Re: [RFC PATCH v3 1/1] gitlab: Use plain docker in container-template.yml

[Alex Bennée]

Fabiano Rosas <farosas@suse.de> writes:

> Our dockerfiles no longer reference layers from other qemu images so
> we can now use 'docker build' on them.
>
> Also reinstate the caching that was disabled due to bad interactions
> with certain runners. See commit 6ddc3dc7a8 ("tests/docker: don't use
> BUILDKIT in GitLab either"). We now believe those issues to be fixed.
>
> The COMMON_TAG needed to be fixed for the caching to work. The
> docker.py script was not using the variable, but constructing the
> correct URL directly.
>
> Signed-off-by: Fabiano Rosas <farosas@suse.de>
> ---
>  .gitlab-ci.d/container-template.yml | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/.gitlab-ci.d/container-template.yml 
> b/.gitlab-ci.d/container-template.yml
> index c434b9c8f3..519b8a9482 100644
> --- a/.gitlab-ci.d/container-template.yml
> +++ b/.gitlab-ci.d/container-template.yml
> @@ -6,17 +6,16 @@
>      - docker:dind
>    before_script:
>      - export TAG="$CI_REGISTRY_IMAGE/qemu/$NAME:latest"
> -    - export COMMON_TAG="$CI_REGISTRY/qemu-project/qemu/$NAME:latest"
> +    - export COMMON_TAG="$CI_REGISTRY/qemu-project/qemu/qemu/$NAME:latest"
>      - apk add python3
>      - docker info
>      - docker login $CI_REGISTRY -u "$CI_REGISTRY_USER" -p 
> "$CI_REGISTRY_PASSWORD"
>    script:
>      - echo "TAG:$TAG"
>      - echo "COMMON_TAG:$COMMON_TAG"
> -    - ./tests/docker/docker.py --engine docker build
> -          -t "qemu/$NAME" -f "tests/docker/dockerfiles/$NAME.docker"
> -          -r $CI_REGISTRY/qemu-project/qemu
> -    - docker tag "qemu/$NAME" "$TAG"
> +    - docker build --tag "$TAG" --cache-from "$TAG" --cache-from 
> "$COMMON_TAG"
> +      --build-arg BUILDKIT_INLINE_CACHE=1
> +      -f "tests/docker/dockerfiles/$NAME.docker" "."

I wonder why this doesn't injest a bunch of context. If I run:

  docker build --cache-from 
registry.gitlab.com/stsquad/qemu/qemu/debian-alpha-cross --build-arg 
BUILDKIT_INLINE_CACHE=1  --build-arg USER=alex --build-arg UID=1000 -t qemu
  /debian-alpha-cross -f 
"/home/alex/lsrc/qemu.git/tests/docker/dockerfiles/debian-alpha-cross.docker" .

it attempts to bring my entire build directory in as build context. This
is why we use the - < docker form in the Makefile.

>      - docker push "$TAG"
>    after_script:
>      - docker logout

So what I don't understand is if I do:

  docker pull registry.gitlab.com/stsquad/qemu/qemu/debian-alpha-cross
  docker build --cache-from 
registry.gitlab.com/stsquad/qemu/qemu/debian-alpha-cross --build-arg
    BUILDKIT_INLINE_CACHE=1 -t qemu/debian-alpha-cross - <
    /home/alex/lsrc/qemu.git/tests/docker/dockerfiles/debian-alpha-cross.docker

I still see pretty much a full rebuild of the image.

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro