cut here---------------start------------->8---
build:
  image: registry.gitlab.inria.fr/…
  tags: ["ci.inria.fr", "linux"]
  before_script:
    - echo "nameserver 10.0.2.3 # XXX" > /etc/resolv.conf
    - guix archive --authorize < /share/guix/ci.guix.gnu.org.pub
    - guix archive --authorize < /share/guix/bordeaux.guix.gnu.org.pub
    - guix-daemon --disable-chroot &
  script:
    - guix shell -m manifest.scm -- rubber --pdf article.tex
  artifacts:
    paths:
      - article.pdf
--8<---------------cut here---------------end--------------->8---

Problem is, name resolution appears to fail in the container image; the
‘resolv.conf’ trick was a crude attempt to work around it, but it
failed.  I guess the problem is that I don’t know how GitLab-CI or
Docker is supposed to set up networking inside those containers.

Thoughts?

Neat tip to upload your Guix-built image to a registry: use Skopeo.

  guix shell skopeo -- skopeo login registry.gitlab.inria.fr
  guix shell skopeo -- skopeo copy \
    docker-archive:///gnu/store/…-docker-image.tar.gz \
    docker://registry.gitlab.inria.fr/… \
    --insecure-policy

(“Insecure policy”, what could possibly go wrong?)

Ludo’.