Init watch on ManagedCluster in gateway controller

Adds the watch for ManagedCluster resources to the gateway controller
and adds an additional step in the reconcile (reconcileClusterLabels) to
map the kuadrant.io labels from cluster(s) to gateway.

reconcileClusterLabels - Not Implemented

pkg/controllers/events/cluster_eventmapper.go

@@ -0,0 +1,72 @@
+package events
+
+import (
+	"context"
+	"encoding/json"
+
+	"github.com/go-logr/logr"
+
+	"sigs.k8s.io/controller-runtime/pkg/client"
+	"sigs.k8s.io/controller-runtime/pkg/reconcile"
+	gatewayapiv1 "sigs.k8s.io/gateway-api/apis/v1"
+
+	"github.com/Kuadrant/multicluster-gateway-controller/pkg/_internal/metadata"
+	"github.com/Kuadrant/multicluster-gateway-controller/pkg/_internal/slice"
+)
+
+// ClusterEventMapper is an EventHandler that maps Cluster object events to gateway events.
+//
+// Cluster object can be anything that represents a cluster and has mgc attribute labels applied to (e.g. OCM ManagedCluster)
+type ClusterEventMapper struct {
+	Logger logr.Logger
+	Client client.Client
+}
+
+func NewClusterEventMapper(logger logr.Logger, client client.Client) *ClusterEventMapper {
+	log := logger.WithName("ClusterEventMapper")
+	return &ClusterEventMapper{
+		Logger: log,
+		Client: client,
+	}
+}
+
+func (m *ClusterEventMapper) MapToGateway(ctx context.Context, obj client.Object) []reconcile.Request {
+	return m.mapToGatewayRequest(ctx, obj)
+}
+
+func (m *ClusterEventMapper) mapToGatewayRequest(ctx context.Context, obj client.Object) []reconcile.Request {
+	logger := m.Logger.V(1).WithValues("object", client.ObjectKeyFromObject(obj))
+
+	if obj.GetDeletionTimestamp() != nil {
+		// Ignore ManagedCluster delete events.
+		// Create/Update events are OK as ManagedCluster custom attributes may change, affecting DNSPolicies.
+		// However, deleting a ManagedCluster shouldn't affect the DNSPolicy directly until the related
+		// Gateway is deleted from that ManagedCluster (and reconciled then via watching Gateways, not ManagedClusters)
+		return []reconcile.Request{}
+	}
+
+	clusterName := obj.GetName()
+
+	allGwList := &gatewayapiv1.GatewayList{}
+	err := m.Client.List(ctx, allGwList)
+	if err != nil {
+		logger.Info("mapToPolicyRequest:", "error", "failed to get gateways")
+		return []reconcile.Request{}
+	}
+
+	requests := make([]reconcile.Request, 0)
+	for _, gw := range allGwList.Items {
+		val := metadata.GetAnnotation(&gw, "kuadrant.io/gateway-clusters")
+		if val == "" {
+			continue
+		}
+		var clusters []string
+		if err = json.Unmarshal([]byte(val), &clusters); err == nil {
+			if slice.ContainsString(clusters, clusterName) {
+				requests = append(requests, reconcile.Request{NamespacedName: client.ObjectKeyFromObject(&gw)})
+			}
+		}
+	}
+
+	return requests
+}

pkg/controllers/gateway/gateway_controller.go

@@ -24,6 +24,7 @@ import (
 	"reflect"
 	"time"
 
+	clusterv1 "open-cluster-management.io/api/cluster/v1"
 	clusterv1beta2 "open-cluster-management.io/api/cluster/v1beta1"
 	workv1 "open-cluster-management.io/api/work/v1"
 
@@ -49,6 +50,7 @@ import (
 	"github.com/Kuadrant/multicluster-gateway-controller/pkg/_internal/gracePeriod"
 	"github.com/Kuadrant/multicluster-gateway-controller/pkg/_internal/metadata"
 	"github.com/Kuadrant/multicluster-gateway-controller/pkg/_internal/slice"
+	"github.com/Kuadrant/multicluster-gateway-controller/pkg/controllers/events"
 	"github.com/Kuadrant/multicluster-gateway-controller/pkg/policysync"
 	"github.com/Kuadrant/multicluster-gateway-controller/pkg/utils"
 )
@@ -195,6 +197,12 @@ func (r *GatewayReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ct
 	}
 	metadata.AddAnnotation(upstreamGateway, GatewayClustersAnnotation, string(serialized))
 
+	// Map cluster labels onto the gateway
+	err = r.reconcileClusterLabels(ctx, upstreamGateway, clusters)
+	if err != nil {
+		return ctrl.Result{}, err
+	}
+
 	if reconcileErr == nil && !reflect.DeepEqual(upstreamGateway, previous) {
 		log.Info("updating upstream gateway")
 		return reconcile.Result{}, r.Update(ctx, upstreamGateway)
@@ -264,6 +272,17 @@ func (r *GatewayReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ct
 	return ctrl.Result{}, reconcileErr
 }
 
+func (r *GatewayReconciler) reconcileClusterLabels(ctx context.Context, gateway *gatewayapiv1.Gateway, clusters []string) error {
+	//ToDo Implement me !!
+
+	//Iterate clusters and for each find the ManagedCluster resource, get its labels and convert all "kuadrant.io/" labels to a cluster specific label and add it to the gateway
+	// (cluster kind-mgc-workload-1 label) kuadrant.io/lb-attribute-custom-weight=AWS = (gateway label) kuadrant.io/kind-mgc-workload-1_lb-attribute-custom-weight=AWS
+	// (cluster kind-mgc-workload-2 label) kuadrant.io/lb-attribute-geo-code=ES = (gateway label) kuadrant.io/kind-mgc-workload-2_lb-attribute-geo-code=ES
+	// etc ...
+
+	return nil
+}
+
 // reconcileDownstreamGateway takes the upstream definition and transforms it as needed to apply it to the downstream spokes
 func (r *GatewayReconciler) reconcileDownstreamFromUpstreamGateway(ctx context.Context, upstreamGateway *gatewayapiv1.Gateway, params *Params) (bool, metav1.ConditionStatus, []string, error) {
 	log := crlog.FromContext(ctx)
@@ -475,7 +494,7 @@ func buildAcceptedCondition(generation int64, acceptedStatus metav1.ConditionSta
 // SetupWithManager sets up the controller with the Manager.
 func (r *GatewayReconciler) SetupWithManager(mgr ctrl.Manager, ctx context.Context) error {
 	log := crlog.FromContext(ctx)
-
+	clusterEventMapper := events.NewClusterEventMapper(log, mgr.GetClient())
 	//TODO need to trigger gateway reconcile when gatewayclass params changes
 	return ctrl.NewControllerManagedBy(mgr).
 		For(&gatewayapiv1.Gateway{}).
@@ -517,6 +536,10 @@ func (r *GatewayReconciler) SetupWithManager(mgr ctrl.Manager, ctx context.Conte
 			return req
 		})).
 		Watches(&corev1.Secret{}, &ClusterEventHandler{client: r.Client}).
+		Watches(
+			&clusterv1.ManagedCluster{},
+			handler.EnqueueRequestsFromMapFunc(clusterEventMapper.MapToGateway),
+		).
 		WithEventFilter(predicate.NewPredicateFuncs(func(object client.Object) bool {
 			gateway, ok := object.(*gatewayapiv1.Gateway)
 			if ok {