diff --git a/variables.tf b/variables.tf
index d85840f..92da1e9 100644
--- a/variables.tf
+++ b/variables.tf
@@ -224,12 +224,12 @@ variable "hello_world_container_ports" {
 }
 
 variable "service_registries" {
-  description = "List of service registry objects as per <https://www.terraform.io/docs/providers/aws/r/ecs_service.html#service_registries-1>. List can only have a single object until <https://github.com/terraform-providers/terraform-provider-aws/issues/9573> is resolved."
+  description = "List of service registry objects as per <https://www.terraform.io/docs/providers/aws/r/ecs_service.html#service_registries-1>. List can only have a single object until <https://github.com/terraform-providers/terraform-provider-aws/issues/9573> is resolved. Either provide container_name and container_port or port"
   type = list(object({
     registry_arn   = string
-    container_name = string
-    container_port = number
-    port           = number
+    container_name = optional(string)
+    container_port = optional(number)
+    port           = optional(number)
   }))
   default = []
 }