Merge pull request #149 from kube-hetzner/control-plane-pool

Control plane pool

README.md

@@ -33,9 +33,10 @@ _Please note that we are not affiliated to Hetzner, this is just an open source
 
 - Maintenance free with auto-upgrade to the latest version of MicroOS and k3s.
 - Proper use of the Hetzner private network to minimize latency and remove the need for encryption.
-- Automatic HA with the default setting of three control-plane nodes and two agent nodepools.
+- Automatic HA with the default setting of three control-plane nodes and two agent nodes.
+- Node pools for both control-plane and agent nodes. Different locations possible (super-HA).
 - Ability to add or remove as many nodes as you want while the cluster stays running.
-- Automatic Traefik ingress controller attached to a Hetzner load balancer with proxy protocol turned on.
+- Traefik ingress controller attached to a Hetzner load balancer with proxy protocol turned on.
 - Tons of flexible configuration options to suits all needs.
 
 _It uses Terraform to deploy as it's easy to use, and Hetzner provides a great [Hetzner Terraform Provider](https://registry.terraform.io/providers/hetznercloud/hcloud/latest/docs)._
@@ -169,14 +170,9 @@ spec:
 
 <summary>Single-node cluster</summary>
 
-Running a development cluster on a single node, without any high-availability is possible as well.
+Running a development cluster on a single node, without any high-availability is possible as well. You need one control plane nodepool with a count of 1, and one agent nodepool with a count of 0.
-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
+In this case, we don't deploy an external load-balancer, but use the default [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 (done automatically).
-control_plane_count = 1
-allow_scheduling_on_control_plane = true
-agent_nodepools = []
-```
 
 </details>
 

agents.tf

@@ -12,11 +12,11 @@ module "agents" {
   placement_group_id     = hcloud_placement_group.k3s.id
   location               = each.value.location
   server_type            = each.value.server_type
-  ipv4_subnet_id         = hcloud_network_subnet.subnet[[for i, v in var.agent_nodepools : i if v.name == each.value.nodepool_name][0] + 2].id
+  ipv4_subnet_id         = hcloud_network_subnet.subnet[[for i, v in var.agent_nodepools : i if v.name == each.value.nodepool_name][0] + length(var.control_plane_nodepools) + 1].id
 
   # We leave some room so 100 eventual Hetzner LBs that can be created perfectly safely
   # It leaves the subnet with 254 x 254 - 100 = 64416 IPs to use, so probably enough.
-  private_ipv4 = cidrhost(local.network_ipv4_subnets[[for i, v in var.agent_nodepools : i if v.name == each.value.nodepool_name][0] + 2], each.value.index + 101)
+  private_ipv4 = cidrhost(local.network_ipv4_subnets[[for i, v in var.agent_nodepools : i if v.name == each.value.nodepool_name][0] + length(var.control_plane_nodepools) + 1], each.value.index + 101)
 
   labels = {
     "provisioner" = "terraform",
@@ -46,7 +46,7 @@ resource "null_resource" "agents" {
   provisioner "file" {
     content = yamlencode({
       node-name     = module.agents[each.key].name
-      server        = "https://${module.control_planes[0].private_ipv4_address}:6443"
+      server        = "https://${module.control_planes[keys(module.control_planes)[0]].private_ipv4_address}:6443"
       token         = random_password.k3s_token.result
       kubelet-arg   = "cloud-provider=external"
       flannel-iface = "eth1"

control_planes.tf

@@ -1,21 +1,22 @@
 module "control_planes" {
   source = "./modules/host"
 
-  count                  = var.control_plane_count
+  for_each = local.control_plane_nodepools
-  name                   = "${var.use_cluster_name_in_node_name ? "${var.cluster_name}-" : ""}control-plane"
+
+  name                   = "${var.use_cluster_name_in_node_name ? "${var.cluster_name}-" : ""}${each.value.nodepool_name}"
   ssh_keys               = [hcloud_ssh_key.k3s.id]
   public_key             = var.public_key
   private_key            = var.private_key
   additional_public_keys = var.additional_public_keys
   firewall_ids           = [hcloud_firewall.k3s.id]
   placement_group_id     = hcloud_placement_group.k3s.id
-  location               = var.location
+  location               = each.value.location
-  server_type            = var.control_plane_server_type
+  server_type            = each.value.server_type
-  ipv4_subnet_id         = hcloud_network_subnet.subnet[1].id
+  ipv4_subnet_id         = hcloud_network_subnet.subnet[[for i, v in var.control_plane_nodepools : i if v.name == each.value.nodepool_name][0] + 1].id
 
   # We leave some room so 100 eventual Hetzner LBs that can be created perfectly safely
   # It leaves the subnet with 254 x 254 - 100 = 64416 IPs to use, so probably enough.
-  private_ipv4 = cidrhost(local.network_ipv4_subnets[1], count.index + 101)
+  private_ipv4 = cidrhost(local.network_ipv4_subnets[[for i, v in var.control_plane_nodepools : i if v.name == each.value.nodepool_name][0] + 1], each.value.index + 101)
 
   labels = {
     "provisioner" = "terraform",
@@ -28,33 +29,33 @@ module "control_planes" {
 }
 
 resource "null_resource" "control_planes" {
-  count = var.control_plane_count
+  for_each = local.control_plane_nodepools
 
   triggers = {
-    control_plane_id = module.control_planes[count.index].id
+    control_plane_id = module.control_planes[each.key].id
   }
 
   connection {
     user           = "root"
     private_key    = local.ssh_private_key
     agent_identity = local.ssh_identity
-    host           = module.control_planes[count.index].ipv4_address
+    host           = module.control_planes[each.key].ipv4_address
   }
 
   # Generating k3s server config file
   provisioner "file" {
     content = yamlencode({
-      node-name                = module.control_planes[count.index].name
+      node-name                = module.control_planes[each.key].name
-      server                   = "https://${element(module.control_planes.*.private_ipv4_address, count.index > 0 ? 0 : 1)}:6443"
+      server                   = length(module.control_planes) == 1 ? null : "https://${module.control_planes[each.key].private_ipv4_address == module.control_planes[keys(module.control_planes)[0]].private_ipv4_address ? module.control_planes[keys(module.control_planes)[1]].private_ipv4_address : module.control_planes[keys(module.control_planes)[0]].private_ipv4_address}:6443"
       token                    = random_password.k3s_token.result
       disable-cloud-controller = true
       disable                  = local.disable_extras
       flannel-iface            = "eth1"
       kubelet-arg              = "cloud-provider=external"
-      node-ip                  = module.control_planes[count.index].private_ipv4_address
+      node-ip                  = module.control_planes[each.key].private_ipv4_address
-      advertise-address        = module.control_planes[count.index].private_ipv4_address
+      advertise-address        = module.control_planes[each.key].private_ipv4_address
-      node-taint               = var.allow_scheduling_on_control_plane ? [] : ["node-role.kubernetes.io/master:NoSchedule"]
+      node-label               = each.value.labels
-      node-label               = var.automatically_upgrade_k3s ? ["k3s_upgrade=true"] : []
+      node-taint               = each.value.taints
     })
     destination = "/tmp/config.yaml"
   }

init.tf

@@ -3,23 +3,23 @@ resource "null_resource" "first_control_plane" {
     user           = "root"
     private_key    = local.ssh_private_key
     agent_identity = local.ssh_identity
-    host           = module.control_planes[0].ipv4_address
+    host           = module.control_planes[keys(module.control_planes)[0]].ipv4_address
   }
 
   # Generating k3s master config file
   provisioner "file" {
     content = yamlencode({
-      node-name                = module.control_planes[0].name
+      node-name                = module.control_planes[keys(module.control_planes)[0]].name
       token                    = random_password.k3s_token.result
       cluster-init             = true
       disable-cloud-controller = true
       disable                  = local.disable_extras
       flannel-iface            = "eth1"
       kubelet-arg              = "cloud-provider=external"
-      node-ip                  = module.control_planes[0].private_ipv4_address
+      node-ip                  = module.control_planes[keys(module.control_planes)[0]].private_ipv4_address
-      advertise-address        = module.control_planes[0].private_ipv4_address
+      advertise-address        = module.control_planes[keys(module.control_planes)[0]].private_ipv4_address
-      node-taint               = var.allow_scheduling_on_control_plane ? [] : ["node-role.kubernetes.io/master:NoSchedule"]
+      node-taint               = local.control_plane_nodepools[keys(module.control_planes)[0]].taints
-      node-label               = var.automatically_upgrade_k3s ? ["k3s_upgrade=true"] : []
+      node-label               = local.control_plane_nodepools[keys(module.control_planes)[0]].labels
     })
     destination = "/tmp/config.yaml"
   }
@@ -66,7 +66,7 @@ resource "null_resource" "kustomization" {
     user           = "root"
     private_key    = local.ssh_private_key
     agent_identity = local.ssh_identity
-    host           = module.control_planes[0].ipv4_address
+    host           = module.control_planes[keys(module.control_planes)[0]].ipv4_address
   }
 
   # Upload kustomization.yaml, containing Hetzner CSI & CSM, as well as kured.
@@ -97,7 +97,7 @@ resource "null_resource" "kustomization" {
         name                       = "${var.cluster_name}-traefik"
         load_balancer_disable_ipv6 = var.load_balancer_disable_ipv6
         load_balancer_type         = var.load_balancer_type
-        location                   = var.location
+        location                   = var.load_balancer_location
         traefik_acme_tls           = var.traefik_acme_tls
         traefik_acme_email         = var.traefik_acme_email
         traefik_additional_options = var.traefik_additional_options

kubeconfig.tf

@@ -1,7 +1,7 @@
 
 data "remote_file" "kubeconfig" {
   conn {
-    host        = module.control_planes[0].ipv4_address
+    host        = module.control_planes[keys(module.control_planes)[0]].ipv4_address
     port        = 22
     user        = "root"
     private_key = local.ssh_private_key
@@ -13,7 +13,7 @@ data "remote_file" "kubeconfig" {
 }
 
 locals {
-  kubeconfig_external = replace(data.remote_file.kubeconfig.content, "127.0.0.1", module.control_planes[0].ipv4_address)
+  kubeconfig_external = replace(data.remote_file.kubeconfig.content, "127.0.0.1", module.control_planes[keys(module.control_planes)[0]].ipv4_address)
   kubeconfig_parsed   = yamldecode(local.kubeconfig_external)
   kubeconfig_data = {
     host                   = local.kubeconfig_parsed["clusters"][0]["cluster"]["server"]

locals.tf

@@ -1,6 +1,6 @@
 locals {
   # 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 + sum(concat([for v in var.agent_nodepools : v.count], [0])) == 1
+  is_single_node_cluster = sum(concat([for v in var.control_plane_nodepools : v.count], [0])) + sum(concat([for v in var.agent_nodepools : v.count], [0])) == 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))
@@ -169,16 +169,30 @@ locals {
   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([
+  control_plane_nodepools = merge([
-    for nodepool_obj in var.agent_nodepools : {
+    for pool_index, nodepool_obj in var.control_plane_nodepools : {
-      for index in range(nodepool_obj.count) :
+      for node_index in range(nodepool_obj.count) :
-      format("%s-%s", nodepool_obj.name, index) => {
+      format("%s-%s-%s", pool_index, node_index, nodepool_obj.name) => {
         nodepool_name : nodepool_obj.name,
         server_type : nodepool_obj.server_type,
         location : nodepool_obj.location,
-        labels : concat(local.default_labels, nodepool_obj.labels),
+        labels : concat(local.default_control_plane_labels, nodepool_obj.labels),
+        taints : concat(local.default_control_plane_taints, nodepool_obj.taints),
+        index : node_index
+      }
+    }
+  ]...)
+
+  agent_nodepools = merge([
+    for pool_index, nodepool_obj in var.agent_nodepools : {
+      for node_index in range(nodepool_obj.count) :
+      format("%s-%s-%s", pool_index, node_index, nodepool_obj.name) => {
+        nodepool_name : nodepool_obj.name,
+        server_type : nodepool_obj.server_type,
+        location : nodepool_obj.location,
+        labels : concat(local.default_agent_labels, nodepool_obj.labels),
         taints : nodepool_obj.taints,
-        index : index
+        index : node_index
       }
     }
   ]...)
@@ -188,12 +202,17 @@ locals {
 
   # The first two subnets are respectively the default subnet 10.0.0.0/16 use for potientially anything and 10.1.0.0/16 used for control plane nodes.
   # the rest of the subnets are for agent nodes in each nodepools.
-  network_ipv4_subnets = [for index in range(length(var.agent_nodepools) + 2) : cidrsubnet(local.network_ipv4_cidr, 8, index)]
+  network_ipv4_subnets = [for index in range(length(var.control_plane_nodepools) + length(var.agent_nodepools) + 1) : cidrsubnet(local.network_ipv4_cidr, 8, index)]
 
   # disable k3s extras
   disable_extras = concat(["local-storage"], local.is_single_node_cluster ? [] : ["servicelb"], var.traefik_enabled ? [] : ["traefik"], var.metrics_server_enabled ? [] : ["metrics-server"])
 
-
   # Default k3s node labels
-  default_labels = concat([], var.automatically_upgrade_k3s ? ["k3s_upgrade=true"] : [])
+  default_agent_labels         = concat([], var.automatically_upgrade_k3s ? ["k3s_upgrade=true"] : [])
+  default_control_plane_labels = concat([], var.automatically_upgrade_k3s ? ["k3s_upgrade=true"] : [])
+
+  allow_scheduling_on_control_plane = local.is_single_node_cluster ? true : var.allow_scheduling_on_control_plane
+
+  # Default k3s node taints
+  default_control_plane_taints = concat([], local.allow_scheduling_on_control_plane ? [] : ["node-role.kubernetes.io/master:NoSchedule"])
 }

output.tf

@@ -4,7 +4,9 @@ output "cluster_name" {
 }
 
 output "control_planes_public_ipv4" {
-  value       = module.control_planes.*.ipv4_address
+  value = [
+    for obj in module.control_planes : obj.ipv4_address
+  ]
   description = "The public IPv4 addresses of the controlplane server."
 }
 
@@ -17,7 +19,9 @@ output "agents_public_ipv4" {
 
 output "load_balancer_public_ipv4" {
   description = "The public IPv4 address of the Hetzner load balancer"
-  value       = local.is_single_node_cluster ? module.control_planes[0].ipv4_address : var.traefik_enabled == false ? null : data.hcloud_load_balancer.traefik[0].ipv4
+  value = local.is_single_node_cluster ? [
+    for obj in module.control_planes : obj.ipv4_address
+  ][0] : var.traefik_enabled == false ? null : data.hcloud_load_balancer.traefik[0].ipv4
 }
 
 output "kubeconfig_file" {

terraform.tfvars.example

@@ -14,37 +14,58 @@ private_key  = "/home/username/.ssh/id_ed25519"
 
 # These can be customized, or left with the default values
 # For Hetzner locations see https://docs.hetzner.com/general/others/data-centers-and-connection/
-location         = "fsn1"       # change to `ash` for us-east Ashburn, Virginia location
 network_region   = "eu-central" # change to `us-east` if location is ash
 
-# At least 3 server nodes is recommended for HA, otherwise you need to turn off automatic upgrade (see ReadMe).
+# For the control-planes, at least 3 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).
+# For instance, 1 is ok (non-HA), 2 not ok, 3 is ok (becomes HA). It does not matter if they are in the same nodepool or not! So they can be in different locations, and of different types.
-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)
+# Of course, you can choose any number of nodepools you want, with the location you want. The only contraint on the location is that you need to stay in the same network region, basically Europe or US, see above.
-control_plane_server_type = "cpx11"
+# For the server type, # The type of control plane nodes, the minimum instance supported is cpx11 (just a few cents more than cx11), see https://www.hetzner.com/cloud.
 
-# As for the agent nodepools, below is just an example, if you do not want nodepools, just use one,
+# IMPORTANT: Once the cluster is created, you can change nodepool count, and even set it to 0 (in the case of the first control-plane nodepool, the minimum is 1),
-# and change the name to what you want, it need not be "agent-big" or "agent-small", also give them the subnet prefer.
+# You can also rename it (if the count is taken to 0), but do not remove a nodepool from the list after the cluster is created. This is due to how IPs are allocated.
-# For single node clusters set this equal to [] or just set the counts to 0.
+# Once the cluster is initialized, you cannot add more control plane nodepools. You can freely add others agent nodepools the end of the list if you want! 
-# IMPORTANT: Once the cluster is created, you can change the count, and even set it to 0, but do not remove a nodepool from the list. 
+# Also, before decreasing the count of any nodepools to 0, it's important to drain and cordon it the nodes in question, otherwise it will leave your cluster in a bad state.
-# You can add others at the end of the list if you want.
+
-# For Hetzner locations see https://docs.hetzner.com/general/others/data-centers-and-connection/
+# Before initializing the cluster, you can change all parameters and add or remove any nodepools.
-# For Hetzner server types see https://www.hetzner.com/cloud
+
-agent_nodepools = [
+# If you want to have a single node cluster, just have 1 control plane nodepools with a count of 1, and one agent nodepool with a count of 0.
+
+# Example below:
+
+control_plane_nodepools = [
   {
-    name        = "agent-small",
+    name        = "control-plane-fsn1",
     server_type = "cpx11",
     location    = "fsn1",
     labels      = [],
     taints      = [],
     count       = 2
   },
+  {
+    name        = "control-plane-nbg1",
+    server_type = "cpx11",
+    location    = "nbg1",
+    labels      = [],
+    taints      = [],
+    count       = 1
+  }
+]
+
+agent_nodepools = [
+  {
+    name        = "agent-small",
+    server_type = "cpx11",
+    location    = "fsn1",
+    labels      = [],
+    taints      = [],
+    count       = 1
+  },
   {
     name        = "agent-large",
     server_type = "cpx21",
-    location    = "fsn1",
+    location    = "nbg1",
     labels      = [],
     taints      = [],
     count       = 1
@@ -66,6 +87,8 @@ 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"
 
+load_balancer_location = "fsn1"
+
 ### The following values are fully optional
 
 # If you want to use a specific Hetzner CCM and CSI version, set them below, otherwise leave as is for the latest versions
@@ -84,7 +107,7 @@ load_balancer_type        = "lb11"
 # metrics_server_enabled = false
 
 # 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.
+# True by default 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".

variables.tf

@@ -20,26 +20,16 @@ variable "additional_public_keys" {
   default     = []
 }
 
-variable "location" {
-  description = "Default server location"
-  type        = string
-}
-
 variable "network_region" {
   description = "Default region for network"
   type        = string
 }
 
-variable "control_plane_server_type" {
+variable "load_balancer_location" {
-  description = "Default control plane server type"
+  description = "Default load balancer location"
   type        = string
 }
 
-variable "control_plane_count" {
-  description = "Number of control plane nodes."
-  type        = number
-}
-
 variable "load_balancer_type" {
   description = "Default load balancer server type"
   type        = string
@@ -51,6 +41,12 @@ variable "load_balancer_disable_ipv6" {
   default     = false
 }
 
+variable "control_plane_nodepools" {
+  description = "Number of control plane nodes."
+  type        = list(any)
+  default     = []
+}
+
 variable "agent_nodepools" {
   description = "Number of agent nodes."
   type        = list(any)