Fix/Add comments on cadvisor implementations

hack/.golint_failures

@@ -148,8 +148,6 @@ pkg/kubelet
 pkg/kubelet/apis/config
 pkg/kubelet/apis/config/v1beta1
 pkg/kubelet/apis/deviceplugin/v1beta1
-pkg/kubelet/cadvisor
-pkg/kubelet/cadvisor/testing
 pkg/kubelet/checkpointmanager/testing/example_checkpoint_formats/v1
 pkg/kubelet/client
 pkg/kubelet/cm

pkg/kubelet/cadvisor/cadvisor_linux.go

@@ -82,6 +82,7 @@ func init() {
 	}
 }
 
+// New creates a new cAdvisor Interface for linux systems.
 func New(imageFsInfoProvider ImageFsInfoProvider, rootPath string, cgroupRoots []string, usingLegacyStats bool) (Interface, error) {
 	sysFs := sysfs.NewRealSysFs()
 
@@ -98,7 +99,7 @@ func New(imageFsInfoProvider ImageFsInfoProvider, rootPath string, cgroupRoots [
 		includedMetrics[cadvisormetrics.DiskUsageMetrics] = struct{}{}
 	}
 
-	// Create and start the cAdvisor container manager.
+	// Create the cAdvisor container manager.
 	m, err := manager.New(memory.New(statsCacheDuration, nil), sysFs, maxHousekeepingInterval, allowDynamicHousekeeping, includedMetrics, http.DefaultClient, cgroupRoots)
 	if err != nil {
 		return nil, err
@@ -114,13 +115,11 @@ func New(imageFsInfoProvider ImageFsInfoProvider, rootPath string, cgroupRoots [
 		}
 	}
 
-	cadvisorClient := &cadvisorClient{
+	return &cadvisorClient{
 		imageFsInfoProvider: imageFsInfoProvider,
 		rootPath:            rootPath,
 		Manager:             m,
-	}
-
-	return cadvisorClient, nil
+	}, nil
 }
 
 func (cc *cadvisorClient) Start() error {

pkg/kubelet/cadvisor/cadvisor_unsupported.go

@@ -31,50 +31,51 @@ type cadvisorUnsupported struct {
 
 var _ Interface = new(cadvisorUnsupported)
 
+// New creates a new cAdvisor Interface for unsupported systems.
 func New(imageFsInfoProvider ImageFsInfoProvider, rootPath string, cgroupsRoots []string, usingLegacyStats bool) (Interface, error) {
 	return &cadvisorUnsupported{}, nil
 }
 
-var unsupportedErr = errors.New("cAdvisor is unsupported in this build")
+var errUnsupported = errors.New("cAdvisor is unsupported in this build")
 
 func (cu *cadvisorUnsupported) Start() error {
-	return unsupportedErr
+	return errUnsupported
 }
 
 func (cu *cadvisorUnsupported) DockerContainer(name string, req *cadvisorapi.ContainerInfoRequest) (cadvisorapi.ContainerInfo, error) {
-	return cadvisorapi.ContainerInfo{}, unsupportedErr
+	return cadvisorapi.ContainerInfo{}, errUnsupported
 }
 
 func (cu *cadvisorUnsupported) ContainerInfo(name string, req *cadvisorapi.ContainerInfoRequest) (*cadvisorapi.ContainerInfo, error) {
-	return nil, unsupportedErr
+	return nil, errUnsupported
 }
 
 func (cu *cadvisorUnsupported) ContainerInfoV2(name string, options cadvisorapiv2.RequestOptions) (map[string]cadvisorapiv2.ContainerInfo, error) {
-	return nil, unsupportedErr
+	return nil, errUnsupported
 }
 
 func (cu *cadvisorUnsupported) SubcontainerInfo(name string, req *cadvisorapi.ContainerInfoRequest) (map[string]*cadvisorapi.ContainerInfo, error) {
-	return nil, unsupportedErr
+	return nil, errUnsupported
 }
 
 func (cu *cadvisorUnsupported) MachineInfo() (*cadvisorapi.MachineInfo, error) {
-	return nil, unsupportedErr
+	return nil, errUnsupported
 }
 
 func (cu *cadvisorUnsupported) VersionInfo() (*cadvisorapi.VersionInfo, error) {
-	return nil, unsupportedErr
+	return nil, errUnsupported
 }
 
 func (cu *cadvisorUnsupported) ImagesFsInfo() (cadvisorapiv2.FsInfo, error) {
-	return cadvisorapiv2.FsInfo{}, unsupportedErr
+	return cadvisorapiv2.FsInfo{}, errUnsupported
 }
 
 func (cu *cadvisorUnsupported) RootFsInfo() (cadvisorapiv2.FsInfo, error) {
-	return cadvisorapiv2.FsInfo{}, unsupportedErr
+	return cadvisorapiv2.FsInfo{}, errUnsupported
 }
 
 func (cu *cadvisorUnsupported) WatchEvents(request *events.Request) (*events.EventChannel, error) {
-	return nil, unsupportedErr
+	return nil, errUnsupported
 }
 
 func (cu *cadvisorUnsupported) GetDirFsInfo(path string) (cadvisorapiv2.FsInfo, error) {

pkg/kubelet/cadvisor/cadvisor_windows.go

@@ -53,6 +53,7 @@ func (cu *cadvisorClient) ContainerInfo(name string, req *cadvisorapi.ContainerI
 	return &cadvisorapi.ContainerInfo{}, nil
 }
 
+// ContainerInfoV2 is only expected to be used for the root container. Returns info for all containers in the node.
 func (cu *cadvisorClient) ContainerInfoV2(name string, options cadvisorapiv2.RequestOptions) (map[string]cadvisorapiv2.ContainerInfo, error) {
 	return cu.winStatsClient.WinContainerInfos()
 }

pkg/kubelet/cadvisor/doc.go

@@ -14,5 +14,5 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-// Kubelet interactions with cAdvisor.
+// Package cadvisor provides an interface for Kubelet interactions with cAdvisor.
 package cadvisor // import "k8s.io/kubernetes/pkg/kubelet/cadvisor"

pkg/kubelet/cadvisor/testing/cadvisor_fake.go

@@ -23,71 +23,85 @@ import (
 	"k8s.io/kubernetes/pkg/kubelet/cadvisor"
 )
 
-// Fake cAdvisor implementation.
+// Fake cadvisor.Interface implementation.
 type Fake struct {
 	NodeName string
 }
 
 const (
-	FakeNumCores           = 1
-	FakeMemoryCapacity     = 4026531840
-	FakeKernelVersion      = "3.16.0-0.bpo.4-amd64"
-	FakeContainerOsVersion = "Debian GNU/Linux 7 (wheezy)"
-	FakeDockerVersion      = "1.13.1"
+	// FakeKernelVersion is a fake kernel version for testing.
+	FakeKernelVersion = "3.16.0-0.bpo.4-amd64"
+	// FakeContainerOSVersion is a fake OS version for testing.
+	FakeContainerOSVersion = "Debian GNU/Linux 7 (wheezy)"
+
+	fakeNumCores       = 1
+	fakeMemoryCapacity = 4026531840
+	fakeDockerVersion  = "1.13.1"
 )
 
 var _ cadvisor.Interface = new(Fake)
 
+// Start is a fake implementation of Interface.Start.
 func (c *Fake) Start() error {
 	return nil
 }
 
+// ContainerInfo is a fake implementation of Interface.ContainerInfo.
 func (c *Fake) ContainerInfo(name string, req *cadvisorapi.ContainerInfoRequest) (*cadvisorapi.ContainerInfo, error) {
 	return new(cadvisorapi.ContainerInfo), nil
 }
 
+// ContainerInfoV2 is a fake implementation of Interface.ContainerInfoV2.
 func (c *Fake) ContainerInfoV2(name string, options cadvisorapiv2.RequestOptions) (map[string]cadvisorapiv2.ContainerInfo, error) {
 	return map[string]cadvisorapiv2.ContainerInfo{}, nil
 }
 
+// SubcontainerInfo is a fake implementation of Interface.SubcontainerInfo.
 func (c *Fake) SubcontainerInfo(name string, req *cadvisorapi.ContainerInfoRequest) (map[string]*cadvisorapi.ContainerInfo, error) {
 	return map[string]*cadvisorapi.ContainerInfo{}, nil
 }
 
+// DockerContainer is a fake implementation of Interface.DockerContainer.
 func (c *Fake) DockerContainer(name string, req *cadvisorapi.ContainerInfoRequest) (cadvisorapi.ContainerInfo, error) {
 	return cadvisorapi.ContainerInfo{}, nil
 }
 
+// MachineInfo is a fake implementation of Interface.MachineInfo.
 func (c *Fake) MachineInfo() (*cadvisorapi.MachineInfo, error) {
 	// Simulate a machine with 1 core and 3.75GB of memory.
 	// We set it to non-zero values to make non-zero-capacity machines in Kubemark.
 	return &cadvisorapi.MachineInfo{
-		NumCores:       FakeNumCores,
+		NumCores:       fakeNumCores,
 		InstanceID:     cadvisorapi.InstanceID(c.NodeName),
-		MemoryCapacity: FakeMemoryCapacity,
+		MemoryCapacity: fakeMemoryCapacity,
 	}, nil
 }
 
+// VersionInfo is a fake implementation of Interface.VersionInfo.
 func (c *Fake) VersionInfo() (*cadvisorapi.VersionInfo, error) {
 	return &cadvisorapi.VersionInfo{
 		KernelVersion:      FakeKernelVersion,
-		ContainerOsVersion: FakeContainerOsVersion,
-		DockerVersion:      FakeDockerVersion,
+		ContainerOsVersion: FakeContainerOSVersion,
+		DockerVersion:      fakeDockerVersion,
 	}, nil
 }
 
+// ImagesFsInfo is a fake implementation of Interface.ImagesFsInfo.
 func (c *Fake) ImagesFsInfo() (cadvisorapiv2.FsInfo, error) {
 	return cadvisorapiv2.FsInfo{}, nil
 }
 
+// RootFsInfo is a fake implementation of Interface.RootFsInfo.
 func (c *Fake) RootFsInfo() (cadvisorapiv2.FsInfo, error) {
 	return cadvisorapiv2.FsInfo{}, nil
 }
 
+// WatchEvents is a fake implementation of Interface.WatchEvents.
 func (c *Fake) WatchEvents(request *events.Request) (*events.EventChannel, error) {
 	return new(events.EventChannel), nil
 }
 
+// GetDirFsInfo is a fake implementation of Interface.GetDirFsInfo.
 func (c *Fake) GetDirFsInfo(path string) (cadvisorapiv2.FsInfo, error) {
 	return cadvisorapiv2.FsInfo{}, nil
 }

pkg/kubelet/cadvisor/testing/cadvisor_mock.go

@@ -24,12 +24,14 @@ import (
 	"k8s.io/kubernetes/pkg/kubelet/cadvisor"
 )
 
+// Mock cadvisor.Interface implementation.
 type Mock struct {
 	mock.Mock
 }
 
 var _ cadvisor.Interface = new(Mock)
 
+// Start is a mock implementation of Interface.Start.
 func (c *Mock) Start() error {
 	args := c.Called()
 	return args.Error(0)
@@ -47,6 +49,7 @@ func (c *Mock) ContainerInfoV2(name string, options cadvisorapiv2.RequestOptions
 	return args.Get(0).(map[string]cadvisorapiv2.ContainerInfo), args.Error(1)
 }
 
+// SubcontainerInfo is a mock implementation of Interface.SubcontainerInfo.
 func (c *Mock) SubcontainerInfo(name string, req *cadvisorapi.ContainerInfoRequest) (map[string]*cadvisorapi.ContainerInfo, error) {
 	args := c.Called(name, req)
 	return args.Get(0).(map[string]*cadvisorapi.ContainerInfo), args.Error(1)
@@ -64,26 +67,31 @@ func (c *Mock) MachineInfo() (*cadvisorapi.MachineInfo, error) {
 	return args.Get(0).(*cadvisorapi.MachineInfo), args.Error(1)
 }
 
+// VersionInfo is a mock implementation of Interface.VersionInfo.
 func (c *Mock) VersionInfo() (*cadvisorapi.VersionInfo, error) {
 	args := c.Called()
 	return args.Get(0).(*cadvisorapi.VersionInfo), args.Error(1)
 }
 
+// ImagesFsInfo is a mock implementation of Interface.ImagesFsInfo.
 func (c *Mock) ImagesFsInfo() (cadvisorapiv2.FsInfo, error) {
 	args := c.Called()
 	return args.Get(0).(cadvisorapiv2.FsInfo), args.Error(1)
 }
 
+// RootFsInfo is a mock implementation of Interface.RootFsInfo.
 func (c *Mock) RootFsInfo() (cadvisorapiv2.FsInfo, error) {
 	args := c.Called()
 	return args.Get(0).(cadvisorapiv2.FsInfo), args.Error(1)
 }
 
+// WatchEvents is a mock implementation of Interface.WatchEvents.
 func (c *Mock) WatchEvents(request *events.Request) (*events.EventChannel, error) {
 	args := c.Called()
 	return args.Get(0).(*events.EventChannel), args.Error(1)
 }
 
+// GetDirFsInfo is a mock implementation of Interface.GetDirFsInfo.
 func (c *Mock) GetDirFsInfo(path string) (cadvisorapiv2.FsInfo, error) {
 	args := c.Called(path)
 	return args.Get(0).(cadvisorapiv2.FsInfo), args.Error(1)

pkg/kubelet/cadvisor/util.go

@@ -28,11 +28,13 @@ import (
 )
 
 const (
+	// CrioSocket is the path to the CRI-O socket.
 	// Please keep this in sync with the one in:
 	// github.com/google/cadvisor/container/crio/client.go
 	CrioSocket = "/var/run/crio/crio.sock"
 )
 
+// CapacityFromMachineInfo returns the capacity of the resources from the machine info.
 func CapacityFromMachineInfo(info *cadvisorapi.MachineInfo) v1.ResourceList {
 	c := v1.ResourceList{
 		v1.ResourceCPU: *resource.NewMilliQuantity(
@@ -54,6 +56,7 @@ func CapacityFromMachineInfo(info *cadvisorapi.MachineInfo) v1.ResourceList {
 	return c
 }
 
+// EphemeralStorageCapacityFromFsInfo returns the capacity of the ephemeral storage from the FsInfo.
 func EphemeralStorageCapacityFromFsInfo(info cadvisorapi2.FsInfo) v1.ResourceList {
 	c := v1.ResourceList{
 		v1.ResourceEphemeralStorage: *resource.NewQuantity(
@@ -63,13 +66,13 @@ func EphemeralStorageCapacityFromFsInfo(info cadvisorapi2.FsInfo) v1.ResourceLis
 	return c
 }
 
+// UsingLegacyCadvisorStats returns true if container stats are provided by cadvisor instead of through the CRI.
 // CRI integrations should get container metrics via CRI. Docker
 // uses the built-in cadvisor to gather such metrics on Linux for
 // historical reasons.
 // cri-o relies on cadvisor as a temporary workaround. The code should
 // be removed. Related issue:
 // https://github.com/kubernetes/kubernetes/issues/51798
-// UsingLegacyCadvisorStats returns true if container stats are provided by cadvisor instead of through the CRI
 func UsingLegacyCadvisorStats(runtime, runtimeEndpoint string) bool {
 	return (runtime == kubetypes.DockerContainerRuntime && goruntime.GOOS == "linux") ||
 		runtimeEndpoint == CrioSocket || runtimeEndpoint == "unix://"+CrioSocket

pkg/kubelet/kubelet_node_status_test.go

@@ -271,7 +271,7 @@ func TestUpdateNewNodeStatus(t *testing.T) {
 						SystemUUID:              "abc",
 						BootID:                  "1b3",
 						KernelVersion:           cadvisortest.FakeKernelVersion,
-						OSImage:                 cadvisortest.FakeContainerOsVersion,
+						OSImage:                 cadvisortest.FakeContainerOSVersion,
 						OperatingSystem:         goruntime.GOOS,
 						Architecture:            goruntime.GOARCH,
 						ContainerRuntimeVersion: "test://1.5.0",
@@ -449,7 +449,7 @@ func TestUpdateExistingNodeStatus(t *testing.T) {
 				SystemUUID:              "abc",
 				BootID:                  "1b3",
 				KernelVersion:           cadvisortest.FakeKernelVersion,
-				OSImage:                 cadvisortest.FakeContainerOsVersion,
+				OSImage:                 cadvisortest.FakeContainerOSVersion,
 				OperatingSystem:         goruntime.GOOS,
 				Architecture:            goruntime.GOARCH,
 				ContainerRuntimeVersion: "test://1.5.0",
@@ -647,7 +647,7 @@ func TestUpdateNodeStatusWithRuntimeStateError(t *testing.T) {
 				SystemUUID:              "abc",
 				BootID:                  "1b3",
 				KernelVersion:           cadvisortest.FakeKernelVersion,
-				OSImage:                 cadvisortest.FakeContainerOsVersion,
+				OSImage:                 cadvisortest.FakeContainerOSVersion,
 				OperatingSystem:         goruntime.GOOS,
 				Architecture:            goruntime.GOARCH,
 				ContainerRuntimeVersion: "test://1.5.0",
@@ -877,7 +877,7 @@ func TestUpdateNodeStatusWithLease(t *testing.T) {
 				SystemUUID:              "abc",
 				BootID:                  "1b3",
 				KernelVersion:           cadvisortest.FakeKernelVersion,
-				OSImage:                 cadvisortest.FakeContainerOsVersion,
+				OSImage:                 cadvisortest.FakeContainerOSVersion,
 				OperatingSystem:         goruntime.GOOS,
 				Architecture:            goruntime.GOARCH,
 				ContainerRuntimeVersion: "test://1.5.0",