KVM

Create a Talos Kubernetes cluster with KVM.

In this guide, you’ll create a Kubernetes cluster using KVM and virsh command-line utility.

Requirements

Make sure you have the following installed and configured:

• Kernel with KVM enabled (/dev/kvm must exist)
• QEMU
• virsh: Command-line interface for managing KVM/QEMU VMs
• kubectl: Kubernetes CLI
• talosctl: CLI for interacting with Talos clusters
• 16 GB RAM: Recommended minimum for running the VMs
• (Optional) virt-manager for a graphical interface

Note: This guide assumes you are running all the commands from the following working directory.

Create a working directory for your project files:

mkdir -p ~/talos-kvm/configs
cd ~/talos-kvm

Download the latest metal-amd64.iso from the Talos GitHub releases page.

Configure the Network

Before we get started, let’s set up an isolated network for your Talos cluster.

Use the following command to write the required network configuration into a file.

IPv4 Only

cat > my-talos-net.xml <<EOF
<network>
  <name>my-talos-net</name>
  <bridge name="talos-bridge" stp="on" delay="0"/>
  <forward mode='nat'>
    <nat/>
  </forward>
  <ip address="10.0.0.1" netmask="255.255.255.0">
    <dhcp>
      <range start="10.0.0.2" end="10.0.0.254"/>
    </dhcp>
  </ip>
</network>
EOF

Use the following command to generate the configurations and define the bridge:

virsh net-define my-talos-net.xml

Use the following command to start the network and flag it to auto start after reboot:

virsh net-start my-talos-net
virsh net-autostart my-talos-net

Verify the network:

virsh net-info my-talos-net

Note: You should see the network as Active.

Expected output:

Name:           my-talos-net
UUID:           <UNIQUE UUID>
Active:         yes
Persistent:     yes
Autostart:      yes
Bridge:         talos-bridge

Provisioning the Environment

Now that you have a dedicated network let’s go ahead and provision VMs.

Note: For the network interface emulation, virtio and e1000 are supported.

In the next command, you will use the --network network=my-talos-net flag to attach the VMs to the Talos network you created earlier.

The values for —ram and —vcpus in this guide are suggestions. You can adjust these to match the resources available on your host machine and the needs of your workload.

Use the following command to create a controlplane node:

virt-install \
  --virt-type kvm \
  --name control-plane-node-1 \
  --ram 2048 \
  --vcpus 2 \
  --disk path=control-plane-node-1-disk.qcow2,bus=virtio,size=40,format=qcow2 \
  --cdrom metal-amd64.iso \
  --os-variant=linux2022 \
  --network network=my-talos-net \
  --boot hd,cdrom --noautoconsole

Use the following command to create a worker node:

virt-install \
  --virt-type kvm \
  --name worker-node-1 \
  --ram 4086 \
  --vcpus 2 \
  --disk path=worker-node-1-disk.qcow2,bus=virtio,size=40,format=qcow2 \
  --cdrom metal-amd64.iso \
  --os-variant=linux2022 \
  --network network=my-talos-net \
  --boot hd,cdrom --noautoconsole

Use the following command to verify that your VMs are in a running state:

virsh list

Configure the Cluster

Now that you have your VMs provisioned it’s time to configure the cluster. This step is done through talosctl command utility.

Use the following command to view your control plane IP address, and do the same for your worker node by adjusting the vm name:

virsh domifaddr control-plane-node-1

This guide is designed to help you get up and running quickly. To simplify the process, you will store the VM IP addresses in two environment variables: CP_IP and NODE_IP.

You can automate this step with the following commands:

export CP_IP=$(virsh domifaddr  control-plane-node-1 | egrep '/' | awk '{print $4}' | cut -d/ -f1)
export NODE_IP=$(virsh domifaddr worker-node-1 | egrep '/' | awk '{print $4}' | cut -d/ -f1)

Currently, your VMs are running Talos directly from the ISO image you downloaded. To install Talos onto the VM disks (so they can boot without the ISO), you need to specify the disk name during the configuration step.

Use the following command to get the name of your VMs disk:

talosctl  get disks --nodes $CP_IP --insecure

You should see a result similar to the following:

NODE   NAMESPACE   TYPE   ID      VERSION   SIZE     READ ONLY   TRANSPORT   ROTATIONAL   WWID   MODEL          SERIAL
       runtime     Disk   loop0   2         73 MB    true
       runtime     Disk   sr0     2         301 MB   false       ata                             QEMU DVD-ROM   QEMU_DVD-ROM_QM00001
       runtime     Disk   vda     2         43 GB    false       virtio      true

Use the following command to generate the Talos configurations:

talosctl gen config my-talos-cluster https://$CP_IP:6443 --install-disk /dev/vda -o configs/

Use the following command to apply the configurations to each VM:

talosctl apply-config --insecure --nodes $CP_IP --file configs/controlplane.yaml
talosctl apply-config --insecure --nodes $NODE_IP --file configs/worker.yaml

At this point your VMs will reboot.

Bootstrapping the Cluster

After your VMs restart, you can bootstrap the cluster. Bootstrap simply means starting up your Kubernetes cluster for the first time.

To do this, provide the talosconfig file (generated earlier) to the talosctl command-line utility. The easiest way is to export the path to talosconfig as an environment variable.

Use the following command to export your talosconfig:

export TALOSCONFIG=$(realpath configs/talosconfig)

Before running the bootstrap, you need to tell talosctl where to connect:

talosctl config endpoint $CP_IP

Note: Keep in mind that it may take a couple of seconds for the bootstraping to complete.

Use the following command to bootstrap the cluster:

talosctl -n $CP_IP bootstrap

At this point you should be able to see all the VMs that are participating in your cluster.

talosctl -n $CP_IP get members

Accessing the cluster

To access your cluster you need to export the kubeconfig file from the Talos cluster.

Use the following command to export the kubeconfig file:

talosctl -n $CP_IP kubeconfig $PWD/configs/kubeconfig

Set the KUBECONFIG environment variable to use your new kubeconfig file.

export KUBECONFIG=$PWD/configs/kubeconfig

That’s it! You can now use kubectl to interact with your Talos Kubernetes cluster. Check the status of your nodes with kubectl to verify they are ready.

kubectl get nodes -o wide

Clean up

When you are finished with your cluster, you can delete the VMs and the isolated network to free up system resources.

virsh destroy <VM-NAME-HERE>
virsh undefine <VM-NAME-HERE> --remove-all-storage

Use the following command to delete the network:

virsh net-destroy --network my-talos-net
virsh net-undefine --network my-talos-net