Allow nullification of customer_gateway_ip_address (#39)

* feat(tf): Make more variables optional

* feat(tf): Base creation of resources on existing variables

* fix(typo)

* fix(tf): Set variable to null by default

* fix(docs): Regenerate documentation

---------

Co-authored-by: Andriy Knysh <[email protected]>

README.md

@@ -142,7 +142,7 @@ Available targets:
 | <a name="input_attributes"></a> [attributes](#input\_attributes) | ID element. Additional attributes (e.g. `workers` or `cluster`) to add to `id`,<br>in the order they appear in the list. New attributes are appended to the<br>end of the list. The elements of the list are joined by the `delimiter`<br>and treated as a single ID element. | `list(string)` | `[]` | no |
 | <a name="input_context"></a> [context](#input\_context) | Single object for setting entire context at once.<br>See description of individual variables for details.<br>Leave string and numeric variables as `null` to use default value.<br>Individual variable settings (non-null) override settings in context object,<br>except for attributes, tags, and additional\_tag\_map, which are merged. | `any` | <pre>{<br>  "additional_tag_map": {},<br>  "attributes": [],<br>  "delimiter": null,<br>  "descriptor_formats": {},<br>  "enabled": true,<br>  "environment": null,<br>  "id_length_limit": null,<br>  "label_key_case": null,<br>  "label_order": [],<br>  "label_value_case": null,<br>  "labels_as_tags": [<br>    "unset"<br>  ],<br>  "name": null,<br>  "namespace": null,<br>  "regex_replace_chars": null,<br>  "stage": null,<br>  "tags": {},<br>  "tenant": null<br>}</pre> | no |
 | <a name="input_customer_gateway_bgp_asn"></a> [customer\_gateway\_bgp\_asn](#input\_customer\_gateway\_bgp\_asn) | The gateway's Border Gateway Protocol (BGP) Autonomous System Number (ASN) | `number` | `65000` | no |
-| <a name="input_customer_gateway_ip_address"></a> [customer\_gateway\_ip\_address](#input\_customer\_gateway\_ip\_address) | The IP address of the gateway's Internet-routable external interface | `string` | n/a | yes |
+| <a name="input_customer_gateway_ip_address"></a> [customer\_gateway\_ip\_address](#input\_customer\_gateway\_ip\_address) | The IP address of the gateway's Internet-routable external interface. Set to null to not create the customer gateway. | `string` | `null` | no |
 | <a name="input_delimiter"></a> [delimiter](#input\_delimiter) | Delimiter to be used between ID elements.<br>Defaults to `-` (hyphen). Set to `""` to use no delimiter at all. | `string` | `null` | no |
 | <a name="input_descriptor_formats"></a> [descriptor\_formats](#input\_descriptor\_formats) | Describe additional descriptors to be output in the `descriptors` output map.<br>Map of maps. Keys are names of descriptors. Values are maps of the form<br>`{<br>   format = string<br>   labels = list(string)<br>}`<br>(Type is `any` so the map values can later be enhanced to provide additional options.)<br>`format` is a Terraform format string to be passed to the `format()` function.<br>`labels` is a list of labels, in order, to pass to `format()` function.<br>Label values will be normalized before being passed to `format()` so they will be<br>identical to how they appear in `id`.<br>Default is `{}` (`descriptors` output will be empty). | `any` | `{}` | no |
 | <a name="input_enabled"></a> [enabled](#input\_enabled) | Set to false to prevent the module from creating any resources | `bool` | `null` | no |

docs/terraform.md

@@ -41,7 +41,7 @@
 | <a name="input_attributes"></a> [attributes](#input\_attributes) | ID element. Additional attributes (e.g. `workers` or `cluster`) to add to `id`,<br>in the order they appear in the list. New attributes are appended to the<br>end of the list. The elements of the list are joined by the `delimiter`<br>and treated as a single ID element. | `list(string)` | `[]` | no |
 | <a name="input_context"></a> [context](#input\_context) | Single object for setting entire context at once.<br>See description of individual variables for details.<br>Leave string and numeric variables as `null` to use default value.<br>Individual variable settings (non-null) override settings in context object,<br>except for attributes, tags, and additional\_tag\_map, which are merged. | `any` | <pre>{<br>  "additional_tag_map": {},<br>  "attributes": [],<br>  "delimiter": null,<br>  "descriptor_formats": {},<br>  "enabled": true,<br>  "environment": null,<br>  "id_length_limit": null,<br>  "label_key_case": null,<br>  "label_order": [],<br>  "label_value_case": null,<br>  "labels_as_tags": [<br>    "unset"<br>  ],<br>  "name": null,<br>  "namespace": null,<br>  "regex_replace_chars": null,<br>  "stage": null,<br>  "tags": {},<br>  "tenant": null<br>}</pre> | no |
 | <a name="input_customer_gateway_bgp_asn"></a> [customer\_gateway\_bgp\_asn](#input\_customer\_gateway\_bgp\_asn) | The gateway's Border Gateway Protocol (BGP) Autonomous System Number (ASN) | `number` | `65000` | no |
-| <a name="input_customer_gateway_ip_address"></a> [customer\_gateway\_ip\_address](#input\_customer\_gateway\_ip\_address) | The IP address of the gateway's Internet-routable external interface | `string` | n/a | yes |
+| <a name="input_customer_gateway_ip_address"></a> [customer\_gateway\_ip\_address](#input\_customer\_gateway\_ip\_address) | The IP address of the gateway's Internet-routable external interface. Set to null to not create the customer gateway. | `string` | `null` | no |
 | <a name="input_delimiter"></a> [delimiter](#input\_delimiter) | Delimiter to be used between ID elements.<br>Defaults to `-` (hyphen). Set to `""` to use no delimiter at all. | `string` | `null` | no |
 | <a name="input_descriptor_formats"></a> [descriptor\_formats](#input\_descriptor\_formats) | Describe additional descriptors to be output in the `descriptors` output map.<br>Map of maps. Keys are names of descriptors. Values are maps of the form<br>`{<br>   format = string<br>   labels = list(string)<br>}`<br>(Type is `any` so the map values can later be enhanced to provide additional options.)<br>`format` is a Terraform format string to be passed to the `format()` function.<br>`labels` is a list of labels, in order, to pass to `format()` function.<br>Label values will be normalized before being passed to `format()` so they will be<br>identical to how they appear in `id`.<br>Default is `{}` (`descriptors` output will be empty). | `any` | `{}` | no |
 | <a name="input_enabled"></a> [enabled](#input\_enabled) | Set to false to prevent the module from creating any resources | `bool` | `null` | no |

main.tf

@@ -12,15 +12,15 @@ locals {
 
 # https://www.terraform.io/docs/providers/aws/r/vpn_gateway.html
 resource "aws_vpn_gateway" "default" {
-  count           = local.enabled && var.transit_gateway_enabled == false ? 1 : 0
+  count           = local.enabled && !var.transit_gateway_enabled ? 1 : 0
   vpc_id          = var.vpc_id
   amazon_side_asn = var.vpn_gateway_amazon_side_asn
   tags            = module.this.tags
 }
 
 # https://www.terraform.io/docs/providers/aws/r/customer_gateway.html
 resource "aws_customer_gateway" "default" {
-  count      = local.enabled ? 1 : 0
+  count      = local.enabled && var.customer_gateway_ip_address != null ? 1 : 0
   bgp_asn    = var.customer_gateway_bgp_asn
   ip_address = var.customer_gateway_ip_address
   type       = "ipsec.1"
@@ -40,7 +40,7 @@ module "logs" {
 
 # https://www.terraform.io/docs/providers/aws/r/vpn_connection.html
 resource "aws_vpn_connection" "default" {
-  count                    = local.enabled ? 1 : 0
+  count                    = local.enabled && var.customer_gateway_ip_address != null ? 1 : 0
   vpn_gateway_id           = local.transit_gateway_enabled == false ? local.vpn_gateway_id : null
   customer_gateway_id      = local.customer_gateway_id
   transit_gateway_id       = local.transit_gateway_enabled ? var.existing_transit_gateway_id : null

variables.tf

@@ -17,7 +17,8 @@ variable "customer_gateway_bgp_asn" {
 
 variable "customer_gateway_ip_address" {
   type        = string
-  description = "The IP address of the gateway's Internet-routable external interface"
+  description = "The IP address of the gateway's Internet-routable external interface. Set to null to not create the customer gateway."
+  default     = null
 }
 
 variable "route_table_ids" {