Module: multi-az-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.
If you are creating subnets inside a VPC, consider using cloudposse/terraform-aws-dynamic-subnets instead.
Screenshots
Example of terraform apply
outputs
Usage
locals {
public_cidr_block = cidrsubnet(var.cidr_block, 1, 0)
private_cidr_block = cidrsubnet(var.cidr_block, 1, 1)
}
module "vpc" {
source = "cloudposse/vpc/aws"
# Cloud Posse recommends pinning every module to a specific version
# version = "x.x.x"
namespace = var.namespace
stage = var.stage
name = var.name
cidr_block = var.cidr_block
}
module "public_subnets" {
source = "cloudposse/multi-az-subnets/aws"
# Cloud Posse recommends pinning every module to a specific version
# version = "x.x.x"
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_block = local.public_cidr_block
type = "public"
igw_id = module.vpc.igw_id
nat_gateway_enabled = "true"
}
module "private_subnets" {
source = "cloudposse/multi-az-subnets/aws"
# Cloud Posse recommends pinning every module to a specific version
# version = "x.x.x"
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_block = local.private_cidr_block
type = "private"
az_ngw_ids = module.public_subnets.az_ngw_ids
}
Examples
Given the following configuration
module "vpc" {
source = "cloudposse/vpc/aws"
# Cloud Posse recommends pinning every module to a specific version
# version = "x.x.x"
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 = "cloudposse/multi-az-subnets/aws"
# Cloud Posse recommends pinning every module to a specific version
# version = "x.x.x"
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_block = local.public_cidr_block
type = "public"
igw_id = module.vpc.igw_id
nat_gateway_enabled = "true"
}
module "private_subnets" {
source = "cloudposse/multi-az-subnets/aws"
# Cloud Posse recommends pinning every module to a specific version
# version = "x.x.x"
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_block = local.private_cidr_block
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")
Requirements
Name | Version |
---|---|
terraform | >= 0.13.0 |
aws | >= 3.0 |
local | >= 1.2 |
null | >= 2.0 |
Providers
Name | Version |
---|---|
aws | >= 3.0 |
Modules
Name | Source | Version |
---|---|---|
private_label | cloudposse/label/null | 0.24.1 |
public_label | cloudposse/label/null | 0.24.1 |
this | cloudposse/label/null | 0.25.0 |
Resources
Name | Type |
---|---|
aws_eip.public | resource |
aws_nat_gateway.public | resource |
aws_network_acl.private | resource |
aws_network_acl.public | resource |
aws_route.default | resource |
aws_route.public | resource |
aws_route.public_ipv6 | resource |
aws_route_table.private | resource |
aws_route_table.public | resource |
aws_route_table_association.private | resource |
aws_route_table_association.public | resource |
aws_subnet.private | resource |
aws_subnet.public | resource |
Inputs
Name | Description | Type | Default | Required |
---|---|---|---|---|
additional_tag_map | Additional key-value pairs to add to each map in tags_as_list_of_maps . Not added to tags or id .This is for some rare cases where resources want additional configuration of tags and therefore take a list of maps with tag key, value, and additional configuration. | map(string) | {} | no |
attributes | ID element. Additional attributes (e.g. workers or cluster ) to add to id ,in the order they appear in the list. New attributes are appended to the end of the list. The elements of the list are joined by the delimiter and treated as a single ID element. | list(string) | [] | no |
availability_zones | List of Availability Zones (e.g. ['us-east-1a', 'us-east-1b', 'us-east-1c'] ) | list(string) | n/a | 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. You should either supply one NAT Gateway ID for each AZ in var.availability_zones or leave the map empty.If empty, no default egress route will be created and you will have to create your own using aws_route . | map(string) | {} | no |
cidr_block | Base CIDR block which is divided into subnet CIDR blocks (e.g. 10.0.0.0/16 ) | string | n/a | yes |
context | Single object for setting entire context at once. See description of individual variables for details. Leave string and numeric variables as null to use default value.Individual variable settings (non-null) override settings in context object, except for attributes, tags, and additional_tag_map, which are merged. | any |
| no |
delimiter | Delimiter to be used between ID elements. Defaults to - (hyphen). Set to "" to use no delimiter at all. | string | null | no |
descriptor_formats | Describe additional descriptors to be output in the descriptors output map.Map of maps. Keys are names of descriptors. Values are maps of the form {<br/> format = string<br/> labels = list(string)<br/>} (Type is any so the map values can later be enhanced to provide additional options.)format is a Terraform format string to be passed to the format() function.labels is a list of labels, in order, to pass to format() function.Label values will be normalized before being passed to format() so they will beidentical to how they appear in id .Default is {} (descriptors output will be empty). | any | {} | no |
enabled | Set to false to prevent the module from creating any resources | bool | null | no |
environment | ID element. Usually used for region e.g. 'uw2', 'us-west-2', OR role 'prod', 'staging', 'dev', 'UAT' | string | null | no |
id_length_limit | Limit id to this many characters (minimum 6).Set to 0 for unlimited length.Set to null for keep the existing setting, which defaults to 0 .Does not affect id_full . | number | null | no |
igw_id | Internet Gateway ID that is used as a default route when creating public subnets (e.g. igw-9c26a123 ) | string | "" | no |
ipv6_cidr_block | Base IPv6 CIDR block which is divided into /64 subnet CIDR blocks | string | null | no |
ipv6_enabled | Flag to enable/disable IPv6 creation in public subnets | bool | false | no |
label_key_case | Controls the letter case of the tags keys (label names) for tags generated by this module.Does not affect keys of tags passed in via the tags input.Possible values: lower , title , upper .Default value: title . | string | null | no |
label_order | The order in which the labels (ID elements) appear in the id .Defaults to ["namespace", "environment", "stage", "name", "attributes"]. You can omit any of the 6 labels ("tenant" is the 6th), but at least one must be present. | list(string) | null | no |
label_value_case | Controls the letter case of ID elements (labels) as included in id ,set as tag values, and output by this module individually. Does not affect values of tags passed in via the tags input.Possible values: lower , title , upper and none (no transformation).Set this to title and set delimiter to "" to yield Pascal Case IDs.Default value: lower . | string | null | no |
labels_as_tags | Set of labels (ID elements) to include as tags in the tags output.Default is to include all labels. Tags with empty values will not be included in the tags output.Set to [] to suppress all generated tags.Notes: The value of the name tag, if included, will be the id , not the name .Unlike other null-label inputs, the initial setting of labels_as_tags cannot bechanged in later chained modules. Attempts to change it will be silently ignored. | set(string) |
| no |
max_subnets | Maximum number of subnets that can be created. The variable is used for CIDR blocks calculation | string | "6" | no |
name | ID element. Usually the component or solution name, e.g. 'app' or 'jenkins'. This is the only ID element not also included as a tag .The "name" tag is set to the full id string. There is no tag with the value of the name input. | string | null | no |
namespace | ID element. Usually an abbreviation of your organization name, e.g. 'eg' or 'cp', to help ensure generated IDs are globally unique | string | null | no |
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)) |
| 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)) |
| no |
public_network_acl_egress | Egress network ACL rules | list(map(string)) |
| 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)) |
| no |
regex_replace_chars | Terraform regular expression (regex) string. Characters matching the regex will be removed from the ID elements. If not set, "/[^a-zA-Z0-9-]/" is used to remove all characters other than hyphens, letters and digits. | string | null | no |
stage | ID element. Usually used to indicate role, e.g. 'prod', 'staging', 'source', 'build', 'test', 'deploy', 'release' | string | null | no |
tags | Additional tags (e.g. {'BusinessUnit': 'XYZ'} ).Neither the tag keys nor the tag values will be modified by this module. | map(string) | {} | no |
tenant | ID element _(Rarely used, not included by default)_. A customer identifier, indicating who this instance of a resource is for | string | null | no |
type | Type of subnets to create (private or public ) | string | "private" | no |
vpc_id | VPC ID | string | n/a | 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_cidr_blocks | Map of AZ names to subnet CIDR blocks |
az_subnet_ids | Map of AZ names to subnet IDs |
az_subnet_ipv6_cidr_blocks | Map of AZ names to subnet IPv6 CIDR blocks |
az_subnet_map | Map of AZ names to map of information about subnets |