add checkpoint structures for dockershim

pkg/kubelet/dockershim/checkpoint_store.go

@@ -0,0 +1,114 @@
+/*
+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 dockershim
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strings"
+)
+
+const (
+	tmpPrefix    = "."
+	tmpSuffix    = ".tmp"
+	keyMaxLength = 250
+)
+
+var keyRegex = regexp.MustCompile("^[a-zA-Z0-9]+$")
+
+// CheckpointStore provides the interface for checkpoint storage backend.
+// CheckpointStore must be thread-safe
+type CheckpointStore interface {
+	// key must contain one or more characters in [A-Za-z0-9]
+	// Write persists a checkpoint with key
+	Write(key string, data []byte) error
+	// Read retrieves a checkpoint with key
+	Read(key string) ([]byte, error)
+	// Delete deletes a checkpoint with key
+	// Delete must not return error if checkpoint does not exist
+	Delete(key string) error
+	// List lists all keys of existing checkpoints
+	List() ([]string, error)
+}
+
+// FileStore is an implementation of CheckpointStore interface which stores checkpoint in file.
+type FileStore struct {
+	// path to the base directory for storing checkpoints
+	path string
+}
+
+func (fstore *FileStore) Write(key string, data []byte) error {
+	if err := validateKey(key); err != nil {
+		return err
+	}
+	if _, err := os.Stat(fstore.path); err != nil {
+		// if directory already exists, proceed
+		if err = os.MkdirAll(fstore.path, 0755); err != nil && !os.IsExist(err) {
+			return err
+		}
+	}
+	tmpfile := filepath.Join(fstore.path, fmt.Sprintf("%s%s%s", tmpPrefix, key, tmpSuffix))
+	if err := ioutil.WriteFile(tmpfile, data, 0644); err != nil {
+		return err
+	}
+	return os.Rename(tmpfile, fstore.getCheckpointPath(key))
+}
+
+func (fstore *FileStore) Read(key string) ([]byte, error) {
+	if err := validateKey(key); err != nil {
+		return nil, err
+	}
+	return ioutil.ReadFile(fstore.getCheckpointPath(key))
+}
+
+func (fstore *FileStore) Delete(key string) error {
+	if err := validateKey(key); err != nil {
+		return err
+	}
+	if err := os.Remove(fstore.getCheckpointPath(key)); err != nil && !os.IsNotExist(err) {
+		return err
+	}
+	return nil
+}
+
+func (fstore *FileStore) List() ([]string, error) {
+	keys := make([]string, 0)
+	files, err := ioutil.ReadDir(fstore.path)
+	if err != nil {
+		return keys, err
+	}
+	for _, f := range files {
+		if !strings.HasSuffix(f.Name(), tmpSuffix) {
+			keys = append(keys, f.Name())
+		}
+	}
+	return keys, nil
+}
+
+func (fstore *FileStore) getCheckpointPath(key string) string {
+	return filepath.Join(fstore.path, key)
+}
+
+func validateKey(key string) error {
+	if len(key) <= keyMaxLength && keyRegex.MatchString(key) {
+		return nil
+	}
+	return fmt.Errorf("checkpoint key %q is not valid.", key)
+}

pkg/kubelet/dockershim/checkpoint_store_test.go

@@ -0,0 +1,161 @@
+/*
+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 dockershim
+
+import (
+	"io/ioutil"
+	"os"
+	"sort"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+const (
+	testPath = "/tmp/testFileStore"
+)
+
+func TestFileStore(t *testing.T) {
+	path, err := ioutil.TempDir("", "FileStore")
+	assert.NoError(t, err)
+	defer cleanUpTestPath(t, path)
+	store := &FileStore{path: path}
+
+	Checkpoints := []struct {
+		key       string
+		data      string
+		expectErr bool
+	}{
+		{
+			"id1",
+			"data1",
+			false,
+		},
+		{
+			"id2",
+			"data2",
+			false,
+		},
+		{
+			"/id1",
+			"data1",
+			true,
+		},
+		{
+			".id1",
+			"data1",
+			true,
+		},
+		{
+			"   ",
+			"data2",
+			true,
+		},
+		{
+			"___",
+			"data2",
+			true,
+		},
+	}
+
+	// Test Add Checkpoint
+	for _, c := range Checkpoints {
+		_, err = store.Read(c.key)
+		assert.Error(t, err)
+
+		err = store.Write(c.key, []byte(c.data))
+		if c.expectErr {
+			assert.Error(t, err)
+			continue
+		} else {
+			assert.NoError(t, err)
+		}
+
+		// Test Read Checkpoint
+		data, err := store.Read(c.key)
+		assert.NoError(t, err)
+		assert.Equal(t, string(data), c.data)
+	}
+
+	// Test list checkpoints.
+	keys, err := store.List()
+	assert.NoError(t, err)
+	sort.Strings(keys)
+	assert.Equal(t, keys, []string{"id1", "id2"})
+
+	// Test Delete Checkpoint
+	for _, c := range Checkpoints {
+		if c.expectErr {
+			continue
+		}
+
+		err = store.Delete(c.key)
+		assert.NoError(t, err)
+		_, err = store.Read(c.key)
+		assert.Error(t, err)
+	}
+
+	// Test delete non existed checkpoint
+	err = store.Delete("id1")
+	assert.NoError(t, err)
+
+	// Test list checkpoints.
+	keys, err = store.List()
+	assert.NoError(t, err)
+	assert.Equal(t, len(keys), 0)
+}
+
+func TestIsValidKey(t *testing.T) {
+	testcases := []struct {
+		key   string
+		valid bool
+	}{
+		{
+			"    ",
+			false,
+		},
+		{
+			"/foo/bar",
+			false,
+		},
+		{
+			".foo",
+			false,
+		},
+		{
+			"a78768279290d33d0b82eaea43cb8346f500057cb5bd250e88c97a5585385d66",
+			true,
+		},
+	}
+
+	for _, tc := range testcases {
+		if tc.valid {
+			assert.NoError(t, validateKey(tc.key))
+		} else {
+			assert.Error(t, validateKey(tc.key))
+		}
+	}
+}
+
+func cleanUpTestPath(t *testing.T, path string) {
+	if _, err := os.Stat(path); !os.IsNotExist(err) {
+		if err := os.RemoveAll(path); err != nil {
+			t.Errorf("Failed to delete test directory: %v", err)
+		}
+	}
+	return
+}

pkg/kubelet/dockershim/docker_checkpoint.go

@@ -0,0 +1,144 @@
+/*
+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 dockershim
+
+import (
+	"encoding/json"
+	"fmt"
+	"github.com/golang/glog"
+	"hash/fnv"
+	hashutil "k8s.io/kubernetes/pkg/util/hash"
+)
+
+const (
+	// default directory to store pod sandbox checkpoint files
+	sandboxCheckpointDir = "/var/lib/dockershim/sandbox"
+	protocolTCP          = Protocol("tcp")
+	protocolUDP          = Protocol("udp")
+	schemaVersion        = "v1"
+)
+
+var CorruptCheckpointError = fmt.Errorf("Checkpoint is corrupted.")
+
+type Protocol string
+
+// PortMapping is the port mapping configurations of a sandbox.
+type PortMapping struct {
+	// Protocol of the port mapping.
+	Protocol *Protocol `json:"protocol,omitempty"`
+	// Port number within the container.
+	ContainerPort *int32 `json:"container_port,omitempty"`
+	// Port number on the host.
+	HostPort *int32 `json:"host_port,omitempty"`
+}
+
+// CheckpointData contains all types of data that can be stored in the checkpoint.
+type CheckpointData struct {
+	PortMappings []*PortMapping `json:"port_mappings,omitempty"`
+}
+
+// PodSandboxCheckpoint is the checkpoint structure for a sandbox
+type PodSandboxCheckpoint struct {
+	// Version of the pod sandbox checkpoint schema.
+	Version string `json:"version"`
+	// Pod name of the sandbox. Same as the pod name in the PodSpec.
+	Name string `json:"name"`
+	// Pod namespace of the sandbox. Same as the pod namespace in the PodSpec.
+	Namespace string `json:"namespace"`
+	// Data to checkpoint for pod sandbox.
+	Data *CheckpointData `json:"data,omitempty"`
+	// Checksum is calculated with fnv hash of the checkpoint object with checksum field set to be zero
+	CheckSum uint64 `json:"checksum"`
+}
+
+// CheckpointHandler provides the interface to manage PodSandbox checkpoint
+type CheckpointHandler interface {
+	// CreateCheckpoint persists sandbox checkpoint in CheckpointStore.
+	CreateCheckpoint(podSandboxID string, checkpoint *PodSandboxCheckpoint) error
+	// GetCheckpoint retrieves sandbox checkpoint from CheckpointStore.
+	GetCheckpoint(podSandboxID string) (*PodSandboxCheckpoint, error)
+	// RemoveCheckpoint removes sandbox checkpoint form CheckpointStore.
+	// WARNING: RemoveCheckpoint will not return error if checkpoint does not exist.
+	RemoveCheckpoint(podSandboxID string) error
+	// ListCheckpoint returns the list of existing checkpoints.
+	ListCheckpoints() ([]string, error)
+}
+
+// PersistentCheckpointHandler is an implementation of CheckpointHandler. It persists checkpoint in CheckpointStore
+type PersistentCheckpointHandler struct {
+	store CheckpointStore
+}
+
+func NewPersistentCheckpointHandler() CheckpointHandler {
+	return &PersistentCheckpointHandler{store: &FileStore{path: sandboxCheckpointDir}}
+}
+
+func (handler *PersistentCheckpointHandler) CreateCheckpoint(podSandboxID string, checkpoint *PodSandboxCheckpoint) error {
+	checkpoint.CheckSum = calculateChecksum(*checkpoint)
+	blob, err := json.Marshal(checkpoint)
+	if err != nil {
+		return err
+	}
+	return handler.store.Write(podSandboxID, blob)
+}
+
+func (handler *PersistentCheckpointHandler) GetCheckpoint(podSandboxID string) (*PodSandboxCheckpoint, error) {
+	blob, err := handler.store.Read(podSandboxID)
+	if err != nil {
+		return nil, err
+	}
+	var checkpoint PodSandboxCheckpoint
+	//TODO: unmarhsal into a struct with just Version, check version, unmarshal into versioned type.
+	err = json.Unmarshal(blob, &checkpoint)
+	if err != nil {
+		glog.Errorf("Failed to unmarshal checkpoint %q: %v", podSandboxID, err)
+		return &checkpoint, CorruptCheckpointError
+	}
+	if checkpoint.CheckSum != calculateChecksum(checkpoint) {
+		glog.Errorf("Checksum of checkpoint %q is not valid", podSandboxID)
+		return &checkpoint, CorruptCheckpointError
+	}
+	return &checkpoint, nil
+}
+
+func (handler *PersistentCheckpointHandler) RemoveCheckpoint(podSandboxID string) error {
+	return handler.store.Delete(podSandboxID)
+}
+
+func (handler *PersistentCheckpointHandler) ListCheckpoints() ([]string, error) {
+	keys, err := handler.store.List()
+	if err != nil {
+		return []string{}, fmt.Errorf("failed to list checkpoint store: %v", err)
+	}
+	return keys, nil
+}
+
+func NewPodSandboxCheckpoint(namespace, name string) *PodSandboxCheckpoint {
+	return &PodSandboxCheckpoint{
+		Version:   schemaVersion,
+		Namespace: namespace,
+		Name:      name,
+		Data:      &CheckpointData{},
+	}
+}
+
+func calculateChecksum(checkpoint PodSandboxCheckpoint) uint64 {
+	checkpoint.CheckSum = 0
+	hash := fnv.New32a()
+	hashutil.DeepHashObject(hash, checkpoint)
+	return uint64(hash.Sum32())
+}

pkg/kubelet/dockershim/docker_checkpoint_test.go

@@ -0,0 +1,98 @@
+/*
+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 dockershim
+
+import (
+	"sort"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	utilstore "k8s.io/kubernetes/pkg/kubelet/dockershim/testing"
+)
+
+func NewTestPersistentCheckpointHandler() CheckpointHandler {
+	return &PersistentCheckpointHandler{store: utilstore.NewMemStore()}
+}
+
+func TestPersistentCheckpointHandler(t *testing.T) {
+	var err error
+	handler := NewTestPersistentCheckpointHandler()
+	port80 := int32(80)
+	port443 := int32(443)
+	proto := protocolTCP
+
+	checkpoint1 := NewPodSandboxCheckpoint("ns1", "sandbox1")
+	checkpoint1.Data.PortMappings = []*PortMapping{
+		{
+			&proto,
+			&port80,
+			&port80,
+		},
+		{
+			&proto,
+			&port443,
+			&port443,
+		},
+	}
+
+	checkpoints := []struct {
+		podSandboxID string
+		checkpoint   *PodSandboxCheckpoint
+	}{
+		{
+			"id1",
+			checkpoint1,
+		},
+		{
+			"id2",
+			NewPodSandboxCheckpoint("ns2", "sandbox2"),
+		},
+	}
+
+	for _, tc := range checkpoints {
+		// Test CreateCheckpoints
+		err = handler.CreateCheckpoint(tc.podSandboxID, tc.checkpoint)
+		assert.NoError(t, err)
+
+		// Test GetCheckpoints
+		checkpoint, err := handler.GetCheckpoint(tc.podSandboxID)
+		assert.NoError(t, err)
+		assert.Equal(t, *checkpoint, *tc.checkpoint)
+	}
+
+	// Test ListCheckpoints
+	keys, err := handler.ListCheckpoints()
+	assert.NoError(t, err)
+	sort.Strings(keys)
+	assert.Equal(t, keys, []string{"id1", "id2"})
+
+	// Test RemoveCheckpoints
+	err = handler.RemoveCheckpoint("id1")
+	assert.NoError(t, err)
+	// Test Remove Nonexisted Checkpoints
+	err = handler.RemoveCheckpoint("id1")
+	assert.NoError(t, err)
+
+	// Test ListCheckpoints
+	keys, err = handler.ListCheckpoints()
+	assert.NoError(t, err)
+	assert.Equal(t, keys, []string{"id2"})
+
+	// Test Get NonExisted Checkpoint
+	_, err = handler.GetCheckpoint("id1")
+	assert.Error(t, err)
+}

pkg/kubelet/dockershim/testing/util.go

@@ -0,0 +1,66 @@
+/*
+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 testing
+
+import (
+	"fmt"
+	"sync"
+)
+
+// MemStore is an implementation of CheckpointStore interface which stores checkpoint in memory.
+type MemStore struct {
+	mem map[string][]byte
+	sync.Mutex
+}
+
+func NewMemStore() *MemStore {
+	return &MemStore{mem: make(map[string][]byte)}
+}
+
+func (mstore *MemStore) Write(key string, data []byte) error {
+	mstore.Lock()
+	defer mstore.Unlock()
+	mstore.mem[key] = data
+	return nil
+}
+
+func (mstore *MemStore) Read(key string) ([]byte, error) {
+	mstore.Lock()
+	defer mstore.Unlock()
+	data, ok := mstore.mem[key]
+	if !ok {
+		return nil, fmt.Errorf("checkpoint %q could not be found", key)
+	}
+	return data, nil
+}
+
+func (mstore *MemStore) Delete(key string) error {
+	mstore.Lock()
+	defer mstore.Unlock()
+	delete(mstore.mem, key)
+	return nil
+}
+
+func (mstore *MemStore) List() ([]string, error) {
+	mstore.Lock()
+	defer mstore.Unlock()
+	keys := make([]string, 0)
+	for key := range mstore.mem {
+		keys = append(keys, key)
+	}
+	return keys, nil
+}