Brickstrap is a tool for turning Docker images into bootable image files for embedded systems.
The name "brickstrap" comes from the fact that it was developed to bootstrap the LEGO MINDSTORMS EV3 Intelligent Brick as part of the ev3dev project. Nevertheless, it works well for other embedded systems too. We have Raspberry Pi and BeagleBone configurations as well.
Since brickstrap is essentially just a bash script, you can run directly from
the source code.
git clone git://github.com/ev3dev/brickstrap
brickstrap/src/brickstrap.sh create-tar my-docker-image my.tar
(Watch out for this bug in Ubuntu 18.04. A workaround for this bug is included in the debian package mentioned below, so you only need to manually fix the bug when running brickstrap from source.)
There is also a Debian package available for Ubuntu in the ev3dev tools package repository.
sudo add-apt-repository ppa:ev3dev/tools
sudo apt update
sudo apt install brickstrap
If you just want to run from git, make sure you have these packages installed.
They will be installed automatically if you use the brickstrap package, so you
can skip this if that is the case. You only need qemu-user-static if the
Docker image is for a foreign architecture.
sudo apt-get install docker-ce libguestfs-tools qemu-user-static
If you have never used libguestfs before, you need do some manual steps:
# add yourself to the kvm group
sudo usermod -a -G kvm $USER
newgrp kvm # or log out and log back in
# fix permissions on /boot/vmlinuz*
sudo chmod +r /boot/vmlinuz*
See the man page or if you installed the Debian package, run man brickstrap.