add option to recreate ASG when LT or LC changes

CHANGELOG.md

@@ -16,6 +16,7 @@ project adheres to [Semantic Versioning](http://semver.org/).
  - Added support for workers iam role tag in `./workers.tf` (@lucas-giaco)
  - Added `required_providers` to enforce provider minimum versions (by @dpiddockcmp)
  - Updated `local.spot_allocation_strategy` docstring to indicate availability of new `capacity-optimized` option. (by @sc250024)
+ - Added option to recreate ASG when LT or LC changes (by @barryib)
 
 ### Changed
 

local.tf

@@ -21,6 +21,7 @@ locals {
     asg_max_size                  = "3"                        # Maximum worker capacity in the autoscaling group.
     asg_min_size                  = "1"                        # Minimum worker capacity in the autoscaling group.
     asg_force_delete              = false                      # Enable forced deletion for the autoscaling group.
+    asg_recreate_on_change        = false                      # Recreate the autoscaling group when LT or LC change.
     instance_type                 = "m4.large"                 # Size of the workers instances.
     spot_price                    = ""                         # Cost of spot instance.
     placement_tenancy             = ""                         # The tenancy of the instance. Valid values are "default" or "dedicated".

versions.tf

@@ -6,5 +6,6 @@ terraform {
     local    = ">= 1.2"
     null     = ">= 2.1"
     template = ">= 2.1"
+    random   = ">= 2.1"
   }
 }

workers.tf

@@ -1,8 +1,17 @@
 # Worker Groups using Launch Configurations
 
 resource "aws_autoscaling_group" "workers" {
-  count       = local.worker_group_count
-  name_prefix = "${aws_eks_cluster.this.name}-${lookup(var.worker_groups[count.index], "name", count.index)}"
+  count = local.worker_group_count
+  name_prefix = join(
+    "-",
+    compact(
+      [
+        aws_eks_cluster.this.name,
+        lookup(var.worker_groups[count.index], "name", count.index),
+        lookup(var.worker_groups[count.index], "asg_recreate_on_change", local.workers_group_defaults["asg_recreate_on_change"]) ? random_pet.workers[count.index].id : ""
+      ]
+    )
+  )
   desired_capacity = lookup(
     var.worker_groups[count.index],
     "asg_desired_capacity",
@@ -210,6 +219,25 @@ resource "aws_launch_configuration" "workers" {
   }
 }
 
+resource "random_pet" "workers" {
+  count = local.worker_group_count
+
+  separator = "-"
+  length    = 2
+
+  keepers = {
+    lt_name = join(
+      "-",
+      compact(
+        [
+          aws_launch_configuration.workers[count.index].name,
+          aws_launch_configuration.workers[count.index].latest_version
+        ]
+      )
+    )
+  }
+}
+
 resource "aws_security_group" "workers" {
   count       = var.worker_create_security_group ? 1 : 0
   name_prefix = aws_eks_cluster.this.name
@@ -390,4 +418,3 @@ data "aws_iam_policy_document" "worker_autoscaling" {
     }
   }
 }
-

workers_launch_template.tf

@@ -2,11 +2,16 @@
 
 resource "aws_autoscaling_group" "workers_launch_template" {
   count = local.worker_group_launch_template_count
-  name_prefix = "${aws_eks_cluster.this.name}-${lookup(
-    var.worker_groups_launch_template[count.index],
-    "name",
-    count.index,
-  )}"
+  name_prefix = join(
+    "-",
+    compact(
+      [
+        aws_eks_cluster.this.name,
+        lookup(var.worker_groups_launch_template[count.index], "name", count.index),
+        lookup(var.worker_groups_launch_template[count.index], "asg_recreate_on_change", local.workers_group_defaults["asg_recreate_on_change"]) ? random_pet.workers_launch_template[count.index].id : ""
+      ]
+    )
+  )
   desired_capacity = lookup(
     var.worker_groups_launch_template[count.index],
     "asg_desired_capacity",
@@ -296,6 +301,25 @@ resource "aws_launch_template" "workers_launch_template" {
   }
 }
 
+resource "random_pet" "workers_launch_template" {
+  count = local.worker_group_launch_template_count
+
+  separator = "-"
+  length    = 2
+
+  keepers = {
+    lt_name = join(
+      "-",
+      compact(
+        [
+          aws_launch_template.workers_launch_template[count.index].name,
+          aws_launch_template.workers_launch_template[count.index].latest_version
+        ]
+      )
+    )
+  }
+}
+
 resource "aws_iam_instance_profile" "workers_launch_template" {
   count       = var.manage_worker_iam_resources ? local.worker_group_launch_template_count : 0
   name_prefix = aws_eks_cluster.this.name

workers_launch_template_mixed.tf

@@ -2,11 +2,17 @@
 
 resource "aws_autoscaling_group" "workers_launch_template_mixed" {
   count = local.worker_group_launch_template_mixed_count
-  name_prefix = "${aws_eks_cluster.this.name}-${lookup(
-    var.worker_groups_launch_template_mixed[count.index],
-    "name",
-    count.index,
-  )}"
+  name_prefix = join(
+    "-",
+    compact(
+      [
+        aws_eks_cluster.this.name,
+        lookup(var.worker_groups_launch_template_mixed[count.index], "name", count.index),
+        lookup(var.worker_groups_launch_template_mixed[count.index], "asg_recreate_on_change", local.workers_group_defaults["asg_recreate_on_change"]) ? random_pet.workers_launch_template_mixed[count.index].id : ""
+      ]
+    )
+  )
+
   desired_capacity = lookup(
     var.worker_groups_launch_template_mixed[count.index],
     "asg_desired_capacity",
@@ -338,6 +344,25 @@ resource "aws_launch_template" "workers_launch_template_mixed" {
   }
 }
 
+resource "random_pet" "workers_launch_template_mixed" {
+  count = local.worker_group_launch_template_mixed_count
+
+  separator = "-"
+  length    = 2
+
+  keepers = {
+    lt_name = join(
+      "-",
+      compact(
+        [
+          aws_launch_template.workers_launch_template_mixed[count.index].name,
+          aws_launch_template.workers_launch_template_mixed[count.index].latest_version
+        ]
+      )
+    )
+  }
+}
+
 resource "aws_iam_instance_profile" "workers_launch_template_mixed" {
   count       = var.manage_worker_iam_resources ? local.worker_group_launch_template_mixed_count : 0
   name_prefix = aws_eks_cluster.this.name