Re-use the RESTMapper from the ctrl.Manager in the dynamic watcher

docs/addon/walkthrough/README.md

@@ -176,7 +176,7 @@ func (r *GuestbookReconciler) SetupWithManager(mgr ctrl.Manager) error {
 	}
 
 	// Watch for changes to deployed objects
-	_, err = declarative.WatchAll(mgr.GetConfig(), c, r, r.watchLabels)
+	_, err = declarative.WatchChildren(declarative.WatchChildrenOptions{Manager: mgr, Controller: c, Reconciler: r, LabelMaker: r.watchLabels})
 	if err != nil {
 		return err
 	}

examples/guestbook-operator/controllers/guestbook_controller.go

@@ -79,7 +79,7 @@ func (r *GuestbookReconciler) SetupWithManager(mgr ctrl.Manager) error {
 	}
 
 	// Watch for changes to deployed objects
-	_, err = declarative.WatchAll(mgr.GetConfig(), c, r, r.watchLabels)
+	_, err = declarative.WatchChildren(declarative.WatchChildrenOptions{Manager: mgr, Controller: c, Reconciler: r, LabelMaker: r.watchLabels})
 	if err != nil {
 		return err
 	}

pkg/patterns/declarative/pkg/watch/dynamic.go

@@ -27,37 +27,27 @@ import (
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/watch"
 	"k8s.io/client-go/dynamic"
-	"k8s.io/client-go/rest"
 	"sigs.k8s.io/controller-runtime/pkg/client"
-	"sigs.k8s.io/controller-runtime/pkg/client/apiutil"
 	"sigs.k8s.io/controller-runtime/pkg/event"
 	"sigs.k8s.io/controller-runtime/pkg/log"
 )
 
 // WatchDelay is the time between a Watch being dropped and attempting to resume it
 const WatchDelay = 30 * time.Second
 
-func NewDynamicWatch(config rest.Config) (*dynamicWatch, chan event.GenericEvent, error) {
-	dw := &dynamicWatch{events: make(chan event.GenericEvent)}
-
-	restMapper, err := apiutil.NewDiscoveryRESTMapper(&config)
-	if err != nil {
-		return nil, nil, err
-	}
-
-	client, err := dynamic.NewForConfig(&config)
-	if err != nil {
-		return nil, nil, err
+// NewDynamicWatch constructs a watcher for unstructured objects.
+// Deprecated: avoid using directly; will move to internal in future.
+func NewDynamicWatch(restMapper meta.RESTMapper, client dynamic.Interface) (*dynamicWatch, chan event.GenericEvent, error) {
+	dw := &dynamicWatch{
+		events:     make(chan event.GenericEvent),
+		restMapper: restMapper,
+		client:     client,
 	}
 
-	dw.restMapper = restMapper
-	dw.config = config
-	dw.client = client
 	return dw, dw.events, nil
 }
 
 type dynamicWatch struct {
-	config     rest.Config
 	client     dynamic.Interface
 	restMapper meta.RESTMapper
 	events     chan event.GenericEvent

pkg/patterns/declarative/watch.go

@@ -21,10 +21,14 @@ import (
 	"fmt"
 	"sync"
 
+	"k8s.io/apimachinery/pkg/api/meta"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/labels"
 	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/client-go/dynamic"
 	"k8s.io/client-go/rest"
+	ctrl "sigs.k8s.io/controller-runtime"
+	"sigs.k8s.io/controller-runtime/pkg/client/apiutil"
 	"sigs.k8s.io/controller-runtime/pkg/controller"
 	"sigs.k8s.io/controller-runtime/pkg/handler"
 	"sigs.k8s.io/controller-runtime/pkg/log"
@@ -45,7 +49,10 @@ type DynamicWatch interface {
 
 // WatchChildrenOptions configures how we want to watch children.
 type WatchChildrenOptions struct {
-	// RESTConfig is the configuration for connecting to the cluster
+	// Manager is used as a factory for the default RESTConfig and the RESTMapper.
+	Manager ctrl.Manager
+
+	// RESTConfig is the configuration for connecting to the cluster.
 	RESTConfig *rest.Config
 
 	// LabelMaker is used to build the labels we should watch on.
@@ -81,7 +88,31 @@ func WatchChildren(options WatchChildrenOptions) (chan struct{}, error) {
 		return nil, fmt.Errorf("labelMaker is required to scope watches")
 	}
 
-	dw, events, err := watch.NewDynamicWatch(*options.RESTConfig)
+	if options.RESTConfig == nil {
+		if options.Manager != nil {
+			options.RESTConfig = options.Manager.GetConfig()
+		} else {
+			return nil, fmt.Errorf("RESTConfig or Manager should be set")
+		}
+	}
+
+	var restMapper meta.RESTMapper
+	if options.Manager != nil {
+		restMapper = options.Manager.GetRESTMapper()
+	} else {
+		rm, err := apiutil.NewDiscoveryRESTMapper(options.RESTConfig)
+		if err != nil {
+			return nil, err
+		}
+		restMapper = rm
+	}
+
+	client, err := dynamic.NewForConfig(options.RESTConfig)
+	if err != nil {
+		return nil, err
+	}
+
+	dw, events, err := watch.NewDynamicWatch(restMapper, client)
 	if err != nil {
 		return nil, fmt.Errorf("creating dynamic watch: %v", err)
 	}