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Add single NAT Gateway flag. (#3)
* add single nat option * remove aws profile * add pre-commit * update README.md * dummy update * update README.md
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‎.pre-commit-config.yaml‎

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repos:
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- repo: git://github.com/antonbabenko/pre-commit-terraform
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rev: v1.27.0
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hooks:
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- id: terraform_fmt
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- id: terraform_docs

‎README.md‎

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Check valid versions on:
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* Github Releases: <https://github.com/cn-terraform/terraform-aws-networking/releases>
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* Terraform Module Registry: <https://registry.terraform.io/modules/cn-terraform/networking/aws>
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<!-- BEGINNING OF PRE-COMMIT-TERRAFORM DOCS HOOK -->
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## Requirements
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| Name | Version |
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| --------- | ------- |
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| terraform | >= 0.13 |
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## Providers
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| Name | Version |
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| ---- | ------- |
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| aws | n/a |
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## Inputs
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| Name | Description | Type | Default | Required |
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| ------------------------------------------------ | ------------------------------------------------------------------ | ------ | ------- | :------: |
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| availability\_zones | List of availability zones to be used by subnets | `list` | n/a | yes |
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| name\_prefix | Name prefix for resources on AWS | `any` | n/a | yes |
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| private\_subnets\_cidrs\_per\_availability\_zone | List of CIDRs to use on each availability zone for private subnets | `list` | n/a | yes |
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| public\_subnets\_cidrs\_per\_availability\_zone | List of CIDRs to use on each availability zone for public subnets | `list` | n/a | yes |
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| single\_nat | enable single NAT Gateway | `bool` | `false` | no |
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| vpc\_cidr\_block | AWS VPC CIDR Block | `any` | n/a | yes |
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## Outputs
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| Name | Description |
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| ---------------------------------- | ------------------------------------------------------------------------------------------------------ |
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| availability\_zones | List of availability zones used by subnets |
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| internet\_gateway\_id | ID of the generated Internet Gateway |
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| nat\_gw\_ids | List with the IDs of the NAT Gateways created on public subnets to provide internet to private subnets |
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| private\_subnets\_ids | List with the Private Subnets IDs |
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| private\_subnets\_route\_table\_id | ID of the Route Table used on Private networks |
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| public\_subnets\_ids | List with the Public Subnets IDs |
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| public\_subnets\_route\_table\_id | ID of the Route Tables used on Public networks |
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| vpc\_cidr\_block | The CIDR block of the VPC |
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| vpc\_id | The ID of the VPC |
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<!-- END OF PRE-COMMIT-TERRAFORM DOCS HOOK -->

‎examples/test/main.tf‎

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}
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module "base-network" {
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source = "../../"
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name_prefix = "base"
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vpc_cidr_block = "192.168.0.0/16"
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availability_zones = ["us-east-1a", "us-east-1b", "us-east-1c", "us-east-1d"]
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public_subnets_cidrs_per_availability_zone = ["192.168.0.0/19", "192.168.32.0/19", "192.168.64.0/19", "192.168.96.0/19"]
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private_subnets_cidrs_per_availability_zone = ["192.168.128.0/19", "192.168.160.0/19", "192.168.192.0/19", "192.168.224.0/19"]
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source = "../../"
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name_prefix = "test"
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single_nat = true
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vpc_cidr_block = "192.168.0.0/16"
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availability_zones = [
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"us-east-1a",
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"us-east-1b"
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]
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public_subnets_cidrs_per_availability_zone = [
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"192.168.0.0/19",
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"192.168.32.0/19"
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]
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private_subnets_cidrs_per_availability_zone = [
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"192.168.128.0/19",
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"192.168.160.0/19"
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]
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}

‎main.tf‎

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# AWS Virtual Private Network
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#------------------------------------------------------------------------------
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resource "aws_vpc" "vpc" {
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cidr_block = var.vpc_cidr_block # The CIDR block for the VPC.
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enable_dns_support = true # A boolean flag to enable/disable DNS support in the VPC.
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enable_dns_hostnames = true # A boolean flag to enable/disable DNS hostnames in the VPC.
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cidr_block = var.vpc_cidr_block
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# The CIDR block for the VPC.
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enable_dns_support = true
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# A boolean flag to enable/disable DNS support in the VPC.
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enable_dns_hostnames = true
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# A boolean flag to enable/disable DNS hostnames in the VPC.
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tags = {
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Name = "${var.name_prefix}-vpc"
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}
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# Elastic IPs for NAT
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resource "aws_eip" "nat_eip" {
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count = length(var.availability_zones)
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count = var.single_nat ? 1 : length(var.availability_zones)
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vpc = true
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tags = {
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Name = "${var.name_prefix}-nat-eip-${element(var.availability_zones, count.index)}"
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# NAT Gateways
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resource "aws_nat_gateway" "nat_gw" {
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count = length(var.availability_zones)
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depends_on = [aws_internet_gateway.internet_gw]
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allocation_id = element(aws_eip.nat_eip.*.id, count.index)
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subnet_id = element(aws_subnet.public_subnets.*.id, count.index)
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count = var.single_nat ? 1 : length(var.availability_zones)
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allocation_id = var.single_nat ? aws_eip.nat_eip.0.id : element(aws_eip.nat_eip.*.id, count.index)
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subnet_id = var.single_nat ? aws_subnet.public_subnets.0.id : element(aws_subnet.public_subnets.*.id, count.index)
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tags = {
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Name = "${var.name_prefix}-nat-gw-${element(var.availability_zones, count.index)}"
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}
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depends_on = [
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aws_internet_gateway.internet_gw
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]
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}
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# Public route table
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]
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route_table_id = element(aws_route_table.private_subnets_route_table.*.id, count.index)
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destination_cidr_block = "0.0.0.0/0"
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nat_gateway_id = element(aws_nat_gateway.nat_gw.*.id, count.index)
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nat_gateway_id = var.single_nat ? aws_nat_gateway.nat_gw.0.id : element(aws_nat_gateway.nat_gw.*.id, count.index)
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}
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# Association of Route Table to Subnets

‎variables.tf‎

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type = list
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description = "List of CIDRs to use on each availability zone for private subnets"
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}
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variable "single_nat" {
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type = bool
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default = false
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description = "enable single NAT Gateway"
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}

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