Merge branch 'kube-hetzner:master' into master

2022-03-05 07:44:38 +01:00 · 2022-03-05 07:44:38 +01:00 · e636be1a0e
commit e636be1a0e
parent 8f39cd1a91 7f11b21d46
15 changed files with 203 additions and 118 deletions
--- a/.gitignore
+++ b/.gitignore
@ -4,5 +4,6 @@ crash.log
 kubeconfig.yaml
 kubeconfig.yaml-e
 terraform.tfvars
-plans.yaml
-traefik_config.yaml
+plans-custom.yaml
+traefik-custom.yaml
+kured-custom.yaml
--- a/README.md
+++ b/README.md
@ -149,7 +149,6 @@ spec:
  tls:
    - hosts:
        - example.com
-      secretName: example-tls
  rules:
    - host: example.com
      http:
@ -166,6 +165,21 @@ spec:

 </details>

+<details>
+
+<summary>single-node cluster</summary>
+
+Running a development cluster on a single node, without any high-availability is possible as well.
+In this case, we don't deploy an external load-balancer, but use [k3s service load balancer](https://rancher.com/docs/k3s/latest/en/networking/#service-load-balancer) on the host itself and open up port 80 & 443 in the firewall.
+
+``` terraform
+control_plane_count = 1
+allow_scheduling_on_control_plane = true
+agent_nodepools = {}
+```
+
+</details>
+
 ## Debugging

 First and foremost, it depends, but it's always good to have a quick look into Hetzner quickly without having to login to the UI. That is where the `hcloud` cli comes in.
--- a/agents.tf
+++ b/agents.tf
@ -44,11 +44,11 @@ resource "null_resource" "agents" {
  provisioner "file" {
    content = yamlencode({
      node-name     = module.agents[each.key].name
-      server        = "https://${local.first_control_plane_network_ipv4}:6443"
+      server        = "https://${module.control_planes[0].private_ipv4_address}:6443"
      token         = random_password.k3s_token.result
      kubelet-arg   = "cloud-provider=external"
      flannel-iface = "eth1"
-      node-ip       = module.agents[each.key].ipv4_address
+      node-ip       = module.agents[each.key].private_ipv4_address
      node-label    = var.automatically_upgrade_k3s ? ["k3s_upgrade=true"] : []
    })
    destination = "/tmp/config.yaml"
--- a/control_planes.tf
+++ b/control_planes.tf
@ -53,7 +53,6 @@ resource "null_resource" "control_planes" {
      kubelet-arg              = "cloud-provider=external"
      node-ip                  = module.control_planes[count.index].private_ipv4_address
      advertise-address        = module.control_planes[count.index].private_ipv4_address
-      tls-san                  = module.control_planes[count.index].private_ipv4_address
      node-taint               = var.allow_scheduling_on_control_plane ? [] : ["node-role.kubernetes.io/master:NoSchedule"]
      node-label               = var.automatically_upgrade_k3s ? ["k3s_upgrade=true"] : []
    })
--- a/examples/tls/ingress.yaml
+++ b/examples/tls/ingress.yaml
@ -9,7 +9,6 @@ spec:
  tls:
    - hosts:
        - example.com
-      secretName: example-tls
  rules:
    - host: example.com
      http:
--- a/init.tf
+++ b/init.tf
@ -13,12 +13,11 @@ resource "null_resource" "first_control_plane" {
      token                    = random_password.k3s_token.result
      cluster-init             = true
      disable-cloud-controller = true
-      disable                  = ["servicelb", "local-storage"]
+      disable                  = concat(["local-storage"], local.is_single_node_cluster ? [] : ["servicelb"])
      flannel-iface            = "eth1"
      kubelet-arg              = "cloud-provider=external"
      node-ip                  = module.control_planes[0].private_ipv4_address
      advertise-address        = module.control_planes[0].private_ipv4_address
-      tls-san                  = module.control_planes[0].private_ipv4_address
      node-taint               = var.allow_scheduling_on_control_plane ? [] : ["node-role.kubernetes.io/master:NoSchedule"]
      node-label               = var.automatically_upgrade_k3s ? ["k3s_upgrade=true"] : []
    })
@ -30,7 +29,7 @@ resource "null_resource" "first_control_plane" {
    inline = local.install_k3s_server
  }

-  # Upon reboot verify that the k3s server is starts, and wait for k3s to be ready to receive commands
+  # Upon reboot start k3s and wait for it to be ready to receive commands
  provisioner "remote-exec" {
    inline = [
      "systemctl start k3s",
@ -75,13 +74,12 @@ resource "null_resource" "kustomization" {
    content = yamlencode({
      apiVersion = "kustomize.config.k8s.io/v1beta1"
      kind       = "Kustomization"
-      resources = [
+      resources = concat([
        "https://github.com/hetznercloud/hcloud-cloud-controller-manager/releases/download/${local.ccm_version}/ccm-networks.yaml",
        "https://raw.githubusercontent.com/hetznercloud/csi-driver/${local.csi_version}/deploy/kubernetes/hcloud-csi.yml",
        "https://github.com/weaveworks/kured/releases/download/${local.kured_version}/kured-${local.kured_version}-dockerhub.yaml",
        "https://raw.githubusercontent.com/rancher/system-upgrade-controller/master/manifests/system-upgrade-controller.yaml",
-        "traefik.yaml",
-      ]
+      ], local.is_single_node_cluster ? [] : ["traefik.yaml"]),
      patchesStrategicMerge = [
        file("${path.module}/kustomize/kured.yaml"),
        file("${path.module}/kustomize/ccm.yaml"),
@ -93,7 +91,7 @@ resource "null_resource" "kustomization" {

  # Upload traefik config
  provisioner "file" {
-    content = templatefile(
+    content = local.is_single_node_cluster ? "" : templatefile(
      "${path.module}/templates/traefik_config.yaml.tpl",
      {
        load_balancer_disable_ipv6 = var.load_balancer_disable_ipv6
@ -127,7 +125,7 @@ resource "null_resource" "kustomization" {

  # Deploy our post-installation kustomization
  provisioner "remote-exec" {
-    inline = [
+    inline = concat([
      "set -ex",
      # This ugly hack is here, because terraform serializes the
      # embedded yaml files with "- |2", when there is more than
@ -141,8 +139,9 @@ resource "null_resource" "kustomization" {
      "kubectl apply -k /tmp/post_install",
      "echo 'Waiting for the system-upgrade-controller deployment to become available...'",
      "kubectl -n system-upgrade wait --for=condition=available --timeout=120s deployment/system-upgrade-controller",
-      "kubectl -n system-upgrade apply -f /tmp/post_install/plans.yaml",
-      <<-EOT
+      "kubectl -n system-upgrade apply -f /tmp/post_install/plans.yaml"
+      ],
+      local.is_single_node_cluster ? [] : [<<-EOT
      timeout 120 bash <<EOF
      until [ -n "\$(kubectl get -n kube-system service/traefik --output=jsonpath='{.status.loadBalancer.ingress[0].ip}' 2> /dev/null)" ]; do
          echo "Waiting for load-balancer to get an IP..."
@ -150,7 +149,7 @@ resource "null_resource" "kustomization" {
      done
      EOF
      EOT
-    ]
+    ])
  }

  depends_on = [
--- a/locals.tf
+++ b/locals.tf
@ -1,7 +1,7 @@
 locals {
-  first_control_plane_network_ipv4 = module.control_planes[0].private_ipv4_address
-
-  ssh_public_key = trimspace(file(var.public_key))
+  # if we are in a single cluster config, we use the default klipper lb instead of Hetzner LB
+  is_single_node_cluster = var.control_plane_count + length(keys(var.agent_nodepools)) == 1
+  ssh_public_key         = trimspace(file(var.public_key))
  # ssh_private_key is either the contents of var.private_key or null to use a ssh agent.
  ssh_private_key = var.private_key == null ? null : trimspace(file(var.private_key))
  # ssh_identity is not set if the private key is passed directly, but if ssh agent is used, the public key tells ssh agent which private key to use.
@ -29,7 +29,7 @@ locals {
    "127.0.0.1/32",
  ]

-  base_firewall_rules = [
+  base_firewall_rules = concat([
    # Allowing internal cluster traffic and Hetzner metadata service and cloud API IPs
    {
      direction  = "in"
@ -133,7 +133,26 @@ locals {
        "0.0.0.0/0"
      ]
    }
-  ]
+    ], !local.is_single_node_cluster ? [] : [
+    # Allow incoming web traffic for single node clusters, because we are using k3s servicelb there,
+    # not an external load-balancer.
+    {
+      direction = "in"
+      protocol  = "tcp"
+      port      = "80"
+      source_ips = [
+        "0.0.0.0/0"
+      ]
+    },
+    {
+      direction = "in"
+      protocol  = "tcp"
+      port      = "443"
+      source_ips = [
+        "0.0.0.0/0"
+      ]
+    }
+  ])

  common_commands_install_k3s = [
    "set -ex",
@ -145,9 +164,10 @@ locals {
    "[ -e /etc/rancher/k3s/k3s.yaml ] && exit 0",
  ]

-  install_k3s_server = concat(local.common_commands_install_k3s, ["curl -sfL https://get.k3s.io | INSTALL_K3S_SKIP_SELINUX_RPM=true INSTALL_K3S_SKIP_START=true INSTALL_K3S_CHANNEL=${var.initial_k3s_channel} INSTALL_K3S_EXEC=server sh -"])
+  apply_k3s_selinux = ["/sbin/semodule -v -i /usr/share/selinux/packages/k3s.pp"]

-  install_k3s_agent = concat(local.common_commands_install_k3s, ["curl -sfL https://get.k3s.io | INSTALL_K3S_SKIP_SELINUX_RPM=true INSTALL_K3S_SKIP_START=true INSTALL_K3S_CHANNEL=${var.initial_k3s_channel} INSTALL_K3S_EXEC=agent sh -"])
+  install_k3s_server = concat(local.common_commands_install_k3s, ["curl -sfL https://get.k3s.io | INSTALL_K3S_SKIP_START=true INSTALL_K3S_SKIP_SELINUX_RPM=true INSTALL_K3S_CHANNEL=${var.initial_k3s_channel} INSTALL_K3S_EXEC=server sh -"], local.apply_k3s_selinux)
+  install_k3s_agent  = concat(local.common_commands_install_k3s, ["curl -sfL https://get.k3s.io | INSTALL_K3S_SKIP_START=true INSTALL_K3S_SKIP_SELINUX_RPM=true INSTALL_K3S_CHANNEL=${var.initial_k3s_channel} INSTALL_K3S_EXEC=agent sh -"], local.apply_k3s_selinux)

  agent_nodepools = merge([
    for nodepool_name, nodepool_obj in var.agent_nodepools : {
--- a/main.tf
+++ b/main.tf
@ -13,12 +13,22 @@ resource "hcloud_network" "k3s" {
  ip_range = var.network_ipv4_range
 }

+# This is the default subnet to be used by the load balancer.
+resource "hcloud_network_subnet" "default" {
+  network_id   = hcloud_network.k3s.id
+  type         = "cloud"
+  network_zone = var.network_region
+  ip_range     = "10.0.0.0/16"
+}
+
 resource "hcloud_network_subnet" "subnet" {
  for_each     = var.network_ipv4_subnets
  network_id   = hcloud_network.k3s.id
  type         = "cloud"
  network_zone = var.network_region
  ip_range     = each.value
+
+  depends_on = [hcloud_network_subnet.default]
 }

 resource "hcloud_firewall" "k3s" {
@ -46,7 +56,8 @@ resource "hcloud_placement_group" "k3s" {
 }

 data "hcloud_load_balancer" "traefik" {
-  name = "traefik"
+  count = local.is_single_node_cluster ? 0 : 1
+  name  = "traefik"

  depends_on = [null_resource.kustomization]
 }
--- a/modules/host/locals.tf
+++ b/modules/host/locals.tf
@ -10,65 +10,4 @@ locals {
  ssh_identity_file = var.private_key == null ? var.public_key : var.private_key
  # shared flags for ssh to ignore host keys, to use our ssh identity file for all connections during provisioning.
  ssh_args = "-o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no -i ${local.ssh_identity_file}"
-
-  microOS_install_commands = [
-    "set -ex",
-    "apt-get update",
-    "apt-get install -y aria2",
-    "aria2c --follow-metalink=mem https://download.opensuse.org/tumbleweed/appliances/openSUSE-MicroOS.x86_64-kvm-and-xen.qcow2.meta4",
-    "qemu-img convert -p -f qcow2 -O host_device $(ls -a | grep -ie '^opensuse.*microos.*qcow2$') /dev/sda",
-    "sgdisk -e /dev/sda",
-    "parted -s /dev/sda resizepart 4 99%",
-    "parted -s /dev/sda mkpart primary ext2 99% 100%",
-    "partprobe /dev/sda && udevadm settle && fdisk -l /dev/sda",
-    "mount /dev/sda4 /mnt/ && btrfs filesystem resize max /mnt && umount /mnt",
-    "mke2fs -L ignition /dev/sda5",
-    "mount /dev/sda5 /mnt",
-    "mkdir /mnt/ignition",
-    "cp /root/config.ign /mnt/ignition/config.ign",
-    "mkdir /mnt/combustion",
-    "cp /root/script /mnt/combustion/script",
-    "umount /mnt"
-  ]
-
-  ignition_config = jsonencode({
-    ignition = {
-      version = "3.0.0"
-    }
-    passwd = {
-      users = [{
-        name              = "root"
-        sshAuthorizedKeys = concat([local.ssh_public_key], var.additional_public_keys)
-      }]
-    }
-    storage = {
-      files = [
-        {
-          path      = "/etc/sysconfig/network/ifcfg-eth1"
-          mode      = 420
-          overwrite = true
-          contents  = { "source" = "data:,BOOTPROTO%3D%27dhcp%27%0ASTARTMODE%3D%27auto%27" }
-        },
-        {
-          path      = "/etc/ssh/sshd_config.d/kube-hetzner.conf"
-          mode      = 420
-          overwrite = true
-          contents  = { "source" = "data:,PasswordAuthentication%20no%0AX11Forwarding%20no%0AMaxAuthTries%202%0AAllowTcpForwarding%20no%0AAllowAgentForwarding%20no%0AAuthorizedKeysFile%20.ssh%2Fauthorized_keys" }
-        }
-      ]
-    }
-  })
-
-  combustion_script = <<EOF
-#!/bin/bash
-sed -i 's#NETCONFIG_NIS_SETDOMAINNAME="yes"#NETCONFIG_NIS_SETDOMAINNAME="no"#g' /etc/sysconfig/network/config
-sed -i 's#WAIT_FOR_INTERFACES="30"#WAIT_FOR_INTERFACES="60"#g' /etc/sysconfig/network/config
-sed -i 's#CHECK_DUPLICATE_IP="yes"#CHECK_DUPLICATE_IP="no"#g' /etc/sysconfig/network/config
-# combustion: network
-rpm --import https://rpm.rancher.io/public.key
-zypper refresh
-zypper --gpg-auto-import-keys install -y https://rpm.rancher.io/k3s/stable/common/microos/noarch/k3s-selinux-0.4-1.sle.noarch.rpm
-udevadm settle || true
-EOF
-
 }
--- a/modules/host/main.tf
+++ b/modules/host/main.tf
@ -8,10 +8,20 @@ resource "hcloud_server" "server" {
  ssh_keys           = var.ssh_keys
  firewall_ids       = var.firewall_ids
  placement_group_id = var.placement_group_id
-
+  user_data          = data.template_cloudinit_config.config.rendered

  labels = var.labels

+  # Prevent destroying the whole cluster if the user changes
+  # any of the attributes that force to recreate the servers.
+  lifecycle {
+    ignore_changes = [
+      location,
+      ssh_keys,
+      user_data,
+    ]
+  }
+
  connection {
    user           = "root"
    private_key    = local.ssh_private_key
@ -19,30 +29,21 @@ resource "hcloud_server" "server" {
    host           = self.ipv4_address
  }

-  provisioner "file" {
-    content     = local.ignition_config
-    destination = "/root/config.ign"
-  }
-
-  # Combustion script file to install k3s-selinux
-  provisioner "file" {
-    content     = local.combustion_script
-    destination = "/root/script"
-  }
-
  # Install MicroOS
  provisioner "remote-exec" {
-    inline = local.microOS_install_commands
+    inline = [
+      "set -ex",
+      "apt-get update",
+      "apt-get install -y aria2",
+      "aria2c --follow-metalink=mem https://download.opensuse.org/tumbleweed/appliances/openSUSE-MicroOS.x86_64-OpenStack-Cloud.qcow2.meta4",
+      "qemu-img convert -p -f qcow2 -O host_device $(ls -a | grep -ie '^opensuse.*microos.*qcow2$') /dev/sda",
+    ]
  }

-  # Issue a reboot command
-  provisioner "local-exec" {
-    command = "ssh ${local.ssh_args} root@${self.ipv4_address} '(sleep 2; reboot)&'; sleep 3"
-  }
-
-  # Wait for MicroOS to reboot and be ready
+  # Issue a reboot command and wait for MicroOS to reboot and be ready
  provisioner "local-exec" {
    command = <<-EOT
+      ssh ${local.ssh_args} root@${self.ipv4_address} '(sleep 2; reboot)&'; sleep 3
      until ssh ${local.ssh_args} -o ConnectTimeout=2 root@${self.ipv4_address} true 2> /dev/null
      do
        echo "Waiting for MicroOS to reboot and become available..."
@ -51,16 +52,25 @@ resource "hcloud_server" "server" {
    EOT
  }

+  # Install k3s-selinux (compatible version)
  provisioner "remote-exec" {
    inline = [
-      # Disable automatic reboot (after transactional updates), and configure the reboot method as kured
      "set -ex",
-      "rebootmgrctl set-strategy off",
-      "echo 'REBOOT_METHOD=kured' > /etc/transactional-update.conf",
-      # set the hostname
-      "hostnamectl set-hostname ${self.name}"
+      "transactional-update pkg install -y k3s-selinux"
    ]
  }
+
+  # Issue a reboot command and wait for MicroOS to reboot and be ready
+  provisioner "local-exec" {
+    command = <<-EOT
+      ssh ${local.ssh_args} root@${self.ipv4_address} '(sleep 2; reboot)&'; sleep 3
+      until ssh ${local.ssh_args} -o ConnectTimeout=2 root@${self.ipv4_address} true 2> /dev/null
+      do
+        echo "Waiting for MicroOS to reboot and become available..."
+        sleep 3
+      done
+    EOT
+  }
 }

 resource "hcloud_server_network" "server" {
@ -68,3 +78,21 @@ resource "hcloud_server_network" "server" {
  server_id = hcloud_server.server.id
  subnet_id = var.ipv4_subnet_id
 }
+
+data "template_cloudinit_config" "config" {
+  gzip          = true
+  base64_encode = true
+
+  # Main cloud-config configuration file.
+  part {
+    filename     = "init.cfg"
+    content_type = "text/cloud-config"
+    content = templatefile(
+      "${path.module}/templates/userdata.yaml.tpl",
+      {
+        hostname          = var.name
+        sshAuthorizedKeys = concat([local.ssh_public_key], var.additional_public_keys)
+      }
+    )
+  }
+}
--- a/modules/host/templates/userdata.yaml.tpl
+++ b/modules/host/templates/userdata.yaml.tpl
@ -0,0 +1,58 @@
+#cloud-config
+
+write_files:
+
+# Configure the private network interface
+- content: |
+    BOOTPROTO='dhcp'
+    STARTMODE='auto'
+  path: /etc/sysconfig/network/ifcfg-eth1
+
+# Disable ssh password authentication
+- content: |
+    PasswordAuthentication no
+    X11Forwarding no
+    MaxAuthTries 2
+    AllowTcpForwarding no
+    AllowAgentForwarding no
+    AuthorizedKeysFile .ssh/authorized_keys
+  path: /etc/ssh/sshd_config.d/kube-hetzner.conf
+
+# Set reboot method as "kured"
+- content: |
+    REBOOT_METHOD=kured
+  path: /etc/transactional-update.conf
+
+# Add ssh authorized keys
+ssh_authorized_keys:
+%{ for key in sshAuthorizedKeys ~}
+  - ${key}
+%{ endfor ~}
+
+# Resize /var, not /, as that's the last partition in MicroOS image.
+growpart:
+    devices: ["/var"]
+
+# Make sure the hostname is set correctly
+hostname: ${hostname}
+preserve_hostname: true
+
+runcmd:
+
+# As above, make sure the hostname is not reset
+- [sed, '-i', 's/NETCONFIG_NIS_SETDOMAINNAME="yes"/NETCONFIG_NIS_SETDOMAINNAME="no"/g', /etc/sysconfig/network/config]
+- [sed, '-i', 's/DHCLIENT_SET_HOSTNAME="yes"/DHCLIENT_SET_HOSTNAME="no"/g', /etc/sysconfig/network/dhcp]
+
+# We set Cloudflare DNS servers, followed by Google as a backup
+- [sed, '-i', 's/NETCONFIG_DNS_STATIC_SERVERS=""/NETCONFIG_DNS_STATIC_SERVERS="1.1.1.1 1.0.0.1 8.8.8.8"/g', /etc/sysconfig/network/config]
+
+# Bounds the amount of logs that can survive on the system
+- [sed, '-i', 's/#SystemMaxUse=/SystemMaxUse=3G/g', /etc/systemd/journald.conf]
+- [sed, '-i', 's/#MaxRetentionSec=/MaxRetentionSec=1week/g', /etc/systemd/journald.conf]
+
+# Reduces the default number of snapshots from 2-10 number limit, to 4 and from 4-10 number limit important, to 2
+- [sed, '-i', 's/NUMBER_LIMIT="2-10"/NUMBER_LIMIT="4"/g', /etc/snapper/configs/root]
+- [sed, '-i', 's/NUMBER_LIMIT_IMPORTANT="4-10"/NUMBER_LIMIT_IMPORTANT="3"/g', /etc/snapper/configs/root]
+
+# Disables unneeded services
+- [systemctl, disable, '--now', 'rebootmgr.service']
--- a/modules/host/versions.tf
+++ b/modules/host/versions.tf
@ -12,5 +12,9 @@ terraform {
      source  = "tenstad/remote"
      version = "~> 0.0.23"
    }
+    template = {
+      source  = "hashicorp/template"
+      version = "~> 2.2.0"
+    }
  }
 }
--- a/output.tf
+++ b/output.tf
@ -12,7 +12,7 @@ output "agents_public_ipv4" {

 output "load_balancer_public_ipv4" {
  description = "The public IPv4 address of the Hetzner load balancer"
-  value       = data.hcloud_load_balancer.traefik.ipv4
+  value       = local.is_single_node_cluster ? module.control_planes[0].ipv4_address : data.hcloud_load_balancer.traefik[0].ipv4
 }

 output "kubeconfig_file" {
--- a/terraform.tfvars.example
+++ b/terraform.tfvars.example
@ -1,7 +1,15 @@
-# You need to replace these
+# Only the first values starting with a * are obligatory, the rest can remain with their default values, or you
+# could adapt them to your needs.
+#
+# Note that some values, notably "location" and "public_key" have no effect after the initial cluster has been setup.
+# This is in order to keep terraform from re-provisioning all nodes at once which would loose data. If you want to update,
+# those, you should instead change the value here and then manually re-provision each node one-by-one. Grep for "lifecycle".
+
+# * Your Hetzner project API token 
 hcloud_token = "xxxxxxxxxxxxxxxxxxYYYYYYYYYYYYYYYYYYYzzzzzzzzzzzzzzzzzzzzz"
+# * Your public key
 public_key   = "/home/username/.ssh/id_ed25519.pub"
-# Must be "private_key = null" when you want to use ssh-agent, for a Yubikey like device auth or an SSH key-pair with passphrase
+# * Your private key, must be "private_key = null" when you want to use ssh-agent, for a Yubikey like device auth or an SSH key-pair with passphrase
 private_key  = "/home/username/.ssh/id_ed25519"

 # These can be customized, or left with the default values
@ -10,9 +18,6 @@ private_key  = "/home/username/.ssh/id_ed25519"
 location         = "fsn1"       # change to `ash` for us-east Ashburn, Virginia location
 network_region   = "eu-central" # change to `us-east` if location is ash

-# It's best to leave the network range as is, unless you know what you are doing. The default is "10.0.0.0/8".
-# network_ipv4_range = "10.0.0.0/8"
-
 # You can have up to as many subnets as you want (preferably if the form of 10.X.0.0/16),
 # their primary use is to logically separate the nodes.
 # The control_plane network is mandatory.
@ -25,13 +30,14 @@ network_ipv4_subnets = {
 # At least 3 server nodes is recommended for HA, otherwise you need to turn off automatic upgrade (see ReadMe).
 # As per rancher docs, it must be always an odd number, never even! See https://rancher.com/docs/k3s/latest/en/installation/ha-embedded/
 # For instance, 1 is ok (non-HA), 2 not ok, 3 is ok (becomes HA).
-control_plane_count       = 3
+control_plane_count = 3

 # The type of control plane nodes, see https://www.hetzner.com/cloud, the minimum instance supported is cpx11 (just a few cents more than cx11)
 control_plane_server_type = "cpx11"

 # As for the agent nodepools, below is just an example, if you do not want nodepools, just use one,
 # and change the name to what you want, it need not be "agent-big" or "agent-small", also give them the subnet prefer.
+# For single node clusters set this equal to {}
 agent_nodepools = {
  agent-big = {
    server_type = "cpx21",
@ -48,6 +54,11 @@ agent_nodepools = {
 # That will depend on how much load you want it to handle, see https://www.hetzner.com/cloud/load-balancer
 load_balancer_type        = "lb11"

+### The following values are fully optional
+
+# It's best to leave the network range as is, unless you know what you are doing. The default is "10.0.0.0/8".
+# network_ipv4_range = "10.0.0.0/8"
+
 # If you want to use a specific Hetzner CCM and CSI version, set them below, otherwise leave as is for the latest versions
 # hetzner_ccm_version = ""
 # hetzner_csi_version = ""
@ -57,6 +68,7 @@ load_balancer_type        = "lb11"
 # traefik_acme_email = "mail@example.com"

 # If you want to allow non-control-plane workloads to run on the control-plane nodes set "true" below. The default is "false".
+# Also good for single node clusters.
 # allow_scheduling_on_control_plane = true

 # If you want to disable automatic upgrade of k3s, you can set this to false, default is "true".
--- a/variables.tf
+++ b/variables.tf
@ -65,6 +65,7 @@ variable "load_balancer_disable_ipv6" {
 variable "agent_nodepools" {
  description = "Number of agent nodes."
  type        = map(any)
+  default     = {}
 }

 variable "hetzner_ccm_version" {