Docker Build Environment

From Variscite Wiki
Docker Build Environment

1 Docker Introduction

Docker is a software platform that allows the creation, testing and distribution of applications via containers.
Containers let you run your applications in resource-isolated processes. There are some similarities to virtual machines, but containers are more portable, more resource-friendly, and enable faster software delivery cycles.
Often used with docker, there's a companion tool known as docker-compose: compose is used for defining and running multi-container Docker applications.

You can check Docker online documentation at:
https://docs.docker.com/get-started/
https://docs.docker.com/compose/
https://training.play-with-docker.com/
https://docker-curriculum.com/

This guide describes how to use Docker as a Host build environment for building Variscite Yocto, Android, Debian and Boot2Qt images.

If you are interested in running Docker containers on top of Yocto, Debian or Boot2Qt, please see our Docker Guide.

2 Why Build using Docker?

Each version of Yocto, Android, Debian and Boot2Qt has unique Host requirements (e.g. Ubuntu 16.04, Ubuntu 18.04...). This can be cumbersome during development if you are working on legacy projects and new projects at the same time. Over time, we've all come up with our own solutions to this problem by using Virtual Machines or even keeping old computers just to build an occasional image.

Docker is a great solution to this problem and provides:

  • A git revision controlled build environment
  • Can run on any OS and hardware that supports the Docker Runtime
  • Does not require strict allocation of RAM and hard drive memory
  • Has very little CPU/IO overhead, does not impact build time
  • Containers start and stop in 1-2 seconds


Docker's efficiency allows multiple containers to be run simultaneously without burdening the host OS.

3 Setting Up Host Computer

3.1 Host Hardware

For building Linux / Android images, it is recommended to have a dedicated build computer.
A machine with a 16 cores/32 threads CPU, 64GiB of RAM and a 2TB SSD is recommended. Compile time is generally reduced linearly with the number of CPU cores.

3.2 Host OS

Install the latest LTS version of Ubuntu: https://ubuntu.com/download

After a fresh installation, install Docker:

$ sudo apt update && sudo apt install docker.io qemu-user-static

Give permissions to run Docker without sudo:

$ sudo usermod -aG docker ${USER}

Install Linux Headers (required for some Yocto versions):

$ sudo apt install linux-headers-$(uname -r)

Logout and login again for permissions to take effect.

4 Using Variscite's Docker Container

Clone Variscite's Docker container repository:

$ git clone https://github.com/varigit/var-host-docker-containers.git ~/var-host-docker-containers

Start your first Docker container. The first time you start the container, it will take some time to build the container.

After the container finishes building, it will enter the docker container with an interactive shell in the current working directory.

Start a Ubuntu 14.04 container:

$ cd ~/var-host-docker-containers
$ ./run.sh -u 14.04
vari@908b2ecb107c:/workdir$ grep DESCRIPTION /etc/lsb-release
DISTRIB_DESCRIPTION="Ubuntu 14.04.6 LTS"

Start a Ubuntu 16.04 container:

$ cd ~/var-host-docker-containers
$ ./run.sh -u 16.04
vari@908b2ecb107c:/workdir$ grep DESCRIPTION /etc/lsb-release
DISTRIB_DESCRIPTION="Ubuntu 16.04.7 LTS"

Start a Ubuntu 18.04 container:

$ cd ~/var-host-docker-containers
$ ./run.sh -u 18.04
vari@4822cf0e987c:/workdir$ grep DESCRIPTION /etc/lsb-release
DISTRIB_DESCRIPTION="Ubuntu 18.04.5 LTS"

Start a Ubuntu 20.04 container:

$ cd ~/var-host-docker-containers
$ ./run.sh -u 20.04
vari@abe078d0f67c:/workdir$ grep DESCRIPTION /etc/lsb-release
DISTRIB_DESCRIPTION="Ubuntu 20.04.2 LTS"

See run options:

$ cd ~/var-host-docker-containers
$ ./run.sh -h

5 Building an image

5.1 Example: Yocto

This example shows how to build a Yocto Dunfell image for the DART-MX8M-MINI using Docker. In general, the process is the same for all target Operating Systems. Please follow Variscite's build guide and host requirements for your specific releases.

Make a working directory from your Host OS:

$ mkdir ~/docker-yocto-build

Download the source code:

$ cd ~/docker-yocto-build
$ repo init -u https://github.com/varigit/variscite-bsp-platform.git -b refs/tags/dunfell-fslc-5.4-2.1.x-mx8mm-v1.4 -m default.xml
$ repo sync -j4

Start a Ubuntu 20.04 Docker container:

$ cd ~/var-host-docker-containers
$ ./run.sh -p -u 20.04 -w ~/docker-yocto-build

Note: the "-p" option starts Docker in privileged mode, which allows access to host devices and is necessary for building Debian images.

Build a Yocto image in the container:

vari@abe078d0f67c:/workdir$ MACHINE=imx8mm-var-dart DISTRO=fslc-xwayland . setup-environment build_xwayland
vari@abe078d0f67c:/workdir$ source setup-environment build_xwayland
vari@abe078d0f67c:/workdir$ bitbake fsl-image-gui

The output images can be accessed from your host computer:

$ ls -l ~/docker-yocto-build/build_xwayland/tmp/deploy/images/imx8mm-var-dart/

5.2 Example: Boot2Qt

This example shows how to build a B2Qt Dunfell image for the DART-MX8M-MINI using Docker. In general, the process is the same for all target Operating Systems. Please follow Variscite's build guide and host requirements for your specific releases.

Make a working directory from your Host OS:

$ mkdir -p ~/var-b2qt/sources/

Start a Ubuntu 20.04 Docker container:

$ cd ~/var-host-docker-containers
$ ./run.sh -p -u 20.04 -w ~/var-b2qt

Get the source code:

$ cd sources
$ git clone https://github.com/varigit/meta-variscite-boot2qt.git -b dunfell-var01
$ cd ..
$ ./sources/meta-variscite-boot2qt/b2qt-init-build-env init --device imx8mm-var-dart

Build the image:

$ MACHINE=imx8mm-var-dart source ./setup-environment.sh
$ MACHINE=imx8mm-var-dart bitbake b2qt-embedded-qt6-image

The output images can be accessed from your host computer:

$ ls -l ~/var-b2qt/build-imx8mm-var-dart/tmp/deploy/images/imx8mm-var-dart/b2qt-embedded-qt6-image-imx8mm-var-dart.img