Disable CDN health probes

Front Door's health probes are designed to detect situations where an origin is unavailable or unhealthy. When a health probe detects a problem with an origin, Front Door can be configured to send traffic to another origin in the origin group.

If you only have a single origin, Front Door always routes traffic to that origin even if its health probe reports an unhealthy status. The status of the health probe doesn't do anything to change Front Door's behavior. In this scenario, health probes don't provide a benefit and you should disable them to reduce the traffic on your origin.

terraform/README.md

@@ -169,6 +169,7 @@ No resources.
 | <a name="input_dns_txt_records"></a> [dns\_txt\_records](#input\_dns\_txt\_records) | DNS TXT records to add to the DNS Zone | <pre>map(<br>    object({<br>      ttl : optional(number, 300),<br>      records : list(string)<br>    })<br>  )</pre> | n/a | yes |
 | <a name="input_dns_zone_domain_name"></a> [dns\_zone\_domain\_name](#input\_dns\_zone\_domain\_name) | DNS zone domain name. If created, records will automatically be created to point to the CDN. | `string` | n/a | yes |
 | <a name="input_enable_cdn_frontdoor"></a> [enable\_cdn\_frontdoor](#input\_enable\_cdn\_frontdoor) | Enable Azure CDN Front Door. This will use the Container Apps endpoint as the origin. | `bool` | n/a | yes |
+| <a name="input_enable_cdn_frontdoor_health_probe"></a> [enable\_cdn\_frontdoor\_health\_probe](#input\_enable\_cdn\_frontdoor\_health\_probe) | Enable CDN Front Door health probe | `bool` | `false` | no |
 | <a name="input_enable_container_registry"></a> [enable\_container\_registry](#input\_enable\_container\_registry) | Set to true to create a container registry | `bool` | n/a | yes |
 | <a name="input_enable_dns_zone"></a> [enable\_dns\_zone](#input\_enable\_dns\_zone) | Conditionally create a DNS zone | `bool` | n/a | yes |
 | <a name="input_enable_event_hub"></a> [enable\_event\_hub](#input\_enable\_event\_hub) | Send Azure Container App logs to an Event Hub sink | `bool` | `false` | no |

terraform/container-apps-hosting.tf

@@ -38,6 +38,7 @@ module "azure_container_apps_hosting" {
   cdn_frontdoor_host_add_response_headers   = local.cdn_frontdoor_host_add_response_headers
   cdn_frontdoor_custom_domains              = local.cdn_frontdoor_custom_domains
   cdn_frontdoor_host_redirects              = local.cdn_frontdoor_host_redirects
+  enable_cdn_frontdoor_health_probe         = local.enable_cdn_frontdoor_health_probe
   container_apps_allow_ips_inbound          = local.container_apps_allow_ips_inbound
 
   enable_monitoring               = local.enable_monitoring

terraform/locals.tf

@@ -30,6 +30,7 @@ locals {
   cdn_frontdoor_custom_domains                 = var.cdn_frontdoor_custom_domains
   cdn_frontdoor_host_redirects                 = var.cdn_frontdoor_host_redirects
   cdn_frontdoor_health_probe_protocol          = var.cdn_frontdoor_health_probe_protocol
+  enable_cdn_frontdoor_health_probe            = var.enable_cdn_frontdoor_health_probe
   key_vault_access_ipv4                        = var.key_vault_access_ipv4
   tfvars_filename                              = var.tfvars_filename
   enable_monitoring                            = var.enable_monitoring

terraform/variables.tf

@@ -269,3 +269,9 @@ variable "statuscake_contact_group_email_addresses" {
   type        = list(string)
   default     = []
 }
+
+variable "enable_cdn_frontdoor_health_probe" {
+  description = "Enable CDN Front Door health probe"
+  type        = bool
+  default     = false
+}