Kubernetes Bootable Container Images

Warning

This project is highly experimental and under active development. Use at your own risk.

This repository provides a framework for building bootable OS images (ISOs, QCOW2s) for various Linux distributions using bootc and podman.

Prerequisites

Ensure you have the following tools installed on your system:

• make
• podman
• sudo (build commands require elevated privileges)

Project Structure

Directory	Description
builds/	Output directory for generated ISO and QCOW2 files.
configs/	Configuration files (.toml) for the bootc-image-builder, defining users, passwords, disk size, etc.
containerfiles/	Containerfile definitions for each image variant. These extend from base images and add specific configurations and packages.
manifests/	imagectl manifests (.yaml) that define the core package sets for the base operating systems.
overlay/	Static configuration files that are copied directly into the image filesystem during the build process.

Configuration

The primary build configuration is managed through the Makefile.

Kubernetes Version

To build the Kubernetes image with a specific version, edit the K8S_VERSION variable in the Makefile. The build script automatically handles using the full version for package installation and the major/minor version for the repository URL.

# Makefile

# ...
K8S_VERSION := 1.33.1
# ...

Building Images

All builds are orchestrated through the Makefile. Commands must be run from the root of the repository.

Build All Images

To build all defined container images, ISOs, and QCOW2 files, run:

make all

Build Individual Container Images

To build a specific container image, use its corresponding target. This is a prerequisite for building bootable media.

• AlmaLinux 10 Base Image:

  make almalinux10-base

• AlmaLinux 10 Kubernetes Image:

  make almalinux10-kube

Build Bootable Media (ISO/QCOW2)

After building the desired container image, you can generate a bootable ISO or a QCOW2 virtual disk image.

• AlmaLinux 10 Kubernetes ISO:

  make almalinux10-kube-iso

• AlmaLinux 10 Kubernetes QCOW2:

  make almalinux10-kube-qcow2

Clean Up

To remove all generated images from the local podman storage and the builds/ directory, run:

make clean

This command converts the container image into a bootable qcow2 file, which can be used directly by virtual machines.

sudo podman run --rm --privileged \
    --security-opt label=type:unconfined_t \
    -v ./images:/output \
    -v ./config.toml:/config.toml:ro \
    -v /var/lib/containers/storage:/var/lib/containers/storage:z \
    quay.io/centos-bootc/bootc-image-builder:latest \
    --type qcow2 \
    --config /config.toml \
    --local localhost/almalinux10-bootc:base

4. Create a Bootable ISO Installer

This command attempts to create a bootable iso installer. This relies on the bootc-image-builder having a built-in, working definition for almalinux-10.

sudo podman run --rm --privileged \
    --security-opt label=type:unconfined_t \
    -v ./images:/output \
    -v ./config.toml:/config.toml:ro \
    -v /var/lib/containers/storage:/var/lib/containers/storage:z \
    quay.io/centos-bootc/bootc-image-builder:latest \
    --type iso \
    --config /config.toml \
    --local localhost/almalinux10-bootc:base