Use annotation instead of field on cluster

Author: Nick Barber

controllers/suite_test.go

@@ -190,10 +190,8 @@ var _ = BeforeSuite(func() {
 		ObjectMeta: metav1.ObjectMeta{
 			Name:      "example-rabbit",
 			Namespace: "default",
-		},
-		Spec: rabbitmqv1beta1.RabbitmqClusterSpec{
-			MessagingTopologyNamespaces: []string{
-				"allowed",
+			Annotations: map[string]string{
+				"rabbitmq.topology.allowed-namespaces": "allowed",
 			},
 		},
 	}
@@ -240,10 +238,8 @@ var _ = BeforeSuite(func() {
 		ObjectMeta: metav1.ObjectMeta{
 			Name:      "allow-all-rabbit",
 			Namespace: "default",
-		},
-		Spec: rabbitmqv1beta1.RabbitmqClusterSpec{
-			MessagingTopologyNamespaces: []string{
-				"*",
+			Annotations: map[string]string{
+				"rabbitmq.topology.allowed-namespaces": "*",
 			},
 		},
 	}

internal/cluster_reference.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"strings"
 
 	rabbitmqv1beta1 "github.com/rabbitmq/cluster-operator/api/v1beta1"
 	topology "github.com/rabbitmq/messaging-topology-operator/api/v1beta1"
@@ -14,7 +15,7 @@ import (
 
 var (
 	NoSuchRabbitmqClusterError = errors.New("RabbitmqCluster object does not exist")
-	ResourceNotAllowedError    = errors.New("Resource is not allowed to reference defined cluster reference. Check the namespace of the resource is allowed as part of the cluster's .spec.messagingTopologyNamespaces field")
+	ResourceNotAllowedError    = errors.New("Resource is not allowed to reference defined cluster reference. Check the namespace of the resource is allowed as part of the cluster's `rabbitmq.topology.allowed-namespaces` annotation")
 )
 
 func ParseRabbitmqClusterReference(ctx context.Context, c client.Client, rmq topology.RabbitmqClusterReference, requestNamespace string) (*rabbitmqv1beta1.RabbitmqCluster, *corev1.Service, *corev1.Secret, error) {
@@ -31,10 +32,12 @@ func ParseRabbitmqClusterReference(ctx context.Context, c client.Client, rmq top
 
 	if rmq.Namespace != "" && rmq.Namespace != requestNamespace {
 		var isAllowed bool
-		for _, allowedNamespace := range cluster.Spec.MessagingTopologyNamespaces {
-			if requestNamespace == allowedNamespace || allowedNamespace == "*" {
-				isAllowed = true
-				break
+		if allowedNamespaces, ok := cluster.Annotations["rabbitmq.topology.allowed-namespaces"]; ok {
+			for _, allowedNamespace := range strings.Split(allowedNamespaces, ",") {
+				if requestNamespace == allowedNamespace || allowedNamespace == "*" {
+					isAllowed = true
+					break
+				}
 			}
 		}
 		if isAllowed == false {