Fix local_ssd_config issue that forces node-pool recreation

modules/compute/gke-node-pool/README.md

@@ -276,8 +276,8 @@ No modules.
 | <a name="input_image_type"></a> [image\_type](#input\_image\_type) | The default image type used by NAP once a new node pool is being created. Use either COS\_CONTAINERD or UBUNTU\_CONTAINERD. | `string` | `"COS_CONTAINERD"` | no |
 | <a name="input_kubernetes_labels"></a> [kubernetes\_labels](#input\_kubernetes\_labels) | Kubernetes labels to be applied to each node in the node group. Key-value pairs. <br>(The `kubernetes.io/` and `k8s.io/` prefixes are reserved by Kubernetes Core components and cannot be specified) | `map(string)` | `null` | no |
 | <a name="input_labels"></a> [labels](#input\_labels) | GCE resource labels to be applied to resources. Key-value pairs. | `map(string)` | n/a | yes |
-| <a name="input_local_ssd_count_ephemeral_storage"></a> [local\_ssd\_count\_ephemeral\_storage](#input\_local\_ssd\_count\_ephemeral\_storage) | The number of local SSDs to attach to each node to back ephemeral storage.<br>Uses NVMe interfaces.  Must be supported by `machine_type`.<br>When set to null, GKE decides about default value.<br>[See above](#local-ssd-storage) for more info. | `number` | `null` | no |
-| <a name="input_local_ssd_count_nvme_block"></a> [local\_ssd\_count\_nvme\_block](#input\_local\_ssd\_count\_nvme\_block) | The number of local SSDs to attach to each node to back block storage.<br>Uses NVMe interfaces.  Must be supported by `machine_type`.<br>When set to null, GKE decides about default value.<br>[See above](#local-ssd-storage) for more info. | `number` | `null` | no |
+| <a name="input_local_ssd_count_ephemeral_storage"></a> [local\_ssd\_count\_ephemeral\_storage](#input\_local\_ssd\_count\_ephemeral\_storage) | The number of local SSDs to attach to each node to back ephemeral storage.<br>Uses NVMe interfaces.  Must be supported by `machine_type`.<br>When set to null,  default value either is [set based on machine\_type](https://cloud.google.com/compute/docs/disks/local-ssd#choose_number_local_ssds) or GKE decides about default value.<br>[See above](#local-ssd-storage) for more info. | `number` | `null` | no |
+| <a name="input_local_ssd_count_nvme_block"></a> [local\_ssd\_count\_nvme\_block](#input\_local\_ssd\_count\_nvme\_block) | The number of local SSDs to attach to each node to back block storage.<br>Uses NVMe interfaces.  Must be supported by `machine_type`.<br>When set to null,  default value either is [set based on machine\_type](https://cloud.google.com/compute/docs/disks/local-ssd#choose_number_local_ssds) or GKE decides about default value.<br>[See above](#local-ssd-storage) for more info. | `number` | `null` | no |
 | <a name="input_machine_type"></a> [machine\_type](#input\_machine\_type) | The name of a Google Compute Engine machine type. | `string` | `"c2-standard-60"` | no |
 | <a name="input_name"></a> [name](#input\_name) | The name of the node pool. If left blank, will default to the machine type. | `string` | `null` | no |
 | <a name="input_project_id"></a> [project\_id](#input\_project\_id) | The project ID to host the cluster in. | `string` | n/a | yes |

modules/compute/gke-node-pool/disk_definitions.tf

@@ -0,0 +1,36 @@
+/**
+ * Copyright 2024 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+*/
+
+## Required variables:
+#  local_ssd_count_ephemeral_storage
+#  local_ssd_count_nvme_block
+#  machine_type
+
+locals {
+
+  local_ssd_machines = {
+    "a3-highgpu-8g" = { local_ssd_count_ephemeral_storage = 16, local_ssd_count_nvme_block = null },
+    "a3-megagpu-8g" = { local_ssd_count_ephemeral_storage = 16, local_ssd_count_nvme_block = null },
+  }
+
+  generated_local_ssd_config = lookup(local.local_ssd_machines, var.machine_type, { local_ssd_count_ephemeral_storage = null, local_ssd_count_nvme_block = null })
+
+  # Select in priority order:
+  # (1) var.local_ssd_count_ephemeral_storage and var.local_ssd_count_nvme_block if any is not null
+  # (2) local.local_ssd_machines if not empty
+  # (3) default to null value for both local_ssd_count_ephemeral_storage and local_ssd_count_nvme_block
+  local_ssd_config = (var.local_ssd_count_ephemeral_storage == null && var.local_ssd_count_nvme_block == null) ? local.generated_local_ssd_config : { local_ssd_count_ephemeral_storage = var.local_ssd_count_ephemeral_storage, local_ssd_count_nvme_block = var.local_ssd_count_nvme_block }
+}

modules/compute/gke-node-pool/main.tf

@@ -105,16 +105,16 @@ resource "google_container_node_pool" "node_pool" {
     }
 
     dynamic "ephemeral_storage_local_ssd_config" {
-      for_each = var.local_ssd_count_ephemeral_storage != null ? [1] : []
+      for_each = local.local_ssd_config.local_ssd_count_ephemeral_storage != null ? [1] : []
       content {
-        local_ssd_count = var.local_ssd_count_ephemeral_storage
+        local_ssd_count = local.local_ssd_config.local_ssd_count_ephemeral_storage
       }
     }
 
     dynamic "local_nvme_ssd_block_config" {
-      for_each = var.local_ssd_count_nvme_block != null ? [1] : []
+      for_each = local.local_ssd_config.local_ssd_count_nvme_block != null ? [1] : []
       content {
-        local_ssd_count = var.local_ssd_count_nvme_block
+        local_ssd_count = local.local_ssd_config.local_ssd_count_nvme_block
       }
     }
 
@@ -189,7 +189,7 @@ resource "google_container_node_pool" "node_pool" {
       error_message = "static_node_count cannot be set with either autoscaling_total_min_nodes or autoscaling_total_max_nodes."
     }
     precondition {
-      condition     = !(coalesce(var.local_ssd_count_ephemeral_storage, 0) > 0 && coalesce(var.local_ssd_count_nvme_block, 0) > 0)
+      condition     = !(coalesce(local.local_ssd_config.local_ssd_count_ephemeral_storage, 0) > 0 && coalesce(local.local_ssd_config.local_ssd_count_nvme_block, 0) > 0)
       error_message = "Only one of local_ssd_count_ephemeral_storage or local_ssd_count_nvme_block can be set to a non-zero value."
     }
     precondition {

modules/compute/gke-node-pool/variables.tf

@@ -93,7 +93,7 @@ variable "local_ssd_count_ephemeral_storage" {
   description = <<-EOT
   The number of local SSDs to attach to each node to back ephemeral storage.  
   Uses NVMe interfaces.  Must be supported by `machine_type`.
-  When set to null, GKE decides about default value.
+  When set to null,  default value either is [set based on machine_type](https://cloud.google.com/compute/docs/disks/local-ssd#choose_number_local_ssds) or GKE decides about default value.
   [See above](#local-ssd-storage) for more info.
   EOT 
   type        = number
@@ -104,7 +104,7 @@ variable "local_ssd_count_nvme_block" {
   description = <<-EOT
   The number of local SSDs to attach to each node to back block storage.  
   Uses NVMe interfaces.  Must be supported by `machine_type`.
-  When set to null, GKE decides about default value.
+  When set to null,  default value either is [set based on machine_type](https://cloud.google.com/compute/docs/disks/local-ssd#choose_number_local_ssds) or GKE decides about default value.
   [See above](#local-ssd-storage) for more info.
 
   EOT