vendor update for CSI 0.3.0

vendor/k8s.io/kubernetes/pkg/kubelet/checkpointmanager/BUILD

@@ -0,0 +1,48 @@
+package(default_visibility = ["//visibility:public"])
+
+load(
+    "@io_bazel_rules_go//go:def.bzl",
+    "go_library",
+    "go_test",
+)
+
+go_library(
+    name = "go_default_library",
+    srcs = ["checkpoint_manager.go"],
+    importpath = "k8s.io/kubernetes/pkg/kubelet/checkpointmanager",
+    deps = [
+        "//pkg/kubelet/checkpointmanager/errors:go_default_library",
+        "//pkg/kubelet/util/store:go_default_library",
+        "//pkg/util/filesystem:go_default_library",
+    ],
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = ["checkpoint_manager_test.go"],
+    embed = [":go_default_library"],
+    deps = [
+        "//pkg/kubelet/checkpointmanager/checksum:go_default_library",
+        "//pkg/kubelet/checkpointmanager/testing:go_default_library",
+        "//pkg/kubelet/checkpointmanager/testing/example_checkpoint_formats/v1:go_default_library",
+        "//vendor/github.com/stretchr/testify/assert:go_default_library",
+    ],
+)
+
+filegroup(
+    name = "package-srcs",
+    srcs = glob(["**"]),
+    tags = ["automanaged"],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "all-srcs",
+    srcs = [
+        ":package-srcs",
+        "//pkg/kubelet/checkpointmanager/checksum:all-srcs",
+        "//pkg/kubelet/checkpointmanager/errors:all-srcs",
+        "//pkg/kubelet/checkpointmanager/testing:all-srcs",
+    ],
+    tags = ["automanaged"],
+)

vendor/k8s.io/kubernetes/pkg/kubelet/checkpointmanager/README.md

@@ -0,0 +1,25 @@
+## DISCLAIMER
+- Sig-Node community has reached a general consensus, as a best practice, to
+avoid introducing any new checkpointing support. We reached this understanding
+after struggling with some hard-to-debug issues in the production environments
+caused by the checkpointing.
+- Any changes to the checkpointed data structure would be considered incompatible and a component should add its own handling if it needs to ensure backward compatibility of reading old-format checkpoint files.
+
+## Introduction
+This folder contains a framework & primitives, Checkpointing Manager, which is
+used by several other Kubelet submodules, `dockershim`, `devicemanager`, `pods`
+and `cpumanager`, to implement checkpointing at each submodule level. As already
+explained in above `Disclaimer` section, think twice before introducing any further
+checkpointing in Kubelet. If still checkpointing is required, then this folder
+provides the common APIs and the framework for implementing checkpointing.
+Using same APIs across all the submodules will help maintaining consistency at
+Kubelet level.
+
+Below is the history of checkpointing support in Kubelet.
+
+| Package | First checkpointing support merged on | PR link |
+| ------- | --------------------------------------| ------- |
+|kubelet/dockershim | Feb 3, 2017 | [[CRI] Implement Dockershim Checkpoint](https://github.com/kubernetes/kubernetes/pull/39903)
+|devicemanager| Sep 6, 2017 | [Deviceplugin checkpoint](https://github.com/kubernetes/kubernetes/pull/51744)
+| kubelet/pod | Nov 22, 2017 | [Initial basic bootstrap-checkpoint support](https://github.com/kubernetes/kubernetes/pull/50984)
+|cpumanager| Oct 27, 2017 |[Add file backed state to cpu manager ](https://github.com/kubernetes/kubernetes/pull/54408)

vendor/k8s.io/kubernetes/pkg/kubelet/checkpointmanager/checkpoint_manager.go

@@ -0,0 +1,110 @@
+/*
+Copyright 2018 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 checkpointmanager
+
+import (
+	"fmt"
+	"sync"
+
+	"k8s.io/kubernetes/pkg/kubelet/checkpointmanager/errors"
+	utilstore "k8s.io/kubernetes/pkg/kubelet/util/store"
+	utilfs "k8s.io/kubernetes/pkg/util/filesystem"
+)
+
+// Checkpoint provides the process checkpoint data
+type Checkpoint interface {
+	MarshalCheckpoint() ([]byte, error)
+	UnmarshalCheckpoint(blob []byte) error
+	VerifyChecksum() error
+}
+
+// CheckpointManager provides the interface to manage checkpoint
+type CheckpointManager interface {
+	// CreateCheckpoint persists checkpoint in CheckpointStore. checkpointKey is the key for utilstore to locate checkpoint.
+	// For file backed utilstore, checkpointKey is the file name to write the checkpoint data.
+	CreateCheckpoint(checkpointKey string, checkpoint Checkpoint) error
+	// GetCheckpoint retrieves checkpoint from CheckpointStore.
+	GetCheckpoint(checkpointKey string, checkpoint Checkpoint) error
+	// WARNING: RemoveCheckpoint will not return error if checkpoint does not exist.
+	RemoveCheckpoint(checkpointKey string) error
+	// ListCheckpoint returns the list of existing checkpoints.
+	ListCheckpoints() ([]string, error)
+}
+
+// impl is an implementation of CheckpointManager. It persists checkpoint in CheckpointStore
+type impl struct {
+	path  string
+	store utilstore.Store
+	mutex sync.Mutex
+}
+
+// NewCheckpointManager returns a new instance of a checkpoint manager
+func NewCheckpointManager(checkpointDir string) (CheckpointManager, error) {
+	fstore, err := utilstore.NewFileStore(checkpointDir, utilfs.DefaultFs{})
+	if err != nil {
+		return nil, err
+	}
+
+	return &impl{path: checkpointDir, store: fstore}, nil
+}
+
+// CreateCheckpoint persists checkpoint in CheckpointStore.
+func (manager *impl) CreateCheckpoint(checkpointKey string, checkpoint Checkpoint) error {
+	manager.mutex.Lock()
+	defer manager.mutex.Unlock()
+	blob, err := checkpoint.MarshalCheckpoint()
+	if err != nil {
+		return err
+	}
+	return manager.store.Write(checkpointKey, blob)
+}
+
+// GetCheckpoint retrieves checkpoint from CheckpointStore.
+func (manager *impl) GetCheckpoint(checkpointKey string, checkpoint Checkpoint) error {
+	manager.mutex.Lock()
+	defer manager.mutex.Unlock()
+	blob, err := manager.store.Read(checkpointKey)
+	if err != nil {
+		if err == utilstore.ErrKeyNotFound {
+			return errors.ErrCheckpointNotFound
+		}
+		return err
+	}
+	err = checkpoint.UnmarshalCheckpoint(blob)
+	if err == nil {
+		err = checkpoint.VerifyChecksum()
+	}
+	return err
+}
+
+// RemoveCheckpoint will not return error if checkpoint does not exist.
+func (manager *impl) RemoveCheckpoint(checkpointKey string) error {
+	manager.mutex.Lock()
+	defer manager.mutex.Unlock()
+	return manager.store.Delete(checkpointKey)
+}
+
+// ListCheckpoints returns the list of existing checkpoints.
+func (manager *impl) ListCheckpoints() ([]string, error) {
+	manager.mutex.Lock()
+	defer manager.mutex.Unlock()
+	keys, err := manager.store.List()
+	if err != nil {
+		return []string{}, fmt.Errorf("failed to list checkpoint store: %v", err)
+	}
+	return keys, nil
+}

vendor/k8s.io/kubernetes/pkg/kubelet/checkpointmanager/checkpoint_manager_test.go

@@ -0,0 +1,245 @@
+/*
+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 checkpointmanager
+
+import (
+	"encoding/json"
+	"sort"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"k8s.io/kubernetes/pkg/kubelet/checkpointmanager/checksum"
+	utilstore "k8s.io/kubernetes/pkg/kubelet/checkpointmanager/testing"
+	"k8s.io/kubernetes/pkg/kubelet/checkpointmanager/testing/example_checkpoint_formats/v1"
+)
+
+var testStore *utilstore.MemStore
+
+type FakeCheckpoint interface {
+	Checkpoint
+	GetData() ([]*PortMapping, bool)
+}
+
+// Data contains all types of data that can be stored in the checkpoint.
+type Data struct {
+	PortMappings []*PortMapping `json:"port_mappings,omitempty"`
+	HostNetwork  bool           `json:"host_network,omitempty"`
+}
+
+type CheckpointDataV2 struct {
+	PortMappings []*PortMapping `json:"port_mappings,omitempty"`
+	HostNetwork  bool           `json:"host_network,omitempty"`
+	V2Field      string         `json:"v2field"`
+}
+
+type protocol string
+
+// portMapping is the port mapping configurations of a sandbox.
+type PortMapping struct {
+	// protocol of the port mapping.
+	Protocol *protocol
+	// Port number within the container.
+	ContainerPort *int32
+	// Port number on the host.
+	HostPort *int32
+}
+
+// CheckpointData is a sample example structure to be used in test cases for checkpointing
+type CheckpointData struct {
+	Version  string
+	Name     string
+	Data     *Data
+	Checksum checksum.Checksum
+}
+
+func newFakeCheckpointV1(name string, portMappings []*PortMapping, hostNetwork bool) FakeCheckpoint {
+	return &CheckpointData{
+		Version: "v1",
+		Name:    name,
+		Data: &Data{
+			PortMappings: portMappings,
+			HostNetwork:  hostNetwork,
+		},
+	}
+}
+
+func (cp *CheckpointData) MarshalCheckpoint() ([]byte, error) {
+	cp.Checksum = checksum.New(*cp.Data)
+	return json.Marshal(*cp)
+}
+
+func (cp *CheckpointData) UnmarshalCheckpoint(blob []byte) error {
+	return json.Unmarshal(blob, cp)
+}
+
+func (cp *CheckpointData) VerifyChecksum() error {
+	return cp.Checksum.Verify(*cp.Data)
+}
+
+func (cp *CheckpointData) GetData() ([]*PortMapping, bool) {
+	return cp.Data.PortMappings, cp.Data.HostNetwork
+}
+
+type checkpointDataV2 struct {
+	Version  string
+	Name     string
+	Data     *CheckpointDataV2
+	Checksum checksum.Checksum
+}
+
+func newFakeCheckpointV2(name string, portMappings []*PortMapping, hostNetwork bool) FakeCheckpoint {
+	return &checkpointDataV2{
+		Version: "v2",
+		Name:    name,
+		Data: &CheckpointDataV2{
+			PortMappings: portMappings,
+			HostNetwork:  hostNetwork,
+		},
+	}
+}
+
+func newFakeCheckpointRemoteV1(name string, portMappings []*v1.PortMapping, hostNetwork bool) Checkpoint {
+	return &v1.CheckpointData{
+		Version: "v1",
+		Name:    name,
+		Data: &v1.Data{
+			PortMappings: portMappings,
+			HostNetwork:  hostNetwork,
+		},
+	}
+}
+
+func (cp *checkpointDataV2) MarshalCheckpoint() ([]byte, error) {
+	cp.Checksum = checksum.New(*cp.Data)
+	return json.Marshal(*cp)
+}
+
+func (cp *checkpointDataV2) UnmarshalCheckpoint(blob []byte) error {
+	return json.Unmarshal(blob, cp)
+}
+
+func (cp *checkpointDataV2) VerifyChecksum() error {
+	return cp.Checksum.Verify(*cp.Data)
+}
+
+func (cp *checkpointDataV2) GetData() ([]*PortMapping, bool) {
+	return cp.Data.PortMappings, cp.Data.HostNetwork
+}
+
+func newTestCheckpointManager() CheckpointManager {
+	return &impl{store: testStore}
+}
+
+func TestCheckpointManager(t *testing.T) {
+	var err error
+	testStore = utilstore.NewMemStore()
+	manager := newTestCheckpointManager()
+	port80 := int32(80)
+	port443 := int32(443)
+	proto := protocol("tcp")
+
+	portMappings := []*PortMapping{
+		{
+			&proto,
+			&port80,
+			&port80,
+		},
+		{
+			&proto,
+			&port443,
+			&port443,
+		},
+	}
+	checkpoint1 := newFakeCheckpointV1("check1", portMappings, true)
+
+	checkpoints := []struct {
+		checkpointKey     string
+		checkpoint        FakeCheckpoint
+		expectHostNetwork bool
+	}{
+		{
+			"key1",
+			checkpoint1,
+			true,
+		},
+		{
+			"key2",
+			newFakeCheckpointV1("check2", nil, false),
+			false,
+		},
+	}
+
+	for _, tc := range checkpoints {
+		// Test CreateCheckpoints
+		err = manager.CreateCheckpoint(tc.checkpointKey, tc.checkpoint)
+		assert.NoError(t, err)
+
+		// Test GetCheckpoints
+		checkpointOut := newFakeCheckpointV1("", nil, false)
+		err := manager.GetCheckpoint(tc.checkpointKey, checkpointOut)
+		assert.NoError(t, err)
+		actualPortMappings, actualHostNetwork := checkpointOut.GetData()
+		expPortMappings, expHostNetwork := tc.checkpoint.GetData()
+		assert.Equal(t, actualPortMappings, expPortMappings)
+		assert.Equal(t, actualHostNetwork, expHostNetwork)
+	}
+	// Test it fails if tried to read V1 structure into V2, a different structure from the structure which is checkpointed
+	checkpointV2 := newFakeCheckpointV2("", nil, false)
+	err = manager.GetCheckpoint("key1", checkpointV2)
+	assert.EqualError(t, err, "checkpoint is corrupted")
+
+	// Test it fails if tried to read V1 structure into the same structure but defined in another package
+	checkpointRemoteV1 := newFakeCheckpointRemoteV1("", nil, false)
+	err = manager.GetCheckpoint("key1", checkpointRemoteV1)
+	assert.EqualError(t, err, "checkpoint is corrupted")
+
+	// Test it works if tried to read V1 structure using into a new V1 structure
+	checkpointV1 := newFakeCheckpointV1("", nil, false)
+	err = manager.GetCheckpoint("key1", checkpointV1)
+	assert.NoError(t, err)
+
+	// Test corrupt checksum case
+	checkpointOut := newFakeCheckpointV1("", nil, false)
+	blob, err := checkpointOut.MarshalCheckpoint()
+	assert.NoError(t, err)
+	testStore.Write("key1", blob)
+	err = manager.GetCheckpoint("key1", checkpoint1)
+	assert.EqualError(t, err, "checkpoint is corrupted")
+
+	// Test ListCheckpoints
+	keys, err := manager.ListCheckpoints()
+	assert.NoError(t, err)
+	sort.Strings(keys)
+	assert.Equal(t, keys, []string{"key1", "key2"})
+
+	// Test RemoveCheckpoints
+	err = manager.RemoveCheckpoint("key1")
+	assert.NoError(t, err)
+	// Test Remove Nonexisted Checkpoints
+	err = manager.RemoveCheckpoint("key1")
+	assert.NoError(t, err)
+
+	// Test ListCheckpoints
+	keys, err = manager.ListCheckpoints()
+	assert.NoError(t, err)
+	assert.Equal(t, keys, []string{"key2"})
+
+	// Test Get NonExisted Checkpoint
+	checkpointNE := newFakeCheckpointV1("NE", nil, false)
+	err = manager.GetCheckpoint("key1", checkpointNE)
+	assert.Error(t, err)
+}

vendor/k8s.io/kubernetes/pkg/kubelet/checkpointmanager/checksum/BUILD

@@ -0,0 +1,26 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
+
+go_library(
+    name = "go_default_library",
+    srcs = ["checksum.go"],
+    importpath = "k8s.io/kubernetes/pkg/kubelet/checkpointmanager/checksum",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//pkg/kubelet/checkpointmanager/errors:go_default_library",
+        "//pkg/util/hash:go_default_library",
+    ],
+)
+
+filegroup(
+    name = "package-srcs",
+    srcs = glob(["**"]),
+    tags = ["automanaged"],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "all-srcs",
+    srcs = [":package-srcs"],
+    tags = ["automanaged"],
+    visibility = ["//visibility:public"],
+)

vendor/k8s.io/kubernetes/pkg/kubelet/checkpointmanager/checksum/checksum.go

@@ -0,0 +1,46 @@
+/*
+Copyright 2018 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 checksum
+
+import (
+	"hash/fnv"
+
+	"k8s.io/kubernetes/pkg/kubelet/checkpointmanager/errors"
+	hashutil "k8s.io/kubernetes/pkg/util/hash"
+)
+
+// Data to be stored as checkpoint
+type Checksum uint64
+
+// VerifyChecksum verifies that passed checksum is same as calculated checksum
+func (cs Checksum) Verify(data interface{}) error {
+	if cs != New(data) {
+		return errors.ErrCorruptCheckpoint
+	}
+	return nil
+}
+
+func New(data interface{}) Checksum {
+	return Checksum(getChecksum(data))
+}
+
+// Get returns calculated checksum of checkpoint data
+func getChecksum(data interface{}) uint64 {
+	hash := fnv.New32a()
+	hashutil.DeepHashObject(hash, data)
+	return uint64(hash.Sum32())
+}

vendor/k8s.io/kubernetes/pkg/kubelet/checkpointmanager/errors/BUILD

@@ -0,0 +1,25 @@
+package(default_visibility = ["//visibility:public"])
+
+load(
+    "@io_bazel_rules_go//go:def.bzl",
+    "go_library",
+)
+
+go_library(
+    name = "go_default_library",
+    srcs = ["errors.go"],
+    importpath = "k8s.io/kubernetes/pkg/kubelet/checkpointmanager/errors",
+)
+
+filegroup(
+    name = "package-srcs",
+    srcs = glob(["**"]),
+    tags = ["automanaged"],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "all-srcs",
+    srcs = [":package-srcs"],
+    tags = ["automanaged"],
+)

vendor/k8s.io/kubernetes/pkg/kubelet/checkpointmanager/errors/errors.go

@@ -0,0 +1,25 @@
+/*
+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 errors
+
+import "fmt"
+
+// ErrCorruptCheckpoint error is reported when checksum does not match
+var ErrCorruptCheckpoint = fmt.Errorf("checkpoint is corrupted")
+
+// ErrCheckpointNotFound is reported when checkpoint is not found for a given key
+var ErrCheckpointNotFound = fmt.Errorf("checkpoint is not found")

vendor/k8s.io/kubernetes/pkg/kubelet/checkpointmanager/testing/BUILD

@@ -0,0 +1,28 @@
+package(default_visibility = ["//visibility:public"])
+
+load(
+    "@io_bazel_rules_go//go:def.bzl",
+    "go_library",
+)
+
+go_library(
+    name = "go_default_library",
+    srcs = ["util.go"],
+    importpath = "k8s.io/kubernetes/pkg/kubelet/checkpointmanager/testing",
+)
+
+filegroup(
+    name = "package-srcs",
+    srcs = glob(["**"]),
+    tags = ["automanaged"],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "all-srcs",
+    srcs = [
+        ":package-srcs",
+        "//pkg/kubelet/checkpointmanager/testing/example_checkpoint_formats/v1:all-srcs",
+    ],
+    tags = ["automanaged"],
+)

vendor/k8s.io/kubernetes/pkg/kubelet/checkpointmanager/testing/example_checkpoint_formats/v1/BUILD

@@ -0,0 +1,23 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
+
+go_library(
+    name = "go_default_library",
+    srcs = ["types.go"],
+    importpath = "k8s.io/kubernetes/pkg/kubelet/checkpointmanager/testing/example_checkpoint_formats/v1",
+    visibility = ["//visibility:public"],
+    deps = ["//pkg/kubelet/checkpointmanager/checksum:go_default_library"],
+)
+
+filegroup(
+    name = "package-srcs",
+    srcs = glob(["**"]),
+    tags = ["automanaged"],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "all-srcs",
+    srcs = [":package-srcs"],
+    tags = ["automanaged"],
+    visibility = ["//visibility:public"],
+)

vendor/k8s.io/kubernetes/pkg/kubelet/checkpointmanager/testing/example_checkpoint_formats/v1/types.go

@@ -0,0 +1,62 @@
+/*
+Copyright 2018 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 v1
+
+import (
+	"encoding/json"
+
+	"k8s.io/kubernetes/pkg/kubelet/checkpointmanager/checksum"
+)
+
+type protocol string
+
+// portMapping is the port mapping configurations of a sandbox.
+type PortMapping struct {
+	// protocol of the port mapping.
+	Protocol *protocol
+	// Port number within the container.
+	ContainerPort *int32
+	// Port number on the host.
+	HostPort *int32
+}
+
+// CheckpointData contains all types of data that can be stored in the checkpoint.
+type Data struct {
+	PortMappings []*PortMapping `json:"port_mappings,omitempty"`
+	HostNetwork  bool           `json:"host_network,omitempty"`
+}
+
+// CheckpointData is a sample example structure to be used in test cases for checkpointing
+type CheckpointData struct {
+	Version  string
+	Name     string
+	Data     *Data
+	Checksum checksum.Checksum
+}
+
+func (cp *CheckpointData) MarshalCheckpoint() ([]byte, error) {
+	cp.Checksum = checksum.New(*cp.Data)
+	return json.Marshal(*cp)
+}
+
+func (cp *CheckpointData) UnmarshalCheckpoint(blob []byte) error {
+	return json.Unmarshal(blob, cp)
+}
+
+func (cp *CheckpointData) VerifyChecksum() error {
+	return cp.Checksum.Verify(*cp.Data)
+}

vendor/k8s.io/kubernetes/pkg/kubelet/checkpointmanager/testing/util.go

@@ -0,0 +1,71 @@
+/*
+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
+}
+
+// NewMemStore returns an instance of MemStore
+func NewMemStore() *MemStore {
+	return &MemStore{mem: make(map[string][]byte)}
+}
+
+// Write writes the data to the store
+func (mstore *MemStore) Write(key string, data []byte) error {
+	mstore.Lock()
+	defer mstore.Unlock()
+	mstore.mem[key] = data
+	return nil
+}
+
+// Read returns data read from store
+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 is not found")
+	}
+	return data, nil
+}
+
+// Delete deletes data from the store
+func (mstore *MemStore) Delete(key string) error {
+	mstore.Lock()
+	defer mstore.Unlock()
+	delete(mstore.mem, key)
+	return nil
+}
+
+// List returns all the keys from the store
+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
+}