adding auto scalling feature

_variables.tf

@@ -143,4 +143,76 @@ variable "task_role_policies_managed" {
 variable "task_role_policies" {
   default     = []
   description = "Custom policies to be added on the task role."
-}
+}
+
+variable "autoscaling_cpu" {
+  default     = false
+  description = "Enables autoscaling based on average CPU tracking"
+}
+
+variable "autoscaling_memory" {
+  default     = false
+  description = "Enables autoscaling based on average Memory tracking"
+}
+
+variable "autoscaling_max" {
+  default     = 4
+  description = "Max number of containers to scale with autoscaling"
+}
+
+variable "autoscaling_min" {
+  default     = 1
+  description = "Min number of containers to scale with autoscaling"
+}
+
+variable "autoscaling_target_cpu" {
+  default     = 50
+  description = "Target average CPU percentage to track for autoscaling"
+}
+
+variable "autoscaling_target_memory" {
+  default     = 90
+  description = "Target average Memory percentage to track for autoscaling"
+}
+
+variable "autoscaling_scale_in_cooldown" {
+  default     = 300
+  description = "Cooldown in seconds to wait between scale in events"
+}
+
+variable "autoscaling_scale_out_cooldown" {
+  default     = 300
+  description = "Cooldown in seconds to wait between scale out events"
+}
+
+variable "enable_schedule" {
+  default     = false
+  description = "Enables schedule to shut down and start up instances outside business hours."
+}
+
+variable "autoscaling_custom" {
+  type = list(object({
+    name               = string
+    scale_in_cooldown  = number
+    scale_out_cooldown = number
+    target_value       = number
+    metric_name        = string
+    namespace          = string
+    statistic          = string
+  }))
+  default     = []
+  description = "Set one or more app autoscaling by customized metric"
+}
+
+variable "schedule_cron_start" {
+  type        = string
+  default     = ""
+  description = "Cron expression to define when to trigger a start of the auto-scaling group. E.g. 'cron(00 21 ? * SUN-THU *)' to start at 8am UTC time."
+}
+
+variable "schedule_cron_stop" {
+  type        = string
+  default     = ""
+  description = "Cron expression to define when to trigger a stop of the auto-scaling group. E.g. 'cron(00 09 ? * MON-FRI *)' to start at 8am UTC time"
+}
+

appautoscaling.tf

@@ -0,0 +1,108 @@
+resource "aws_appautoscaling_target" "ecs" {
+  count              = var.autoscaling_cpu || var.autoscaling_memory || length(var.autoscaling_custom) > 0 ? 1 : 0
+  max_capacity       = var.autoscaling_max
+  min_capacity       = var.autoscaling_min
+  resource_id        = "service/${var.cluster_name}/${aws_ecs_service.default.name}"
+  scalable_dimension = "ecs:service:DesiredCount"
+  service_namespace  = "ecs"
+}
+
+resource "aws_appautoscaling_policy" "scale_cpu" {
+  count              = var.autoscaling_cpu ? 1 : 0
+  name               = "scale-cpu"
+  policy_type        = "TargetTrackingScaling"
+  resource_id        = aws_appautoscaling_target.ecs[0].resource_id
+  scalable_dimension = aws_appautoscaling_target.ecs[0].scalable_dimension
+  service_namespace  = aws_appautoscaling_target.ecs[0].service_namespace
+
+  target_tracking_scaling_policy_configuration {
+    target_value       = var.autoscaling_target_cpu
+    disable_scale_in   = false
+    scale_in_cooldown  = var.autoscaling_scale_in_cooldown
+    scale_out_cooldown = var.autoscaling_scale_out_cooldown
+
+    predefined_metric_specification {
+      predefined_metric_type = "ECSServiceAverageCPUUtilization"
+    }
+  }
+}
+
+resource "aws_appautoscaling_policy" "scale_memory" {
+  count              = var.autoscaling_memory ? 1 : 0
+  name               = "scale-memory"
+  policy_type        = "TargetTrackingScaling"
+  resource_id        = aws_appautoscaling_target.ecs[0].resource_id
+  scalable_dimension = aws_appautoscaling_target.ecs[0].scalable_dimension
+  service_namespace  = aws_appautoscaling_target.ecs[0].service_namespace
+
+  target_tracking_scaling_policy_configuration {
+    target_value       = var.autoscaling_target_memory
+    disable_scale_in   = false
+    scale_in_cooldown  = var.autoscaling_scale_in_cooldown
+    scale_out_cooldown = var.autoscaling_scale_out_cooldown
+
+    predefined_metric_specification {
+      predefined_metric_type = "ECSServiceAverageMemoryUtilization"
+    }
+  }
+}
+
+resource "aws_appautoscaling_policy" "scale_custom" {
+  for_each = { for custom in var.autoscaling_custom : custom.name => custom }
+
+  name               = each.value.name
+  policy_type        = "TargetTrackingScaling"
+  resource_id        = aws_appautoscaling_target.ecs[0].resource_id
+  scalable_dimension = aws_appautoscaling_target.ecs[0].scalable_dimension
+  service_namespace  = aws_appautoscaling_target.ecs[0].service_namespace
+
+  target_tracking_scaling_policy_configuration {
+    scale_in_cooldown  = each.value.scale_in_cooldown
+    scale_out_cooldown = each.value.scale_out_cooldown
+    target_value       = each.value.target_value
+
+    customized_metric_specification {
+      metric_name = each.value.metric_name
+      namespace   = each.value.namespace
+      statistic   = each.value.statistic
+      dimensions {
+        name  = "ClusterName"
+        value = var.cluster_name
+      }
+      dimensions {
+        name  = "ServiceName"
+        value = var.name
+      }
+    }
+  }
+}
+
+resource "aws_appautoscaling_scheduled_action" "scale_service_out" {
+  count              = var.enable_schedule ? 1 : 0
+  name               = "${var.name}-scale-out"
+  service_namespace  = aws_appautoscaling_target.ecs[0].service_namespace
+  resource_id        = aws_appautoscaling_target.ecs[0].resource_id
+  scalable_dimension = aws_appautoscaling_target.ecs[0].scalable_dimension
+  schedule           = var.schedule_cron_stop
+  timezone           = "UTC"
+
+  scalable_target_action {
+    min_capacity = 0
+    max_capacity = 0
+  }
+}
+
+resource "aws_appautoscaling_scheduled_action" "scale_service_in" {
+  count              = var.enable_schedule ? 1 : 0
+  name               = "${var.name}-scale-in"
+  service_namespace  = aws_appautoscaling_target.ecs[0].service_namespace
+  resource_id        = aws_appautoscaling_target.ecs[0].resource_id
+  scalable_dimension = aws_appautoscaling_target.ecs[0].scalable_dimension
+  schedule           = var.schedule_cron_start
+  timezone           = "UTC"
+
+  scalable_target_action {
+    min_capacity = var.autoscaling_min
+    max_capacity = var.autoscaling_max
+  }
+}