installer-immutable-sysext

WARNING: This project is under active development and is NOT ready for production use. APIs, configurations, and behavior may change without notice. Use at your own risk.

This repository is a partial fork of flatcar/sysext-bakery. Not all features from the original project are included, and significant modifications have been made to fit the needs of this project.

Build and publish systemd system extensions (.raw images) for Kubernetes and Containerd on immutable Linux distributions (e.g., Flatcar Container Linux).

Based on the flatcar/sysext-bakery framework.

Extensions

Extension	Components
kubernetes	kubelet, kubeadm, kubectl, CNI plugins
containerd	containerd (static), runc
etcd	etcd
kubeadm	kubeadm configuration and setup

Usage

List available extensions

./bakery.sh list

List available versions

./bakery.sh list kubernetes
./bakery.sh list containerd

Build a sysext image

# Kubernetes (latest patch of each supported minor)
./bakery.sh create kubernetes v1.32.0 --arch x86-64

# Containerd
./bakery.sh create containerd 2.0.0 --arch x86-64

Build prerequisites (Linux)

sudo apt install curl jq squashfs-tools xz-utils erofs-utils
# yq is required for kubernetes version listing
sudo wget -qO /usr/local/bin/yq https://github.com/mikefarah/yq/releases/latest/download/yq_linux_amd64
sudo chmod +x /usr/local/bin/yq

CI/CD

The GitHub Actions workflow (.github/workflows/release.yaml) runs weekly (Mondays at 5am UTC) or on manual dispatch. It:

1. Checks release_build_versions.txt for versions to build
2. Resolves latest to actual version numbers
3. Builds both x86-64 and arm64 images for each version
4. Publishes GitHub Releases with .raw images, SHA256SUMS, and sysupdate configs

Configuration

The .env file overrides the bakery defaults:

bakery="sighupio/installer-immutable-sysext"
bakery_hub=""

Applying a sysext on a Flatcar node

# Download the .raw image
curl -LO https://github.com/sighupio/installer-immutable-sysext/releases/download/kubernetes-v1.32.0/kubernetes-v1.32.0-x86-64.raw

# Place it in the extensions directory
sudo cp kubernetes-v1.32.0-x86-64.raw /etc/extensions/kubernetes.raw

# Refresh system extensions
sudo systemd-sysext refresh

License

Based on flatcar/sysext-bakery, licensed under the Apache 2.0 License.