feat: Allow snapshot_id to be specified for additional_ebs_volumes (terraform-aws-modules#1431)

Author: omjadas

locals.tf

@@ -78,10 +78,11 @@ locals {
     service_linked_role_arn           = ""                          # Arn of custom service linked role that Auto Scaling group will use. Useful when you have encrypted EBS
     termination_policies              = []                          # A list of policies to decide how the instances in the auto scale group should be terminated.
     platform                          = var.default_platform        # Platform of workers. Either "linux" or "windows".
-    additional_ebs_volumes            = []                          # A list of additional volumes to be attached to the instances on this Auto Scaling group. Each volume should be an object with the following: block_device_name (required), volume_size, volume_type, iops, throughput, encrypted, kms_key_id (only on launch-template), delete_on_termination. Optional values are grabbed from root volume or from defaults
+    additional_ebs_volumes            = []                          # A list of additional volumes to be attached to the instances on this Auto Scaling group. Each volume should be an object with the following: block_device_name (required), volume_size, volume_type, iops, throughput, encrypted, kms_key_id (only on launch-template), delete_on_termination, snapshot_id. Optional values are grabbed from root volume or from defaults
     additional_instance_store_volumes = []                          # A list of additional instance store (local disk) volumes to be attached to the instances on this Auto Scaling group. Each volume should be an object with the following: block_device_name (required), virtual_name.
     warm_pool                         = null                        # If this block is configured, add a Warm Pool to the specified Auto Scaling group.
     timeouts                          = {}                          # A map of timeouts for create/update/delete operations
+    snapshot_id                       = null                        # A custom snapshot ID.
 
     # Settings for launch templates
     root_block_device_name               = concat(data.aws_ami.eks_worker.*.root_device_name, [""])[0]         # Root device name for Linux workers. If not provided, will assume default Linux AMI was used.

workers.tf

@@ -344,6 +344,11 @@ resource "aws_launch_configuration" "workers" {
         "encrypted",
         local.workers_group_defaults["root_encrypted"],
       )
+      snapshot_id = lookup(
+        block_device_mappings.value,
+        "snapshot_id",
+        local.workers_group_defaults["snapshot_id"],
+      )
       delete_on_termination = lookup(ebs_block_device.value, "delete_on_termination", true)
     }
   }

workers_launch_template.tf

@@ -524,6 +524,11 @@ resource "aws_launch_template" "workers_launch_template" {
           "kms_key_id",
           local.workers_group_defaults["root_kms_key_id"],
         )
+        snapshot_id = lookup(
+          block_device_mappings.value,
+          "snapshot_id",
+          local.workers_group_defaults["snapshot_id"],
+        )
         delete_on_termination = lookup(block_device_mappings.value, "delete_on_termination", true)
       }
     }