Merge pull request #2110 from govuk-forms/allow-aurora-to-scale

Allow aurora to scale

Author: cadmiumcat

infra/deployments/forms/inputs.tf

@@ -195,6 +195,8 @@ variable "environmental_settings" {
     enable_alert_actions                     = bool
     forms_product_page_support_url           = string
     rds_maintenance_window                   = string
+    rds_minimum_capacity_acus                = number
+    rds_maxium_capacity_acus                 = number
     ips_to_block                             = list(string)
     rate_limit_bypass_cidrs                  = list(string)
     enable_shield_advanced_healthchecks      = bool

infra/deployments/forms/rds/main.tf

@@ -16,6 +16,8 @@ module "rds" {
 
   apply_immediately        = var.apply_immediately
   rds_maintenance_window   = var.environmental_settings.rds_maintenance_window
+  min_capacity             = var.environmental_settings.rds_minimum_capacity_acus
+  max_capacity             = var.environmental_settings.rds_maxium_capacity_acus
   auto_pause               = var.environmental_settings.pause_databases_on_inactivity
   seconds_until_auto_pause = var.environmental_settings.pause_databases_after_inactivity_seconds
   backup_retention_period  = var.environmental_settings.database_backup_retention_period_days
@@ -40,6 +42,8 @@ module "forms_runner_rds" {
 
   apply_immediately        = var.apply_immediately
   rds_maintenance_window   = var.environmental_settings.rds_maintenance_window
+  min_capacity             = var.environmental_settings.rds_minimum_capacity_acus
+  max_capacity             = var.environmental_settings.rds_maxium_capacity_acus
   auto_pause               = var.environmental_settings.pause_databases_on_inactivity
   seconds_until_auto_pause = var.environmental_settings.pause_databases_after_inactivity_seconds
   backup_retention_period  = var.environmental_settings.database_backup_retention_period_days

infra/deployments/forms/tfvars/dev.tfvars

@@ -17,6 +17,8 @@ environmental_settings = {
   enable_alert_actions                     = false
   forms_product_page_support_url           = "https://www.dev.forms.service.gov.uk/support"
   rds_maintenance_window                   = "wed:04:00-wed:04:30"
+  rds_minimum_capacity_acus                = 0.5
+  rds_maxium_capacity_acus                 = 2
   ips_to_block                             = []
   rate_limit_bypass_cidrs                  = []
   enable_shield_advanced_healthchecks      = false

infra/deployments/forms/tfvars/production.tfvars

@@ -40,6 +40,8 @@ environmental_settings = {
   ]
   forms_product_page_support_url      = "https://www.forms.service.gov.uk/support"
   rds_maintenance_window              = "wed:04:00-wed:04:30"
+  rds_minimum_capacity_acus           = 2
+  rds_maxium_capacity_acus            = 10
   ips_to_block                        = []
   rate_limit_bypass_cidrs             = []
   enable_shield_advanced_healthchecks = true

infra/deployments/forms/tfvars/staging.tfvars

@@ -19,6 +19,8 @@ environmental_settings = {
   enable_alert_actions                = true
   forms_product_page_support_url      = "https://www.staging.forms.service.gov.uk/support"
   rds_maintenance_window              = "wed:04:00-wed:04:30"
+  rds_minimum_capacity_acus           = 1
+  rds_maxium_capacity_acus            = 2
   ips_to_block                        = []
   rate_limit_bypass_cidrs             = []
   enable_shield_advanced_healthchecks = false

infra/modules/rds/rds.tf

@@ -24,29 +24,6 @@ locals {
   performance_insights_retention_period = var.enable_advanced_database_insights ? 465 : null
 }
 
-locals {
-  serverlessv2_scaling_profiles = {
-
-    dev = {
-      # 0.5 is the lowest value that keeps the cluster warm (no cold start on first connection).
-      # Setting min_capacity = 0 would enable auto-pause but cause ~20-30s wake-up delays.
-      min_capacity = 0.5
-      max_capacity = 2
-    }
-
-    default = {
-      min_capacity = var.min_capacity
-      max_capacity = var.max_capacity
-    }
-  }
-
-  serverlessv2_scaling = lookup(
-    local.serverlessv2_scaling_profiles,
-    var.env_name,
-    local.serverlessv2_scaling_profiles["default"]
-  )
-}
-
 resource "aws_rds_cluster" "cluster_aurora_v2" {
   #checkov:skip=CKV2_AWS_8:AWS RDS inbuilt backup process is sufficient
   #checkov:skip=CKV2_AWS_27:Query logging is not required at this time
@@ -91,15 +68,9 @@ resource "aws_rds_cluster" "cluster_aurora_v2" {
   performance_insights_enabled          = var.enable_advanced_database_insights
   performance_insights_retention_period = local.performance_insights_retention_period
 
-  dynamic "serverlessv2_scaling_configuration" {
-    for_each = [local.serverlessv2_scaling]
-
-    content {
-      min_capacity = serverlessv2_scaling_configuration.value.min_capacity
-      max_capacity = serverlessv2_scaling_configuration.value.max_capacity
-
-      seconds_until_auto_pause = try(serverlessv2_scaling_configuration.value.seconds_until_auto_pause, null)
-    }
+  serverlessv2_scaling_configuration {
+    max_capacity = var.max_capacity
+    min_capacity = var.min_capacity
   }
 
   lifecycle {