Getting Started

Getting started with Kairos

Ready to launch your Kubernetes cluster with ease? With Kairos, deployment is a breeze! Simply download the pre-packaged artifacts, boot up on a VM or bare metal, and let Kairos handle the rest. Whether you’re a Linux or Windows user, our quickstart guide will have you up and running in no time. Kairos can build a Kubernetes cluster for you with just a few simple steps!

The goal of this quickstart is to help you quickly and easily deploy a Kubernetes cluster using Kairos releases. With Kairos, you can easily build a k3s cluster in a VM, or a baremetal using our pre-packaged artifacts, even if you don’t already have a cluster. This process can also be used on bare metal hosts with some configuration adjustments. Check out our documentation further for more detailed instructions and examples.

To create a Kubernetes cluster with Kairos, the only thing needed is one or more machines that will become the Kubernetes nodes. No previously existing clusters is needed.

Once the installation is complete, you can begin using your Kubernetes cluster.

Prerequisites

  • A VM (hypervisor) or a physical server (bare-metal) that boots ISOs
  • A Linux or a Windows machine where to run the Kairos CLI (optional, we will see)
  • A cloud-init configuration file (example below)
  • At least 30+ Gb of available disk space.

Download

  1. Visit the Kairos release page on GitHub
  2. Select the latest release and download the assets of your flavor. For example, pick the kairos-opensuse-leap-15.5-standard-amd64-generic-v2.5.0-k3sv1.29.0+k3s1.iso ISO file for the openSUSE based version, where k3sv1.29.0+k3s1 in the name is the k3s version and v2.5.0 is the Kairos one to deploy on a VM.
  3. You can also use netboot to boot Kairos over the network

Checking artifacts signatures

Our ISO releases have sha256 files to checksum the validity of the artifacts. At the same time, our sha256 files are signed automatically in the CI during the release workflow to verify that they haven’t been tampered with, adding an extra step to the supply chain.

It is recommended that before starting any installation the whole security chain is validated by verifying our sha256 signature and validating that the checksum matches with the download artifacts.

To validate the whole chain you would need:

  1. sha256sum which is usually installed by default on most linux distributions.
  2. cosign to verify the signatures of the sha256 file. You can install cosign via their installation docs
  3. ISO, sha256, certificate and signature files for the release/flavor that you want to verify. All the artifacts are available on the kairos release page

In this example we will use the v2.5.0 version and opensuse flavor and leap-15.5 flavor release.

First we check that we have all needed files:

$ ls      
kairos-opensuse-leap-15.5-core-amd64-generic-v2.5.0.iso         kairos-opensuse-leap-15.5-core-amd64-generic-v2.5.0.iso.sha256.pem
kairos-opensuse-leap-15.5-core-amd64-generic-v2.5.0.iso.sha256  kairos-opensuse-leap-15.5-core-amd64-generic-v2.5.0.iso.sha256.sig

We first verify that the sha256 checksums haven’t been tampered with:

$ COSIGN_EXPERIMENTAL=1 cosign verify-blob --cert kairos-opensuse-leap-15.5-core-amd64-generic-v2.5.0.iso.sha256.pem --signature kairos-opensuse-leap-15.5-core-amd64-generic-v2.5.0.iso.sha256.sig kairos-opensuse-leap-15.5-core-amd64-generic-v2.5.0.iso.sha256 
tlog entry verified with uuid: 51ef927a43557386ad7912802607aa421566772524319703a99f8331f0bb778f index: 11977200
Verified OK

Once we see that Verified OK we can be sure that the file hasn’t been tampered with, and we can continue verifying the iso checksum.

For an example of a failure validation see below:

$ COSIGN_EXPERIMENTAL=1 cosign verify-blob --enforce-sct --cert kairos-opensuse-leap-15.5-core-amd64-generic-v2.5.0.iso.sha256.pem --signature kairos-opensuse-leap-15.5-core-amd64-generic-v2.5.0.iso.sha256.sig kairos-opensuse-leap-15.5-core-amd64-generic-v2.5.0.iso.sha256.modified
Error: verifying blob [kairos-opensuse-leap-15.5-core-amd64-generic-v2.5.0.iso.sha256.modified]: invalid signature when validating ASN.1 encoded signature
main.go:62: error during command execution: verifying blob [kairos-opensuse-leap-15.5-core-amd64-generic-v2.5.0.iso.sha256.modified]: invalid signature when validating ASN.1 encoded signature

Now we can verify that the integrity of the ISO hasnt been compromise:

$ sha256sum -c kairos-opensuse-leap-15.5-core-amd64-generic-v2.5.0.iso.sha256 
kairos-opensuse-leap-15.5-core-amd64-generic-v2.5.0.iso: OK

Once we reached this point, we can be sure that from the ISO hasn’t been tampered with since it was created by our release workflow.

Booting

Now that you have the ISO at hand, it’s time to boot!

Here are some additional helpful tips depending on the physical/virtual machine you’re using.

When deploying on a bare metal server, directly flash the image into a USB stick. There are multiple ways to do this:

From the command line using the dd command

dd if=/path/to/iso of=/path/to/dev bs=4MB

From the GUI

For example using an application like balenaEtcher but can be any other application which allows you to write bootable USBs.

This would be the way to start it via the command line, but you can also use the GUI
  virt-install --name my-first-kairos-vm \
              --vcpus 1 \
              --memory 1024 \
              --cdrom /path/to/kairos-opensuse-leap-15.5-standard-amd64-generic-v2.5.0-k3sv1.29.0+k3s1.iso \
              --disk size=30 \
              --os-variant opensuse-factory \
              --virt-type kvm
Immediately after open a viewer so you can interact with the boot menu:
virt-viewer my-first-kairos-vm

After booting you’ll be greeted with a GRUB boot menu with multiple options. The option you choose will depend on how you plan to install Kairos:

  • The first entry will boot into installation with a QR code or WebUI, which we’ll cover in the next step.
  • The second entry will boot into Manual installation mode, where you can install Kairos manually using the console.
  • The third boot option boots into Interactive installation mode, where you can use the terminal host to drive the installation and skip the Configuration and Provisioning step.

To begin the installation process, select the first entry and let the machine boot. Eventually, a QR code will be printed on the screen. Follow the next step in the documentation to complete the installation.

livecd

Configuration

After booting up the ISO, the machine will wait for you to provide configuration details before continuing with the installation process. There are different ways to provide these details:

The configuration file is a YAML file with cloud-init syntax and additional Kairos configuration details. In this example, we’ll configure the node as a single-node Kubernetes cluster using K3s. We’ll also set a default password for the Kairos user and define SSH keys.

Here’s an example configuration file that you can use as a starting point:

#cloud-config

# Define the user accounts on the node.
users:
- name: "kairos"                       # The username for the user.
  passwd: "kairos"                      # The password for the user.
  ssh_authorized_keys:                  # A list of SSH keys to add to the user's authorized keys.
  - github:mudler                       # A key from the user's GitHub account.
  - "ssh-rsa AAA..."                    # A raw SSH key.

# Enable K3s on the node.
k3s:
  enabled: true                         # Set to true to enable K3s.

Save this file as config.yaml and use it to start the installation process with kairos-agent manual-install config.yaml. This will configure the node as a single-node Kubernetes cluster and set the default password and SSH keys as specified in the configuration file.

Check out the full configuration reference.

Note:

  • users: This block defines the user accounts on the node. In this example, it creates a user named kairos with the password kairos and adds two SSH keys to the user’s authorized keys.
  • k3s: This block enables K3s on the node.
  • If you want to enable experimental P2P support, check out P2P installation

Provisioning

To trigger the installation process via QR code, you need to use the Kairos CLI. The CLI is currently available only for Linux and Windows. It can be downloaded from the release artifact:

curl -L https://github.com/kairos-io/provider-kairos/releases/download/v2.6.3/kairosctl-v2.6.3-linux-amd64.tar.gz -o - | tar -xvzf - -C .
# optionally, install the CLI locally
mv kairosctl /usr/local/bin/kairosctl
chmod +x /usr/local/bin/kairosctl

The CLI allows to register a node with a QR Code screenshot, an QR Code image, or an EdgeVPN token. During pairing, the configuration is sent over, and the node will continue the installation process.

In a terminal window from your desktop/workstation, run:

kairosctl register --reboot --device /dev/sda --config config.yaml

Note:

  • By default, the CLI will automatically take a screenshot to get the QR code. Make sure it fits into the screen. Alternatively, an image path or an EdgeVPN token can be supplied via arguments (e.g. kairosctl register /img/path or kairosctl register <EdgeVPN token>).
  • The --reboot flag will make the node reboot automatically after the installation is completed.
  • The --device flag determines the specific drive where Kairos will be installed. Replace /dev/sda with your drive. Any existing data will be overwritten, so please be cautious.
  • The --config flag is used to specify the config file used by the installation process.

After a few minutes, the configuration is distributed to the node and the installation starts. At the end of the installation, the system is automatically rebooted.

Accessing the Node

After the boot process, the node starts and is loaded into the system. You should already have SSH connectivity when the console is available.

To access to the host, log in as kairos:

ssh kairos@IP

Note:

  • sudo permissions are configured for the Kairos user.

You will be greeted with a welcome message:

Welcome to Kairos!

Refer to https://kairos.io for documentation.
kairos@kairos:~>

It can take a few moments to get the K3s server running. However, you should be able to inspect the service and see K3s running. For example, with systemd-based flavors:

$ sudo systemctl status k3s
● k3s.service - Lightweight Kubernetes
     Loaded: loaded (/etc/systemd/system/k3s.service; enabled; vendor preset: disabled)
    Drop-In: /etc/systemd/system/k3s.service.d
             └─override.conf
     Active: active (running) since Thu 2022-09-01 12:02:39 CEST; 4 days ago
       Docs: https://k3s.io
   Main PID: 1834 (k3s-server)
      Tasks: 220

The K3s kubeconfig file is available at /etc/rancher/k3s/k3s.yaml. Please refer to the K3s documentation.

See Also

There are other ways to install Kairos:

What’s Next?


Last modified February 21, 2024: kairosctl download link fix. (#150) (4fc6bc0)