[YUNIKORN-2502] Add YuniKorn internal domain name to yunikorn-scheduler-interface (#132)

Closes: #132

Signed-off-by: Yu-Lin Chen <chenyulin0719@apache.org>
diff --git a/lib/go/common/constants.go b/lib/go/common/constants.go
index c28b8f9..ce01fa8 100644
--- a/lib/go/common/constants.go
+++ b/lib/go/common/constants.go
@@ -39,8 +39,9 @@
 // Constants for allocation tags
 const (
 	// Domains
-	DomainK8s      = "kubernetes.io/"
-	DomainYuniKorn = "yunikorn.apache.org/"
+	DomainK8s              = "kubernetes.io/"
+	DomainYuniKorn         = "yunikorn.apache.org/"
+	DomainYuniKornInternal = "internal.yunikorn.apache.org/"
 
 	// Groups
 	GroupMeta       = "meta/"
diff --git a/scheduler-interface-spec.md b/scheduler-interface-spec.md
index 3f98633..67aa3df 100644
--- a/scheduler-interface-spec.md
+++ b/scheduler-interface-spec.md
@@ -744,8 +744,9 @@
 // Constants for allocation tags
 const (
 	// Domains
-	DomainK8s      = "kubernetes.io/"
-	DomainYuniKorn = "yunikorn.apache.org/"
+	DomainK8s              = "kubernetes.io/"
+	DomainYuniKorn         = "yunikorn.apache.org/"
+	DomainYuniKornInternal = "internal.yunikorn.apache.org/"
 
 	// Groups
 	GroupMeta       = "meta/"