Add optional cluster_domain_suffix variable

* Allow kube-dns to respond to DNS queries with a custom
suffix, instead of the default 'cluster.local'
* Useful when multiple clusters exist on the same local
network and wish to query services on one another

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

@@ -2,12 +2,13 @@
 module "bootkube" {
   source = "git::https://github.com/poseidon/terraform-render-bootkube.git?ref=v0.9.1"
 
-  cluster_name = "${var.cluster_name}"
-  api_servers  = ["${format("%s.%s", var.cluster_name, var.dns_zone)}"]
-  etcd_servers = "${module.controllers.etcd_fqdns}"
-  asset_dir    = "${var.asset_dir}"
-  networking   = "${var.networking}"
-  network_mtu  = 1440
-  pod_cidr     = "${var.pod_cidr}"
-  service_cidr = "${var.service_cidr}"
+  cluster_name          = "${var.cluster_name}"
+  api_servers           = ["${format("%s.%s", var.cluster_name, var.dns_zone)}"]
+  etcd_servers          = "${module.controllers.etcd_fqdns}"
+  asset_dir             = "${var.asset_dir}"
+  networking            = "${var.networking}"
+  network_mtu           = 1440
+  pod_cidr              = "${var.pod_cidr}"
+  service_cidr          = "${var.service_cidr}"
+  cluster_domain_suffix = "${var.cluster_domain_suffix}"
 }

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

@@ -15,6 +15,7 @@ module "controllers" {
   # configuration
   networking              = "${var.networking}"
   service_cidr            = "${var.service_cidr}"
+  cluster_domain_suffix   = "${var.cluster_domain_suffix}"
   kubeconfig_ca_cert      = "${module.bootkube.ca_cert}"
   kubeconfig_kubelet_cert = "${module.bootkube.kubelet_cert}"
   kubeconfig_kubelet_key  = "${module.bootkube.kubelet_key}"
@@ -36,6 +37,7 @@ module "workers" {
 
   # configuration
   service_cidr            = "${var.service_cidr}"
+  cluster_domain_suffix   = "${var.cluster_domain_suffix}"
   kubeconfig_ca_cert      = "${module.bootkube.ca_cert}"
   kubeconfig_kubelet_cert = "${module.bootkube.kubelet_cert}"
   kubeconfig_kubelet_key  = "${module.bootkube.kubelet_key}"

google-cloud/container-linux/kubernetes/controllers/cl/controller.yaml.tmpl

@@ -74,7 +74,7 @@ systemd:
           --anonymous-auth=false \
           --client-ca-file=/etc/kubernetes/ca.crt \
           --cluster_dns=${k8s_dns_service_ip} \
-          --cluster_domain=cluster.local \
+          --cluster_domain=${cluster_domain_suffix} \
           --cni-conf-dir=/etc/kubernetes/cni/net.d \
           --exit-on-lock-contention \
           --kubeconfig=/etc/kubernetes/kubeconfig \

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

@@ -66,6 +66,7 @@ data "template_file" "controller_config" {
     etcd_initial_cluster = "${join(",", formatlist("%s=https://%s:2380", null_resource.repeat.*.triggers.name, null_resource.repeat.*.triggers.domain))}"
 
     k8s_dns_service_ip      = "${cidrhost(var.service_cidr, 10)}"
+    cluster_domain_suffix   = "${var.cluster_domain_suffix}"
     ssh_authorized_key      = "${var.ssh_authorized_key}"
     kubeconfig_ca_cert      = "${var.kubeconfig_ca_cert}"
     kubeconfig_kubelet_cert = "${var.kubeconfig_kubelet_cert}"

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

@@ -69,6 +69,12 @@ EOD
   default = "10.3.0.0/16"
 }
 
+variable "cluster_domain_suffix" {
+  description = "Queries for domains with the suffix will be answered by kube-dns. Default is cluster.local (e.g. foo.default.svc.cluster.local) "
+  type        = "string"
+  default     = "cluster.local"
+}
+
 // kubeconfig
 
 variable "kubeconfig_ca_cert" {

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

@@ -80,3 +80,9 @@ EOD
   type    = "string"
   default = "10.3.0.0/16"
 }
+
+variable "cluster_domain_suffix" {
+  description = "Queries for domains with the suffix will be answered by kube-dns. Default is cluster.local (e.g. foo.default.svc.cluster.local) "
+  type        = "string"
+  default     = "cluster.local"
+}

google-cloud/container-linux/kubernetes/workers/cl/worker.yaml.tmpl

@@ -50,7 +50,7 @@ systemd:
           --anonymous-auth=false \
           --client-ca-file=/etc/kubernetes/ca.crt \
           --cluster_dns=${k8s_dns_service_ip} \
-          --cluster_domain=cluster.local \
+          --cluster_domain=${cluster_domain_suffix} \
           --cni-conf-dir=/etc/kubernetes/cni/net.d \
           --exit-on-lock-contention \
           --kubeconfig=/etc/kubernetes/kubeconfig \

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

@@ -59,6 +59,12 @@ EOD
   default = "10.3.0.0/16"
 }
 
+variable "cluster_domain_suffix" {
+  description = "Queries for domains with the suffix will be answered by kube-dns. Default is cluster.local (e.g. foo.default.svc.cluster.local) "
+  type        = "string"
+  default     = "cluster.local"
+}
+
 # kubeconfig
 
 variable "kubeconfig_ca_cert" {

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

@@ -24,6 +24,7 @@ data "template_file" "worker_config" {
   vars = {
     k8s_dns_service_ip      = "${cidrhost(var.service_cidr, 10)}"
     k8s_etcd_service_ip     = "${cidrhost(var.service_cidr, 15)}"
+    cluster_domain_suffix   = "${var.cluster_domain_suffix}"
     ssh_authorized_key      = "${var.ssh_authorized_key}"
     kubeconfig_ca_cert      = "${var.kubeconfig_ca_cert}"
     kubeconfig_kubelet_cert = "${var.kubeconfig_kubelet_cert}"