k0s

README

k0s - Zero Friction Kubernetes

k0s is yet another Kubernetes distro. Yes. But we do some of the things pretty different from other distros out there.

k0s is a single binary all-inclusive Kubernetes distribution with all the required bells and whistles preconfigured to make building a Kubernetes clusters a matter of just copying an executable to every host and running it.

Motivation

Note: Some of these goals are not 100% fulfilled yet.

We have seen a gap between the host OS and Kubernetes that runs on top of it: How to ensure they work together as they are upgraded independent from each other? Who’s responsible for vulnerabilities or performance issues originating from the host OS that affect the K8S on top?

→ k0s Kubernetes is fully self contained. It’s distributed as a single binary with no host OS deps besides the kernel. Any vulnerability or perf issues may be fixed in k0s Kubernetes.

We have seen K8S with partial FIPS security compliance: How to ensure security compliance for critical applications if only part of the system is FIPS compliant?

→ k0s Kubernetes core + all included host OS dependencies + components on top may be compiled and packaged as a 100% FIPS compliant distribution with a proper toolchain.

We have seen Kubernetes with cumbersome lifecycle management, high minimum system requirements, weird host OS and infra restrictions, and/or need to use different distros to meet different use cases.

→ k0s Kubernetes is designed to be lightweight at its core. It comes with a tool to automate cluster lifecycle management. It works on any host OS and infrastructure, and may be extended to work with any use cases such as edge, IoT, telco, public clouds, private data centers, and hybrid & hyper converged cloud applications without sacrificing the pure Kubernetes compliance or amazing developer experience.

Some of the high level goals of the project:

• Packaged as a single binary
• Self-hosted, isolated control plane
• Variety of storage backends: etcd, SQLite, MySQL (or any compatible), PostgreSQL
• Elastic control-plane
• Vanilla upstream Kubernetes

See more in architecture docs

Features

• One static binary
• Kubernetes 1.19
• Containerd 1.4
• Control plane storage options:
  • sqlite (in-cluster)
  • etcd (in-cluster, managed, default)
  • mysql (external)
  • postgresql (external)
• CNI providers
  • Calico 3.15 (default)
  • Custom (bring-your-own)
• Control plane isolation:
  • fully isolated (default)
  • tainted worker
• Control plane - node communication
  • Konnectivity service (default)
• CoreDNS 1.7
• Metrics-server 0.3
• Custom roles\profiles for worker nodes

Build

k0s can be built in 3 different ways:

Fetch official binaries (except kine and konnectivity-server, which are built from source):

make EMBEDDED_BINS_BUILDMODE=fetch

Build Kubernetes components from source as static binaries (requires docker):

make EMBEDDED_BINS_BUILDMODE=docker

Build k0s without any embedded binaries (requires that Kubernetes binaries are pre-installed on the runtime system):

make EMBEDDED_BINS_BUILDMODE=none

Builds can be done in parallel:

make -j$(nproc)

Smoke test

To run a smoke test after build:

make check-basic

Cluster bootstrapping

Move the built k0s binary to each of the nodes.

k0s server

This creates all the necessary certs and configs in /var/lib/k0s/pki. k0s runs all control plane components in separate "naked" processes, does not depend on kubelet or container engine.

After control plane boots up, we need to create a join token for worker node:

k0s token create --role=worker

Join a new worker node to the cluster by running:

k0s worker "superlongtokenfrompreviousphase"

For more detailed description see creating cluster documentation

k0s-in-docker

Note: Running k0s, or any other Kubernetes distro, like this is not really a production ready setup. :)

To run a single node controller+worker combo, just run it in docker with:

docker run -d --name k0s-controller --hostname controller --privileged -v /var/lib/k0s -p 6443:6443 docker.pkg.github.com/k0sproject/k0s/k0s:<version>

Replace <version> with a released version number, we build the image for all tagged releases.

That's it, in a minute or so there should be controller+worker combo running in the container.

Just grab the kubeconfig with docker exec k0s-controller cat /var/lib/k0s/pki/admin.conf and paste e.g. into Lens. ;)

Read more details at running k0s in Docker

Documentation

Overview

Copyright 2020 Mirantis, Inc.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.