DTOSS-00000: Add alerting availability test

The application insights web availability test was firing but it was not
firing the alert to the email group because the azurerm_monitor_metric_alert
resource was missing. This simply adds this alert into the child module.

Author: mrlockstar

infrastructure/modules/application-insights-availability-test/main.tf

@@ -14,3 +14,21 @@ resource "azurerm_application_insights_standard_web_test" "this" {
 
   geo_locations = var.geo_locations
 }
+
+resource "azurerm_monitor_metric_alert" "this" {
+  name                = "${var.name}-availability-alert"
+  resource_group_name = var.resource_group_name
+  scopes              = [azurerm_application_insights_standard_web_test.this.id, var.application_insights_id]
+  description         = "availability test alert"
+  severity            = 0
+
+  application_insights_web_test_location_availability_criteria {
+    web_test_id           = azurerm_application_insights_standard_web_test.this.id
+    component_id          = var.application_insights_id
+    failed_location_count = 2
+  }
+
+  action {
+    action_group_id = var.action_group_id
+  }
+}

infrastructure/modules/application-insights-availability-test/tfdocs.md

@@ -4,6 +4,12 @@
 
 The following input variables are required:
 
+### <a name="input_action_group_id"></a> [action\_group\_id](#input\_action\_group\_id)
+
+Description: ID of the action group to notify.
+
+Type: `string`
+
 ### <a name="input_application_insights_id"></a> [application\_insights\_id](#input\_application\_insights\_id)
 
 Description: The Application Insights resource id to associate the availability test with
@@ -78,3 +84,4 @@ Default: `30`
 The following resources are used by this module:
 
 - [azurerm_application_insights_standard_web_test.this](https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/application_insights_standard_web_test) (resource)
+- [azurerm_monitor_metric_alert.this](https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/monitor_metric_alert) (resource)

infrastructure/modules/application-insights-availability-test/variables.tf

@@ -23,6 +23,11 @@ variable "application_insights_id" {
   description = "The Application Insights resource id to associate the availability test with"
 }
 
+variable "action_group_id" {
+  type        = string
+  description = "ID of the action group to notify."
+}
+
 variable "frequency" {
   type    = number
   default = 300