Container optimized OSes

• Top Minimal Container Operating Systems for Kubernetes
• A Guide to Linux Operating Systems for Kubernetes
• https://www.reddit.com/r/devops/comments/iz4zf9/is_there_an_open_source_container_optimized_os/

Talos

• Talos The Kubernetes Operating System
• No SSH, no console, only API
• No auto-upgrade
• terraform-libvirtd-talos
• Most popular k8s distribution besides k3s in the k8s-at-home community

Flatcar

• Flatcar website
• Kinvolk, the company behind Flatcar got acquired by Microsoft
• Flatcar Container Linux is a drop-in replacement for CoreOS Container Linux
• Running Flatcar Container Linux on libvirt
  • Terraform and libvirt
• Terraform

Features:

• minimal amount of tools to run container workloads: Docker, Kubernetes
  • Open feature request: Flatcar Podman extension
• Automated atomic updates
• Immutable filesystem
• OS image is immutable (/usr is a read-only partition and there’s no package manager to install packages)
• Flatcar uses the USR-A and USR-B update mechanism, first introduced by ChromeOS

Photon OS

• Website
• By vmware
• No qcow2 images

Fedora CoreOS (FCOS)

Fedora CoreOS is the official successor to CoreOS Container Linux

• Docs
• Issues

Features:

• automatically-updating

Installation

FCOS reads and applies the configuration file with Ignition.

• What is ignition ? https://github.com/coreos/ignition

Install with libvirt

https://docs.fedoraproject.org/en-US/fedora-coreos/getting-started/#_launching_with_qemu_or_libvirt

Ignition file

https://docs.fedoraproject.org/en-US/fedora-coreos/producing-ign/

docker pull quay.io/coreos/fcct:release
docker run -i --rm quay.io/coreos/fcct:release --pretty --strict < varac.fcc > varac.ign

Install

cd ~/kubernetes/os/coreos
wget https://builds.coreos.fedoraproject.org/prod/streams/stable/builds/31.20200210.3.0/x86_64/fedora-coreos-31.20200210.3.0-qemu.x86_64.qcow2.xz
unxz fedora-coreos-31.20200210.3.0-qemu.x86_64.qcow2.xz
./install.sh

Run

Questions:

• sudo ?

Running procs after boot

• systemd
  • init
  • systemd-journal
  • systemd-logind
• NetworkManager
• chronyd
• sssd (System Security Services Daemon)
  • sssd_be
  • sssd_nss
• dbus-broker-launch / dbus-broker
• sshd
• zincati (OS update daemon)
• polkitd
• dhclient
• agetty

Kairos

• Website

BalenaOS

• BalenaOS

Out of scope

• Google Container-Optimized OS
• AWS Bottlerocket Open Source OS for Container Hosting from Amazon

Deprecated / outdates OSes

Flow Linux

• Floe Linux Floe is a lightweight Linux distribution made specifically to run Linux containers. It uses Tiny Core Linux, runs completely from RAM and is a ~25 MB download*.

Kutter OS

• Kutter OS The aim is to make a minimal OS for running Kubernetes.

boot2podman

• boot2podman

HypriotOS

• HypriotOS: make container technology a first class citizen on ARM and IoT devices

k3os

• see ./k3os.md
• The project is dead but ready to get into contributor mode

CoreOS Container Linux

from https://coreos.com/os/eol/:

End-of-life announcement for CoreOS Container Linux On May 26, 2020, CoreOS Container Linux will reach its end of life and will no longer receive updates. We strongly recommend that users begin migrating their workloads to another operating system as soon as possible.

https://coreos.com/os/docs/latest/

From https://en.wikipedia.org/wiki/Container_Linux:

Container Linux (formerly CoreOS Linux) is an open-source lightweight operating system based on the Linux kernel and designed for providing infrastructure to clustered deployments, while focusing on automation, ease of application deployment, security, reliability and scalability

Rancher OS

• Docs

Note that RancherOS 1.x is currently in a maintain-only-as-essential mode, and it is no longer being actively maintained at a code level other than addressing critical or security fixes.

Unrelated

• kured: Kubernetes Reboot Daemon