Add suport for cluster scoped controllers

Some worload controllers need to watch resoruces in the mangement plane
and react to them. But, they should only react to resources that
correspond to their cluster. This adds framework support for that.

controller/cluster_check.go

@@ -0,0 +1,59 @@
+package controller
+
+import (
+	"reflect"
+	"strings"
+)
+
+func ObjectInCluster(cluster string, obj interface{}) bool {
+	var clusterName string
+	if c := getValue(obj, "ClusterName"); c.IsValid() {
+		clusterName = c.String()
+	}
+	if clusterName == "" {
+		if c := getValue(obj, "Spec", "ClusterName"); c.IsValid() {
+			clusterName = c.String()
+		}
+
+	}
+	if clusterName == "" {
+		if c := getValue(obj, "ProjectName"); c.IsValid() {
+			if parts := strings.SplitN(c.String(), ":", 2); len(parts) == 2 {
+				clusterName = parts[0]
+			}
+		}
+	}
+	if clusterName == "" {
+		if c := getValue(obj, "Spec", "ProjectName"); c.IsValid() {
+			if parts := strings.SplitN(c.String(), ":", 2); len(parts) == 2 {
+				clusterName = parts[0]
+			}
+		}
+	}
+
+	return clusterName == cluster
+}
+
+func getValue(obj interface{}, name ...string) reflect.Value {
+	v := reflect.ValueOf(obj)
+	t := v.Type()
+	if t.Kind() == reflect.Ptr {
+		v = v.Elem()
+		t = v.Type()
+	}
+
+	field := v.FieldByName(name[0])
+	if !field.IsValid() || len(name) == 1 {
+		return field
+	}
+
+	return getFieldValue(field, name[1:]...)
+}
+
+func getFieldValue(v reflect.Value, name ...string) reflect.Value {
+	field := v.FieldByName(name[0])
+	if len(name) == 1 {
+		return field
+	}
+	return getFieldValue(field, name[1:]...)
+}