Add a sandbox metadata store based on the metadata store

Signed-off-by: Random-Liu <lantaol@google.com>

pkg/metadata/sandbox.go

@@ -0,0 +1,157 @@
+/*
+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"
+
+	"k8s.io/kubernetes/pkg/kubelet/api/v1alpha1/runtime"
+)
+
+// TODO(random-liu): Handle versioning around all marshal/unmarshal.
+// version and versionedSandboxMetadata is not used now, but should be used
+// in the future:
+// 1) Only versioned metadata should be written into the store;
+// 2) Only unversioned metadata should be returned to the user;
+// 3) A conversion function is needed to convert any supported versioned
+// metadata into unversioned metadata.
+
+// sandboxMetadataVersion is current version of sandbox metadata.
+const sandboxMetadataVersion = "v1" // nolint
+
+// versionedSandboxMetadata is the internal struct representing the versioned
+// sandbox metadata
+// nolint
+type versionedSandboxMetadata struct {
+	// Version indicates the version of the versioned sandbox metadata.
+	Version string
+	SandboxMetadata
+}
+
+// SandboxMetadata is the unversioned sandbox metadata.
+type SandboxMetadata struct {
+	// ID is the sandbox id.
+	ID string
+	// Name is the sandbox name.
+	Name string
+	// Config is the CRI sandbox config.
+	Config *runtime.PodSandboxConfig
+	// CreatedAt is the created timestamp.
+	CreatedAt int64
+	// NetNS is the network namespace used by the sandbox.
+	NetNS string
+}
+
+// SandboxUpdateFunc is the function used to update SandboxMetadata.
+type SandboxUpdateFunc func(SandboxMetadata) (SandboxMetadata, error)
+
+// sandboxToStoreUpdateFunc generates a metadata store UpdateFunc from SandboxUpdateFunc.
+func sandboxToStoreUpdateFunc(u SandboxUpdateFunc) store.UpdateFunc {
+	return func(data []byte) ([]byte, error) {
+		meta := &SandboxMetadata{}
+		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)
+	}
+}
+
+// SandboxStore is the store for metadata of all sandboxes.
+type SandboxStore interface {
+	// Create creates a sandbox from SandboxMetadata in the store.
+	Create(SandboxMetadata) error
+	// Get gets the specified sandbox.
+	Get(string) (*SandboxMetadata, error)
+	// Update updates a specified sandbox.
+	Update(string, SandboxUpdateFunc) error
+	// List lists all sandboxes.
+	List() ([]*SandboxMetadata, error)
+	// Delete deletes the sandbox from the store.
+	Delete(string) error
+}
+
+// sandboxStore is an implmentation of SandboxStore.
+type sandboxStore struct {
+	store store.MetadataStore
+}
+
+// NewSandboxStore creates a SandboxStore from a basic MetadataStore.
+func NewSandboxStore(store store.MetadataStore) SandboxStore {
+	return &sandboxStore{store: store}
+}
+
+// Create creates a sandbox from SandboxMetadata in the store.
+func (s *sandboxStore) Create(metadata SandboxMetadata) error {
+	data, err := json.Marshal(&metadata)
+	if err != nil {
+		return err
+	}
+	return s.store.Create(metadata.ID, data)
+}
+
+// Get gets the specified sandbox.
+func (s *sandboxStore) Get(sandboxID string) (*SandboxMetadata, error) {
+	data, err := s.store.Get(sandboxID)
+	if err != nil {
+		return nil, err
+	}
+	// Return nil without error if the corresponding metadata
+	// does not exist.
+	if data == nil {
+		return nil, nil
+	}
+	sandbox := &SandboxMetadata{}
+	if err := json.Unmarshal(data, sandbox); err != nil {
+		return nil, err
+	}
+	return sandbox, nil
+}
+
+// Update updates a specified sandbox. The function is running in a
+// transaction. Update will not be applied when the update function
+// returns error.
+func (s *sandboxStore) Update(sandboxID string, u SandboxUpdateFunc) error {
+	return s.store.Update(sandboxID, sandboxToStoreUpdateFunc(u))
+}
+
+// List lists all sandboxes.
+func (s *sandboxStore) List() ([]*SandboxMetadata, error) {
+	allData, err := s.store.List()
+	if err != nil {
+		return nil, err
+	}
+	var sandboxes []*SandboxMetadata
+	for _, data := range allData {
+		sandbox := &SandboxMetadata{}
+		if err := json.Unmarshal(data, sandbox); err != nil {
+			return nil, err
+		}
+		sandboxes = append(sandboxes, sandbox)
+	}
+	return sandboxes, nil
+}
+
+// Delete deletes the sandbox from the store.
+func (s *sandboxStore) Delete(sandboxID string) error {
+	return s.store.Delete(sandboxID)
+}