From 9b00da871faa3fc6e8e932d8120867250ba734c3 Mon Sep 17 00:00:00 2001
From: Alexander Apalikov <alexander.apalikov@globant.com>
Date: Tue, 5 May 2020 01:04:30 +0300
Subject: [PATCH] Add locals and lookup to handle missing keys

Avoid situation when missing one key could break deployment.
---
 examples/terraform-submodules/gke/module.tf   | 17 +++-----
 install/terraform/modules/gke/cluster.tf      | 42 ++++++++++++-------
 .../en/docs/Installation/Terraform/gke.md     |  3 +-
 3 files changed, 34 insertions(+), 28 deletions(-)

diff --git a/examples/terraform-submodules/gke/module.tf b/examples/terraform-submodules/gke/module.tf
index 82d74b7922..cca6939a36 100644
--- a/examples/terraform-submodules/gke/module.tf
+++ b/examples/terraform-submodules/gke/module.tf
@@ -64,10 +64,6 @@ variable "feature_gates" {
   default = ""
 }
 
-variable "kubernetes_version" {
-  default = "1.15"
-}
-
 module "gke_cluster" {
   // ***************************************************************************************************
   // Update ?ref= to the agones release you are installing. For example, ?ref=release-1.3.0 corresponds
@@ -76,13 +72,12 @@ module "gke_cluster" {
   source = "git::https://github.com/googleforgames/agones.git//install/terraform/modules/gke/?ref=master"
 
   cluster = {
-    "name"              = var.name
-    "zone"              = var.zone
-    "machineType"       = var.machine_type
-    "initialNodeCount"  = var.node_count
-    "project"           = var.project
-    "network"           = var.network
-    "kubernetesVersion" = var.kubernetes_version
+    "name"             = var.name
+    "zone"             = var.zone
+    "machineType"      = var.machine_type
+    "initialNodeCount" = var.node_count
+    "project"          = var.project
+    "network"          = var.network
   }
 }
 
diff --git a/install/terraform/modules/gke/cluster.tf b/install/terraform/modules/gke/cluster.tf
index d3ba17d679..630ea11664 100644
--- a/install/terraform/modules/gke/cluster.tf
+++ b/install/terraform/modules/gke/cluster.tf
@@ -19,10 +19,22 @@ terraform {
 
 data "google_client_config" "default" {}
 
+# A list of all parameters used in interpolation var.cluster
+# Set values to default if not key was not set in original map
+locals {
+  project           = lookup(var.cluster, "project", "agones")
+  zone              = lookup(var.cluster, "zone", "us-west1-c")
+  name              = lookup(var.cluster, "name", "test-cluster")
+  machineType       = lookup(var.cluster, "machineType", "n1-standard-4")
+  initialNodeCount  = lookup(var.cluster, "initialNodeCount", "4")
+  network           = lookup(var.cluster, "network", "default")
+  kubernetesVersion = lookup(var.cluster, "kubernetesVersion", "1.15")
+}
+
 data "google_container_engine_versions" "kubernetes" {
-  project        = var.cluster["project"]
-  location       = var.cluster["zone"]
-  version_prefix = var.cluster["kubernetesVersion"]
+  project        = local.project
+  location       = local.zone
+  version_prefix = local.kubernetesVersion
 }
 
 # echo command used for debugging purpose
@@ -31,18 +43,18 @@ resource "null_resource" "test-setting-variables" {
   provisioner "local-exec" {
     command = <<EOT
     ${format("echo Current variables set as following - name: %s, project: %s, machineType: %s, initialNodeCount: %s, network: %s, zone: %s",
-    var.cluster["name"], var.cluster["project"],
-    var.cluster["machineType"], var.cluster["initialNodeCount"], var.cluster["network"],
-var.cluster["zone"])}
+    local.name, local.project,
+    local.machineType, local.initialNodeCount, local.network,
+local.zone)}
     EOT
 }
 }
 
 resource "google_container_cluster" "primary" {
-  name     = var.cluster["name"]
-  location = var.cluster["zone"]
-  project  = var.cluster["project"]
-  network  = var.cluster["network"]
+  name     = local.name
+  location = local.zone
+  project  = local.project
+  network  = local.network
 
   min_master_version = data.google_container_engine_versions.kubernetes.latest_master_version
 
@@ -50,14 +62,14 @@ resource "google_container_cluster" "primary" {
 
   node_pool {
     name       = "default"
-    node_count = var.cluster["initialNodeCount"]
+    node_count = local.initialNodeCount
 
     management {
       auto_upgrade = false
     }
 
     node_config {
-      machine_type = var.cluster["machineType"]
+      machine_type = local.machineType
 
       oauth_scopes = [
         "https://www.googleapis.com/auth/devstorage.read_only",
@@ -140,9 +152,9 @@ resource "google_container_cluster" "primary" {
 }
 
 resource "google_compute_firewall" "default" {
-  name    = "game-server-firewall-firewall-${var.cluster["name"]}"
-  project = var.cluster["project"]
-  network = var.cluster["network"]
+  name    = "game-server-firewall-firewall-${local.name}"
+  project = local.project
+  network = local.network
 
   allow {
     protocol = "udp"
diff --git a/site/content/en/docs/Installation/Terraform/gke.md b/site/content/en/docs/Installation/Terraform/gke.md
index db7a062a5d..dc5d0bbfc3 100644
--- a/site/content/en/docs/Installation/Terraform/gke.md
+++ b/site/content/en/docs/Installation/Terraform/gke.md
@@ -92,7 +92,6 @@ Configurable parameters:
 - network - the name of the VPC network you want your cluster and firewall rules to be connected to (default is "default")
 - log_level - possible values: Fatal, Error, Warn, Info, Debug (default is "info")
 - feature_gates - a list of alpha and beta version features to enable. For example, "PlayerTracking=true&ContainerPortAllocation=true"
-- kubernetes_version - a Kubernetes version of the GKE cluster
 
 {{% alert title="Warning" color="warning"%}}
 On the lines that read `source = "git::https://github.com/googleforgames/agones.git//install/terraform/modules/gke/?ref=master"`
@@ -140,7 +139,7 @@ You should have 6 nodes in `Ready` state.
 
 To delete all resources provisioned by Terraform:
 ```
-terraform destroy
+terraform destroy -var project="<YOUR_GCP_ProjectID>"
 ```
 
 ## Next Steps