fix: remove requirement for a kms key to be provided when using an existing instance of elasticsearch (#281)

Author: MatthewLemmond

solutions/standard/main.tf

@@ -11,7 +11,7 @@ locals {
   elasticsearch_key_ring_name = var.prefix != null ? "${var.prefix}-${var.elasticsearch_key_ring_name}" : var.elasticsearch_key_ring_name
 
 
-  kms_key_crn = var.existing_kms_key_crn != null ? var.existing_kms_key_crn : module.kms[0].keys[format("%s.%s", local.elasticsearch_key_ring_name, local.elasticsearch_key_name)].crn
+  kms_key_crn = var.existing_db_instance_crn != null ? null : (var.existing_kms_key_crn != null ? var.existing_kms_key_crn : module.kms[0].keys[format("%s.%s", local.elasticsearch_key_ring_name, local.elasticsearch_key_name)].crn)
 
   existing_db_instance_guid = var.existing_db_instance_crn != null ? element(split(":", var.existing_db_instance_crn), length(split(":", var.existing_db_instance_crn)) - 3) : null
   use_existing_db_instance  = var.existing_db_instance_crn != null