autoscaling.tf

/*
 * AutoScaling for ECS Service
 *
 * The below resources is optional.
 */

resource "aws_appautoscaling_target" "main" {
  max_capacity       = var.autoscale_max_capacity
  min_capacity       = var.autoscale_min_capacity
  resource_id        = "service/${var.cluster_name}/${var.name}"
  role_arn           = var.autoscale_iam_role_arn
  scalable_dimension = "ecs:service:DesiredCount"
  service_namespace  = "ecs"
  depends_on = [aws_ecs_service.main]
  lifecycle {
    ignore_changes = [
      max_capacity,
    ]
  }
}

// Memory Utilization

resource "aws_appautoscaling_policy" "memory_high" {
  count = lookup(var.scale_out_thresholds, "memory", "") != "" ? 1 : 0

  name               = "${var.name}-ecs_service-scale_out-memory_utilization"
  resource_id        = "service/${var.cluster_name}/${var.name}"
  scalable_dimension = "ecs:service:DesiredCount"
  service_namespace  = "ecs"

  step_scaling_policy_configuration {
    adjustment_type         = "ChangeInCapacity"
    cooldown                = var.autoscale_cooldown
    metric_aggregation_type = "Average"

    step_adjustment {
      metric_interval_lower_bound = var.scale_out_step_adjustment["metric_interval_lower_bound"]
      scaling_adjustment          = var.scale_out_step_adjustment["scaling_adjustment"]
    }
  }

  depends_on = [aws_appautoscaling_target.main]
}

resource "aws_cloudwatch_metric_alarm" "memory_high" {
  count = lookup(var.scale_out_thresholds, "memory", "") != "" ? 1 : 0

  alarm_name          = "${var.name}-ECSService-MemoryUtilization-High"
  alarm_description   = "${var.name} scale-out pushed by memory-utilization"
  comparison_operator = "GreaterThanOrEqualToThreshold"
  evaluation_periods  = var.scale_out_evaluation_periods
  metric_name         = "MemoryUtilization"
  namespace           = "AWS/ECS"
  period              = var.autoscale_cooldown
  statistic           = "Average"
  threshold           = var.scale_out_thresholds["memory"]
  treat_missing_data  = "notBreaching"
  ok_actions          = compact(var.scale_out_ok_actions)
  alarm_actions = compact(
    concat(
      [aws_appautoscaling_policy.memory_high[0].arn],
      var.scale_out_more_alarm_actions,
    ),
  )

  dimensions = {
    ClusterName = var.cluster_name
    ServiceName = var.name
  }
}

resource "aws_appautoscaling_policy" "memory_low" {
  count = lookup(var.scale_in_thresholds, "memory", "") != "" ? 1 : 0

  name               = "${var.name}-ecs_service-scale_in-memory_utilization"
  resource_id        = "service/${var.cluster_name}/${var.name}"
  scalable_dimension = "ecs:service:DesiredCount"
  service_namespace  = "ecs"

  step_scaling_policy_configuration {
    adjustment_type         = "ChangeInCapacity"
    cooldown                = var.autoscale_cooldown
    metric_aggregation_type = "Average"

    step_adjustment {
      metric_interval_upper_bound = var.scale_in_step_adjustment["metric_interval_upper_bound"]
      scaling_adjustment          = var.scale_in_step_adjustment["scaling_adjustment"]
    }
  }

  depends_on = [aws_appautoscaling_target.main]
}

resource "aws_cloudwatch_metric_alarm" "memory_low" {
  count = lookup(var.scale_in_thresholds, "memory", "") != "" ? 1 : 0

  alarm_name          = "${var.name}-ECSService-MemoryUtilization-Low"
  alarm_description   = "${var.name} scale-in pushed by memory-utilization"
  comparison_operator = "LessThanOrEqualToThreshold"
  evaluation_periods  = var.scale_in_evaluation_periods
  metric_name         = "MemoryUtilization"
  namespace           = "AWS/ECS"
  period              = var.autoscale_cooldown
  statistic           = "Average"
  threshold           = var.scale_in_thresholds["memory"]
  treat_missing_data  = "notBreaching"
  ok_actions          = compact(var.scale_in_ok_actions)
  alarm_actions = compact(
    concat(
      [aws_appautoscaling_policy.memory_low[0].arn],
      var.scale_in_more_alarm_actions,
    ),
  )

  dimensions = {
    ClusterName = var.cluster_name
    ServiceName = var.name
  }
}

// CPU Utilization

resource "aws_appautoscaling_policy" "cpu_high" {
  count = lookup(var.scale_out_thresholds, "cpu", "") != "" ? 1 : 0

  name               = "${var.name}-ecs_service-scale_out-cpu_utilization"
  resource_id        = "service/${var.cluster_name}/${var.name}"
  scalable_dimension = "ecs:service:DesiredCount"
  service_namespace  = "ecs"

  step_scaling_policy_configuration {
    adjustment_type         = "ChangeInCapacity"
    cooldown                = var.autoscale_cooldown
    metric_aggregation_type = "Average"

    step_adjustment {
      metric_interval_lower_bound = var.scale_out_step_adjustment["metric_interval_lower_bound"]
      scaling_adjustment          = var.scale_out_step_adjustment["scaling_adjustment"]
    }
  }

  depends_on = [aws_appautoscaling_target.main]
}

resource "aws_cloudwatch_metric_alarm" "cpu_high" {
  count = lookup(var.scale_out_thresholds, "cpu", "") != "" ? 1 : 0

  alarm_name          = "${var.name}-ECSService-CPUUtilization-High"
  alarm_description   = "${var.name} scale-out pushed by cpu-utilization"
  comparison_operator = "GreaterThanOrEqualToThreshold"
  evaluation_periods  = var.scale_out_evaluation_periods
  metric_name         = "CPUUtilization"
  namespace           = "AWS/ECS"
  period              = var.autoscale_cooldown
  statistic           = "Average"
  threshold           = var.scale_out_thresholds["cpu"]
  treat_missing_data  = "notBreaching"
  ok_actions          = compact(var.scale_out_ok_actions)
  alarm_actions = compact(
    concat(
      [aws_appautoscaling_policy.cpu_high[0].arn],
      var.scale_out_more_alarm_actions,
    ),
  )

  dimensions = {
    ClusterName = var.cluster_name
    ServiceName = var.name
  }
}

resource "aws_appautoscaling_policy" "cpu_low" {
  count = lookup(var.scale_in_thresholds, "cpu", "") != "" ? 1 : 0

  name               = "${var.name}-ecs_service-scale_in-cpu_utilization"
  resource_id        = "service/${var.cluster_name}/${var.name}"
  scalable_dimension = "ecs:service:DesiredCount"
  service_namespace  = "ecs"

  step_scaling_policy_configuration {
    adjustment_type         = "ChangeInCapacity"
    cooldown                = var.autoscale_cooldown
    metric_aggregation_type = "Average"

    step_adjustment {
      metric_interval_upper_bound = var.scale_in_step_adjustment["metric_interval_upper_bound"]
      scaling_adjustment          = var.scale_in_step_adjustment["scaling_adjustment"]
    }
  }

  depends_on = [aws_appautoscaling_target.main]
}

resource "aws_cloudwatch_metric_alarm" "cpu_low" {
  count = lookup(var.scale_in_thresholds, "cpu", "") != "" ? 1 : 0

  alarm_name          = "${var.name}-ECSService-CPUUtilization-Low"
  alarm_description   = "${var.name} scale-in pushed by cpu-utilization"
  comparison_operator = "LessThanOrEqualToThreshold"
  evaluation_periods  = var.scale_in_evaluation_periods
  metric_name         = "CPUUtilization"
  namespace           = "AWS/ECS"
  period              = var.autoscale_cooldown
  statistic           = "Average"
  threshold           = var.scale_in_thresholds["cpu"]
  treat_missing_data  = "notBreaching"
  ok_actions          = compact(var.scale_in_ok_actions)
  alarm_actions = compact(
    concat(
      [aws_appautoscaling_policy.cpu_low[0].arn],
      var.scale_in_more_alarm_actions,
    ),
  )

  dimensions = {
    ClusterName = var.cluster_name
    ServiceName = var.name
  }
}