k3s-io / k3s

K3s - Lightweight Kubernetes
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Lightweight Kubernetes. Production ready, easy to install, half the memory, all in a binary less than 100 MB.
Great for:
* Edge
* IoT
* CI
* Development
* ARM
* Embedding k8s
* Situations where a PhD in k8s clusterology is infeasible
What is this?
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K3s is a fully conformant production-ready Kubernetes distribution with the following changes:
1. It is packaged as a single binary.
1. It adds support for sqlite3 as the default storage backend. Etcd3, MariaDB, MySQL, and Postgres are also supported.
1. It wraps Kubernetes and other components in a single, simple launcher.
1. It is secure by default with reasonable defaults for lightweight environments.
1. It has minimal to no OS dependencies (just a sane kernel and cgroup mounts needed).
1. It eliminates the need to expose a port on Kubernetes worker nodes for the kubelet API by exposing this API to the Kubernetes control plane nodes over a websocket tunnel.
K3s bundles the following technologies together into a single cohesive distribution:
* Containerd & runc
* Flannel for CNI
* CoreDNS
* Metrics Server
* Traefik for ingress
* Klipper-lb as an embedded service load balancer provider
* Kube-router netpol controller for network policy
* Helm-controller to allow for CRD-driven deployment of helm manifests
* Kine as a datastore shim that allows etcd to be replaced with other databases
* Local-path-provisioner for provisioning volumes using local storage
* Host utilities such as iptables/nftables, ebtables, ethtool, & socat
These technologies can be disabled or swapped out for technologies of your choice.
Additionally, K3s simplifies Kubernetes operations by maintaining functionality for:
* Managing the TLS certificates of Kubernetes components
* Managing the connection between worker and server nodes
* Auto-deploying Kubernetes resources from local manifests in realtime as they are changed.
* Managing an embedded etcd cluster
What's with the name?
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We wanted an installation of Kubernetes that was half the size in terms of memory footprint. Kubernetes is a
10 letter word stylized as k8s. So something half as big as Kubernetes would be a 5 letter word stylized as
K3s. A '3' is also an '8' cut in half vertically. There is neither a long-form of K3s nor official pronunciation.
Is this a fork?
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No, it's a distribution. A fork implies continued divergence from the original. This is not K3s's goal or practice. K3s explicitly intends not to change any core Kubernetes functionality. We seek to remain as close to upstream Kubernetes as possible. However, we maintain a small set of patches (well under 1000 lines) important to K3s's use case and deployment model. We maintain patches for other components as well. When possible, we contribute these changes back to the upstream projects, for example, with SELinux support in containerd. This is a common practice amongst software distributions.
K3s is a di