improvement: Allow to create VPC with custom CIDR

modules/vpc/README.md

@@ -9,36 +9,49 @@ Create a VPC for a specific environment, all other resources will be created ins
 
 | Name | Version |
 |------|---------|
-| terraform | >= 0.13 |
+| <a name="requirement_terraform"></a> [terraform](#requirement\_terraform) | >= 0.13 |
 
 ## Providers
 
 | Name | Version |
 |------|---------|
-| aws | n/a |
+| <a name="provider_aws"></a> [aws](#provider\_aws) | n/a |
+
+## Modules
+
+| Name | Source | Version |
+|------|--------|---------|
+| <a name="module_nat_instance"></a> [nat\_instance](#module\_nat\_instance) | int128/nat-instance/aws | 2.0.0 |
+| <a name="module_vpc"></a> [vpc](#module\_vpc) | terraform-aws-modules/vpc/aws | 2.70.0 |
+
+## Resources
+
+| Name | Type |
+|------|------|
+| [aws_eip.nat_instance](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/eip) | resource |
 
 ## Inputs
 
 | Name | Description | Type | Default | Required |
 |------|-------------|------|---------|:--------:|
-| enable\_nat\_gateway | Create NAT gateway(s) to allow private subnets to route traffic out to the public internet. If this is set to false, it will create a NAT instance instead. This can be useful in non-production environments to reduce cost, though in some cases it may lead to network instability or lower throughput. | `bool` | n/a | yes |
-| environment | The environment (stage/prod) | `any` | n/a | yes |
-| kubernetes\_cluster\_name | Kubernetes cluster name used to associate with subnets for auto LB placement | `any` | n/a | yes |
-| nat\_instance\_types | Candidates of instance type for the NAT instance | `list(any)` | <pre>[<br>  "t3.nano",<br>  "t3a.nano"<br>]</pre> | no |
-| project | The name of the project, mostly for tagging | `any` | n/a | yes |
-| region | The AWS region to create resources in | `any` | n/a | yes |
-| single\_nat\_gateway | Use single nat-gateway instead of nat-gateway per subnet | `bool` | n/a | yes |
+| <a name="input_cidr"></a> [cidr](#input\_cidr) | The CIDR for the VPC, must be a /16 at least | `string` | `"10.10.0.0/16"` | no |
+| <a name="input_enable_nat_gateway"></a> [enable\_nat\_gateway](#input\_enable\_nat\_gateway) | Create NAT gateway(s) to allow private subnets to route traffic out to the public internet. If this is set to false, it will create a NAT instance instead. This can be useful in non-production environments to reduce cost, though in some cases it may lead to network instability or lower throughput. | `bool` | n/a | yes |
+| <a name="input_environment"></a> [environment](#input\_environment) | The environment (stage/prod) | `any` | n/a | yes |
+| <a name="input_kubernetes_cluster_name"></a> [kubernetes\_cluster\_name](#input\_kubernetes\_cluster\_name) | Kubernetes cluster name used to associate with subnets for auto LB placement | `any` | n/a | yes |
+| <a name="input_nat_instance_types"></a> [nat\_instance\_types](#input\_nat\_instance\_types) | Candidates of instance type for the NAT instance | `list(any)` | <pre>[<br>  "t3.nano",<br>  "t3a.nano"<br>]</pre> | no |
+| <a name="input_project"></a> [project](#input\_project) | The name of the project, mostly for tagging | `any` | n/a | yes |
+| <a name="input_region"></a> [region](#input\_region) | The AWS region to create resources in | `any` | n/a | yes |
+| <a name="input_single_nat_gateway"></a> [single\_nat\_gateway](#input\_single\_nat\_gateway) | Use single nat-gateway instead of nat-gateway per subnet | `bool` | n/a | yes |
 
 ## Outputs
 
 | Name | Description |
 |------|-------------|
-| azs | Availability zones for the VPC |
-| database\_subnet\_group | List of subnet groups |
-| database\_subnets | List of public subnets |
-| private\_subnets | List of private subnets |
-| public\_subnets | List of public subnets |
-| vpc\_cidr\_block | The CIDR block of the VPC |
-| vpc\_id | The ID of the created VPC |
-
+| <a name="output_azs"></a> [azs](#output\_azs) | Availability zones for the VPC |
+| <a name="output_database_subnet_group"></a> [database\_subnet\_group](#output\_database\_subnet\_group) | List of subnet groups |
+| <a name="output_database_subnets"></a> [database\_subnets](#output\_database\_subnets) | List of public subnets |
+| <a name="output_private_subnets"></a> [private\_subnets](#output\_private\_subnets) | List of private subnets |
+| <a name="output_public_subnets"></a> [public\_subnets](#output\_public\_subnets) | List of public subnets |
+| <a name="output_vpc_cidr_block"></a> [vpc\_cidr\_block](#output\_vpc\_cidr\_block) | The CIDR block of the VPC |
+| <a name="output_vpc_id"></a> [vpc\_id](#output\_vpc\_id) | The ID of the created VPC |
 <!-- END OF PRE-COMMIT-TERRAFORM DOCS HOOK -->

modules/vpc/main.tf

@@ -3,12 +3,12 @@ module "vpc" {
   version = "2.70.0"
 
   name = "${var.project}-${var.environment}-vpc"
-  cidr = "10.10.0.0/16"
+  cidr = var.cidr
 
   azs              = ["${var.region}a", "${var.region}b"] # Most regions have 3+ azs
-  private_subnets  = ["10.10.32.0/19", "10.10.64.0/19"]
-  public_subnets   = ["10.10.1.0/24", "10.10.2.0/24"]
-  database_subnets = ["10.10.10.0/24", "10.10.11.0/24"]
+  private_subnets  = [cidrsubnet(var.cidr, 3, 1), cidrsubnet(var.cidr, 3, 2)]
+  public_subnets   = [cidrsubnet(var.cidr, 8, 1), cidrsubnet(var.cidr, 8, 2)]
+  database_subnets = [cidrsubnet(var.cidr, 8, 10), cidrsubnet(var.cidr, 8, 11)]
 
   # Allow kubernetes ALB ingress controller to auto-detect
   private_subnet_tags = {

modules/vpc/variables.tf

@@ -30,3 +30,9 @@ variable "nat_instance_types" {
   default     = ["t3.nano", "t3a.nano"]
 }
 
+
+variable "cidr" {
+  description = "The CIDR for the VPC, must be a /16 at least"
+  type        = string
+  default     = "10.10.0.0/16"
+}