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}"
 
-  name  = "${var.cluster_name}"
-  type  = "A"
-  ttl   = 300
+  # DNS record (will be prepended to domain)
+  name = "${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