Docker in Docker with buildx

Docker in docker 20.10.7 with buildx 0.6.0, tested and used in .gitlab-ci.yml pipeline, useful to build multi-arch images (amd64 and arm).

# docker --version
Docker version 20.10.7, build f0df350

Gitlab-ci boilerplate

.gitlab-ci.yml working example: builds an image and pushes it to gitlab's container registry.

variables:
  DOCKER_HOST: tcp://docker:2375/
  DOCKER_DRIVER: overlay2

stages:
  - build

docker-build-master:
  image: guglio/dind-buildx:latest
  stage: build
  services:
    - docker:20.10-dind
  before_script:
    - docker login -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD" $CI_REGISTRY
  script:
    - docker run --rm --privileged multiarch/qemu-user-static --reset -p yes; docker buildx create --use
    - docker buildx build --push --platform linux/arm/v7,linux/arm64/v8,linux/amd64 --tag "$CI_REGISTRY_IMAGE" .
  only:
    - master


docker-build-tag:
  image: guglio/dind-buildx:latest
  stage: build
  services:
    - docker:20.10-dind
  before_script:
    - docker login -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD" $CI_REGISTRY
  script:
    - docker run --rm --privileged multiarch/qemu-user-static --reset -p yes; docker buildx create --use
    - docker buildx build --push --platform linux/arm/v7,linux/arm64/v8,linux/amd64 --tag "$CI_REGISTRY_IMAGE:$CI_COMMIT_TAG" .
  only:
    - tags