Add 'WithTransform' SharedInformerOption

Also add support for metadata informer factory to use SharedInformerOption

Signed-off-by: Eric Lin <exlin@google.com>

staging/src/k8s.io/client-go/metadata/metadatainformer/informer.go

@@ -21,6 +21,7 @@ import (
 	"sync"
 	"time"
 
+	v1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
@@ -31,6 +32,17 @@ import (
 	"k8s.io/client-go/tools/cache"
 )
 
+// SharedInformerOption defines the functional option type for metadataSharedInformerFactory.
+type SharedInformerOption func(*metadataSharedInformerFactory) *metadataSharedInformerFactory
+
+// WithTransform sets a transform on all informers.
+func WithTransform(transform cache.TransformFunc) SharedInformerOption {
+	return func(factory *metadataSharedInformerFactory) *metadataSharedInformerFactory {
+		factory.transform = transform
+		return factory
+	}
+}
+
 // NewSharedInformerFactory constructs a new instance of metadataSharedInformerFactory for all namespaces.
 func NewSharedInformerFactory(client metadata.Interface, defaultResync time.Duration) SharedInformerFactory {
 	return NewFilteredSharedInformerFactory(client, defaultResync, metav1.NamespaceAll, nil)
@@ -49,10 +61,29 @@ func NewFilteredSharedInformerFactory(client metadata.Interface, defaultResync t
 	}
 }
 
+// NewSharedInformerFactoryWithOptions constructs a new instance of metadataSharedInformerFactory with additional options.
+func NewSharedInformerFactoryWithOptions(client metadata.Interface, defaultResync time.Duration, options ...SharedInformerOption) SharedInformerFactory {
+	factory := &metadataSharedInformerFactory{
+		client:           client,
+		namespace:        v1.NamespaceAll,
+		defaultResync:    defaultResync,
+		informers:        map[schema.GroupVersionResource]informers.GenericInformer{},
+		startedInformers: make(map[schema.GroupVersionResource]bool),
+	}
+
+	// Apply all options
+	for _, opt := range options {
+		factory = opt(factory)
+	}
+
+	return factory
+}
+
 type metadataSharedInformerFactory struct {
 	client        metadata.Interface
 	defaultResync time.Duration
 	namespace     string
+	transform     cache.TransformFunc
 
 	lock      sync.Mutex
 	informers map[schema.GroupVersionResource]informers.GenericInformer
@@ -80,6 +111,7 @@ func (f *metadataSharedInformerFactory) ForResource(gvr schema.GroupVersionResou
 	}
 
 	informer = NewFilteredMetadataInformer(f.client, gvr, f.namespace, f.defaultResync, cache.Indexers{cache.NamespaceIndex: cache.MetaNamespaceIndexFunc}, f.tweakListOptions)
+	informer.Informer().SetTransform(f.transform)
 	f.informers[key] = informer
 
 	return informer

staging/src/k8s.io/code-generator/cmd/informer-gen/generators/factory.go

@@ -75,6 +75,7 @@ func (g *factoryGenerator) GenerateType(c *generator.Context, t *types.Type, w i
 	}
 	m := map[string]interface{}{
 		"cacheSharedIndexInformer":       c.Universe.Type(cacheSharedIndexInformer),
+		"cacheTransformFunc":             c.Universe.Type(cacheTransformFunc),
 		"groupVersions":                  g.groupVersions,
 		"gvInterfaces":                   gvInterfaces,
 		"gvNewFuncs":                     gvNewFuncs,
@@ -109,6 +110,7 @@ type sharedInformerFactory struct {
 	lock {{.syncMutex|raw}}
 	defaultResync {{.timeDuration|raw}}
 	customResync map[{{.reflectType|raw}}]{{.timeDuration|raw}}
+	transform {{.cacheTransformFunc|raw}}
 
 	informers map[{{.reflectType|raw}}]{{.cacheSharedIndexInformer|raw}}
 	// startedInformers is used for tracking which informers have been started.
@@ -147,6 +149,14 @@ func WithNamespace(namespace string) SharedInformerOption {
 	}
 }
 
+// WithTransform sets a transform on all informers.
+func WithTransform(transform {{.cacheTransformFunc|raw}}) SharedInformerOption {
+	return func(factory *sharedInformerFactory) *sharedInformerFactory {
+		factory.transform = transform
+		return factory
+	}
+}
+
 // NewSharedInformerFactory constructs a new instance of sharedInformerFactory for all namespaces.
 func NewSharedInformerFactory(client {{.clientSetInterface|raw}}, defaultResync {{.timeDuration|raw}}) SharedInformerFactory {
 	return NewSharedInformerFactoryWithOptions(client, defaultResync)
@@ -252,11 +262,11 @@ func (f *sharedInformerFactory) InformerFor(obj {{.runtimeObject|raw}}, newFunc
   }
 
   informer = newFunc(f.client, resyncPeriod)
+  informer.SetTransform(f.transform)
   f.informers[informerType] = informer
 
   return informer
 }
-
 `
 
 var sharedInformerFactoryInterface = `

staging/src/k8s.io/code-generator/cmd/informer-gen/generators/types.go

@@ -28,6 +28,7 @@ var (
 	cacheNewGenericLister       = types.Name{Package: "k8s.io/client-go/tools/cache", Name: "NewGenericLister"}
 	cacheNewSharedIndexInformer = types.Name{Package: "k8s.io/client-go/tools/cache", Name: "NewSharedIndexInformer"}
 	cacheSharedIndexInformer    = types.Name{Package: "k8s.io/client-go/tools/cache", Name: "SharedIndexInformer"}
+	cacheTransformFunc          = types.Name{Package: "k8s.io/client-go/tools/cache", Name: "TransformFunc"}
 	listOptions                 = types.Name{Package: "k8s.io/kubernetes/pkg/apis/core", Name: "ListOptions"}
 	reflectType                 = types.Name{Package: "reflect", Name: "Type"}
 	runtimeObject               = types.Name{Package: "k8s.io/apimachinery/pkg/runtime", Name: "Object"}