initial implementation for image management

Signed-off-by: Mike Brown <brownwm@us.ibm.com>

pkg/metadata/image_metadata.go

@@ -0,0 +1,150 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package metadata
+
+import (
+	"encoding/json"
+
+	"github.com/kubernetes-incubator/cri-containerd/pkg/metadata/store"
+)
+
+// The code is very similar to sandbox.go, but there is no template support
+// in golang, thus similar files for different types.
+// TODO(random-liu): Figure out a way to simplify this.
+// TODO(random-liu): Handle versioning
+
+// imageMetadataVersion is current version of image metadata.
+const imageMetadataVersion = "v1" // nolint
+
+// versionedImageMetadata is the internal struct representing the versioned
+// image metadata
+// nolint
+type versionedImageMetadata struct {
+	// Version indicates the version of the versioned image metadata.
+	Version string `json:"version,omitempty"`
+	ImageMetadata
+}
+
+// ImageMetadata is the unversioned image metadata.
+type ImageMetadata struct {
+	// Id of the image. Normally the Digest
+	ID string `json:"id,omitempty"`
+	// Other names by which this image is known.
+	RepoTags []string `json:"repo_tags,omitempty"`
+	// Digests by which this image is known.
+	RepoDigests []string `json:"repo_digests,omitempty"`
+	// Size of the image in bytes. Must be > 0.
+	Size uint64 `json:"size,omitempty"`
+}
+
+// ImageMetadataUpdateFunc is the function used to update ImageMetadata.
+type ImageMetadataUpdateFunc func(ImageMetadata) (ImageMetadata, error)
+
+// imageMetadataToStoreUpdateFunc generates a metadata store UpdateFunc from ImageMetadataUpdateFunc.
+func imageMetadataToStoreUpdateFunc(u ImageMetadataUpdateFunc) store.UpdateFunc {
+	return func(data []byte) ([]byte, error) {
+		meta := &ImageMetadata{}
+		if err := json.Unmarshal(data, meta); err != nil {
+			return nil, err
+		}
+		newMeta, err := u(*meta)
+		if err != nil {
+			return nil, err
+		}
+		return json.Marshal(newMeta)
+	}
+}
+
+// ImageMetadataStore is the store for metadata of all images.
+type ImageMetadataStore interface {
+	// Create creates an image's metadata from ImageMetadata in the store.
+	Create(ImageMetadata) error
+	// Get gets the specified image metadata.
+	Get(string) (*ImageMetadata, error)
+	// Update updates a specified image metatdata.
+	Update(string, ImageMetadataUpdateFunc) error
+	// List lists all image metadatas.
+	List() ([]*ImageMetadata, error)
+	// Delete deletes the image's metatdata from the store.
+	Delete(string) error
+}
+
+// imageMetadataStore is an implmentation of ImageMetadataStore.
+type imageMetadataStore struct {
+	store store.MetadataStore
+}
+
+// NewImageMetadataStore creates an ImageMetadataStore from a basic MetadataStore.
+func NewImageMetadataStore(store store.MetadataStore) ImageMetadataStore {
+	return &imageMetadataStore{store: store}
+}
+
+// Create creates a image's metadata from ImageMetadata in the store.
+func (s *imageMetadataStore) Create(metadata ImageMetadata) error {
+	data, err := json.Marshal(&metadata)
+	if err != nil {
+		return err
+	}
+	return s.store.Create(metadata.ID, data)
+}
+
+// Get gets the specified image metadata.
+func (s *imageMetadataStore) Get(digest string) (*ImageMetadata, error) {
+	data, err := s.store.Get(digest)
+	if err != nil {
+		return nil, err
+	}
+	// Return nil without error if the corresponding metadata
+	// does not exist.
+	if data == nil {
+		return nil, nil
+	}
+	imageMetadata := &ImageMetadata{}
+	if err := json.Unmarshal(data, imageMetadata); err != nil {
+		return nil, err
+	}
+	return imageMetadata, nil
+}
+
+// Update updates a specified image's metadata. The function is running in a
+// transaction. Update will not be applied when the update function
+// returns error.
+func (s *imageMetadataStore) Update(digest string, u ImageMetadataUpdateFunc) error {
+	return s.store.Update(digest, imageMetadataToStoreUpdateFunc(u))
+}
+
+// List lists all image metadata.
+func (s *imageMetadataStore) List() ([]*ImageMetadata, error) {
+	allData, err := s.store.List()
+	if err != nil {
+		return nil, err
+	}
+	var imageMetadataA []*ImageMetadata
+	for _, data := range allData {
+		imageMetadata := &ImageMetadata{}
+		if err := json.Unmarshal(data, imageMetadata); err != nil {
+			return nil, err
+		}
+		imageMetadataA = append(imageMetadataA, imageMetadata)
+	}
+	return imageMetadataA, nil
+}
+
+// Delete deletes the image metadata from the store.
+func (s *imageMetadataStore) Delete(digest string) error {
+	return s.store.Delete(digest)
+}

pkg/metadata/image_metadata_test.go

@@ -0,0 +1,87 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package metadata
+
+import (
+	"testing"
+
+	assertlib "github.com/stretchr/testify/assert"
+
+	"github.com/kubernetes-incubator/cri-containerd/pkg/metadata/store"
+)
+
+func TestImageMetadataStore(t *testing.T) {
+	imageMetadataMap := map[string]*ImageMetadata{
+		"1": {
+			ID:   "1", // TODO(mikebrow): fill
+			Size: 10,
+		},
+		"2": {
+			ID:   "2",
+			Size: 20,
+		},
+		"3": {
+			ID:   "3",
+			Size: 30,
+		},
+	}
+	assert := assertlib.New(t)
+
+	s := NewImageMetadataStore(store.NewMetadataStore())
+
+	t.Logf("should be able to create image metadata")
+	for _, meta := range imageMetadataMap {
+		assert.NoError(s.Create(*meta))
+	}
+
+	t.Logf("should be able to get image metadata")
+	for id, expectMeta := range imageMetadataMap {
+		meta, err := s.Get(id)
+		assert.NoError(err)
+		assert.Equal(expectMeta, meta)
+	}
+
+	t.Logf("should be able to list image metadata")
+	imgs, err := s.List()
+	assert.NoError(err)
+	assert.Len(imgs, 3)
+
+	t.Logf("should be able to update image metadata")
+	testID := "2"
+	newSize := uint64(200)
+	expectMeta := *imageMetadataMap[testID]
+	expectMeta.Size = newSize
+	err = s.Update(testID, func(o ImageMetadata) (ImageMetadata, error) {
+		o.Size = newSize
+		return o, nil
+	})
+	assert.NoError(err)
+	newMeta, err := s.Get(testID)
+	assert.NoError(err)
+	assert.Equal(&expectMeta, newMeta)
+
+	t.Logf("should be able to delete image metadata")
+	assert.NoError(s.Delete(testID))
+	imgs, err = s.List()
+	assert.NoError(err)
+	assert.Len(imgs, 2)
+
+	t.Logf("get should return nil without error after deletion")
+	meta, err := s.Get(testID)
+	assert.NoError(err)
+	assert.Nil(meta)
+}