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

[Fabiano Rosas <farosas@suse.de>]

Alex Bennée <alex.bennee@linaro.org> writes:

> 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.
>

I only see that without DOCKER_BUILDKIT=1. With the variable set it does
like in the CI jobs. I presume it is being set automatically by gitlab,
but we could add it to the script to be explicit.

>>      - 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.

I don't use docker and podman does not support caching. I have
fresh-installed docker today and indeed it seems to not use the cache at
every build. We're missing something.

Sometimes it works:

===
$ docker system prune -a -f
Deleted build cache objects:                                                                                                                                                                   
xzbxmzaib3a8s0ufetop5ikhi                                                                                                                                                                      
0ce9qln4ipd2vgf9xw9to0fdb                                                                                                                                                                      
se4hq3rce3lad20t9sqqnubob

Total reclaimed space: 5.845kB

$ docker images -a
REPOSITORY   TAG       IMAGE ID   CREATED   SIZE

$ DOCKER_BUILDKIT=1 docker build --tag
registry.gitlab.com/farosas/qemu/qemu/debian-amd64:latest --cache-from
registry.gitlab.com/farosas/qemu/qemu/debian-amd64:latest --build-arg
BUILDKIT_INLINE_CACHE=1 -f debian-amd64.docker .

[+] Building 57.8s (12/12) FINISHED                                                                                                                                                            
 => [internal] load build definition from debian-amd64.docker                                                                                                                             0.2s
 => => transferring dockerfile: 5.90kB                                                                                                                                                    0.0s
 => [internal] load .dockerignore                                                                                                                                                         0.3s
 => => transferring context: 2B                                                                                                                                                           0.0s
 => [internal] load metadata for docker.io/library/debian:11-slim                                                                                                                         1.8s
 => importing cache manifest from registry.gitlab.com/farosas/qemu/qemu/debian-amd64:latest                                                                                               0.7s
 => [1/6] FROM docker.io/library/debian:11-slim@sha256:8eaee63a5ea83744e62d5bf88e7d472d7f19b5feda3bfc6a2304cc074f269269                                                                   0.0s
 => CACHED [2/6] RUN export DEBIAN_FRONTEND=noninteractive &&     apt-get update &&     apt-get install -y eatmydata &&     eatmydata apt-get dist-upgrade -y &&     eatmydata apt-get i  0.0s
 => CACHED [3/6] RUN DEBIAN_FRONTEND=noninteractive eatmydata   apt install -y --no-install-recommends   cscope  global  linux-headers-amd64                                              0.0s
 => CACHED [4/6] RUN git clone https://github.com/luigirizzo/netmap.git /usr/src/netmap                                                                                                   0.0s
 => CACHED [5/6] RUN cd /usr/src/netmap && git checkout v11.3                                                                                                                             0.0s
 => CACHED [6/6] RUN cd /usr/src/netmap/LINUX && ./configure --no-drivers --no-apps --kernel-dir=$(ls -d /usr/src/linux-headers-*-amd64) && make install                                 54.9s
 => => pulling sha256:bb263680fed18eecdc67f885094df6f589bafc19004839d7fdf141df236a61aa                                                                                                    1.2s
 => => pulling sha256:f63092d28e024c119d6a4e257d0c62bb2117be93605f1f2363b1d9cb8fc9dc6c                                                                                                   44.6s
 => => pulling sha256:30fcedea9de9f22da43e20a79b40516c6e4a55e70eea401acacca18912e86769                                                                                                    4.5s
 => => pulling sha256:6f498daa6d20055a31e4681ec878e86129c3c1eaf5cf40f7ed87631accef1906                                                                                                    3.6s
 => => pulling sha256:79b1b0d7bce9a16b4a01e2055cd402d93e04efded50e2ffcf6be0d7c67e4895a                                                                                                    0.6s
 => => pulling sha256:250b927c5ce2d6d3e9d24bf085f649ce951966c9ec9c9e00ab8292dfb02c8b17                                                                                                    0.7s
 => exporting to image                                                                                                                                                                    0.1s
 => => exporting layers                                                                                                                                                                   0.0s
 => => writing image sha256:3663223c0a31c2be678c2fe110ba284b80b8d04d2d3290c14be7a4d7320f8a67                                                                                              0.0s
 => => naming to registry.gitlab.com/farosas/qemu/qemu/debian-amd64:latest                                                                                                                0.0s
 => exporting cache                                                                                                                                                                       0.0s
 => => preparing build cache for export  
===

There are issues pointing to some general unreliability of the cache:

https://github.com/moby/buildkit/issues/2274
https://github.com/moby/buildkit/issues/1981

What is your docker version? Mine is 20.10.17-ce and Gitlab's is
23.0.1. The issues above are on 20.10.11.