Build a Kubernetes cluster using K3s via Ansible

Author: https://github.com/itwars Current Maintainer: https://github.com/dereknola

Easily bring up a cluster on machines running:

• Debian
• Ubuntu
• Raspberry Pi OS
• RHEL Family (CentOS, Redhat, Rocky Linux...)
• SUSE Family (SLES, OpenSUSE Leap, Tumbleweed...)
• ArchLinux

on processor architectures:

• x64
• arm64
• armhf

System requirements

The control node must have Ansible 2.10.0+

All managed nodes in inventory must have:

• Passwordless SSH access
• Root access (or a user with equivalent permissions)

It is also recommended that all managed nodes disable firewalls and swap. See K3s Requirements for more information.

Usage

First copy the sample inventory to inventory.yml.

cp inventory-sample.yml inventory.yml

Second edit the inventory file to match your cluster setup. For example:

k3s_cluster:
  children:
    server:
      hosts:
        192.16.35.11
    agent:
      hosts:
        192.16.35.12
        192.16.35.13

If needed, you can also edit vars section at the bottom to match your environment.

If multiple hosts are in the server group the playbook will automatically setup k3s in HA mode with embedded etcd. An odd number of server nodes is required (3,5,7). Read the offical documentation below for more information and options. https://rancher.com/docs/k3s/latest/en/installation/ha-embedded/

Setting up a loadbalancer or VIP beforehand to use as the API endpoint is possible but not covered here.

Start provisioning of the cluster using the following command:

ansible-playbook playbook/site.yml -i inventory.yml

Upgrading

A playbook is provided to upgrade K3s on all nodes in the cluster. To use it, update k3s_version with the desired version in inventory.yml and run:

ansible-playbook playbook/upgrade.yml -i inventory.yml

Kubeconfig

After successful bringup, the kubeconfig of the cluster is copied to the control node and set as default (~/.kube/config). Assuming you have kubectl installed, you to confirm access to your Kubernetes cluster use the following:

kubectl get nodes

Local Testing

A Vagrantfile is provided that provision a 5 nodes cluster using Vagrant (LibVirt or Virtualbox as provider). To use it:

vagrant up

By default, each node is given 2 cores and 2GB of RAM and runs Ubuntu 20.04. You can customize these settings by editing the Vagrantfile.

Need More Features?

This project is intended to provide a "vanilla" K3s install. If you need more features, such as:

• Private Registry
• Advanced Storage (Longhorn, Ceph, etc)
• External Database
• External Load Balancer or VIP
• Alternative CNIs

See these other projects:

• https://github.com/PyratLabs/ansible-role-k3s
• https://github.com/techno-tim/k3s-ansible
• https://github.com/jon-stumpf/k3s-ansible
• https://github.com/alexellis/k3sup