# Create a Kubernetes Node

This guide walks you through booting a VM from the network and installing Debian `12.x` (Bookworm),
using a PXE server. Moreover, you will learn how to use a [preseed](https://wiki.debian.org/DebianInstaller/Preseed)
file to automate the installation of Debian `12.x` on any VM.

## Step 1: Define the Worker VM

In this section, you define a new VM. We will use this as a use case. Then, you can deploy any VM
you want to create a Kubernetes cluster (e.g., a control plane, another worker, etc.) using exactly
the same process.

### What you'll need

To complete this guide, you will need the following:

* A working [QEMU/KVM installation](../qemu-kvm).
* A configured [PXE Server](pxe-server).

### Procedure

Follow the steps below to define a new VM:

1. Create a new `QCOW2` virtual disk for the VM:

    ```console
    user:~/virtml$ qemu-img create -f qcow2 /var/lib/libvirt/images/node1.qcow2 96G
    Formatting '/var/lib/libvirt/images/node1.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=103079215104 lazy_refcounts=off refcount_bits=16
    ```

1. Define a new VM, using the XML file inside the `infra` directory:

    ```console
    user:~/virtml$ virsh define --file infra/node1.xml
    Domain 'node1' defined from node1.xml
    ```

    ```{note}
    The `node1.xml` file is a template for the VM. You can modify it to fit your needs. Pay close
    attention to the sections where you specify the path to the `QCOW2` file.
    ```

### Verify

Verify that the VM has been defined correctly and is in the `shut off` state:

1. List the VMs you have defined:

    ```console
    user:~/virtml$ virsh list --all
    Id   Name           State
    -----------------------------
    1    virtml-admin   running
    -    node1          shut off
    ```

## Step 2: Configure the PXE Server

In this section, you configure your PXE Server to repond to request from this specific VM. To
achieve this, you use the MAC address of your newly created machine.

### What you'll need

To complete this guide, you will need the following:

* A defined worker VM.

### Procedure

1. Decide on login credentials for the `root` user of new worker VM:

    ```console
    user:~/virtml$ export ROOTPW_HASH=$(openssl passwd -6)
    ```

1. Export your public SSH key:

    ```console
    user:~/virtml$ export SSH_KEY=$(cat ~/.ssh/id_rsa.pub)
    ```

1. Export the hostname of the node VM:

    ```console
    user:~/virtml$ export HOSTNAME=node1
    ```

1. Export the domain name of the node VM:

    ```console
    user:~/virtml$ export DOMAIN=example.com
    ```

1. Render the preseed file:

    ```console
    user:~/virtml$ j2 infra/k8s_preseed.cfg.j2 > infra/k8s_preseed.cfg
    ```

1. Copy the preseed file onto the PXE Server:

    ```console
    user:~/virtml$ scp infra/k8s_preseed.cfg root@virtml-admin:/srv/tftp/preseed.cfg
    ```

1. Decide on the IP address and the hostname of the worker VM:

    a. Set the VM's IP address:

    ```console
    user:~/virtml$ export CLIENT_IP=192.168.20.101
    ```

    b. Set the VM's MAC address:

    ```console
    user:~/virtml$ export CLIENT_MAC=$(sudo virsh dumpxml node1 | grep "<mac address=" | awk -F"'" '{print $2}')
    ```

    c. Set the VM's hostname:

    ```console
    user:~/virtml$ export CLIENT_HOSTNAME=node1
    ```

1. Render the `dnsmasq` configuration:

    ```console
    user:~/virtml$ j2 infra/dnsmasq.conf.j2 > infra/dnsmasq.conf-01-${CLIENT_MAC//:/-}
    ```

1. Copy the configuration file onto the PXE Server:

    ```console
    user:~/virtml$ scp infra/dnsmasq.conf-01-${CLIENT_MAC//:/-} root@virtml-admin:/etc/dnsmasq.d/dnsmasq.conf-01-${CLIENT_MAC//:/-}
    ```

1. SSH into the PXE server VM:

    ```console
    user:~/virtml$ ssh root@virtml-admin
    ```

1. Restart the `dnsmasq` service:

    ```console
    root@virtml-admin:~# systemctl restart dnsmasq
    ```

1. Log out the PXE Server:

    ```console
    root@virtml-admin:~# exit
    ```

## Step 3: Start the worker VM

In this final section, you start the worker VM and watch as it boots from the network and installs
Debian automatically.

### What you'll need

* A defined worker VM.
* A configured PXE Server, ready to respond to DHCP discover requests from a spcific MAC address.

### Procedure

1. Start the worker VM:

    ```console
    user:~/virtml$ virsh start node1
    Domain 'node1' started
    ```

### Verify

1. Connect to the node1 through your terminal and watch as the Debian installer automatically
   installs the OS, without any human intervention.

    ```console
    user:~/virtml$ virsh console node1
    ```

1. SSH into the node1 VM:

    ```console
    user:~/virtml$ ssh root@node1
    ```

    ```{note}
    Replace `node1` with the IP address of the VM. Alternatively, you can set the hostname for the
    VM in your `/etc/hosts` file.
    ```