fix: enable transit mode encryption var as it is now available in redis

Author: willejs

main.tf

@@ -58,7 +58,8 @@ resource "aws_elasticache_cluster" "this" {
   snapshot_retention_limit     = local.in_replication_group ? null : var.snapshot_retention_limit
   snapshot_window              = local.in_replication_group ? null : var.snapshot_window
   subnet_group_name            = local.in_replication_group ? null : local.subnet_group_name
-  transit_encryption_enabled   = var.engine == "memcached" ? var.transit_encryption_enabled : null
+  # this makes it so that the transit encryption is enabled by default for memcached, which prevents a backwards incompatible change
+  transit_encryption_enabled   = var.engine == "memcached" ? true : var.transit_encryption_enabled
 
   tags = local.tags
 

variables.tf

@@ -176,9 +176,9 @@ variable "snapshot_window" {
 }
 
 variable "transit_encryption_enabled" {
-  description = "Enable encryption in-transit. Supported only with Memcached versions `1.6.12` and later, running in a VPC"
+  description = "Enable encryption in-transit."
   type        = bool
-  default     = true
+  default     = null
 }
 
 variable "transit_encryption_mode" {