fix(cloudwatch_metrics): revert to cron expression

modules/cloudwatch_metrics/main.tf

@@ -36,10 +36,20 @@ resource "aws_iam_role_policy_attachment" "this" {
   policy_arn = aws_iam_policy.this.arn
 }
 
+
+
+locals {
+  cron_expression = coalesce(
+    var.interval >= 60 && var.interval < 60 * 60 ? "*/${var.interval / 60} * * * ? *" : "",                # minutely
+    var.interval >= 60 * 60 && var.interval < 24 * 60 * 60 ? "0 */${var.interval / 60 / 60} * * ? *" : "", # hourly
+    var.interval >= 24 * 60 * 60 ? "0 0 */${var.interval / 24 / 60 / 60} * ? *" : "",                      # daily
+  )
+}
+
 resource "aws_cloudwatch_event_rule" "trigger" {
   name_prefix         = var.eventbridge_name_prefix
   description         = "Periodically trigger Observe Lambda to collect CloudWatch metrics"
-  schedule_expression = var.interval == 60 ? "rate(1 minute)" : "rate(${var.interval / 60} minutes)"
+  schedule_expression = "cron(${local.cron_expression})"
   event_bus_name      = var.eventbridge_schedule_event_bus_name
 }
 

modules/cloudwatch_metrics/variables.tf

@@ -35,8 +35,8 @@ variable "interval" {
   nullable    = false
   default     = 300
   validation {
-    condition     = var.interval >= 60 && var.interval <= 10800
-    error_message = "interval must be in [60, 10800] (1 minute to 3 hours)"
+    condition     = (var.interval >= 60 && var.interval <= 60 * 60) || (var.interval >= 60 * 60 && var.interval <= 24 * 60 * 60 && var.interval % (60 * 60) == 0)
+    error_message = "interval must be minutely, up to an hour, or hourly, up to a day"
   }
 }