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.
This project is part of our comprehensive "SweetOps" approach towards DevOps.
It's 100% Open Source and licensed under the APACHE2.
Example of
terraform apply
outputs
module "vpc" {
source = "git::https://github.com/cloudposse/terraform-aws-vpc.git?ref=master"
namespace = "${var.namespace}"
name = "vpc"
stage = "${var.stage}"
cidr_block = "${var.cidr_block}"
}
locals {
public_cidr_block = "${cidrsubnet(module.vpc.vpc_cidr_block, 1, 0)}"
private_cidr_block = "${cidrsubnet(module.vpc.vpc_cidr_block, 1, 1)}"
}
module "public_subnets" {
source = "git::https://github.com/cloudposse/terraform-aws-multi-az-subnets.git?ref=master"
namespace = "${var.namespace}"
stage = "${var.stage}"
name = "${var.name}"
availability_zones = ["us-east-1a", "us-east-1b", "us-east-1c"]
vpc_id = "${module.vpc.vpc_id}"
cidr_block = "${local.public_cidr_block}"
type = "public"
igw_id = "${module.vpc.igw_id}"
nat_gateway_enabled = "true"
}
module "private_subnets" {
source = "git::https://github.com/cloudposse/terraform-aws-multi-az-subnets.git?ref=master"
namespace = "${var.namespace}"
stage = "${var.stage}"
name = "${var.name}"
availability_zones = ["us-east-1a", "us-east-1b", "us-east-1c"]
vpc_id = "${module.vpc.vpc_id}"
cidr_block = "${local.private_cidr_block}"
type = "private"
# Map of AZ names to NAT Gateway IDs that was created in "public_subnets" module
az_ngw_ids = "${module.public_subnets.az_ngw_ids}"
# Need to explicitly provide the count since Terraform currently can't use dynamic count on computed resources from different modules
# https://github.com/hashicorp/terraform/issues/10857
# https://github.com/hashicorp/terraform/issues/12125
# https://github.com/hashicorp/terraform/issues/4149
az_ngw_count = 3
}
Given the following configuration
module "vpc" {
source = "git::https://github.com/cloudposse/terraform-aws-vpc.git?ref=master"
namespace = "${var.namespace}"
name = "vpc"
stage = "${var.stage}"
cidr_block = "${var.cidr_block}"
}
locals {
public_cidr_block = "${cidrsubnet(module.vpc.vpc_cidr_block, 1, 0)}"
private_cidr_block = "${cidrsubnet(module.vpc.vpc_cidr_block, 1, 1)}"
}
module "public_subnets" {
source = "git::https://github.com/cloudposse/terraform-aws-multi-az-subnets.git?ref=master"
namespace = "${var.namespace}"
stage = "${var.stage}"
name = "${var.name}"
availability_zones = ["us-east-1a", "us-east-1b", "us-east-1c"]
vpc_id = "${module.vpc.vpc_id}"
cidr_block = "${local.public_cidr_block}"
type = "public"
igw_id = "${module.vpc.igw_id}"
nat_gateway_enabled = "true"
}
module "private_subnets" {
source = "git::https://github.com/cloudposse/terraform-aws-multi-az-subnets.git?ref=master"
namespace = "${var.namespace}"
stage = "${var.stage}"
name = "${var.name}"
availability_zones = ["us-east-1a", "us-east-1b", "us-east-1c"]
vpc_id = "${module.vpc.vpc_id}"
cidr_block = "${local.private_cidr_block}"
type = "private"
az_ngw_ids = "${module.public_subnets.az_ngw_ids}"
az_ngw_count = 3
}
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-1a = subnet-ea58d78e
us-east-1b = subnet-556ee131
us-east-1c = subnet-6f54db0b
}
private_az_subnet_ids = {
us-east-1a = subnet-376de253
us-east-1b = subnet-9e53dcfa
us-east-1c = 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-1a"]
lookup(private_az_subnet_ids, "us-east-1b")
Available targets:
help This help screen
help/all Display help for all targets
lint Lint terraform code
Name | Description | Type | Default | Required |
---|---|---|---|---|
attributes | Additional attributes (e.g. policy or role ) |
list | <list> |
no |
availability_zones | List of Availability Zones (e.g. ['us-east-1a', 'us-east-1b', 'us-east-1c'] ) |
list | <list> |
no |
az_ngw_count | Count of items in the az_ngw_ids map. Needs to be explicitly provided since Terraform currently can't use dynamic count on computed resources from different modules. hashicorp/terraform#10857 |
string | 0 |
no |
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 | <map> |
no |
cidr_block | Base CIDR block which is divided into subnet CIDR blocks (e.g. 10.0.0.0/16 ) |
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 | <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 | <list> |
no |
public_network_acl_egress | Egress network ACL rules | list | <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 | <list> |
no |
stage | Stage (e.g. prod , dev , staging ) |
string | - | yes |
tags | Additional tags (e.g. map(BusinessUnit ,XYZ ) |
map | <map> |
no |
type | Type of subnets to create (private or public ) |
string | private |
no |
vpc_id | VPC ID | string | - | yes |
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_ids | Map of AZ names to subnet IDs |
Check out these related projects.
- terraform-aws-named-subnets - Terraform module for named subnets provisioning.
- terraform-aws-dynamic-subnets - Terraform module for public and private subnets provisioning in existing VPC
- terraform-aws-vpc - Terraform Module that defines a VPC with public/private subnets across multiple AZs with Internet Gateways
- terraform-aws-cloudwatch-flow-logs - Terraform module for enabling flow logs for vpc and subnets.
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Copyright © 2017-2018 Cloud Posse, LLC
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
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