feat: adding retention support to Cloudwatch log group (#266)

* feat: adding retention support to Cloudwatch log group

* terraform-docs: automated action

---------

Co-authored-by: Benjamin Valiente (Contractor) <benjamin.valiente@thoughtbot.com>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Author: 3 people

aws/network/modules/vpc/README.md

@@ -36,6 +36,7 @@ Module for creating a VPC in AWS.
 | <a name="input_cidr_block"></a> [cidr\_block](#input\_cidr\_block) | CIDR block to be used for the VPC, such as 10.0.0.0/16 | `string` | n/a | yes |
 | <a name="input_enable_flow_logs"></a> [enable\_flow\_logs](#input\_enable\_flow\_logs) | Set to true to enable VPC flow logs | `bool` | `false` | no |
 | <a name="input_enable_ipv6"></a> [enable\_ipv6](#input\_enable\_ipv6) | Set to false to disable IPV6 | `bool` | `false` | no |
+| <a name="input_flow_logs_retention_days"></a> [flow\_logs\_retention\_days](#input\_flow\_logs\_retention\_days) | Number of days to retain VPC Flow Logs in CloudWatch. | `number` | `null` | no |
 | <a name="input_name"></a> [name](#input\_name) | Name for this network | `string` | n/a | yes |
 | <a name="input_namespace"></a> [namespace](#input\_namespace) | Prefix to be applied to created resources | `list(string)` | `[]` | no |
 | <a name="input_tags"></a> [tags](#input\_tags) | Tags to be applied to created resources | `map(string)` | `{}` | no |

aws/network/modules/vpc/main.tf

@@ -69,5 +69,6 @@ data "aws_iam_policy_document" "flow_logs" {
 resource "aws_cloudwatch_log_group" "flow_logs" {
   count = var.enable_flow_logs ? 1 : 0
 
-  name = join("/", concat([""], var.namespace, [var.name, "flow-logs"]))
+  name              = join("/", concat([""], var.namespace, [var.name, "flow-logs"]))
+  retention_in_days = var.flow_logs_retention_days
 }

aws/network/modules/vpc/variables.tf

@@ -31,3 +31,9 @@ variable "cidr_block" {
   type        = string
   description = "CIDR block to be used for the VPC, such as 10.0.0.0/16"
 }
+
+variable "flow_logs_retention_days" {
+  description = "Number of days to retain VPC Flow Logs in CloudWatch." # Only applies when enable_flow_logs is true.
+  type        = number
+  default     = null # null = retain forever
+}