add support for custom periods in factory budgets (#3674)

modules/billing-account/README.md

@@ -247,7 +247,7 @@ module "billing-account" {
     budgets_data_path = "data/billing-budgets"
   }
 }
-# tftest modules=1 resources=2 files=test-1  inventory=budget-monitoring-channel.yaml
+# tftest modules=1 resources=2 files=test-1  inventory=budget-factory.yaml
 ```
 
 ```yaml
@@ -256,7 +256,11 @@ amount:
   units: 100
 filter:
   period:
-    calendar: MONTH
+    custom:
+      start_date:
+        day: 1
+        month: 1
+        year: 2026
   resource_ancestors:
   - folders/1234567890
 threshold_rules:

modules/billing-account/budgets.tf

@@ -54,10 +54,6 @@ resource "google_monitoring_notification_channel" "default" {
 #       condition     = local.factory_budgets == null
 #       error_message = yamlencode(local.factory_budgets)
 #     }
-#     precondition {
-#       condition     = local.factory_budgets == null
-#       error_message = yamlencode(local.ctx.project_sets)
-#     }
 #   }
 # }
 

modules/billing-account/factory.tf

@@ -44,7 +44,11 @@ locals {
             v.filter.credit_types_treatment
           )
         )
-        label              = try(v.filter.label, null)
+        label = try(v.filter.label, null)
+        period = try(v.filter.period, null) == null ? null : merge(
+          { calendar = null, end_date = null, start_date = null },
+          v.filter.period
+        )
         projects           = try(v.filter.projects, [])
         resource_ancestors = try(v.filter.resource_ancestors, [])
         services           = try(v.filter.services, null)