Update predicate

generic.go

@@ -105,9 +105,10 @@ func NewGeneric(config *Config, queue workqueue.RateLimitingInterface, workers i
 				return nil, errors.Errorf("controller for GVK %s should have registered an informer for that GVK", descr.Gvk)
 			}
 			inf.AddEventHandler(&GenericHandler{
-				Logger:       controllerLogger,
-				WorkQueue:    queueGvk,
-				ZapNameField: logz.ControllerName,
+				Logger:              controllerLogger,
+				WorkQueue:           queueGvk,
+				IsInterestingUpdate: descr.IsInterestingUpdate,
+				ZapNameField:        logz.ControllerName,
 			})
 
 			controllers[descr.Gvk] = constructed.Interface

generic_handler.go

@@ -4,21 +4,27 @@ import (
 	"github.com/atlassian/ctrl/logz"
 	"go.uber.org/zap"
 	meta_v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/client-go/tools/cache"
 )
 
 // This handler assumes that the Logger already has the obj_gk/ctrl_gk field set.
 type GenericHandler struct {
-	Logger       *zap.Logger
-	WorkQueue    WorkQueueProducer
-	ZapNameField ZapNameField
+	Logger    *zap.Logger
+	WorkQueue WorkQueueProducer
+	// IsInterestingUpdate is an optional predicate that is consulted before enqueuing an object on update event.
+	IsInterestingUpdate func(oldObj, newObj runtime.Object) bool
+	ZapNameField        ZapNameField
 }
 
 func (g *GenericHandler) OnAdd(obj interface{}) {
 	g.add(obj.(meta_v1.Object), "added")
 }
 
 func (g *GenericHandler) OnUpdate(oldObj, newObj interface{}) {
+	if g.IsInterestingUpdate != nil && !g.IsInterestingUpdate(oldObj.(runtime.Object), newObj.(runtime.Object)) {
+		return
+	}
 	g.add(newObj.(meta_v1.Object), "updated")
 }
 

types.go

@@ -22,6 +22,8 @@ type ZapNameField func(name string) zap.Field
 type Descriptor struct {
 	// Group Version Kind of objects a controller can process.
 	Gvk schema.GroupVersionKind
+	// IsInterestingUpdate is an optional predicate that is consulted before enqueuing an object on update event.
+	IsInterestingUpdate func(oldObj, newObj runtime.Object) bool
 }
 
 type Server interface {