Adding alarm for low credit balance on EFS

Author: adenot

_variables.tf

@@ -125,6 +125,11 @@ variable "alarm_alb_400_errors_threshold" {
   default     = 10
 }
 
+variable "alarm_efs_credits_low_threshold" {
+  description = "Alerts when EFS credits fell below this number in bytes - default 1000000000000 is 1TB of a maximum of 2.31T of credits (use 0 to disable this alarm)"
+  default     = 1000000000000
+}
+
 variable "expire_backup_efs" {
   default     = 0
   description = "Number of days the backup will be expired"

cloutwatch-alarms-efs.tf

@@ -0,0 +1,21 @@
+resource "aws_cloudwatch_metric_alarm" "efs_credits_low" {
+  count = length(var.alarm_sns_topics) > 0 && var.alarm_efs_credits_low_threshold != 0 ? 1 : 0
+
+  alarm_name                = "${data.aws_iam_account_alias.current.account_alias}-ecs-${var.name}-efs-credits-low"
+  comparison_operator       = "LessThanOrEqualToThreshold"
+  evaluation_periods        = "3"
+  metric_name               = "BurstCreditBalance"
+  namespace                 = "AWS/EFS"
+  period                    = "120"
+  statistic                 = "Average"
+  threshold                 = var.alarm_efs_credits_low_threshold
+  alarm_description         = "EFS credits below threshold"
+  alarm_actions             = var.alarm_sns_topics
+  ok_actions                = var.alarm_sns_topics
+  insufficient_data_actions = []
+  treat_missing_data        = "ignore"
+
+  dimensions = {
+    FileSystemId = aws_efs_file_system.ecs.id
+  }
+}