Use weighted routing

ministryofjustice · Oct 26, 2023 · 442baf8 · 442baf8
1 parent 5a7c20d
commit 442baf8
Show file tree

Hide file tree

Showing 5 changed files with 45 additions and 21 deletions.
diff --git a/terraform/environment/refactor.tf b/terraform/environment/refactor.tf
@@ -864,47 +864,47 @@ moved {
 
 moved {
   from = aws_cloudwatch_metric_alarm.actor_health_check_alarm
-  to   = module.eu_west_1.module.actor_use_my_lpa[0].aws_cloudwatch_metric_alarm.this[0]
+  to   = module.eu_west_1.module.actor_use_my_lpa.aws_cloudwatch_metric_alarm.this[0]
 }
 
 moved {
   from = aws_cloudwatch_metric_alarm.viewer_health_check_alarm
-  to   = module.eu_west_1.module.viewer_use_my_lpa[0].aws_cloudwatch_metric_alarm.this[0]
+  to   = module.eu_west_1.module.viewer_use_my_lpa.aws_cloudwatch_metric_alarm.this[0]
 }
 
 moved {
   from = aws_route53_health_check.actor_health_check
-  to   = module.eu_west_1.module.actor_use_my_lpa[0].aws_route53_health_check.this[0]
+  to   = module.eu_west_1.module.actor_use_my_lpa.aws_route53_health_check.this[0]
 }
 
 moved {
   from = aws_route53_health_check.viewer_health_check
-  to   = module.eu_west_1.module.viewer_use_my_lpa[0].aws_route53_health_check.this[0]
+  to   = module.eu_west_1.module.viewer_use_my_lpa.aws_route53_health_check.this[0]
 }
 
 moved {
   from = aws_route53_record.actor_use_my_lpa
-  to   = module.eu_west_1.module.actor_use_my_lpa[0].aws_route53_record.this
+  to   = module.eu_west_1.module.actor_use_my_lpa.aws_route53_record.this
 }
 
 moved {
   from = aws_route53_record.admin_use_my_lpa
-  to   = module.eu_west_1.module.admin_use_my_lpa[0].aws_route53_record.this
+  to   = module.eu_west_1.module.admin_use_my_lpa.aws_route53_record.this
 }
 
 moved {
   from = aws_route53_record.public_facing_use_lasting_power_of_attorney
-  to   = module.eu_west_1.module.public_facing_use_lasting_power_of_attorney[0].aws_route53_record.this
+  to   = module.eu_west_1.module.public_facing_use_lasting_power_of_attorney.aws_route53_record.this
 }
 
 moved {
   from = aws_route53_record.public_facing_view_lasting_power_of_attorney
-  to   = module.eu_west_1.module.public_facing_view_lasting_power_of_attorney[0].aws_route53_record.this
+  to   = module.eu_west_1.module.public_facing_view_lasting_power_of_attorney.aws_route53_record.this
 }
 
 moved {
   from = aws_route53_record.viewer_use_my_lpa
-  to   = module.eu_west_1.module.viewer_use_my_lpa[0].aws_route53_record.this
+  to   = module.eu_west_1.module.viewer_use_my_lpa.aws_route53_record.this
 }
 
 moved {

diff --git a/terraform/environment/region/dns.tf b/terraform/environment/region/dns.tf
@@ -21,10 +21,11 @@ resource "aws_service_discovery_private_dns_namespace" "internal_ecs" {
 }
 
 module "public_facing_view_lasting_power_of_attorney" {
-  count  = local.is_active_region ? 1 : 0
   source = "./modules/dns"
 
   dns_namespace_env = var.dns_namespace_env
+  is_active_region  = local.is_active_region
+  current_region    = data.aws_region.current.name
   zone_id           = data.aws_route53_zone.live_service_view_lasting_power_of_attorney.zone_id
   loadbalancer      = aws_lb.viewer
   dns_name          = data.aws_route53_zone.live_service_view_lasting_power_of_attorney.name
@@ -37,10 +38,11 @@ module "public_facing_view_lasting_power_of_attorney" {
 }
 
 module "viewer_use_my_lpa" {
-  count  = local.is_active_region ? 1 : 0
   source = "./modules/dns"
 
   dns_namespace_env   = var.dns_namespace_env
+  is_active_region    = local.is_active_region
+  current_region      = data.aws_region.current.name
   zone_id             = data.aws_route53_zone.opg_service_justice_gov_uk.zone_id
   loadbalancer        = aws_lb.viewer
   dns_name            = "view.lastingpowerofattorney"
@@ -56,10 +58,11 @@ module "viewer_use_my_lpa" {
 }
 
 module "public_facing_use_lasting_power_of_attorney" {
-  count  = local.is_active_region ? 1 : 0
   source = "./modules/dns"
 
   dns_namespace_env = var.dns_namespace_env
+  is_active_region  = local.is_active_region
+  current_region    = data.aws_region.current.name
   zone_id           = data.aws_route53_zone.live_service_use_lasting_power_of_attorney.zone_id
   dns_name          = data.aws_route53_zone.live_service_use_lasting_power_of_attorney.name
   loadbalancer      = aws_lb.actor
@@ -72,10 +75,11 @@ module "public_facing_use_lasting_power_of_attorney" {
 }
 
 module "actor_use_my_lpa" {
-  count  = local.is_active_region ? 1 : 0
   source = "./modules/dns"
 
   dns_namespace_env   = var.dns_namespace_env
+  is_active_region    = local.is_active_region
+  current_region      = data.aws_region.current.name
   zone_id             = data.aws_route53_zone.opg_service_justice_gov_uk.zone_id
   loadbalancer        = aws_lb.actor
   dns_name            = "use.lastingpowerofattorney"
@@ -91,12 +95,14 @@ module "actor_use_my_lpa" {
 }
 
 module "admin_use_my_lpa" {
-  count  = local.is_active_region ? 1 : 0
   source = "./modules/dns"
 
   dns_namespace_env = var.dns_namespace_env
+  is_active_region  = local.is_active_region
+  current_region    = data.aws_region.current.name
   zone_id           = data.aws_route53_zone.opg_service_justice_gov_uk.zone_id
   loadbalancer      = aws_lb.admin
+  service_name      = "admin"
   dns_name          = "admin.lastingpowerofattorney"
   environment_name  = var.environment_name
 

diff --git a/terraform/environment/region/locals.tf b/terraform/environment/region/locals.tf
@@ -26,10 +26,10 @@ locals {
   }
 
   route53_fqdns = {
-    public_facing_view = local.is_active_region ? module.public_facing_view_lasting_power_of_attorney[0].fqdn : ""
-    public_facing_use  = local.is_active_region ? module.public_facing_use_lasting_power_of_attorney[0].fqdn : ""
-    admin              = local.is_active_region ? module.admin_use_my_lpa[0].fqdn : ""
-    actor              = local.is_active_region ? module.actor_use_my_lpa[0].fqdn : ""
-    viewer             = local.is_active_region ? module.viewer_use_my_lpa[0].fqdn : ""
+    public_facing_view = local.is_active_region ? module.public_facing_view_lasting_power_of_attorney.fqdn : ""
+    public_facing_use  = local.is_active_region ? module.public_facing_use_lasting_power_of_attorney.fqdn : ""
+    admin              = local.is_active_region ? module.admin_use_my_lpa.fqdn : ""
+    actor              = local.is_active_region ? module.actor_use_my_lpa.fqdn : ""
+    viewer             = local.is_active_region ? module.viewer_use_my_lpa.fqdn : ""
   }
 }
diff --git a/terraform/environment/region/modules/dns/main.tf b/terraform/environment/region/modules/dns/main.tf
@@ -1,5 +1,6 @@
 locals {
-  create_alarm = var.create_alarm && var.create_health_check
+  create_alarm = var.create_alarm && var.create_health_check && var.is_active_region
+  route_weight = var.is_active_region ? 100 : 0
 }
 
 resource "aws_route53_record" "this" {
@@ -13,11 +14,16 @@ resource "aws_route53_record" "this" {
     zone_id                = var.loadbalancer.zone_id
   }
 
+  weighted_routing_policy {
+    weight = local.route_weight
+  }
+
   lifecycle {
     create_before_destroy = true
   }
 
-  provider = aws.management
+  set_identifier = "${var.current_region}-${var.environment_name}-${var.service_name}"
+  provider       = aws.management
 }
 
 resource "aws_route53_health_check" "this" {

diff --git a/terraform/environment/region/modules/dns/variables.tf b/terraform/environment/region/modules/dns/variables.tf
@@ -39,3 +39,15 @@ variable "service_name" {
   type        = string
   default     = ""
 }
+
+variable "is_active_region" {
+  description = "Should traffic be routed to this region. Used to create a weighted record set"
+  type        = bool
+  default     = false
+}
+
+variable "current_region" {
+  description = "The current region"
+  type        = string
+  default     = "eu-west-1"
+}