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Creating a Docker Image

Assumptions:

  • This document assumes that docker has been set up on the host system.
  • Details for setting up Docker can be found under DockerSetup.md

Dockerfile

  • There are two dockerfiles in this repository. They are:
  1. DockerFileDevEnv
  2. DockerFileProdEnv
  • The files create the image using two build stages.
  • Everything in the intermediate stage is removed from the final image, including "id_rsa".
  • Using --from=intermediate allows us to copy git repositories to the final image.
  • Run commands are concatenated to reduce complexity of image by decreasing layers created.

Getting private bitbucket repositories into the development image

  • Git repos are installed as part of the image using ssh.
  • The user must create a public ssh key to be able to add these repos.
ssh-keygen
ssh-add -k ~/.ssh/id_rsa
cat ~/.ssh/id_rsa.pub | xclip -sel clip
  • The last command copies the ssh key onto the clip board.
  • Login to user bitbucket account in a browser, click on the user icon at the top right, and navigate to Personal Settings->SSH Keys
  • Click "Add keys", paste the public ssh key into the box, and give the key a name.
  • Then it will be required to copy the file ~/.ssh/id_rsa into this repo. The .gitignore excludes this file from pushes.
  • At this point, repos can be added to the Development file as part of the image using an ssh clone request.

Production File

  • DockerFileProdEnv is used to create a production environment for an arm device.
  • The production environment is a minimally set up image to be able to run projects in Ubuntu 18.04.
  • Git is not installed. Therefore, cannot pull other git repos. Not meant to be a development environment.

Development File

  • DockerFileDevEnv file is used to create a development environment.
  • The image is intended to be used on a host machine such as a laptop.
  • Git is installed and therefore users can pull git repos into this image (must mount git repo to host if persistent changes are desired).
  • Zerotier is not installed in the image. It should be installed on the host machine if it will be used.

Docker Hub Account

  • The user should have a docker hub account to have a username
  • This will make moving images around devices easier with docker pull and push

Docker Command to Create Image

  • There are multiple ways to create images and images with different host architectures
  • To create an image matching the host architecture, run:
sudo docker build --no-cache=true -t username/example:0.00.01 -f ./${DOCKER_FILE} .
  • In the above example, DOCKER_FILE can be replaced with any of the two files in this repository.
  • To be able to create architectures not matching the host, run
docker run --privileged --rm tonistiigi/binfmt --install all
  • This command above sometimes needs re-run after a prune.
  • It is likely that if the non-host architecture failed, that it needs re-run.
  • To create an image matching that builds multiple architectures, run:
sudo docker buildx create --use
sudo docker buildx build --platform=linux/amd64,linux/arm64 --no-cache=true -t username/example:0.00.01 -f ./${DOCKER_FILE} --push .
  • The above will create platforms for both Ubuntu desktop and arm64. Platforms can be added or removed as needed.
  • The images are pushed to the Docker Hub Account after creation.
  • To build a single image that does not match the host architecture, run:
sudo docker buildx create --use
sudo docker buildx build --platform=linux/arm64 --no-cache=true -t username/example:0.00.01 -f ./${DOCKER_FILE} --push .
  • Again, platform flag argument can be replaced with whatever architecture system that is desired.
  • The image will be pushed to Docker Hub once completed.
  • Using make files in this repo, images can be created with the following commands:
sudo make build-host-arch-image
sudo make build-multiple-arch-images
sudo make build-user-defined-arch-image
  • Using the above make command will require setting the appropriate variables in the upper level makefile.
  1. PROJECT_NAME
  2. DOCKER_VERSION # Version of the image being created
  3. DOCKER_HUB_USER # Your docker hub user name
  4. DOCKER_SYS_ARCH # Tells docker what platform to build image as.
  5. DOCKER_OPEN_ARCH # Tells Docker what platform to open under. Should match image system architecture.
  6. HOST_MOUNT_PATH # Tells where to mount src directory on host