Fixes #6741

* Add support for frontdoor_id computed attribute

* Updated name of new attribute

azurerm/internal/services/frontdoor/frontdoor_resource.go

@@ -51,6 +51,11 @@ func resourceArmFrontDoor() *schema.Resource {
 				Computed: true,
 			},
 
+			"header_frontdoor_id": {
+				Type:     schema.TypeString,
+				Computed: true,
+			},
+
 			"friendly_name": {
 				Type:     schema.TypeString,
 				Optional: true,
@@ -705,6 +710,7 @@ func resourceArmFrontDoorRead(d *schema.ResourceData, meta interface{}) error {
 		}
 
 		d.Set("cname", properties.Cname)
+		d.Set("header_frontdoor_id", properties.FrontdoorID)
 		d.Set("load_balancer_enabled", properties.EnabledState == frontdoor.EnabledStateEnabled)
 		d.Set("friendly_name", properties.FriendlyName)
 

website/docs/r/frontdoor.html.markdown

@@ -294,12 +294,12 @@ The following attributes are exported:
 
 * `cname` - The host that each frontendEndpoint must CNAME to.
 
+* `header_frontdoor_id` - The unique ID of the Front Door which is embedded into the incoming headers `X-Azure-FDID` attribute and maybe used to filter traffic sent by the Front Door to your backend.
+
 * `id` - The ID of the FrontDoor.
 
 ## Timeouts
 
-
-
 The `timeouts` block allows you to specify [timeouts](https://www.terraform.io/docs/configuration/resources.html#timeouts) for certain actions:
 
 * `create` - (Defaults to 6 hours) Used when creating the FrontDoor.