feat: Enable update in place for node groups with cluster placement group strategy

modules/eks-managed-node-group/README.md

@@ -97,7 +97,7 @@ module "eks_managed_node_group" {
 | [aws_iam_policy_document.role](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/iam_policy_document) | data source |
 | [aws_partition.current](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/partition) | data source |
 | [aws_ssm_parameter.ami](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/ssm_parameter) | data source |
-| [aws_subnets.efa](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/subnets) | data source |
+| [aws_subnets.placement_group](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/subnets) | data source |
 
 ## Inputs
 
@@ -169,6 +169,7 @@ module "eks_managed_node_group" {
 | <a name="input_name"></a> [name](#input\_name) | Name of the EKS managed node group | `string` | `""` | no |
 | <a name="input_network_interfaces"></a> [network\_interfaces](#input\_network\_interfaces) | Customize network interfaces to be attached at instance boot time | `list(any)` | `[]` | no |
 | <a name="input_placement"></a> [placement](#input\_placement) | The placement of the instance | `map(string)` | `{}` | no |
+| <a name="input_placement_group_az"></a> [placement\_group\_az](#input\_placement\_group\_az) | Availability zone where placement group is created (ex. `eu-west-1c`) | `string` | `null` | no |
 | <a name="input_placement_group_strategy"></a> [placement\_group\_strategy](#input\_placement\_group\_strategy) | The placement group strategy | `string` | `"cluster"` | no |
 | <a name="input_platform"></a> [platform](#input\_platform) | [DEPRECATED - use `ami_type` instead. Will be removed in `v21.0`] Identifies the OS platform as `bottlerocket`, `linux` (AL2), `al2023`, or `windows` | `string` | `"linux"` | no |
 | <a name="input_post_bootstrap_user_data"></a> [post\_bootstrap\_user\_data](#input\_post\_bootstrap\_user\_data) | User data that is appended to the user data script after of the EKS bootstrap script. Not used when `ami_type` = `BOTTLEROCKET_*` | `string` | `""` | no |

modules/eks-managed-node-group/main.tf

@@ -39,6 +39,8 @@ data "aws_ec2_instance_type" "this" {
 }
 
 locals {
+  enable_efa_support = var.create && var.enable_efa_support
+
   efa_instance_type = try(element(var.instance_types, 0), "")
   num_network_cards = try(data.aws_ec2_instance_type.this[0].maximum_network_cards, 0)
 
@@ -52,7 +54,7 @@ locals {
     }
   ]
 
-  network_interfaces = var.enable_efa_support ? local.efa_network_interfaces : var.network_interfaces
+  network_interfaces = local.enable_efa_support ? local.efa_network_interfaces : var.network_interfaces
 }
 
 ################################################################################
@@ -63,7 +65,7 @@ locals {
   launch_template_name = coalesce(var.launch_template_name, "${var.name}-eks-node-group")
   security_group_ids   = compact(concat([var.cluster_primary_security_group_id], var.vpc_security_group_ids))
 
-  placement = var.create && (var.enable_efa_support || var.create_placement_group) ? { group_name = aws_placement_group.this[0].name } : var.placement
+  placement = local.create_placement_group ? { group_name = aws_placement_group.this[0].name } : var.placement
 }
 
 resource "aws_launch_template" "this" {
@@ -390,7 +392,7 @@ resource "aws_eks_node_group" "this" {
   # Required
   cluster_name  = var.cluster_name
   node_role_arn = var.create_iam_role ? aws_iam_role.this[0].arn : var.iam_role_arn
-  subnet_ids    = var.enable_efa_support ? data.aws_subnets.efa[0].ids : var.subnet_ids
+  subnet_ids    = local.create_placement_group ? data.aws_subnets.placement_group[0].ids : var.subnet_ids
 
   scaling_config {
     min_size     = var.min_size
@@ -605,8 +607,12 @@ resource "aws_iam_role_policy" "this" {
 # Placement Group
 ################################################################################
 
+locals {
+  create_placement_group = var.create && (local.enable_efa_support || var.create_placement_group)
+}
+
 resource "aws_placement_group" "this" {
-  count = var.create && (var.enable_efa_support || var.create_placement_group) ? 1 : 0
+  count = local.create_placement_group ? 1 : 0
 
   name     = "${var.cluster_name}-${var.name}"
   strategy = var.placement_group_strategy
@@ -624,8 +630,11 @@ resource "aws_placement_group" "this" {
 ################################################################################
 
 # Find the availability zones supported by the instance type
+# TODO - remove at next breaking change
+# Force users to be explicit about which AZ to use when using placement groups,
+# with or without EFA support
 data "aws_ec2_instance_type_offerings" "this" {
-  count = var.create && var.enable_efa_support ? 1 : 0
+  count = local.enable_efa_support ? 1 : 0
 
   filter {
     name   = "instance-type"
@@ -637,17 +646,31 @@ data "aws_ec2_instance_type_offerings" "this" {
 
 # Reverse the lookup to find one of the subnets provided based on the availability
 # availability zone ID of the queried instance type (supported)
-data "aws_subnets" "efa" {
-  count = var.create && var.enable_efa_support ? 1 : 0
+data "aws_subnets" "placement_group" {
+  count = local.create_placement_group ? 1 : 0
 
   filter {
     name   = "subnet-id"
     values = var.subnet_ids
   }
 
-  filter {
-    name   = "availability-zone-id"
-    values = data.aws_ec2_instance_type_offerings.this[0].locations
+  # The data source can lookup the first available AZ or you can specify an AZ (next filter)
+  dynamic "filter" {
+    for_each = var.enable_efa_support && var.placement_group_az == null ? [1] : []
+
+    content {
+      name   = "availability-zone-id"
+      values = data.aws_ec2_instance_type_offerings.this[0].locations
+    }
+  }
+
+  dynamic "filter" {
+    for_each = var.placement_group_az != null ? [var.placement_group_az] : []
+
+    content {
+      name   = "availability-zone"
+      values = [filter.value]
+    }
   }
 }
 

modules/eks-managed-node-group/variables.tf

@@ -303,6 +303,7 @@ variable "create_placement_group" {
   default     = false
 }
 
+# TODO - remove at next breaking change
 variable "placement_group_strategy" {
   description = "The placement group strategy"
   type        = string
@@ -337,6 +338,12 @@ variable "subnet_ids" {
   default     = null
 }
 
+variable "placement_group_az" {
+  description = "Availability zone where placement group is created (ex. `eu-west-1c`)"
+  type        = string
+  default     = null
+}
+
 variable "min_size" {
   description = "Minimum number of instances/nodes"
   type        = number

modules/self-managed-node-group/README.md

@@ -78,7 +78,7 @@ module "self_managed_node_group" {
 | [aws_iam_policy_document.role](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/iam_policy_document) | data source |
 | [aws_partition.current](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/partition) | data source |
 | [aws_ssm_parameter.ami](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/ssm_parameter) | data source |
-| [aws_subnets.efa](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/subnets) | data source |
+| [aws_subnets.placement_group](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/subnets) | data source |
 
 ## Inputs
 
@@ -110,6 +110,7 @@ module "self_managed_node_group" {
 | <a name="input_create_iam_instance_profile"></a> [create\_iam\_instance\_profile](#input\_create\_iam\_instance\_profile) | Determines whether an IAM instance profile is created or to use an existing IAM instance profile | `bool` | `true` | no |
 | <a name="input_create_iam_role_policy"></a> [create\_iam\_role\_policy](#input\_create\_iam\_role\_policy) | Determines whether an IAM role policy is created or not | `bool` | `true` | no |
 | <a name="input_create_launch_template"></a> [create\_launch\_template](#input\_create\_launch\_template) | Determines whether to create launch template or not | `bool` | `true` | no |
+| <a name="input_create_placement_group"></a> [create\_placement\_group](#input\_create\_placement\_group) | Determines whether a placement group is created & used by the node group | `bool` | `false` | no |
 | <a name="input_create_schedule"></a> [create\_schedule](#input\_create\_schedule) | Determines whether to create autoscaling group schedule or not | `bool` | `true` | no |
 | <a name="input_credit_specification"></a> [credit\_specification](#input\_credit\_specification) | Customize the credit specification of the instance | `map(string)` | `{}` | no |
 | <a name="input_default_cooldown"></a> [default\_cooldown](#input\_default\_cooldown) | The amount of time, in seconds, after a scaling activity completes before another scaling activity can start | `number` | `null` | no |
@@ -170,6 +171,7 @@ module "self_managed_node_group" {
 | <a name="input_network_interfaces"></a> [network\_interfaces](#input\_network\_interfaces) | Customize network interfaces to be attached at instance boot time | `list(any)` | `[]` | no |
 | <a name="input_placement"></a> [placement](#input\_placement) | The placement of the instance | `map(string)` | `{}` | no |
 | <a name="input_placement_group"></a> [placement\_group](#input\_placement\_group) | The name of the placement group into which you'll launch your instances, if any | `string` | `null` | no |
+| <a name="input_placement_group_az"></a> [placement\_group\_az](#input\_placement\_group\_az) | Availability zone where placement group is created (ex. `eu-west-1c`) | `string` | `null` | no |
 | <a name="input_platform"></a> [platform](#input\_platform) | [DEPRECATED - must use `ami_type` instead. Will be removed in `v21.0`] | `string` | `null` | no |
 | <a name="input_post_bootstrap_user_data"></a> [post\_bootstrap\_user\_data](#input\_post\_bootstrap\_user\_data) | User data that is appended to the user data script after of the EKS bootstrap script. Not used when `ami_type` = `BOTTLEROCKET_*` | `string` | `""` | no |
 | <a name="input_pre_bootstrap_user_data"></a> [pre\_bootstrap\_user\_data](#input\_pre\_bootstrap\_user\_data) | User data that is injected into the user data script ahead of the EKS bootstrap script. Not used when `ami_type` = `BOTTLEROCKET_*` | `string` | `""` | no |

modules/self-managed-node-group/main.tf

@@ -745,7 +745,7 @@ resource "aws_autoscaling_group" "this" {
 
   target_group_arns         = var.target_group_arns
   termination_policies      = var.termination_policies
-  vpc_zone_identifier       = local.enable_efa_support ? data.aws_subnets.efa[0].ids : var.subnet_ids
+  vpc_zone_identifier       = local.enable_efa_support ? data.aws_subnets.placement_group[0].ids : var.subnet_ids
   wait_for_capacity_timeout = var.wait_for_capacity_timeout
   wait_for_elb_capacity     = var.wait_for_elb_capacity
 
@@ -930,8 +930,12 @@ resource "aws_iam_role_policy" "this" {
 # Placement Group
 ################################################################################
 
+locals {
+  create_placement_group = var.create && (local.enable_efa_support || var.create_placement_group)
+}
+
 resource "aws_placement_group" "this" {
-  count = local.enable_efa_support ? 1 : 0
+  count = local.create_placement_group ? 1 : 0
 
   name     = "${var.cluster_name}-${var.name}"
   strategy = "cluster"
@@ -949,6 +953,9 @@ resource "aws_placement_group" "this" {
 ################################################################################
 
 # Find the availability zones supported by the instance type
+# TODO - remove at next breaking change
+# Force users to be explicit about which AZ to use when using placement groups,
+# with or without EFA support
 data "aws_ec2_instance_type_offerings" "this" {
   count = local.enable_efa_support ? 1 : 0
 
@@ -962,17 +969,31 @@ data "aws_ec2_instance_type_offerings" "this" {
 
 # Reverse the lookup to find one of the subnets provided based on the availability
 # availability zone ID of the queried instance type (supported)
-data "aws_subnets" "efa" {
-  count = local.enable_efa_support ? 1 : 0
+data "aws_subnets" "placement_group" {
+  count = local.create_placement_group ? 1 : 0
 
   filter {
     name   = "subnet-id"
     values = var.subnet_ids
   }
 
-  filter {
-    name   = "availability-zone-id"
-    values = data.aws_ec2_instance_type_offerings.this[0].locations
+  # The data source can lookup the first available AZ or you can specify an AZ (next filter)
+  dynamic "filter" {
+    for_each = local.create_placement_group && var.placement_group_az == null ? [1] : []
+
+    content {
+      name   = "availability-zone-id"
+      values = data.aws_ec2_instance_type_offerings.this[0].locations
+    }
+  }
+
+  dynamic "filter" {
+    for_each = var.placement_group_az != null ? [var.placement_group_az] : []
+
+    content {
+      name   = "availability-zone"
+      values = [filter.value]
+    }
   }
 }
 

modules/self-managed-node-group/variables.tf

@@ -256,6 +256,12 @@ variable "placement" {
   default     = {}
 }
 
+variable "create_placement_group" {
+  description = "Determines whether a placement group is created & used by the node group"
+  type        = bool
+  default     = false
+}
+
 variable "private_dns_name_options" {
   description = "The options for the instance hostname. The default values are inherited from the subnet"
   type        = map(string)
@@ -384,6 +390,12 @@ variable "availability_zones" {
   default     = null
 }
 
+variable "placement_group_az" {
+  description = "Availability zone where placement group is created (ex. `eu-west-1c`)"
+  type        = string
+  default     = null
+}
+
 variable "subnet_ids" {
   description = "A list of subnet IDs to launch resources in. Subnets automatically determine which availability zones the group will reside. Conflicts with `availability_zones`"
   type        = list(string)

node_groups.tf

@@ -376,9 +376,10 @@ module "eks_managed_node_group" {
   enable_monitoring                  = try(each.value.enable_monitoring, var.eks_managed_node_group_defaults.enable_monitoring, true)
   enable_efa_support                 = try(each.value.enable_efa_support, var.eks_managed_node_group_defaults.enable_efa_support, false)
   create_placement_group             = try(each.value.create_placement_group, var.eks_managed_node_group_defaults.create_placement_group, false)
+  placement                          = try(each.value.placement, var.eks_managed_node_group_defaults.placement, {})
+  placement_group_az                 = try(each.value.placement_group_az, var.eks_managed_node_group_defaults.placement_group_az, null)
   placement_group_strategy           = try(each.value.placement_group_strategy, var.eks_managed_node_group_defaults.placement_group_strategy, "cluster")
   network_interfaces                 = try(each.value.network_interfaces, var.eks_managed_node_group_defaults.network_interfaces, [])
-  placement                          = try(each.value.placement, var.eks_managed_node_group_defaults.placement, {})
   maintenance_options                = try(each.value.maintenance_options, var.eks_managed_node_group_defaults.maintenance_options, {})
   private_dns_name_options           = try(each.value.private_dns_name_options, var.eks_managed_node_group_defaults.private_dns_name_options, {})
 
@@ -444,7 +445,9 @@ module "self_managed_node_group" {
   context                   = try(each.value.context, var.self_managed_node_group_defaults.context, null)
 
   target_group_arns         = try(each.value.target_group_arns, var.self_managed_node_group_defaults.target_group_arns, [])
+  create_placement_group    = try(each.value.create_placement_group, var.self_managed_node_group_defaults.create_placement_group, false)
   placement_group           = try(each.value.placement_group, var.self_managed_node_group_defaults.placement_group, null)
+  placement_group_az        = try(each.value.placement_group_az, var.self_managed_node_group_defaults.placement_group_az, null)
   health_check_type         = try(each.value.health_check_type, var.self_managed_node_group_defaults.health_check_type, null)
   health_check_grace_period = try(each.value.health_check_grace_period, var.self_managed_node_group_defaults.health_check_grace_period, null)
 

tests/eks-managed-node-group/main.tf

@@ -90,11 +90,16 @@ module "eks" {
       }
     }
 
+    placement_group = {
+      create_placement_group = true
+      # forces the subnet lookup to be restricted to this availability zone
+      placement_group_az = element(local.azs, 3)
+    }
+
     # AL2023 node group utilizing new user data format which utilizes nodeadm
     # to join nodes to the cluster (instead of /etc/eks/bootstrap.sh)
     al2023_nodeadm = {
-      ami_type = "AL2023_x86_64_STANDARD"
-
+      ami_type                       = "AL2023_x86_64_STANDARD"
       use_latest_ami_release_version = true
 
       cloudinit_pre_nodeadm = [
@@ -376,9 +381,7 @@ module "eks_managed_node_group" {
 
   subnet_ids                        = module.vpc.private_subnets
   cluster_primary_security_group_id = module.eks.cluster_primary_security_group_id
-  vpc_security_group_ids = [
-    module.eks.node_security_group_id,
-  ]
+  vpc_security_group_ids            = [module.eks.node_security_group_id]
 
   ami_type = "BOTTLEROCKET_x86_64"