How To Use Docker Buildx in Remote Docker?

If you are using Docker version 20.x you can use Buildx as-is.

Below is a sample config to enable set the Remote Docker version, and use `docker buildx build`. 

version: 2.1

workflows:
  build-deploy:
    jobs:
      - build

jobs:
  build:
    docker:
      - image: cimg/base:stable
  steps:
    - setup_remote_docker:
        version: 20.10.11
    - checkout
    - run: docker buildx build . 

If you are using Docker version 19.03 , please note that you must enable the "Experimental features" option.

Below is a sample config to showcase how to enable the "Experimental features" option on the remote Docker daemon.

version: 2.1

workflows:
  build-deploy:
    jobs:
     - build

jobs:
  build:
    docker:
      - image: cimg/base:stable
    steps:
      - setup_remote_docker:
          version: 19.03.14
      - checkout
   - run: |
        ssh remote-docker \<<EOF
          sudo bash -c 'echo "{\"experimental\": true}" > /etc/docker/daemon.json'
          sudo systemctl restart docker
          sudo docker info
        EOF
   - run: |
          docker buildx build .     

If the above configuration is not working for your image, please try the below configuration:

version: 2.1

workflows:
  build-deploy:
    jobs:
     - build

jobs:
  build:
    docker:
      - image: cimg/base:stable
    steps:
      - setup_remote_docker:
          version: 19.03.14
      - checkout
      - run: |
          export DOCKER_CLI_EXPERIMENTAL=enabled
          docker buildx build .

There may also be cases where you get the error:

could not create a builder instance with TLS data loaded from environment

To resolve this, please create a context with commands like the following:

docker context create buildx-build
docker buildx create --use buildx-build

Please note that if you are using a docker image other than one of our `cimg` images, you will need to make sure that buildx is available within that image.

References:

1. https://docs.docker.com/buildx/working-with-buildx/
2. https://circleci.com/docs/2.0/building-docker-images/#docker-version
3. https://github.com/kelvintaywl-cci/docker-buildx