[Issue 1051] Fix CIDR overlap

infra/modules/dms-networking/main.tf

@@ -1,6 +1,6 @@
 locals {
-  our_target_cidr_block   = "172.31.0.0/16" # our [Nava] cidr block, where the target database for the DMS is located
-  their_source_cidr_block = "10.220.0.0/16" # their [MicroHealth] cidr block, where the origin database for the DMS is located
+  our_target_cidr_block   = var.dms_target_cidr_block # our [Nava] cidr block, where the target database for the DMS is located
+  their_source_cidr_block = var.dms_source_cidr_block # their [MicroHealth] cidr block, where the origin database for the DMS is located
 }
 
 # docs: https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/ssm_parameter

infra/modules/dms-networking/variables.tf

@@ -1,3 +1,11 @@
 variable "vpc_id" {
   type = string
 }
+
+variable "dms_target_cidr_block" {
+  type = string
+}
+
+variable "dms_source_cidr_block" {
+  type = string
+}

infra/modules/network/main.tf

@@ -1,7 +1,7 @@
 data "aws_availability_zones" "available" {}
 
 locals {
-  vpc_cidr               = "10.0.0.0/20"
+  vpc_cidr               = "10.${var.second_octet}.0.0/20"
   num_availability_zones = 3
   availability_zones     = slice(data.aws_availability_zones.available.names, 0, local.num_availability_zones)
 }
@@ -14,9 +14,9 @@ module "aws_vpc" {
   azs  = local.availability_zones
   cidr = local.vpc_cidr
 
-  public_subnets             = ["10.0.10.0/24", "10.0.11.0/24", "10.0.12.0/24"]
-  private_subnets            = ["10.0.0.0/24", "10.0.1.0/24", "10.0.2.0/24"]
-  database_subnets           = ["10.0.5.0/24", "10.0.6.0/24", "10.0.7.0/24"]
+  public_subnets             = ["10.${var.second_octet}.10.0/24", "10.${var.second_octet}.11.0/24", "10.${var.second_octet}.12.0/24"]
+  private_subnets            = ["10.${var.second_octet}.0.0/24", "10.${var.second_octet}.1.0/24", "10.${var.second_octet}.2.0/24"]
+  database_subnets           = ["10.${var.second_octet}.5.0/24", "10.${var.second_octet}.6.0/24", "10.${var.second_octet}.7.0/24"]
   public_subnet_tags         = { subnet_type = "public" }
   private_subnet_tags        = { subnet_type = "private" }
   database_subnet_tags       = { subnet_type = "database" }

infra/modules/network/outputs.tf

@@ -1,3 +1,7 @@
 output "vpc_id" {
   value = module.aws_vpc.vpc_id
 }
+
+output "vpc_cidr" {
+  value = local.vpc_cidr
+}

infra/modules/network/variables.tf

@@ -3,6 +3,11 @@ variable "name" {
   description = "Name to give the VPC. Will be added to the VPC under the 'network_name' tag."
 }
 
+variable "second_octet" {
+  type        = number
+  description = "Second octet of the VPC CIDR block. Must be between 0 and 255."
+}
+
 variable "aws_services_security_group_name_prefix" {
   type        = string
   description = "Prefix for the name of the security group attached to VPC endpoints"

infra/networks/main.tf

@@ -37,11 +37,6 @@ module "app_config" {
   source = "../api/app-config"
 }
 
-module "dms_networking" {
-  source = "../modules/dms-networking"
-  vpc_id = module.network.vpc_id
-}
-
 data "aws_vpc" "default" {
   default = true
 }
@@ -58,4 +53,12 @@ module "network" {
   name                                    = var.environment_name
   database_subnet_group_name              = var.environment_name
   aws_services_security_group_name_prefix = var.environment_name
+  second_octet                            = module.project_config.network_configs[var.environment_name].second_octet
+}
+
+module "dms_networking" {
+  source                = "../modules/dms-networking"
+  vpc_id                = module.network.vpc_id
+  dms_target_cidr_block = module.network.vpc_cidr
+  dms_source_cidr_block = module.project_config.network_configs[var.environment_name].dms_source_cidr_block
 }

infra/project-config/main.tf

@@ -19,8 +19,20 @@ locals {
 
   network_configs = {
     # TODO(https://github.com/HHS/simpler-grants-gov/issues/1051) deploy to a non-default VPC in every environment
-    dev     = { vpc_name = "default" }
-    staging = { vpc_name = "staging" }
-    prod    = { vpc_name = "default" }
+    dev = {
+      vpc_name              = "default"
+      second_octet          = 0               # The second octet our the VPC CIDR block
+      dms_source_cidr_block = "10.220.0.0/16" # MicroHealth cidr block, where the origin database for the DMS is located
+    }
+    staging = {
+      vpc_name              = "staging"
+      second_octet          = 1               # The second octet our the VPC CIDR block
+      dms_source_cidr_block = "10.220.0.0/16" # MicroHealth cidr block, where the origin database for the DMS is located
+    }
+    prod = {
+      vpc_name              = "default"
+      second_octet          = 3               # The second octet our the VPC CIDR block
+      dms_source_cidr_block = "10.220.0.0/16" # !PLACEHOLDER! We haven't been provided with this yet
+    }
   }
 }