Support Kubernetes 1.28, replace deprecated null_data_source by `lo…

…cal`, allow setting extra config in `KubeletConfiguration` (#89)

* Upgrade to Kubernetes 1.28

* Replace deprecated `null_data_source` by `local`

* Allow setting extra config in `KubeletConfiguration`

security/ufw/main.tf

@@ -25,11 +25,21 @@ variable "additional_rules" {
   default = []
 }
 
+locals {
+  ufw_config = templatefile("${path.module}/scripts/ufw.sh", {
+    private_interface    = var.private_interface
+    kubernetes_interface = var.kubernetes_interface
+    vpn_interface        = var.vpn_interface
+    vpn_port             = var.vpn_port
+    additional_rules     = join("\nufw ", flatten(["", var.additional_rules]))
+  })
+}
+
 resource "null_resource" "firewall" {
   count = var.node_count
 
   triggers = {
-    template = data.null_data_source.ufw.outputs.content
+    template = local.ufw_config
   }
 
   connection {
@@ -39,20 +49,6 @@ resource "null_resource" "firewall" {
   }
 
   provisioner "remote-exec" {
-    inline = [
-      data.null_data_source.ufw.outputs.content
-    ]
-  }
-}
-
-data "null_data_source" "ufw" {
-  inputs = {
-    content = templatefile("${path.module}/scripts/ufw.sh", {
-      private_interface    = var.private_interface
-      kubernetes_interface = var.kubernetes_interface
-      vpn_interface        = var.vpn_interface
-      vpn_port             = var.vpn_port
-      additional_rules     = join("\nufw ", flatten(["", var.additional_rules]))
-    })
+    inline = [local.ufw_config]
   }
 }

service/etcd/main.tf

@@ -29,7 +29,7 @@ resource "null_resource" "etcd" {
   count = var.node_count
 
   triggers = {
-    template = join("", data.null_data_source.etcd-service.*.outputs.content)
+    template = join("", local.etcd_service)
   }
 
   connection {
@@ -47,7 +47,7 @@ resource "null_resource" "etcd" {
   }
 
   provisioner "file" {
-    content     = element(data.null_data_source.etcd-service.*.outputs.content, count.index)
+    content     = element(local.etcd_service, count.index)
     destination = "/etc/systemd/system/etcd.service"
   }
 
@@ -64,29 +64,20 @@ resource "null_resource" "etcd" {
   }
 }
 
-data "null_data_source" "etcd-service" {
-  count = var.node_count
-
-  inputs = {
-    content = templatefile("${path.module}/templates/etcd.service", {
-      hostname              = element(local.etcd_hostnames, count.index)
+locals {
+  etcd_service = [
+    for n in range(var.node_count) :
+    templatefile("${path.module}/templates/etcd.service", {
+      hostname              = element(local.etcd_hostnames, n)
       intial_cluster        = "${join(",", formatlist("%s=http://%s:2380", local.etcd_hostnames, local.etcd_vpn_ips))}"
-      listen_client_urls    = "http://${element(local.etcd_vpn_ips, count.index)}:2379"
-      advertise_client_urls = "http://${element(local.etcd_vpn_ips, count.index)}:2379"
-      listen_peer_urls      = "http://${element(local.etcd_vpn_ips, count.index)}:2380"
+      listen_client_urls    = "http://${element(local.etcd_vpn_ips, n)}:2379"
+      advertise_client_urls = "http://${element(local.etcd_vpn_ips, n)}:2379"
+      listen_peer_urls      = "http://${element(local.etcd_vpn_ips, n)}:2380"
       vpn_unit              = var.vpn_unit
     })
-  }
-}
-
-data "null_data_source" "endpoints" {
-  depends_on = [null_resource.etcd]
-
-  inputs = {
-    list = "${join(",", formatlist("http://%s:2379", local.etcd_vpn_ips))}"
-  }
+  ]
 }
 
 output "endpoints" {
-  value = split(",", data.null_data_source.endpoints.outputs["list"])
+  value = formatlist("http://%s:2379", local.etcd_vpn_ips)
 }

service/kubernetes/main.tf

@@ -14,6 +14,15 @@ variable "apiserver_extra_volumes" {
   default = []
 }
 
+variable "kubelet_extra_config" {
+  # `map(any)` together with `yamlencode` might turn boolean values into strings, making the YAML
+  # invalid, so we instead support verbatim YAML input
+  type = string
+
+  description = "Extra config appended to KubeletConfiguration. Only applies at cluster creation."
+  default     = ""
+}
+
 variable "node_count" {}
 
 variable "connections" {
@@ -93,6 +102,7 @@ resource "null_resource" "kubernetes" {
       apiserver_extra_volumes = yamlencode(var.apiserver_extra_volumes)
       etcd_endpoints          = "- ${join("\n    - ", var.etcd_endpoints)}"
       cert_sans               = "- ${element(var.connections, 0)}"
+      kubelet_extra_config    = var.kubelet_extra_config
     })
     destination = "/tmp/master-configuration.yml"
   }

service/kubernetes/scripts/install.sh

@@ -2,7 +2,7 @@
 set -e
 
 # https://kubernetes.io/docs/tasks/tools/install-kubectl-linux/#install-using-native-package-management (yes, `xenial` is correct even for newer Ubuntu versions)
-curl -fsSL https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo gpg --dearmor -o /etc/apt/keyrings/kubernetes-archive-keyring.gpg
+curl -fsSL https://packages.cloud.google.com/apt/doc/apt-key.gpg | gpg --dearmor -o /etc/apt/keyrings/kubernetes-archive-keyring.gpg
 echo "deb [signed-by=/etc/apt/keyrings/kubernetes-archive-keyring.gpg] https://apt.kubernetes.io/ kubernetes-xenial main" > /etc/apt/sources.list.d/kubernetes.list
 
 curl -fsSL https://download.docker.com/linux/ubuntu/gpg | gpg --dearmour -o /etc/apt/keyrings/docker.gpg
@@ -13,8 +13,8 @@ apt-get update
 
 # Use `DEBIAN_FRONTEND=noninteractive` to avoid starting containerd already with Ubuntu's minimal config.
 #
-# Kubernetes 1.26 requires at least containerd v1.6
-DEBIAN_FRONTEND=noninteractive apt-get install -y containerd.io=1.6.15-1
+# Kubernetes 1.26+ requires at least containerd v1.6.
+DEBIAN_FRONTEND=noninteractive apt-get install -y containerd.io=1.6.22-1
 
 containerd config default > /etc/containerd/config.toml
 sed -i 's/SystemdCgroup = false/SystemdCgroup = true/' /etc/containerd/config.toml
@@ -23,7 +23,7 @@ systemctl restart containerd
 
 # Pin Kubernetes major version since there are breaking changes between releases.
 # For example, Kubernetes 1.26 requires a newer containerd (https://kubernetes.io/blog/2022/11/18/upcoming-changes-in-kubernetes-1-26/#cri-api-removal).
-apt-get install -y kubelet=1.26.0-00 kubeadm=1.26.0-00 kubectl=1.26.0-00 # kubernetes-cni package comes as dependency of the others
+apt-get install -y kubelet=1.28.0-00 kubeadm=1.28.1-00 kubectl=1.28.1-00 # kubernetes-cni package comes as dependency of the others
 apt-mark hold kubelet kubeadm kubectl kubernetes-cni
 
 echo "Installation of packages done"

service/kubernetes/templates/master-configuration.yml

@@ -23,3 +23,4 @@ apiVersion: kubelet.config.k8s.io/v1beta1
 kind: KubeletConfiguration
 failSwapOn: false
 cgroupDriver: systemd
+${kubelet_extra_config}