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terraform-aws-subnets

Terraform module for multi-AZ subnets provisioning.

The module creates private and public subnets in the provided Availability Zones.

The public subnets are routed to the Internet Gateway specified by var.igw_id.

nat_gateway_enabled flag controls the creation of NAT Gateways in the public subnets.

The private subnets are routed to the NAT Gateways provided in the var.az_ngw_ids map.

Screenshots

terraform-aws-subnets Example of terraform apply outputs

Usage

module "vpc" {
  source     = "git::https://github.com/ceibo-it/terraform-aws-vpc.git?ref=0.0.1"
  namespace  = var.namespace
  stage      = var.stage
  name       = var.name
  cidr_block = var.cidr_block
}

module "public_subnets" {
  source              = "git::https://github.com/ceibo-it/terraform-aws-subnets.git?ref=0.0.1"
  namespace           = var.namespace
  stage               = var.stage
  name                = var.name
  availability_zones  = ["us-east-2a", "us-east-2b", "us-east-2c"]
  vpc_id              = module.vpc.vpc_id
  cidr_blocks          = ["10.0.0.0/24", "10.0.1.0/24", "10.0.2.0/24"]
  type                = "public"
  igw_id              = module.vpc.igw_id
  nat_gateway_enabled = "true"
}

module "private_subnets" {
  source             = "git::https://github.com/ceibo-it/terraform-aws-subnets.git?ref=0.0.1"
  namespace          = var.namespace
  stage              = var.stage
  name               = var.name
  availability_zones = ["us-east-2a", "us-east-2b", "us-east-2c"]
  vpc_id             = module.vpc.vpc_id
  cidr_blocks         = ["10.0.10.0/24", "10.0.11.0/24", "10.0.12.0/24"]
  type               = "private"

  az_ngw_ids = module.public_subnets.az_ngw_ids
}

Examples

Given the following configuration

module "vpc" {
  source     = "git::https://github.com/ceibo-it/terraform-aws-vpc.git?ref=0.0.1"
  namespace  = var.namespace
  name       = "vpc"
  stage      = var.stage
  cidr_block = var.cidr_block
}

module "public_subnets" {
  source              = "git::https://github.com/ceibo-it/terraform-aws-multi-az-subnets.git?ref=0.0.1"
  namespace           = var.namespace
  stage               = var.stage
  name                = var.name
  availability_zones  = ["us-east-2a", "us-east-2b", "us-east-2c"]
  vpc_id              = module.vpc.vpc_id
  cidr_blocks          = ["10.0.0.0/24", "10.0.1.0/24", "10.0.2.0/24"]
  type                = "public"
  igw_id              = module.vpc.igw_id
  nat_gateway_enabled = "true"
}

module "private_subnets" {
  source              = "git::https://github.com/ceibo-it/terraform-aws-multi-az-subnets.git?ref=0.0.1"
  namespace           = var.namespace
  stage               = var.stage
  name                = var.name
  availability_zones  = ["us-east-2a", "us-east-2b", "us-east-2c"]
  vpc_id              = module.vpc.vpc_id
  cidr_blocks          = ["10.0.10.0/24", "10.0.11.0/24", "10.0.12.0/24"]
  type                = "private"
  az_ngw_ids          = module.public_subnets.az_ngw_ids
}

output "private_az_subnet_ids" {
  value = module.private_subnets.az_subnet_ids
}

output "public_az_subnet_ids" {
  value = module.public_subnets.az_subnet_ids
}

the output Maps of AZ names to subnet IDs look like these

public_az_subnet_ids = {
  us-east-2a = subnet-ea58d78e
  us-east-2b = subnet-556ee131
  us-east-2c = subnet-6f54db0b
}
private_az_subnet_ids = {
  us-east-2a = subnet-376de253
  us-east-2b = subnet-9e53dcfa
  us-east-2c = subnet-a86fe0cc
}

and the created subnet IDs could be found by the AZ names using map["key"] or lookup(map, key, [default]),

for example:

public_az_subnet_ids["us-east-2a"]

lookup(private_az_subnet_ids, "us-east-2b")

Inputs

Name Description Type Default Required
attributes Additional attributes (e.g. policy or role) list(string) <list> no
availability_zones List of Availability Zones (e.g. ['us-east-1a', 'us-east-1b', 'us-east-1c']) list(string) - yes
az_ngw_ids Only for private subnets. Map of AZ names to NAT Gateway IDs that are used as default routes when creating private subnets map(string) <map> no
cidr_blocks List of CIDR blocks corresponding with each Availability Zone (e.g. ['10.0.0.0/24', '10.0.1.0/24', '10.0.2.0/24']) string - yes
delimiter Delimiter to be used between namespace, stage, name and attributes string - no
enabled Set to false to prevent the module from creating any resources string true no
igw_id Internet Gateway ID that is used as a default route when creating public subnets (e.g. igw-9c26a123) string `` no
max_subnets Maximum number of subnets that can be created. The variable is used for CIDR blocks calculation string 6 no
name Application or solution name string - yes
namespace Namespace (e.g. cp or cloudposse) string - yes
nat_gateway_enabled Flag to enable/disable NAT Gateways creation in public subnets string true no
private_network_acl_egress Egress network ACL rules list(map(string)) <list> no
private_network_acl_id Network ACL ID that is added to the private subnets. If empty, a new ACL will be created string `` no
private_network_acl_ingress Egress network ACL rules list(map(string)) <list> no
public_network_acl_egress Egress network ACL rules list(map(string)) <list> no
public_network_acl_id Network ACL ID that is added to the public subnets. If empty, a new ACL will be created string `` no
public_network_acl_ingress Egress network ACL rules list(map(string)) <list> no
stage Stage (e.g. prod, dev, staging) string - yes
tags Additional tags (e.g. map(BusinessUnit,XYZ) map(string) <map> no
type Type of subnets to create (private or public) string private no
vpc_id VPC ID string - yes

Outputs

Name Description
az_ngw_ids Map of AZ names to NAT Gateway IDs (only for public subnets)
az_route_table_ids Map of AZ names to Route Table IDs
az_subnet_arns Map of AZ names to subnet ARNs
az_subnet_ids Map of AZ names to subnet IDs

Copyright

Copyright © 2020 Ceibo

License

License

See LICENSE for full details.

Licensed to the Apache Software Foundation (ASF) under one
or more contributor license agreements.  See the NOTICE file
distributed with this work for additional information
regarding copyright ownership.  The ASF licenses this file
to you under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance
with the License.  You may obtain a copy of the License at

  https://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing,
software distributed under the License is distributed on an
"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
KIND, either express or implied.  See the License for the
specific language governing permissions and limitations
under the License.

Trademarks

All other trademarks referenced herein are the property of their respective owners.

NOTICE

terraform-aws-subnets Copyright 2020 Ceibo

This product includes software developed by Cloud Posse, LLC (c) (https://cloudposse.com/) Licensed under Apache License, Version 2.0 Copyright © 2017-2019 Cloud Posse, LLC