node: devicemgr: Address warnings from golint

Signed-off-by: Swati Sehgal <swsehgal@redhat.com>

pkg/kubelet/cm/devicemanager/checkpoint/checkpoint.go

@@ -74,10 +74,10 @@ func (dev DevicesPerNUMA) Devices() sets.String {
 
 // New returns an instance of Checkpoint - must be an alias for the most recent version
 func New(devEntries []PodDevicesEntry, devices map[string][]string) DeviceManagerCheckpoint {
-	return NewV2(devEntries, devices)
+	return newV2(devEntries, devices)
 }
 
-func NewV2(devEntries []PodDevicesEntry, devices map[string][]string) DeviceManagerCheckpoint {
+func newV2(devEntries []PodDevicesEntry, devices map[string][]string) DeviceManagerCheckpoint {
 	return &Data{
 		Data: checkpointData{
 			PodDeviceEntries:  devEntries,

pkg/kubelet/cm/devicemanager/checkpoint/checkpointv1.go

@@ -28,7 +28,7 @@ import (
 	"k8s.io/kubernetes/pkg/kubelet/checkpointmanager/errors"
 )
 
-// PodDevicesEntry connects pod information to devices, without topology information (k8s <= 1.19)
+// PodDevicesEntryV1 connects pod information to devices, without topology information (k8s <= 1.19)
 type PodDevicesEntryV1 struct {
 	PodUID        string
 	ContainerName string
@@ -37,7 +37,7 @@ type PodDevicesEntryV1 struct {
 	AllocResp     []byte
 }
 
-// checkpointData struct is used to store pod to device allocation information
+// checkpointDataV1 struct is used to store pod to device allocation information
 // in a checkpoint file, without topology information (k8s <= 1.19)
 type checkpointDataV1 struct {
 	PodDeviceEntries  []PodDevicesEntryV1
@@ -63,13 +63,13 @@ func (cp checkpointDataV1) checksum() checksum.Checksum {
 	return checksum.Checksum(hash.Sum32())
 }
 
-// Data holds checkpoint data and its checksum, in V1 (k8s <= 1.19) format
+// DataV1 holds checkpoint data and its checksum, in V1 (k8s <= 1.19) format
 type DataV1 struct {
 	Data     checkpointDataV1
 	Checksum checksum.Checksum
 }
 
-// New returns an instance of Checkpoint, in V1 (k8s <= 1.19) format.
+// NewV1 returns an instance of Checkpoint, in V1 (k8s <= 1.19) format.
 // Users should avoid creating checkpoints in formats different than the most recent one,
 // use the old formats only to validate existing checkpoint and convert them to most recent
 // format. The only exception should be test code.
@@ -90,7 +90,7 @@ func (cp *DataV1) MarshalCheckpoint() ([]byte, error) {
 	return json.Marshal(*cp)
 }
 
-// MarshalCheckpoint returns marshalled data
+// UnmarshalCheckpoint returns unmarshalled data
 func (cp *DataV1) UnmarshalCheckpoint(blob []byte) error {
 	return json.Unmarshal(blob, cp)
 }

pkg/kubelet/cm/devicemanager/endpoint.go

@@ -50,7 +50,7 @@ type endpointImpl struct {
 // This is to be used during normal device plugin registration.
 func newEndpointImpl(p plugin.DevicePlugin) *endpointImpl {
 	return &endpointImpl{
-		api:          p.Api(),
+		api:          p.API(),
 		resourceName: p.Resource(),
 	}
 }

pkg/kubelet/cm/devicemanager/manager.go

@@ -163,6 +163,8 @@ func newManagerImpl(socketPath string, topology []cadvisorapi.Node, topologyAffi
 	return manager, nil
 }
 
+// CleanupPluginDirectory is to remove all existing unix sockets
+// from /var/lib/kubelet/device-plugins on Device Plugin Manager start
 func (m *ManagerImpl) CleanupPluginDirectory(dir string) error {
 	d, err := os.Open(dir)
 	if err != nil {
@@ -200,8 +202,10 @@ func (m *ManagerImpl) CleanupPluginDirectory(dir string) error {
 	return errorsutil.NewAggregate(errs)
 }
 
+// PluginConnected is to connect a plugin to a new endpoint.
+// This is done as part of device plugin registration.
 func (m *ManagerImpl) PluginConnected(resourceName string, p plugin.DevicePlugin) error {
-	options, err := p.Api().GetDevicePluginOptions(context.Background(), &pluginapi.Empty{})
+	options, err := p.API().GetDevicePluginOptions(context.Background(), &pluginapi.Empty{})
 	if err != nil {
 		return fmt.Errorf("failed to get device plugin options: %v", err)
 	}
@@ -215,6 +219,8 @@ func (m *ManagerImpl) PluginConnected(resourceName string, p plugin.DevicePlugin
 	return nil
 }
 
+// PluginDisconnected is to disconnect a plugin from an endpoint.
+// This is done as part of device plugin deregistration.
 func (m *ManagerImpl) PluginDisconnected(resourceName string) {
 	m.mutex.Lock()
 	defer m.mutex.Unlock()
@@ -227,6 +233,10 @@ func (m *ManagerImpl) PluginDisconnected(resourceName string) {
 	m.endpoints[resourceName].e.setStopTime(time.Now())
 }
 
+// PluginListAndWatchReceiver receives ListAndWatchResponse from a device plugin
+// and ensures that an upto date state (e.g. number of devices and device health)
+// is captured. Also, registered device and device to container allocation
+// information is checkpointed to the disk.
 func (m *ManagerImpl) PluginListAndWatchReceiver(resourceName string, resp *pluginapi.ListAndWatchResponse) {
 	var devices []pluginapi.Device
 	for _, d := range resp.Devices {

pkg/kubelet/cm/devicemanager/plugin/v1beta1/api.go

@@ -20,10 +20,13 @@ import (
 	api "k8s.io/kubelet/pkg/apis/deviceplugin/v1beta1"
 )
 
+// RegistrationHandler is an interface for handling device plugin registration
+// and plugin directory cleanup.
 type RegistrationHandler interface {
 	CleanupPluginDirectory(string) error
 }
 
+// ClientHandler is an interface for handling device plugin connections.
 type ClientHandler interface {
 	PluginConnected(string, DevicePlugin) error
 	PluginDisconnected(string)

pkg/kubelet/cm/devicemanager/plugin/v1beta1/client.go

@@ -30,12 +30,14 @@ import (
 	api "k8s.io/kubelet/pkg/apis/deviceplugin/v1beta1"
 )
 
+// DevicePlugin interface provides methods for accessing Device Plugin resources, API and unix socket.
 type DevicePlugin interface {
-	Api() api.DevicePluginClient
+	API() api.DevicePluginClient
 	Resource() string
 	SocketPath() string
 }
 
+// Client interface provides methods for establishing/closing gRPC connection and running the device plugin gRPC client.
 type Client interface {
 	Connect() error
 	Run()
@@ -51,6 +53,7 @@ type client struct {
 	client   api.DevicePluginClient
 }
 
+// NewPluginClient returns an initialized device plugin client.
 func NewPluginClient(r string, socketPath string, h ClientHandler) Client {
 	return &client{
 		resource: r,
@@ -59,6 +62,7 @@ func NewPluginClient(r string, socketPath string, h ClientHandler) Client {
 	}
 }
 
+// Connect is for establishing a gRPC connection between device manager and device plugin.
 func (c *client) Connect() error {
 	client, conn, err := dial(c.socket)
 	if err != nil {
@@ -70,6 +74,7 @@ func (c *client) Connect() error {
 	return c.handler.PluginConnected(c.resource, c)
 }
 
+// Run is for running the device plugin gRPC client.
 func (c *client) Run() {
 	stream, err := c.client.ListAndWatch(context.Background(), &api.Empty{})
 	if err != nil {
@@ -88,6 +93,7 @@ func (c *client) Run() {
 	}
 }
 
+// Disconnect is for closing gRPC connection between device manager and device plugin.
 func (c *client) Disconnect() error {
 	c.mutex.Lock()
 	if c.grpc != nil {
@@ -105,7 +111,7 @@ func (c *client) Resource() string {
 	return c.resource
 }
 
-func (c *client) Api() api.DevicePluginClient {
+func (c *client) API() api.DevicePluginClient {
 	return c.client
 }
 

pkg/kubelet/cm/devicemanager/plugin/v1beta1/server.go

@@ -36,6 +36,7 @@ import (
 	"k8s.io/kubernetes/pkg/kubelet/pluginmanager/cache"
 )
 
+// Server interface provides methods for Device plugin registration server.
 type Server interface {
 	cache.PluginHandler
 	Start() error
@@ -54,6 +55,7 @@ type server struct {
 	clients    map[string]Client
 }
 
+// NewServer returns an initialized device plugin registration server.
 func NewServer(socketPath string, rh RegistrationHandler, ch ClientHandler) (Server, error) {
 	if socketPath == "" || !filepath.IsAbs(socketPath) {
 		return nil, fmt.Errorf(errBadSocket+" %s", socketPath)

pkg/kubelet/cm/devicemanager/pod_devices.go

@@ -343,11 +343,11 @@ func (pdev *podDevices) getContainerDevices(podUID, contName string) ResourceDev
 		}
 		devicePluginMap := make(map[string]pluginapi.Device)
 		for numaid, devlist := range allocateInfo.deviceIds {
-			for _, devId := range devlist {
+			for _, devID := range devlist {
 				var topology *pluginapi.TopologyInfo
 				if numaid != nodeWithoutTopology {
 					NUMANodes := []*pluginapi.NUMANode{{ID: numaid}}
-					if pDev, ok := devicePluginMap[devId]; ok && pDev.Topology != nil {
+					if pDev, ok := devicePluginMap[devID]; ok && pDev.Topology != nil {
 						if nodes := pDev.Topology.GetNodes(); nodes != nil {
 							NUMANodes = append(NUMANodes, nodes...)
 						}
@@ -356,7 +356,7 @@ func (pdev *podDevices) getContainerDevices(podUID, contName string) ResourceDev
 					// ID and Healthy are not relevant here.
 					topology = &pluginapi.TopologyInfo{Nodes: NUMANodes}
 				}
-				devicePluginMap[devId] = pluginapi.Device{
+				devicePluginMap[devID] = pluginapi.Device{
 					Topology: topology,
 				}
 			}
@@ -372,10 +372,12 @@ type DeviceInstances map[string]pluginapi.Device
 // ResourceDeviceInstances is a mapping resource name -> DeviceInstances
 type ResourceDeviceInstances map[string]DeviceInstances
 
+// NewResourceDeviceInstances returns a new ResourceDeviceInstances
 func NewResourceDeviceInstances() ResourceDeviceInstances {
 	return make(ResourceDeviceInstances)
 }
 
+// Clone returns a clone of ResourceDeviceInstances
 func (rdev ResourceDeviceInstances) Clone() ResourceDeviceInstances {
 	clone := NewResourceDeviceInstances()
 	for resourceName, resourceDevs := range rdev {

pkg/kubelet/cm/devicemanager/pod_devices_test.go

@@ -42,14 +42,14 @@ func TestGetContainerDevices(t *testing.T) {
 	contDevices, ok := resContDevices[resourceName1]
 	require.True(t, ok, "resource %q not present", resourceName1)
 
-	for devId, plugInfo := range contDevices {
+	for devID, plugInfo := range contDevices {
 		nodes := plugInfo.GetTopology().GetNodes()
 		require.Equal(t, len(nodes), len(devices), "Incorrect container devices: %v - %v (nodes %v)", devices, contDevices, nodes)
 
 		for _, node := range plugInfo.GetTopology().GetNodes() {
 			dev, ok := devices[node.ID]
 			require.True(t, ok, "NUMA id %v doesn't exist in result", node.ID)
-			require.Equal(t, devId, dev[0], "Can't find device %s in result", dev[0])
+			require.Equal(t, devID, dev[0], "Can't find device %s in result", dev[0])
 		}
 	}
 }