Base bootc images for Fedora

Motivation

The original Docker container model of using "layers" to model applications has been extremely successful. This project aims to apply the same technique for bootable host systems - using standard OCI/Docker containers as a transport and delivery format for base operating system updates.

More information on bootc

See: https://containers.github.io/bootc/

Images

At present there are two images:

`full`

This image is a fairly large, generic base image that can be deployed in cloud or bare metal (e.g. it has full linux-firmware etc.)

`minimal`

This image has just effectively:

podman systemd kernel bootc

And represents a smaller target reference image.

Building

At the current time, the Containerfile requires podman or buildah; it will not build with docker or other container build systems that don't inherit from containers/storage.

podman build --security-opt=label=disable --cap-add=all -t localhost/fedora-bootc:40 .

The default uses Fedora 40; to generate e.g. Fedora rawhide content, use

podman build --from=quay.io/fedora/fedora:rawhide --security-opt=label=disable --cap-add=all -t localhost/fedora-bootc:rawhide .

etc.

For more about how the build system came to be, see README-build-rationale.md.

Extending/deriving

The implementation details of this container are definitely subject to change.

If you want to make a custom image, one recommendation is to include this project as a git submodule.

Then, you could create a copy of the Containerfile, and insert the logic you desire in between the different phases.

Again: all details of this container such as the executable scripts, the location of /workdir/rootfs etc. are subject to change; however, a best effort will be made to avoid "silent" incompatible changes. For example, if a script changes semantics, it will change name.

Adding some packages

There's an example in the Containerfile, but just for reference this is e.g.:

RUN --mount=type=cache,target=/workdir /src/build/dnf-installroot /workdir/rootfs install -y vim

Or feel free to use install-imagedir to support installing a full .spec file of dependencies.

Adding arbitrary content, making arbitrary changes

The /workdir/rootfs is the target directory. You can install whatever tools you desire in the builder container, and manipulate the target root. For example, run e.g.

RUN dnf -y install tree && tree /workdir/rootfs

to inspect the filesystem (verbosely). Or run a permissions checker, etc.

gerblesh/experimental-bootc-cosmic