terraform/gcp: Allow to use preemptible VM instances (#8480)

contrib/terraform/gcp/README.md

@@ -80,8 +80,12 @@ ansible-playbook -i contrib/terraform/gcs/inventory.ini cluster.yml -b -v
 * `prefix`: Prefix to use for all resources, required to be unique for all clusters in the same project *(Defaults to `default`)*
 * `master_sa_email`: Service account email to use for the master nodes *(Defaults to `""`, auto generate one)*
 * `master_sa_scopes`: Service account email to use for the master nodes *(Defaults to `["https://www.googleapis.com/auth/cloud-platform"]`)*
+* `master_preemptible`: Enable [preemptible](https://cloud.google.com/compute/docs/instances/preemptible)
+  for the master nodes *(Defaults to `false`)*
 * `worker_sa_email`: Service account email to use for the worker nodes *(Defaults to `""`, auto generate one)*
 * `worker_sa_scopes`: Service account email to use for the worker nodes *(Defaults to `["https://www.googleapis.com/auth/cloud-platform"]`)*
+* `worker_preemptible`: Enable [preemptible](https://cloud.google.com/compute/docs/instances/preemptible)
+  for the worker nodes *(Defaults to `false`)*
 
 An example variables file can be found `tfvars.json`
 

contrib/terraform/gcp/main.tf

@@ -21,10 +21,12 @@ module "kubernetes" {
   machines    = var.machines
   ssh_pub_key = var.ssh_pub_key
 
-  master_sa_email  = var.master_sa_email
+  master_sa_email    = var.master_sa_email
-  master_sa_scopes = var.master_sa_scopes
+  master_sa_scopes   = var.master_sa_scopes
-  worker_sa_email  = var.worker_sa_email
+  master_preemptible = var.master_preemptible
-  worker_sa_scopes = var.worker_sa_scopes
+  worker_sa_email    = var.worker_sa_email
+  worker_sa_scopes   = var.worker_sa_scopes
+  worker_preemptible = var.worker_preemptible
 
   ssh_whitelist        = var.ssh_whitelist
   api_server_whitelist = var.api_server_whitelist

contrib/terraform/gcp/modules/kubernetes-cluster/main.tf

@@ -231,6 +231,11 @@ resource "google_compute_instance" "master" {
   lifecycle {
     ignore_changes = [attached_disk]
   }
+
+  scheduling {
+    preemptible = var.master_preemptible
+    automatic_restart = !var.master_preemptible
+  }
 }
 
 resource "google_compute_forwarding_rule" "master_lb" {
@@ -328,6 +333,11 @@ resource "google_compute_instance" "worker" {
   lifecycle {
     ignore_changes = [attached_disk]
   }
+
+  scheduling {
+    preemptible = var.worker_preemptible
+    automatic_restart = !var.worker_preemptible
+  }
 }
 
 resource "google_compute_address" "worker_lb" {

contrib/terraform/gcp/modules/kubernetes-cluster/variables.tf

@@ -27,6 +27,10 @@ variable "master_sa_scopes" {
   type = list(string)
 }
 
+variable "master_preemptible" {
+  type = bool
+}
+
 variable "worker_sa_email" {
   type = string
 }
@@ -35,6 +39,10 @@ variable "worker_sa_scopes" {
   type = list(string)
 }
 
+variable "worker_preemptible" {
+  type = bool
+}
+
 variable "ssh_pub_key" {}
 
 variable "ssh_whitelist" {

contrib/terraform/gcp/variables.tf

@@ -44,6 +44,11 @@ variable "master_sa_scopes" {
   default = ["https://www.googleapis.com/auth/cloud-platform"]
 }
 
+variable "master_preemptible" {
+  type    = bool
+  default = false
+}
+
 variable "worker_sa_email" {
   type    = string
   default = ""
@@ -54,6 +59,11 @@ variable "worker_sa_scopes" {
   default = ["https://www.googleapis.com/auth/cloud-platform"]
 }
 
+variable "worker_preemptible" {
+  type    = bool
+  default = false
+}
+
 variable ssh_pub_key {
   description = "Path to public SSH key file which is injected into the VMs."
   type        = string