## 6. Monitoring & Cost Alerts

```hcl
resource "aws_sns_topic" "alerts" {
  name = "${var.project}-${var.environment}-alerts"
}

resource "aws_cloudwatch_metric_alarm" "alb_5xx" {
  alarm_name          = "${var.project}-high-5xx"
  namespace           = "AWS/ApplicationELB"
  metric_name         = "HTTPCode_Target_5XX_Count"
  statistic           = "Sum"
  period              = 300
  evaluation_periods  = 2
  threshold           = 50
  comparison_operator = "GreaterThanThreshold"
  alarm_actions       = [aws_sns_topic.alerts.arn]
  dimensions          = { LoadBalancer = var.alb_arn_suffix }
}

resource "aws_cloudwatch_metric_alarm" "latency_p99" {
  alarm_name          = "${var.project}-high-latency"
  namespace           = "AWS/ApplicationELB"
  metric_name         = "TargetResponseTime"
  extended_statistic  = "p99"
  period              = 300
  evaluation_periods  = 3
  threshold           = 2
  comparison_operator = "GreaterThanThreshold"
  alarm_actions       = [aws_sns_topic.alerts.arn]
  dimensions          = { LoadBalancer = var.alb_arn_suffix }
}

resource "aws_cloudwatch_metric_alarm" "ecs_cpu" {
  alarm_name          = "${var.project}-ecs-cpu"
  namespace           = "AWS/ECS"
  metric_name         = "CPUUtilization"
  statistic           = "Average"
  period              = 300
  evaluation_periods  = 3
  threshold           = 80
  comparison_operator = "GreaterThanThreshold"
  alarm_actions       = [aws_sns_topic.alerts.arn]
  dimensions          = { ClusterName = var.ecs_cluster_name, ServiceName = var.ecs_service_name }
}

resource "aws_budgets_budget" "monthly" {
  name         = "${var.project}-monthly"
  budget_type  = "COST"
  limit_amount = "500"
  limit_unit   = "USD"
  time_unit    = "MONTHLY"

  notification {
    comparison_operator        = "GREATER_THAN"
    threshold                  = 80
    threshold_type             = "PERCENTAGE"
    notification_type          = "ACTUAL"
    subscriber_email_addresses = [var.alert_email]
  }
}
```

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