feat(subnet_group): Allow to pass an existing subnet group

Create a dedicated subnet group per cluster is most of the
time not required.
This is also useful when importing manually created resources
into terraform
Also
- pre-commit hook updated because a bug
- docs are up-to-date now

Author: egarbi

.pre-commit-config.yaml

@@ -1,6 +1,6 @@
 repos:
 - repo: https://github.com/pre-commit/pre-commit-hooks
-  rev: v4.3.0
+  rev: v4.4.0
   hooks:
   - id: check-added-large-files
     args: ['--maxkb=500']
@@ -18,7 +18,7 @@ repos:
     args: ['--allow-missing-credentials']
   - id: trailing-whitespace
 - repo: https://github.com/antonbabenko/pre-commit-terraform
-  rev: v1.74.0
+  rev: v1.80.0
   hooks:
   - id: terraform_fmt
   - id: terraform_docs

README.md

@@ -122,6 +122,7 @@ No modules.
 | <a name="input_cluster_mode_enabled"></a> [cluster\_mode\_enabled](#input\_cluster\_mode\_enabled) | Enable creation of a native redis cluster. | `bool` | `false` | no |
 | <a name="input_data_tiering_enabled"></a> [data\_tiering\_enabled](#input\_data\_tiering\_enabled) | Enables data tiering. Data tiering is only supported for replication groups using the r6gd node type. This parameter must be set to true when using r6gd nodes. | `bool` | `false` | no |
 | <a name="input_description"></a> [description](#input\_description) | The description of the all resources. | `string` | `"Managed by Terraform"` | no |
+| <a name="input_egress_cidr_blocks"></a> [egress\_cidr\_blocks](#input\_egress\_cidr\_blocks) | List of Egress CIDR blocks. | `list(string)` | <pre>[<br>  "0.0.0.0/0"<br>]</pre> | no |
 | <a name="input_engine_version"></a> [engine\_version](#input\_engine\_version) | The version number of the cache engine to be used for the cache clusters in this replication group. | `string` | `"6.x"` | no |
 | <a name="input_family"></a> [family](#input\_family) | The family of the ElastiCache parameter group. | `string` | `"redis6.x"` | no |
 | <a name="input_final_snapshot_identifier"></a> [final\_snapshot\_identifier](#input\_final\_snapshot\_identifier) | The name of your final node group (shard) snapshot. ElastiCache creates the snapshot from the primary node in the cluster. If omitted, no final snapshot will be made. | `string` | `null` | no |
@@ -131,7 +132,7 @@ No modules.
 | <a name="input_kms_key_id"></a> [kms\_key\_id](#input\_kms\_key\_id) | The ARN of the key that you wish to use if encrypting at rest. If not supplied, uses service managed encryption. Can be specified only if `at_rest_encryption_enabled = true` | `string` | `""` | no |
 | <a name="input_log_delivery_configuration"></a> [log\_delivery\_configuration](#input\_log\_delivery\_configuration) | Log Delivery configuration for the cluster. | <pre>list(object({<br>    destination_type = string<br>    destination      = string<br>    log_format       = string<br>    log_type         = string<br>  }))</pre> | `[]` | no |
 | <a name="input_maintenance_window"></a> [maintenance\_window](#input\_maintenance\_window) | Specifies the weekly time range for when maintenance on the cache cluster is performed. | `string` | `""` | no |
-| <a name="input_multi_az_enabled"></a> [multi\_az\_enabled](#input\_multi\_az\_enabled) | Specifies whether to enable Multi-AZ Support for the replication group. If true, `automatic_failover_enabled` must also be enabled. Defaults to false. | `string` | `false` | no |
+| <a name="input_multi_az_enabled"></a> [multi\_az\_enabled](#input\_multi\_az\_enabled) | Specifies whether to enable Multi-AZ Support for the replication group. If true, `automatic_failover_enabled` must also be enabled. Defaults to false. | `bool` | `false` | no |
 | <a name="input_name_prefix"></a> [name\_prefix](#input\_name\_prefix) | The replication group identifier. This parameter is stored as a lowercase string. | `string` | n/a | yes |
 | <a name="input_node_type"></a> [node\_type](#input\_node\_type) | The compute and memory capacity of the nodes in the node group. | `string` | n/a | yes |
 | <a name="input_notification_topic_arn"></a> [notification\_topic\_arn](#input\_notification\_topic\_arn) | An Amazon Resource Name (ARN) of an SNS topic to send ElastiCache notifications to. Example: `arn:aws:sns:us-east-1:012345678999:my_sns_topic` | `string` | `""` | no |
@@ -144,10 +145,11 @@ No modules.
 | <a name="input_security_group_ids"></a> [security\_group\_ids](#input\_security\_group\_ids) | List of Security Groups. | `list(string)` | `[]` | no |
 | <a name="input_snapshot_retention_limit"></a> [snapshot\_retention\_limit](#input\_snapshot\_retention\_limit) | The number of days for which ElastiCache will retain automatic cache cluster snapshots before deleting them. | `number` | `30` | no |
 | <a name="input_snapshot_window"></a> [snapshot\_window](#input\_snapshot\_window) | The daily time range (in UTC) during which ElastiCache will begin taking a daily snapshot of your cache cluster. | `string` | `""` | no |
-| <a name="input_subnet_ids"></a> [subnet\_ids](#input\_subnet\_ids) | List of VPC Subnet IDs for the cache subnet group. | `list(string)` | n/a | yes |
+| <a name="input_subnet_group_name"></a> [subnet\_group\_name](#input\_subnet\_group\_name) | The name of the subnet group. If it is not specified, the module will create one for you | `string` | `null` | no |
+| <a name="input_subnet_ids"></a> [subnet\_ids](#input\_subnet\_ids) | List of VPC Subnet IDs for the cache subnet group. | `list(string)` | `[]` | no |
 | <a name="input_tags"></a> [tags](#input\_tags) | A mapping of tags to assign to all resources. | `map(string)` | `{}` | no |
 | <a name="input_transit_encryption_enabled"></a> [transit\_encryption\_enabled](#input\_transit\_encryption\_enabled) | Whether to enable encryption in transit. | `bool` | `true` | no |
-| <a name="input_user_group_ids"></a> [user\_group\_id](#input\_user\_group\_id) | User Group ID to associate with the replication group. | `list(string)` | n/a | no |
+| <a name="input_user_group_ids"></a> [user\_group\_ids](#input\_user\_group\_ids) | User Group ID to associate with the replication group | `list(string)` | `null` | no |
 | <a name="input_vpc_id"></a> [vpc\_id](#input\_vpc\_id) | VPC Id to associate with Redis ElastiCache. | `string` | n/a | yes |
 
 ## Outputs

main.tf

@@ -1,8 +1,12 @@
+locals {
+  subnet_group_name = var.subnet_group_name != null ? var.subnet_group_name : aws_elasticache_subnet_group.redis[0].name
+}
+
 resource "aws_elasticache_replication_group" "redis" {
   engine = var.global_replication_group_id == null ? "redis" : null
 
   parameter_group_name = var.global_replication_group_id == null ? aws_elasticache_parameter_group.redis.name : null
-  subnet_group_name    = aws_elasticache_subnet_group.redis.name
+  subnet_group_name    = local.subnet_group_name
   security_group_ids   = concat(var.security_group_ids, [aws_security_group.redis.id])
 
   preferred_cache_cluster_azs = var.preferred_cache_cluster_azs
@@ -87,6 +91,7 @@ resource "aws_elasticache_parameter_group" "redis" {
 }
 
 resource "aws_elasticache_subnet_group" "redis" {
+  count       = var.subnet_group_name == null && length(var.subnet_ids) > 0 ? 1 : 0
   name        = var.global_replication_group_id == null ? "${var.name_prefix}-redis-sg" : "${var.name_prefix}-redis-sg-replica"
   subnet_ids  = var.subnet_ids
   description = var.description

variables.tf

@@ -23,6 +23,13 @@ variable "node_type" {
 variable "subnet_ids" {
   type        = list(string)
   description = "List of VPC Subnet IDs for the cache subnet group."
+  default     = []
+}
+
+variable "subnet_group_name" {
+  type        = string
+  description = "The name of the subnet group. If it is not specified, the module will create one for you"
+  default     = null
 }
 
 variable "vpc_id" {