Remove the cluster_domain_suffix variable

* Drop support for `cluster_domain_suffix` customization and
always use `cluster.local`. Many components in the Kubernetes
ecosystem assume this default suffix and its very rare to be
setting a special value here these days
* Cleanup a few variables that are seldom used

azure/fedora-coreos/kubernetes/bootstrap.tf

@@ -14,7 +14,6 @@ module "bootstrap" {
 
   pod_cidr              = var.pod_cidr
   service_cidr          = var.service_cidr
-  cluster_domain_suffix = var.cluster_domain_suffix
   enable_reporting      = var.enable_reporting
   enable_aggregation    = var.enable_aggregation
   daemonset_tolerations = var.daemonset_tolerations

azure/fedora-coreos/kubernetes/butane/controller.yaml

@@ -144,7 +144,7 @@ storage:
           cgroupDriver: systemd
           clusterDNS:
             - ${cluster_dns_service_ip}
-          clusterDomain: ${cluster_domain_suffix}
+          clusterDomain: cluster.local
           healthzPort: 0
           rotateCertificates: true
           shutdownGracePeriod: 45s

azure/fedora-coreos/kubernetes/controllers.tf

@@ -163,7 +163,6 @@ data "ct_config" "controllers" {
     kubeconfig             = indent(10, module.bootstrap.kubeconfig-kubelet)
     ssh_authorized_key     = var.ssh_authorized_key
     cluster_dns_service_ip = cidrhost(var.service_cidr, 10)
-    cluster_domain_suffix  = var.cluster_domain_suffix
   })
   strict   = true
   snippets = var.controller_snippets

azure/fedora-coreos/kubernetes/variables.tf

@@ -27,7 +27,6 @@ variable "os_image" {
   description = "Fedora CoreOS image for instances"
 }
 
-
 variable "controller_count" {
   type        = number
   description = "Number of controllers (i.e. masters)"
@@ -145,6 +144,14 @@ EOD
   default     = "10.3.0.0/16"
 }
 
+variable "worker_node_labels" {
+  type        = list(string)
+  description = "List of initial worker node labels"
+  default     = []
+}
+
+# advanced
+
 variable "enable_reporting" {
   type        = bool
   description = "Enable usage or analytics reporting to upstreams (Calico)"
@@ -157,20 +164,6 @@ variable "enable_aggregation" {
   default     = true
 }
 
-variable "worker_node_labels" {
-  type        = list(string)
-  description = "List of initial worker node labels"
-  default     = []
-}
-
-# unofficial, undocumented, unsupported
-
-variable "cluster_domain_suffix" {
-  type        = string
-  description = "Queries for domains with the suffix will be answered by coredns. Default is cluster.local (e.g. foo.default.svc.cluster.local) "
-  default     = "cluster.local"
-}
-
 variable "daemonset_tolerations" {
   type        = list(string)
   description = "List of additional taint keys kube-system DaemonSets should tolerate (e.g. ['custom-role', 'gpu-role'])"

azure/fedora-coreos/kubernetes/workers.tf

@@ -9,20 +9,20 @@ module "workers" {
   security_group_id        = azurerm_network_security_group.worker.id
   backend_address_pool_ids = local.backend_address_pool_ids
 
+  # instances
+  os_image       = var.os_image
   worker_count   = var.worker_count
   vm_type        = var.worker_type
-  os_image       = var.os_image
   disk_type      = var.worker_disk_type
   disk_size      = var.worker_disk_size
   ephemeral_disk = var.worker_ephemeral_disk
   priority       = var.worker_priority
 
   # configuration
-  kubeconfig            = module.bootstrap.kubeconfig-kubelet
-  ssh_authorized_key    = var.ssh_authorized_key
-  azure_authorized_key  = var.azure_authorized_key
-  service_cidr          = var.service_cidr
-  cluster_domain_suffix = var.cluster_domain_suffix
-  snippets              = var.worker_snippets
-  node_labels           = var.worker_node_labels
+  kubeconfig           = module.bootstrap.kubeconfig-kubelet
+  ssh_authorized_key   = var.ssh_authorized_key
+  azure_authorized_key = var.azure_authorized_key
+  service_cidr         = var.service_cidr
+  snippets             = var.worker_snippets
+  node_labels          = var.worker_node_labels
 }

azure/fedora-coreos/kubernetes/workers/butane/worker.yaml

@@ -99,7 +99,7 @@ storage:
           cgroupDriver: systemd
           clusterDNS:
             - ${cluster_dns_service_ip}
-          clusterDomain: ${cluster_domain_suffix}
+          clusterDomain: cluster.local
           healthzPort: 0
           rotateCertificates: true
           shutdownGracePeriod: 45s

azure/fedora-coreos/kubernetes/workers/variables.tf

@@ -120,12 +120,3 @@ variable "node_taints" {
   description = "List of initial node taints"
   default     = []
 }
-
-# unofficial, undocumented, unsupported
-
-variable "cluster_domain_suffix" {
-  description = "Queries for domains with the suffix will be answered by coredns. Default is cluster.local (e.g. foo.default.svc.cluster.local) "
-  type        = string
-  default     = "cluster.local"
-}
-

azure/fedora-coreos/kubernetes/workers/workers.tf

@@ -84,7 +84,6 @@ data "ct_config" "worker" {
     kubeconfig             = indent(10, var.kubeconfig)
     ssh_authorized_key     = var.ssh_authorized_key
     cluster_dns_service_ip = cidrhost(var.service_cidr, 10)
-    cluster_domain_suffix  = var.cluster_domain_suffix
     node_labels            = join(",", var.node_labels)
     node_taints            = join(",", var.node_taints)
   })