feat: Added custom route for NAT gateway (#748)

Author: piersf

README.md

@@ -410,6 +410,7 @@ No modules.
 | <a name="input_map_public_ip_on_launch"></a> [map\_public\_ip\_on\_launch](#input\_map\_public\_ip\_on\_launch) | Should be false if you do not want to auto-assign public IP on launch | `bool` | `true` | no |
 | <a name="input_name"></a> [name](#input\_name) | Name to be used on all the resources as identifier | `string` | `""` | no |
 | <a name="input_nat_eip_tags"></a> [nat\_eip\_tags](#input\_nat\_eip\_tags) | Additional tags for the NAT EIP | `map(string)` | `{}` | no |
+| <a name="input_nat_gateway_destination_cidr_block"></a> [nat\_gateway\_destination\_cidr\_block](#input\_nat\_gateway\_destination\_cidr\_block) | Used to pass a custom destination route for private NAT Gateway. If not specified, the default 0.0.0.0/0 is used as a destination route. | `string` | `"0.0.0.0/0"` | no |
 | <a name="input_nat_gateway_tags"></a> [nat\_gateway\_tags](#input\_nat\_gateway\_tags) | Additional tags for the NAT gateways | `map(string)` | `{}` | no |
 | <a name="input_one_nat_gateway_per_az"></a> [one\_nat\_gateway\_per\_az](#input\_one\_nat\_gateway\_per\_az) | Should be true if you want only one NAT Gateway per availability zone. Requires `var.azs` to be set, and the number of `public_subnets` created to be greater than or equal to the number of availability zones specified in `var.azs`. | `bool` | `false` | no |
 | <a name="input_outpost_acl_tags"></a> [outpost\_acl\_tags](#input\_outpost\_acl\_tags) | Additional tags for the outpost subnets network ACL | `map(string)` | `{}` | no |

main.tf

@@ -1043,7 +1043,7 @@ resource "aws_route" "private_nat_gateway" {
   count = var.create_vpc && var.enable_nat_gateway ? local.nat_gateway_count : 0
 
   route_table_id         = element(aws_route_table.private[*].id, count.index)
-  destination_cidr_block = "0.0.0.0/0"
+  destination_cidr_block = var.nat_gateway_destination_cidr_block
   nat_gateway_id         = element(aws_nat_gateway.this[*].id, count.index)
 
   timeouts {

variables.tf

@@ -298,6 +298,12 @@ variable "enable_nat_gateway" {
   default     = false
 }
 
+variable "nat_gateway_destination_cidr_block" {
+  description = "Used to pass a custom destination route for private NAT Gateway. If not specified, the default 0.0.0.0/0 is used as a destination route."
+  type        = string
+  default     = "0.0.0.0/0"
+}
+
 variable "single_nat_gateway" {
   description = "Should be true if you want to provision a single shared NAT Gateway across all of your private networks"
   type        = bool