Input variable for replication_group_id (#28)

* adding an input variable for replication_group_id

* fix formatting

* updating docs

docs/terraform.md

@@ -24,6 +24,7 @@
 | notification_topic_arn | Notification topic arn | string | `` | no |
 | parameter | A list of Redis parameters to apply. Note that parameters may differ from one Redis family to another | list | `<list>` | no |
 | port | Redis port | string | `6379` | no |
+| replication_group_id | Replication group ID with the following constraints:  A name must contain from 1 to 20 alphanumeric characters or hyphens.   The first character must be a letter.   A name cannot end with a hyphen or contain two consecutive hyphens. | string | `` | no |
 | security_groups | AWS security group ids | list | `<list>` | no |
 | stage | Stage | string | `default` | no |
 | subnets | AWS subnet ids | list | `<list>` | no |

main.tf

@@ -52,7 +52,7 @@ resource "aws_elasticache_replication_group" "default" {
   count = "${var.enabled == "true" ? 1 : 0}"
 
   auth_token                    = "${var.auth_token}"
-  replication_group_id          = "${module.label.id}"
+  replication_group_id          = "${var.replication_group_id == "" ? module.label.id : var.replication_group_id}"
   replication_group_description = "${module.label.id}"
   node_type                     = "${var.instance_type}"
   number_cache_clusters         = "${var.cluster_size}"

variables.tf

@@ -147,3 +147,9 @@ variable "auth_token" {
   description = "Auth token for password protecting redis, transit_encryption_enabled must be set to 'true'! Password must be longer than 16 chars"
   default     = ""
 }
+
+variable "replication_group_id" {
+  type        = "string"
+  description = "Replication group ID with the following constraints: \nA name must contain from 1 to 20 alphanumeric characters or hyphens. \n The first character must be a letter. \n A name cannot end with a hyphen or contain two consecutive hyphens."
+  default     = ""
+}