Merge pull request #610 from alphagov/per-az-worker-count

Tidy config around per-AZ worker counts

hack/lint-terraform-values-output.sh

@@ -19,6 +19,8 @@ set -eu
 		--var cluster_domain=x \
 		--var aws_account_role_arn=x \
 		--var eks_version=x \
+		--var minimum_workers_per_az_count=1 \
+		--var maximum_workers_per_az_count=3 \
 )
 
 

modules/gsp-cluster/main.tf

@@ -1,15 +1,16 @@
 module "k8s-cluster" {
-  source                     = "../k8s-cluster"
-  vpc_id                     = "${var.vpc_id}"
-  private_subnet_ids         = ["${var.private_subnet_ids}"]
-  public_subnet_ids          = ["${var.public_subnet_ids}"]
-  cluster_name               = "${var.cluster_name}"
-  worker_count               = "${var.worker_count}"
-  worker_instance_type       = "${var.worker_instance_type}"
-  extra_workers_per_az_count = "${var.extra_workers_per_az_count}"
-  ci_worker_count            = "${var.ci_worker_count}"
-  ci_worker_instance_type    = "${var.ci_worker_instance_type}"
-  eks_version                = "${var.eks_version}"
+  source                       = "../k8s-cluster"
+  vpc_id                       = "${var.vpc_id}"
+  private_subnet_ids           = ["${var.private_subnet_ids}"]
+  public_subnet_ids            = ["${var.public_subnet_ids}"]
+  cluster_name                 = "${var.cluster_name}"
+  worker_count                 = "${var.worker_count}"
+  worker_instance_type         = "${var.worker_instance_type}"
+  minimum_workers_per_az_count = "${var.minimum_workers_per_az_count}"
+  maximum_workers_per_az_count = "${var.maximum_workers_per_az_count}"
+  ci_worker_count              = "${var.ci_worker_count}"
+  ci_worker_instance_type      = "${var.ci_worker_instance_type}"
+  eks_version                  = "${var.eks_version}"
 
   apiserver_allowed_cidrs = ["${concat(
       formatlist("%s/32", var.egress_ips),

modules/gsp-cluster/variables.tf

@@ -60,9 +60,14 @@ variable "worker_instance_type" {
   default = "t3.medium"
 }
 
-variable "extra_workers_per_az_count" {
+variable "minimum_workers_per_az_count" {
   type    = "string"
-  default = "0"
+  default = "1"
+}
+
+variable "maximum_workers_per_az_count" {
+  type    = "string"
+  default = "5"
 }
 
 variable "ci_worker_count" {

modules/k8s-cluster/main.tf

@@ -93,9 +93,9 @@ resource "aws_cloudformation_stack" "worker-nodes-per-az" {
     ClusterControlPlaneSecurityGroup = "${aws_security_group.controller.id}"
     NodeGroupName                    = "worker-${element(data.aws_subnet.private_subnets.*.availability_zone, count.index)}"
 
-    NodeAutoScalingGroupMinSize         = "${var.extra_workers_per_az_count}"     # "${var.worker_count / 3}"
-    NodeAutoScalingGroupDesiredCapacity = "${var.extra_workers_per_az_count}"     # "${var.worker_count / 3}"
-    NodeAutoScalingGroupMaxSize         = "${var.extra_workers_per_az_count + 2}" # "${var.worker_count / 3 + 2}"
+    NodeAutoScalingGroupMinSize         = "${var.minimum_workers_per_az_count}"
+    NodeAutoScalingGroupDesiredCapacity = "${var.minimum_workers_per_az_count}"
+    NodeAutoScalingGroupMaxSize         = "${var.maximum_workers_per_az_count}"
 
     NodeInstanceType    = "${var.worker_instance_type}"
     NodeInstanceProfile = "${aws_cloudformation_stack.worker-nodes.outputs["NodeInstanceProfile"]}"

modules/k8s-cluster/variables.tf

@@ -32,9 +32,14 @@ variable "worker_count" {
   default = "3"
 }
 
-variable "extra_workers_per_az_count" {
+variable "minimum_workers_per_az_count" {
   type    = "string"
-  default = "0"
+  default = "1"
+}
+
+variable "maximum_workers_per_az_count" {
+  type    = "string"
+  default = "5"
 }
 
 variable "ci_worker_instance_type" {

pipelines/deployer/deployer.defaults.yaml

@@ -20,7 +20,8 @@ disable-destroy: true
 config-approvers: []
 config-approval-count: 2
 
-extra-workers-per-az-count: 0
+minimum-workers-per-az-count: 1
+maximum-workers-per-az-count: 5
 
 task-toolbox-image: govsvc/task-toolbox
 task-toolbox-tag: latest

pipelines/deployer/deployer.tf

@@ -58,7 +58,11 @@ variable "worker_count" {
   default = "3"
 }
 
-variable "extra_workers_per_az_count" {
+variable "minimum_workers_per_az_count" {
+  type = "string"
+}
+
+variable "maximum_workers_per_az_count" {
   type = "string"
 }
 
@@ -134,12 +138,13 @@ module "gsp-cluster" {
     "3.8.110.67/32",     # autom8 concourse
   ]
 
-  eks_version                = "${var.eks_version}"
-  worker_instance_type       = "${var.worker_instance_type}"
-  worker_count               = "${var.worker_count}"
-  extra_workers_per_az_count = "${var.extra_workers_per_az_count}"
-  ci_worker_instance_type    = "${var.ci_worker_instance_type}"
-  ci_worker_count            = "${var.ci_worker_count}"
+  eks_version                  = "${var.eks_version}"
+  worker_instance_type         = "${var.worker_instance_type}"
+  worker_count                 = "${var.worker_count}"
+  minimum_workers_per_az_count = "${var.minimum_workers_per_az_count}"
+  maximum_workers_per_az_count = "${var.maximum_workers_per_az_count}"
+  ci_worker_instance_type      = "${var.ci_worker_instance_type}"
+  ci_worker_count              = "${var.ci_worker_count}"
 
   vpc_id               = "${module.gsp-network.vpc_id}"
   private_subnet_ids   = "${module.gsp-network.private_subnet_ids}"

pipelines/deployer/deployer.yaml

@@ -537,7 +537,8 @@ resources:
       eks_version: ((eks-version))
       worker_instance_type: ((worker-instance-type))
       worker_count: ((worker-count))
-      extra_workers_per_az_count: ((extra-workers-per-az-count))
+      minimum_workers_per_az_count: ((minimum-workers-per-az-count))
+      maximum_workers_per_az_count: ((maximum-workers-per-az-count))
       enable_nlb: ((enable-nlb))
       ci_worker_instance_type: ((ci-worker-instance-type))
       ci_worker_count: ((ci-worker-count))