Add elasticache in subnet group instead of creating a new

main.tf

@@ -6,7 +6,7 @@
 resource "aws_elasticache_replication_group" "default" {
   engine               = "redis"
   parameter_group_name = aws_elasticache_parameter_group.default.name
-  subnet_group_name    = aws_elasticache_subnet_group.default.name
+  subnet_group_name    = var.subnet_group_name == null ? aws_elasticache_subnet_group.default[0].name : var.subnet_group_name
   security_group_ids   = [aws_security_group.default.id]
 
   # The replication group identifier. This parameter is stored as a lowercase string.
@@ -104,6 +104,7 @@ resource "aws_elasticache_parameter_group" "default" {
 
 # https://www.terraform.io/docs/providers/aws/r/elasticache_subnet_group.html
 resource "aws_elasticache_subnet_group" "default" {
+  count       = var.subnet_group_name == null ? 1 : 0
   name        = var.name
   subnet_ids  = var.subnet_ids
   description = var.description

variables.tf

@@ -16,11 +16,18 @@ variable "node_type" {
 variable "subnet_ids" {
   type        = list(string)
   description = "List of VPC Subnet IDs for the cache subnet group."
+  default     = []
 }
 
 variable "vpc_id" {
   type        = string
   description = "VPC Id to associate with Redis ElastiCache."
+  default     = ""
+}
+
+variable "subnet_group_name" {
+  type        = string
+  description = "VPC Id to associate with Redis ElastiCache."
 }
 
 variable "source_cidr_blocks" {