# Terraform Module for Amazon VPC IP Address Manager on AWS
Note: For information regarding the 2.0 upgrade see our [upgrade guide](https://github.com/aws-ia/terraform-aws-ipam/blob/main/docs/UPGRADE-GUIDE-2.0.md).
This module helps deploy AWS IPAM including IPAM Pools, Provisioned CIDRs, and can help with sharing those pools via AWS RAM.
Built to accommodate a wide range of use cases, this Terraform module can deploy both simple and complex Amazon Virtual Private Cloud (Amazon VPC) IP Address Manager (IPAM) configurations. It supports both symmetrically nested, multi-Region deployments (most common IPAM designs) as well as [asymmetically nested deployments](https://github.com/aws-ia/terraform-aws-ipam/blob/main/images/asymmetrical_example.png).
Refer to the [examples/](https://github.com/aws-ia/terraform-aws-ipam/blob/main/examples) directory in this GitHub repository for examples.
The embedded example below describes a symmetrically nested pool structure, including its configuration, implementation details, requirements, and more.
## Architecture Example
\_Note: The diagram above is an example of the type of Pool design you can deploy using this module.\_
## Configuration
This module strongly relies on the `var.pool_configuration` variable, which is a multi-level, nested map that describes how to nest your IPAM pools. It can accept most `aws_vpc_ipam_pool` and `aws_vpc_ipam_pool_cidr` attributes (detailed below) as well as RAM share pools (at any level) to valid AWS principals. Nested pools do not inherit attributes from their source pool(s), so all configuration options are available at each level. `locale` is implied in sub pools after declared in a parent.
In this module, pools can be nested up to four levels, including one root pool and up to three nested pools. The root pool defines the `address_family` variable. If you want to deploy an IPv4 and IPv6 pool structure, you must instantiate the module for each type.
The `pool_configurations` variable is the structure of the other three levels. The `sub_pool` submodule has a `var.pool_config` variable that defines the structure that each pool can accept. The variable has the following structure:
```
pool_configurations = {
my_pool_name = {
description = "my pool"
cidr = ["10.0.0.0/16"]
locale = "us-east-1"
sub_pools = {
sandbox = {
cidr = ["10.0.48.0/20"]
ram_share_principals = [local.dev_ou_arn]
# ...any pool_config argument (below)
}
}
}
}
```
The key of a `pool_config` variable is the name of the pool, followed by its attributes `ram_share_principals` and a `sub_pools` map, which is another nested `pool_config` variable.
```terraform
variable "pool_config" {
type = object({
cidr = list(string)
ram_share_principals = optional(list(string))
name = optional(string)
locale = optional(string)
allocation_default_netmask_length = optional(string)
allocation_max_netmask_length = optional(string)
allocation_min_netmask_length = optional(string)
auto_import = optional(string)
aws_service = optional(string)
description = optional(string)
publicly_advertisable = optional(bool)
allocation_resource_tags = optional(map(string))
tags = optional(map(string))
sub_pools = optional(any)
})
}
```
## RAM Sharing
This module allows you to share invidual pools to any valid RAM principal. All levels of `var.pool_configurations` accept an argument `ram_share_principals` which should be a list of valid RAM share principals (org-id, ou-id, or account id).
## Using Outputs
Since resources are dynamically generated based on user configuration, we roll them into grouped outputs. For example, to get attributes off your level 2 pools:
The output `pools_level_2` offers you a map of every pool where the name is the route of the tree keys [example `"corporate-us-west-2/dev"`](https://github.com/aws-ia/terraform-aws-ipam/blob/a7d508cb0be2f68d99952682c2392b6d7d541d96/examples/single_scope_ipv4/main.tf#L28).
To get a specific ID:
```
> module.basic.pools_level_2["corporate-us-west-2/dev"].id
"ipam-pool-0c816929a16f08747"
```
To get all IDs
```terraform
> [ for pool in module.basic.pools_level_2: pool["id"]]
[
"ipam-pool-0c816929a16f08747",
"ipam-pool-0192c70b370384661",
"ipam-pool-037bb0524f8b3278e",
"ipam-pool-09400d26a6d1df4a5",
"ipam-pool-0ee5ebe8f8d2d7187",
]
```
## Implementation
### Implied pool names and descriptions
By default, pool `Name` tags and pool descriptions are implied from the name-hierarchy structure of the pool. For example, a pool with two parents `us-east-1` and `dev` has an implied name and description value of `us-east-1/dev`. You can override either or both name and description at any pool level by specifying a `name` or `description` value.
### Locales
IPAM pools do not inherit attributes from their parent pools. Locales cannot change from parent to child. For that reason, after a pool in the `var.pool_configurations` variable defines a `locale` value, all other child pools have an `implied_locale` value.
### Operating Regions
The IPAM `operating_region` variable must be set for the primary Region in your Terraform provider block and any Regions you want to set a `locale`. For that reason, the value of the `aws_vpc_ipam.operating_regions` variable is constructed by combining the `pool_configurations` and `data.aws_region.current.name` attributes.
## Requirements
| Name | Version |
|------|---------|
| [terraform](#requirement\_terraform) | >= 1.3.0 |
| [aws](#requirement\_aws) | >= 4.53.0 |
## Providers
| Name | Version |
|------|---------|
| [aws](#provider\_aws) | >= 4.53.0 |
## Modules
| Name | Source | Version |
|------|--------|---------|
| [level\_one](#module\_level\_one) | ./modules/sub_pool | n/a |
| [level\_three](#module\_level\_three) | ./modules/sub_pool | n/a |
| [level\_two](#module\_level\_two) | ./modules/sub_pool | n/a |
| [level\_zero](#module\_level\_zero) | ./modules/sub_pool | n/a |
## Resources
| Name | Type |
|------|------|
| [aws_vpc_ipam.main](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/vpc_ipam) | resource |
| [aws_region.current](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/region) | data source |
## Inputs
| Name | Description | Type | Default | Required |
|------|-------------|------|---------|:--------:|
| [top\_cidr](#input\_top\_cidr) | Top-level CIDR blocks. | `list(string)` | n/a | yes |
| [address\_family](#input\_address\_family) | IPv4/6 address family. | `string` | `"ipv4"` | no |
| [create\_ipam](#input\_create\_ipam) | Determines whether to create an IPAM. If `false`, you must also provide a var.ipam\_scope\_id. | `bool` | `true` | no |
| [ipam\_scope\_id](#input\_ipam\_scope\_id) | (Optional) Required if `var.ipam_id` is set. Determines which scope to deploy pools into. | `string` | `null` | no |
| [ipam\_scope\_type](#input\_ipam\_scope\_type) | Which scope type to use. Valid inputs include `public` or `private`. You can alternatively provide your own scope ID. | `string` | `"private"` | no |
| [pool\_configurations](#input\_pool\_configurations) | A multi-level, nested map describing nested IPAM pools. Can nest up to three levels with the top level being outside the `pool_configurations` in vars prefixed `top_`. If arugument descriptions are omitted, you can find them in the [official documentation](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/vpc_ipam_pool#argument-reference).
- `ram_share_principals` = (optional, list(string)) of valid organization principals to create ram shares to.
- `name` = (optional, string) name to give the pool, the key of your map in var.pool\_configurations will be used if omitted.
- `description` = (optional, string) description to give the pool, the key of your map in var.pool\_configurations will be used if omitted.
- `cidr` = (optional, list(string)) list of CIDRs to provision into pool. Conflicts with `netmask_length`.
- `netmask_length` = (optional, number) netmask length to request provisioned into pool. Conflicts with `cidr`.
- `locale` = (optional, string) locale to set for pool.
- `auto_import` = (optional, string)
- `tags` = (optional, map(string))
- `allocation_default_netmask_length` = (optional, string)
- `allocation_max_netmask_length` = (optional, string)
- `allocation_min_netmask_length` = (optional, string)
- `allocation_resource_tags` = (optional, map(string))
The following arguments are available but only relevant for public ips
- `cidr_authorization_context` = (optional, map(string)) Details found in [official documentation](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/vpc_ipam_pool_cidr#cidr_authorization_context).
- `aws_service` = (optional, string)
- `publicly_advertisable` = (optional, bool)
- `sub_pools` = (nested repeats of pool\_configuration object above) | `any` | `{}` | no |
| [tags](#input\_tags) | Tags to add to the aws\_vpc\_ipam resource. | `any` | `{}` | no |
| [top\_auto\_import](#input\_top\_auto\_import) | `auto_import` setting for top-level pool. | `bool` | `null` | no |
| [top\_cidr\_authorization\_contexts](#input\_top\_cidr\_authorization\_contexts) | CIDR must match a CIDR defined in `var.top_cidr`. A list of signed documents that proves that you are authorized to bring the specified IP address range to Amazon using BYOIP. Document is not stored in the state file. For more information, refer to https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/vpc_ipam_pool_cidr#cidr_authorization_context. | list(object({
cidr = string
message = string
signature = string
})) | `[]` | no |
| [top\_description](#input\_top\_description) | Description of top-level pool. | `string` | `""` | no |
| [top\_name](#input\_top\_name) | Name of top-level pool. | `string` | `null` | no |
| [top\_netmask\_length](#input\_top\_netmask\_length) | Top-level netmask length to request. Not possible to use for IPv4. Only possible to use with amazon provided ipv6. | `number` | `null` | no |
| [top\_ram\_share\_principals](#input\_top\_ram\_share\_principals) | Principals to create RAM shares for top-level pool. | `list(string)` | `null` | no |
## Outputs
| Name | Description |
|------|-------------|
| [ipam\_info](#output\_ipam\_info) | If created, ouput the IPAM object information. |
| [operating\_regions](#output\_operating\_regions) | List of all IPAM operating regions. |
| [pool\_level\_0](#output\_pool\_level\_0) | Map of all pools at level 0. |
| [pool\_names](#output\_pool\_names) | List of all pool names. |
| [pools\_level\_1](#output\_pools\_level\_1) | Map of all pools at level 1. |
| [pools\_level\_2](#output\_pools\_level\_2) | Map of all pools at level 2. |
| [pools\_level\_3](#output\_pools\_level\_3) | Map of all pools at level 3. |