Push multiple docker images to manifest without tags

Here's the solution I came to -- though for most people the added steps and workarounds here are unnecessary when compared to Jean's answer. You should go with that answer unless you specifically need what mine provides.

I wanted to run the builds on different machines -- an arm box and an amd64 box -- to achieve better build speeds than qemu could provide. However, GitLab / GitHub runners can't communicate with each other, so I couldn't use buildx's ability to run on multiple machines natively. What I came up with was to build the images, push them to an intermediate registry (or export & import them locally if no registry is avaliable was available), pull & use them as cache for another final buildx.

Something like this in GitLab CI:

# Build your images separately however you need, tagging with -${arch}# Do testing on the image to make sure it validates, then...deploy_image:  stage: deploy  script:    - >      for arch in "amd64 arm64 armv7"; do        export name="$<YOUR CONTAINER URL AND TAG>-${arch}"        docker pull "NAME" # or `docker load`        export ARCH_IMAGES_CACHE="$ARCH_IMAGES_CACHE --cache-from $NAME"      done    # Docker will detect that the images we pulled are entirely cacheable, and use those without building    - docker buildx build --push --pull $ARCH_IMAGES_CACHE --build-arg BUILDKIT_INLINE_CACHE=1 --platform="linux/amd64,linux/arm64,linux/arm/v7" -t "$<YOUR CONTAINER URL>:${CI_COMMIT_SHORT_SHA}" .

There are probably better methods or abstractions that could be done using docker manifest or docker buildx imagetools, but this was the best solution I came up with.

You want to build multi-arch images and it can be done using buildx (assuming they share the same dockerfile in the current directory):

docker buildx build --platform linux/amd64,linux/arm64,linux/arm/v7 -t yourorg/your-image-name:r1234 --push .

On Gitlab-CI this should look like this :

variables:  DOCKER_HOST: tcp://docker:2375/  DOCKER_DRIVER: overlay2services:  - docker:dindbuild-multi-arch-images:  stage: build-images  image: jdrouet/docker-with-buildx:stable  script:   - docker buildx create --use   - docker buildx build --platform linux/amd64,linux/arm64,linux/arm/v7 -t yourorg/your-image-name:r1234 --push .stages:  - build-images

Then for r1234-gui I would suggest a second dockerfile using this trick at the top:

ARG MYAPP_IMAGE=yourorg/your-image-name:latestFROM $MYAPP_IMAGE

Which will allow you to provide MYAPP_IMAGE as a command line paramether:

docker buildx build -f yourdockerfile --platform linux/amd64,linux/arm64,linux/arm/v7 -t yourorg/your-image-name:r1234-gui --build-arg MYAPP_IMAGE=yourorg/your-image-name:r1234 --push .