Pass regions variable to region module

terraform/environment/dynamodb.tf

@@ -15,9 +15,18 @@ resource "aws_dynamodb_table" "actor_codes_table" {
     enabled = true
   }
 
-  replica {
-    region_name    = "eu-west-2"
-    propagate_tags = true
+  # For each region in the environment that is not the primary_region, create a DynamoDB replica.
+
+  dynamic "replica" {
+    for_each = [
+      for region in local.environment.regions : region
+      if region.is_primary != true
+    ]
+
+    content {
+      region_name    = replica.value.name
+      propagate_tags = true
+    }
   }
 
   lifecycle {
@@ -45,9 +54,16 @@ resource "aws_dynamodb_table" "stats_table" {
     enabled = true
   }
 
-  replica {
-    region_name    = "eu-west-2"
-    propagate_tags = true
+  dynamic "replica" {
+    for_each = [
+      for region in local.environment.regions : region
+      if region.is_primary != true
+    ]
+
+    content {
+      region_name    = replica.value.name
+      propagate_tags = true
+    }
   }
 
   lifecycle {
@@ -125,9 +141,16 @@ resource "aws_dynamodb_table" "actor_users_table" {
     enabled = true
   }
 
-  replica {
-    region_name    = "eu-west-2"
-    propagate_tags = true
+  dynamic "replica" {
+    for_each = [
+      for region in local.environment.regions : region
+      if region.is_primary != true
+    ]
+
+    content {
+      region_name    = replica.value.name
+      propagate_tags = true
+    }
   }
 
   lifecycle {
@@ -171,11 +194,19 @@ resource "aws_dynamodb_table" "viewer_codes_table" {
     enabled = true
   }
 
-  replica {
-    region_name    = "eu-west-2"
-    propagate_tags = true
+  dynamic "replica" {
+    for_each = [
+      for region in local.environment.regions : region
+      if region.is_primary != true
+    ]
+
+    content {
+      region_name    = replica.value.name
+      propagate_tags = true
+    }
   }
 
+
   lifecycle {
     prevent_destroy = false
   }
@@ -205,11 +236,19 @@ resource "aws_dynamodb_table" "viewer_activity_table" {
     enabled = true
   }
 
-  replica {
-    region_name    = "eu-west-2"
-    propagate_tags = true
+  dynamic "replica" {
+    for_each = [
+      for region in local.environment.regions : region
+      if region.is_primary != true
+    ]
+
+    content {
+      region_name    = replica.value.name
+      propagate_tags = true
+    }
   }
 
+
   lifecycle {
     prevent_destroy = false
   }
@@ -272,9 +311,16 @@ resource "aws_dynamodb_table" "user_lpa_actor_map" {
     enabled = true
   }
 
-  replica {
-    region_name    = "eu-west-2"
-    propagate_tags = true
+  dynamic "replica" {
+    for_each = [
+      for region in local.environment.regions : region
+      if region.is_primary != true
+    ]
+
+    content {
+      region_name    = replica.value.name
+      propagate_tags = true
+    }
   }
 
   lifecycle {

terraform/environment/locals.tf

@@ -104,7 +104,14 @@ variable "environments" {
         stats = object({
           name = string
         })
-      })
+      }),
+      regions = map(
+        object({
+          name       = string
+          is_active  = bool
+          is_primary = bool
+        })
+      )
     })
   )
 }

terraform/environment/region.tf

@@ -25,6 +25,7 @@ module "eu_west_1" {
   parameter_store_arns                      = [aws_ssm_parameter.system_message_view_en.arn, aws_ssm_parameter.system_message_view_cy.arn, aws_ssm_parameter.system_message_use_en.arn, aws_ssm_parameter.system_message_use_cy.arn]
   pdf_container_version                     = local.environment.pdf_container_version
   public_access_enabled                     = var.public_access_enabled
+  regions                                   = local.environment.regions
   session_expires_use                       = local.environment.session_expires_use
   session_expires_view                      = local.environment.session_expires_view
   session_expiry_warning                    = local.environment.session_expiry_warning
@@ -73,7 +74,6 @@ module "eu_west_1" {
     "viewer"      = aws_route53_record.viewer_use_my_lpa.fqdn
   }
 
-
   providers = {
     aws.region     = aws.eu_west_1
     aws.management = aws.management

terraform/environment/region/actor_ecs.tf

@@ -5,7 +5,7 @@ resource "aws_ecs_service" "actor" {
   name             = "actor-service"
   cluster          = aws_ecs_cluster.use_an_lpa.id
   task_definition  = aws_ecs_task_definition.actor.arn
-  desired_count    = var.autoscaling.use.minimum
+  desired_count    = local.use_desired_count
   platform_version = "1.4.0"
 
   network_configuration {

terraform/environment/region/admin_ecs.tf

@@ -5,7 +5,7 @@ resource "aws_ecs_service" "admin" {
   name             = "admin-service"
   cluster          = aws_ecs_cluster.use_an_lpa.id
   task_definition  = aws_ecs_task_definition.admin.arn
-  desired_count    = 1
+  desired_count    = local.admin_desired_count
   platform_version = "1.4.0"
 
   network_configuration {

terraform/environment/region/api_ecs.tf

@@ -5,7 +5,7 @@ resource "aws_ecs_service" "api" {
   name                              = "api-service"
   cluster                           = aws_ecs_cluster.use_an_lpa.id
   task_definition                   = aws_ecs_task_definition.api.arn
-  desired_count                     = var.autoscaling.api.minimum
+  desired_count                     = local.api_desired_count
   platform_version                  = "1.4.0"
   health_check_grace_period_seconds = 0
 

terraform/environment/region/locals.tf

@@ -1,14 +1,26 @@
 locals {
   policy_region_prefix = lower(replace(data.aws_region.current.name, "-", ""))
 
+  # The primary region is the region where the DynamoDB tables are created and replicated to the secondary region.
+  primary_region    = keys({ for region, region_data in var.regions : region => region_data if region_data.is_primary })[0]
+  is_primary_region = local.primary_region == data.aws_region.current.name ? true : false
+  is_active_region  = var.regions[data.aws_region.current.name].is_active
+
+  # Desired count of the ECS services. Only an active region will have a desired count greater than 0.
+  use_desired_count   = local.is_active_region ? var.autoscaling.use.minimum : 0
+  pdf_desired_count   = local.is_active_region ? var.autoscaling.pdf.minimum : 0
+  view_desired_count  = local.is_active_region ? var.autoscaling.view.minimum : 0
+  api_desired_count   = local.is_active_region ? var.autoscaling.api.minimum : 0
+  admin_desired_count = local.is_active_region ? 1 : 0
+
   # Replace the region in the ARN of the DynamoDB tables with the region of the current stack as the tables are created in the primary region
   # and replicated to the secondary region. This allows use to grant access to the tables in the secondary region for applications running in the secondary region.
   dynamodb_tables_arns = {
-    actor_codes_table_arn     = replace(var.dynamodb_tables.actor_codes_table.arn, var.primary_region, data.aws_region.current.name)
-    stats_table_arn           = replace(var.dynamodb_tables.stats_table.arn, var.primary_region, data.aws_region.current.name)
-    actor_users_table_arn     = replace(var.dynamodb_tables.actor_users_table.arn, var.primary_region, data.aws_region.current.name)
-    viewer_codes_table_arn    = replace(var.dynamodb_tables.viewer_codes_table.arn, var.primary_region, data.aws_region.current.name)
-    viewer_activity_table_arn = replace(var.dynamodb_tables.viewer_activity_table.arn, var.primary_region, data.aws_region.current.name)
-    user_lpa_actor_map_arn    = replace(var.dynamodb_tables.user_lpa_actor_map.arn, var.primary_region, data.aws_region.current.name)
+    actor_codes_table_arn     = replace(var.dynamodb_tables.actor_codes_table.arn, local.primary_region, data.aws_region.current.name)
+    stats_table_arn           = replace(var.dynamodb_tables.stats_table.arn, local.primary_region, data.aws_region.current.name)
+    actor_users_table_arn     = replace(var.dynamodb_tables.actor_users_table.arn, local.primary_region, data.aws_region.current.name)
+    viewer_codes_table_arn    = replace(var.dynamodb_tables.viewer_codes_table.arn, local.primary_region, data.aws_region.current.name)
+    viewer_activity_table_arn = replace(var.dynamodb_tables.viewer_activity_table.arn, local.primary_region, data.aws_region.current.name)
+    user_lpa_actor_map_arn    = replace(var.dynamodb_tables.user_lpa_actor_map.arn, local.primary_region, data.aws_region.current.name)
   }
 }

terraform/environment/region/pdf_ecs.tf

@@ -5,7 +5,7 @@ resource "aws_ecs_service" "pdf" {
   name             = "pdf-service"
   cluster          = aws_ecs_cluster.use_an_lpa.id
   task_definition  = aws_ecs_task_definition.pdf.arn
-  desired_count    = var.autoscaling.pdf.minimum
+  desired_count    = local.pdf_desired_count
   platform_version = "1.4.0"
 
   network_configuration {

terraform/environment/region/variables.tf

@@ -174,10 +174,17 @@ variable "public_access_enabled" {
   default     = false
 }
 
-variable "primary_region" {
-  description = "The region that is used for the primary DynamoDB table. This is the region that is normally active."
-  type        = string
-  default     = "eu-west-1"
+variable "regions" {
+  description = "Information about which regions are being used"
+  type = map(object({
+    is_primary = bool
+    is_active  = bool
+  }))
+
+  validation {
+    condition     = length([for region in keys(var.regions) : region if var.regions[region].is_primary]) == 1
+    error_message = "One (and only one) region must be marked as primary"
+  }
 }
 
 variable "route_53_fqdns" {
@@ -204,4 +211,4 @@ variable "session_expiry_warning" {
 variable "sirius_account_id" {
   description = "The AWS ID of the Sirius account."
   type        = string
-}
+}

terraform/environment/region/viewer_ecs.tf

@@ -5,7 +5,7 @@ resource "aws_ecs_service" "viewer" {
   name             = "viewer-service"
   cluster          = aws_ecs_cluster.use_an_lpa.id
   task_definition  = aws_ecs_task_definition.viewer.arn
-  desired_count    = var.autoscaling.view.minimum
+  desired_count    = local.view_desired_count
   platform_version = "1.4.0"
 
   network_configuration {

terraform/environment/terraform.tfvars.json

@@ -73,6 +73,13 @@
         "stats": {
           "name": "Stats"
         }
+      },
+      "regions": {
+        "eu-west-1": {
+          "name": "eu-west-1",
+          "is_active": true,
+          "is_primary": true
+        }
       }
     },
     "demo": {
@@ -148,6 +155,13 @@
         "stats": {
           "name": "Stats"
         }
+      },
+      "regions": {
+        "eu-west-1": {
+          "name": "eu-west-1",
+          "is_active": true,
+          "is_primary": true
+        }
       }
     },
     "preproduction": {
@@ -223,6 +237,18 @@
         "stats": {
           "name": "Stats"
         }
+      },
+      "regions": {
+        "eu-west-1": {
+          "name": "eu-west-1",
+          "is_active": true,
+          "is_primary": true
+        },
+        "eu-west-2": {
+          "name": "eu-west-2",
+          "is_active": true,
+          "is_primary": false
+        }
       }
     },
     "production": {
@@ -298,6 +324,13 @@
         "stats": {
           "name": "Stats"
         }
+      },
+      "regions": {
+        "eu-west-1": {
+          "name": "eu-west-1",
+          "is_active": true,
+          "is_primary": true
+        }
       }
     }
   }