terraformで死活監視(ALBのhalthyhostsを監視)

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resource "aws_sns_topic" "cloudwatch_topic" {
  name = "${var.app_name}-${var.env}-cloudwatch-topic"
}

resource "aws_cloudwatch_metric_alarm" "alb_healthyhosts" {
  alarm_name          = "${var.app_name}-${var.env}-alb-healthyhosts"
  namespace           = "AWS/ApplicationELB"
  metric_name         = "HealthyHostCount"
  comparison_operator = "LessThanThreshold"
  evaluation_periods  = 2
  period              = 60
  statistic           = "Average"
  threshold           = 1
  alarm_actions       = [aws_sns_topic.cloudwatch_topic.arn]
  ok_actions          = [aws_sns_topic.cloudwatch_topic.arn]
  dimensions = {
    TargetGroup  = aws_lb_target_group.xxx..arn_suffix
    LoadBalancer = aws_alb.xxx.arn_suffix
  }
}