Add support for placement groups (#306)

CHANGELOG.md

@@ -11,6 +11,7 @@ project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Added
 
+- Ability to specify a placement group for each worker group (by @matheuss)
 - "k8s.io/cluster-autoscaler/{cluster-name}" and "k8s.io/cluster-autoscaler/node-template/resources/ephemeral-storage" tags for autoscaling groups (by @tbarrella)
 - Added "ec2:DescribeLaunchTemplateVersions" action to worker instance role (by @skang0601)
 - Adding ebs encryption for workers launched using workers_launch_template (by @russki)

local.tf

@@ -38,6 +38,7 @@ locals {
     suspended_processes           = ""                              # A comma delimited string of processes to to suspend. i.e. AZRebalance,HealthCheck,ReplaceUnhealthy
     target_group_arns             = ""                              # A comma delimited list of ALB target group ARNs to be associated to the ASG
     enabled_metrics               = ""                              # A comma delimited list of metrics to be collected i.e. GroupMinSize,GroupMaxSize,GroupDesiredCapacity
+    placement_group               = ""                              # The name of the placement group into which to launch the instances, if any.
   }
 
   workers_group_defaults = "${merge(local.workers_group_defaults_defaults, var.workers_group_defaults)}"

workers.tf

@@ -13,6 +13,7 @@ resource "aws_autoscaling_group" "workers" {
   suspended_processes   = ["${compact(split(",", coalesce(lookup(var.worker_groups[count.index], "suspended_processes", ""), local.workers_group_defaults["suspended_processes"])))}"]
   enabled_metrics       = ["${compact(split(",", coalesce(lookup(var.worker_groups[count.index], "enabled_metrics", ""), local.workers_group_defaults["enabled_metrics"])))}"]
   count                 = "${var.worker_group_count}"
+  placement_group       = "${lookup(var.worker_groups[count.index], "placement_group", local.workers_group_defaults["placement_group"])}"
 
   tags = ["${concat(
     list(