Simplify google-cloud cluster variables

* Remove k8s_domain_name input variable, the controller DNS
record will be "${var.cluster_name}.${dns_zone}"
* Rename dns_base_zone to dns_zone
* Rename dns_base_zone_name to dns_zone_name

digital-ocean/container-linux/kubernetes/controllers.tf

@@ -1,13 +1,16 @@
-# Controller DNS records
+# Controller Instance DNS records
 resource "digitalocean_record" "controllers" {
   count = "${var.controller_count}"
 
   # DNS zone where record should be created
   domain = "${var.dns_zone}"
 
+  # DNS record (will be prepended to domain)
   name = "${var.cluster_name}"
   type = "A"
   ttl  = 300
+
+  # IPv4 addresses of controllers
   value = "${element(digitalocean_droplet.controllers.*.ipv4_address, count.index)}"
 }
 

digital-ocean/container-linux/kubernetes/variables.tf

@@ -44,7 +44,7 @@ variable "worker_count" {
 
 variable "ssh_fingerprints" {
   type        = "list"
-  description = "SSH public key fingerprints. Use ssh-add -l -E md5."
+  description = "SSH public key fingerprints. (e.g. see `ssh-add -l -E md5`)"
 }
 
 # bootkube assets

google-cloud/container-linux/controllers/network.tf

@@ -1,16 +1,14 @@
-# DNS record set to the network load balancer over controllers
-resource "google_dns_record_set" "k8s_dns" {
-  # Managed DNS Zone name
-  managed_zone = "${var.dns_base_zone_name}"
-
-  # Name of the DNS record
-  #name = "${format("%s.%s.", var.cluster_name, var.dns_base_zone)}"
-  name = "${var.k8s_domain_name}."
+# Controller Network Load balancer DNS record
+resource "google_dns_record_set" "controllers" {
+  # DNS Zone name where record should be created
+  managed_zone = "${var.dns_zone_name}"
 
+  # DNS record
+  name = "${format("%s.%s.", var.cluster_name, var.dns_zone)}"
   type = "A"
   ttl  = 300
 
-  # compute instance public IP
+  # IPv4 address of controllers' network load balancer
   rrdatas = ["${google_compute_address.controllers-ip.address}"]
 }
 

google-cloud/container-linux/controllers/variables.tf

@@ -13,21 +13,16 @@ variable "network" {
   description = "Name of the network to attach to the compute instance interfaces"
 }
 
-variable "dns_base_zone" {
+variable "dns_zone" {
   type        = "string"
   description = "Google Cloud DNS Zone value to create etcd/k8s subdomains (e.g. dghubble.io)"
 }
 
-variable "dns_base_zone_name" {
+variable "dns_zone_name" {
   type        = "string"
   description = "Google Cloud DNS Zone name to create etcd/k8s subdomains (e.g. dghubble-io)"
 }
 
-variable "k8s_domain_name" {
-  type        = "string"
-  description = "Controller DNS name which resolves to the controller instance. Kubectl and workers use TLS client credentials to communicate via this endpoint."
-}
-
 # instances
 
 variable "count" {

google-cloud/container-linux/kubernetes/bootkube.tf

@@ -3,7 +3,7 @@ module "bootkube" {
   source = "git::https://github.com/purenetes/bootkube-terraform.git?ref=v0.6.0"
 
   cluster_name                  = "${var.cluster_name}"
-  api_servers                   = ["${var.k8s_domain_name}"]
+  api_servers                   = ["${format("%s.%s", var.cluster_name, var.dns_zone)}"]
   etcd_servers                  = ["http://127.0.0.1:2379"]
   asset_dir                     = "${var.asset_dir}"
   pod_cidr                      = "${var.pod_cidr}"

google-cloud/container-linux/kubernetes/cluster.tf

@@ -6,10 +6,9 @@ module "controllers" {
   # GCE
   network       = "${google_compute_network.network.name}"
   count         = "${var.controller_count}"
-  dns_base_zone      = "${var.dns_base_zone}"
-  dns_base_zone_name = "${var.dns_base_zone_name}"
-  k8s_domain_name    = "${var.k8s_domain_name}"
   zone          = "${var.zone}"
+  dns_zone      = "${var.dns_zone}"
+  dns_zone_name = "${var.dns_zone_name}"
   machine_type  = "${var.machine_type}"
   os_image      = "${var.os_image}"
   preemptible   = "${var.controller_preemptible}"

google-cloud/container-linux/kubernetes/ssh.tf

@@ -6,7 +6,7 @@ resource "null_resource" "bootkube-start" {
   # TODO: SSH to a controller's IP instead of waiting on DNS resolution
   connection {
     type    = "ssh"
-    host    = "${var.k8s_domain_name}"
+    host    = "${format("%s.%s", var.cluster_name, var.dns_zone)}"
     user    = "core"
     timeout = "15m"
   }

google-cloud/container-linux/kubernetes/variables.tf

@@ -3,40 +3,35 @@ variable "cluster_name" {
   description = "Cluster name"
 }
 
-variable "ssh_authorized_key" {
-  type        = "string"
-  description = "SSH public key for logging in as user 'core'"
-}
-
-variable "dns_base_zone" {
-  type        = "string"
-  description = "Google Cloud DNS Zone value to create etcd/k8s subdomains (e.g. dghubble.io)"
-}
-
-variable "dns_base_zone_name" {
-  type        = "string"
-  description = "Google Cloud DNS Zone name to create etcd/k8s subdomains (e.g. dghubble-io)"
-}
-
-variable "k8s_domain_name" {
-  type        = "string"
-  description = "Controller DNS name which resolves to the controller instance. Kubectl and workers use TLS client credentials to communicate via this endpoint."
-}
-
 variable "zone" {
   type        = "string"
-  description = "Google zone that compute instances should be created in (e.g. gcloud compute zones list)"
+  description = "Google Cloud zone (e.g. us-central1-f, see `gcloud compute zones list`)"
+}
+
+variable "dns_zone" {
+  type        = "string"
+  description = "Google Cloud DNS Zone (e.g. google-cloud.dghubble.io)"
+}
+
+variable "dns_zone_name" {
+  type        = "string"
+  description = "Google Cloud DNS Zone name (e.g. google-cloud-prod-zone)"
+}
+
+variable "ssh_authorized_key" {
+  type        = "string"
+  description = "SSH public key for user 'core'"
 }
 
 variable "machine_type" {
   type        = "string"
   default     = "n1-standard-1"
-  description = "Machine type for compute instances (e.g. gcloud compute machine-types list)"
+  description = "Machine type for compute instances (see `gcloud compute machine-types list`)"
 }
 
 variable "os_image" {
   type        = "string"
-  description = "OS image from which to initialize the disk (e.g. gcloud compute images list)"
+  description = "OS image from which to initialize the disk (see `gcloud compute images list`)"
 }
 
 variable "controller_count" {