Expose the monitoring path in the Cloud Run module, otherwise we can't set it up.

Also remove the alerting_enabled default to false for two reasons:
1) To force the developer to make a decision on monitoring
2) If alerting_enabled is true but alerting_email_address is not set up, then there is not much point as we don't have any other channel set up.

main.tf

@@ -145,8 +145,9 @@ module "uptime_monitoring" {
   source           = "./modules/monitoring"
   project          = var.project
   email_address    = var.alerting_email_address
-  monitored_domain = var.dns_name
   uptime_timeout   = var.alerting_uptime_timeout
   uptime_period    = var.alerting_uptime_period
+  monitored_domain = var.dns_name
+  polling_path     = var.monitoring_path
   enabled          = var.alerting_enabled
 }

variables.tf

@@ -113,6 +113,11 @@ variable "alerting_uptime_period" {
 
 variable "alerting_enabled" {
   type        = bool
-  default     = true
   description = "Whether alerting policy is enabled"
 }
+
+variable "monitoring_path" {
+  type        = string
+  default     = "/"
+  description = "path component of url to be monitored"
+}