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Provide layers referenced by an image stream as layers subresource
Adds a new GET endpoint to an image stream as a subresource `layers` that returns an array of every layer referenced by the image stream and the tags and images included by the image. The subresource is fed by a store driven informer that caches and indexes only the layers. Clients get a 500 retry error if the cache has not initialized yet (the client will silently retry). Turns the registry access check for a given layer into an O(1) check instead of O(N) where N is the number of images in the image stream.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,186 @@ | ||
| package etcd | ||
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| import ( | ||
| "fmt" | ||
|
|
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| metainternalversion "k8s.io/apimachinery/pkg/apis/meta/internalversion" | ||
| metav1 "k8s.io/apimachinery/pkg/apis/meta/v1" | ||
| "k8s.io/apimachinery/pkg/runtime" | ||
| "k8s.io/apimachinery/pkg/runtime/schema" | ||
| "k8s.io/apimachinery/pkg/types" | ||
| "k8s.io/apimachinery/pkg/watch" | ||
| apirequest "k8s.io/apiserver/pkg/endpoints/request" | ||
| "k8s.io/apiserver/pkg/registry/rest" | ||
| "k8s.io/client-go/tools/cache" | ||
|
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| imageapi "github.com/openshift/origin/pkg/image/apis/image" | ||
| ) | ||
|
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| // ImageLayerIndex is a cache of image digests to the layers they contain. | ||
| // Because a very large number of images can exist on a cluster, we only | ||
| // hold in memory a small subset of the full image object. | ||
| type ImageLayerIndex interface { | ||
| cache.SharedIndexInformer | ||
| } | ||
|
|
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| type ImageStore interface { | ||
| rest.Watcher | ||
| rest.Lister | ||
| } | ||
|
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| // NewImageLayerIndex creates a new index over a store that must return | ||
| // images. | ||
| func NewImageLayerIndex(store ImageStore) ImageLayerIndex { | ||
| ctx := apirequest.NewContext() | ||
| informer := cache.NewSharedIndexInformer(&cache.ListWatch{ | ||
| ListFunc: func(options metav1.ListOptions) (runtime.Object, error) { | ||
| obj, err := store.List(ctx, &metainternalversion.ListOptions{ | ||
| ResourceVersion: options.ResourceVersion, | ||
| Limit: options.Limit, | ||
| Continue: options.Continue, | ||
| }) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| list, ok := obj.(*imageapi.ImageList) | ||
| if !ok { | ||
| return nil, fmt.Errorf("unexpected store type %T for layer index", obj) | ||
| } | ||
| // reduce the full image list to a smaller subset. | ||
| out := &metainternalversion.List{ | ||
| Items: make([]runtime.Object, len(list.Items)), | ||
| } | ||
| out.Continue = list.Continue | ||
| out.ResourceVersion = list.ResourceVersion | ||
| for i, image := range list.Items { | ||
| out.Items[i] = &ImageLayers{ | ||
| Name: image.Name, | ||
| Layers: image.DockerImageLayers, | ||
| Manifest: manifestFromImage(&image), | ||
| } | ||
| } | ||
| return out, nil | ||
| }, | ||
| WatchFunc: func(options metav1.ListOptions) (watch.Interface, error) { | ||
| w, err := store.Watch(ctx, &metainternalversion.ListOptions{ | ||
| ResourceVersion: options.ResourceVersion, | ||
| }) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| return watch.Filter(w, func(in watch.Event) (out watch.Event, keep bool) { | ||
| if in.Object == nil { | ||
| return in, true | ||
| } | ||
| // reduce each object to the minimal subset we need for the cache | ||
| image, ok := in.Object.(*imageapi.Image) | ||
| if !ok { | ||
| return in, true | ||
| } | ||
| in.Object = &ImageLayers{ | ||
| Name: image.Name, | ||
| ResourceVersion: image.ResourceVersion, | ||
| Layers: image.DockerImageLayers, | ||
| Manifest: manifestFromImage(image), | ||
| } | ||
| return in, true | ||
| }), nil | ||
| }, | ||
| }, &ImageLayers{}, 0, cache.Indexers{ | ||
| // layers allows fast access to the images with a given layer | ||
| "layers": func(obj interface{}) ([]string, error) { | ||
| entry, ok := obj.(*ImageLayers) | ||
| if !ok { | ||
| return nil, fmt.Errorf("unexpected cache object %T", obj) | ||
| } | ||
| keys := make([]string, 0, len(entry.Layers)) | ||
| for _, layer := range entry.Layers { | ||
| keys = append(keys, layer.Name) | ||
| } | ||
| return keys, nil | ||
| }, | ||
| }) | ||
| return informer | ||
| } | ||
|
|
||
| // manifestFromImage attempts to find a manifest blob description from | ||
| // an image. Images older than schema2 in Docker do not have a manifest blob. | ||
| func manifestFromImage(image *imageapi.Image) *imageapi.ImageLayer { | ||
| if image.DockerImageManifestMediaType != "application/vnd.docker.distribution.manifest.v2+json" { | ||
| return nil | ||
| } | ||
| return &imageapi.ImageLayer{ | ||
| Name: image.DockerImageMetadata.ID, | ||
| MediaType: image.DockerImageManifestMediaType, | ||
| } | ||
| } | ||
|
|
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| // ImageLayers is the minimal set of data we need to retain to provide the cache. | ||
| // Unlike a more general informer cache, we do not retain the full object because of | ||
| // the potential size of the objects being stored. Even a small cluster may have 20k | ||
| // or more images in active use. | ||
| type ImageLayers struct { | ||
| Name string | ||
| ResourceVersion string | ||
| Manifest *imageapi.ImageLayer | ||
| Layers []imageapi.ImageLayer | ||
| } | ||
|
|
||
| var ( | ||
| _ runtime.Object = &ImageLayers{} | ||
| _ metav1.Object = &ImageLayers{} | ||
| ) | ||
|
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| func (l *ImageLayers) GetObjectKind() schema.ObjectKind { return &metav1.TypeMeta{} } | ||
| func (l *ImageLayers) DeepCopyObject() runtime.Object { | ||
| var layers []imageapi.ImageLayer | ||
| if l.Layers != nil { | ||
| layers = make([]imageapi.ImageLayer, len(l.Layers)) | ||
| copy(layers, l.Layers) | ||
| } | ||
| return &ImageLayers{ | ||
| Name: l.Name, | ||
| Layers: layers, | ||
| } | ||
| } | ||
|
|
||
| // client-go/cache.SharedIndexInformer hardcodes the key function to assume ObjectMeta. | ||
| // Here we implement the relevant accessors to allow a minimal index to be created. | ||
| // SharedIndexInformer will be refactored to require a more minimal subset of actions | ||
| // in the near future. | ||
|
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||
| func (l *ImageLayers) GetName() string { return l.Name } | ||
| func (l *ImageLayers) GetNamespace() string { return "" } | ||
| func (l *ImageLayers) GetResourceVersion() string { return l.ResourceVersion } | ||
| func (l *ImageLayers) SetResourceVersion(version string) { l.ResourceVersion = version } | ||
|
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| // These methods are unused stubs to satisfy meta.Object. | ||
|
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| func (l *ImageLayers) SetNamespace(namespace string) {} | ||
| func (l *ImageLayers) SetName(name string) {} | ||
| func (l *ImageLayers) GetGenerateName() string { return "" } | ||
| func (l *ImageLayers) SetGenerateName(name string) {} | ||
| func (l *ImageLayers) GetUID() types.UID { return "" } | ||
| func (l *ImageLayers) SetUID(uid types.UID) {} | ||
| func (l *ImageLayers) GetGeneration() int64 { return 0 } | ||
| func (l *ImageLayers) SetGeneration(generation int64) {} | ||
| func (l *ImageLayers) GetSelfLink() string { return "" } | ||
| func (l *ImageLayers) SetSelfLink(selfLink string) {} | ||
| func (l *ImageLayers) GetCreationTimestamp() metav1.Time { return metav1.Time{} } | ||
| func (l *ImageLayers) SetCreationTimestamp(timestamp metav1.Time) {} | ||
| func (l *ImageLayers) GetDeletionTimestamp() *metav1.Time { return nil } | ||
| func (l *ImageLayers) SetDeletionTimestamp(timestamp *metav1.Time) {} | ||
| func (l *ImageLayers) GetDeletionGracePeriodSeconds() *int64 { return nil } | ||
| func (l *ImageLayers) SetDeletionGracePeriodSeconds(*int64) {} | ||
| func (l *ImageLayers) GetLabels() map[string]string { return nil } | ||
| func (l *ImageLayers) SetLabels(labels map[string]string) {} | ||
| func (l *ImageLayers) GetAnnotations() map[string]string { return nil } | ||
| func (l *ImageLayers) SetAnnotations(annotations map[string]string) {} | ||
| func (l *ImageLayers) GetInitializers() *metav1.Initializers { return nil } | ||
| func (l *ImageLayers) SetInitializers(initializers *metav1.Initializers) {} | ||
| func (l *ImageLayers) GetFinalizers() []string { return nil } | ||
| func (l *ImageLayers) SetFinalizers(finalizers []string) {} | ||
| func (l *ImageLayers) GetOwnerReferences() []metav1.OwnerReference { return nil } | ||
| func (l *ImageLayers) SetOwnerReferences([]metav1.OwnerReference) {} | ||
| func (l *ImageLayers) GetClusterName() string { return "" } | ||
| func (l *ImageLayers) SetClusterName(clusterName string) {} |