Handle image digests in node status and image GC

Start including Docker image digests in the node status and consider image digests during image
garbage collection.

pkg/kubelet/container/image_puller_test.go

@@ -108,7 +108,7 @@ func TestPuller(t *testing.T) {
 		fakeRecorder := &record.FakeRecorder{}
 		puller := NewImagePuller(fakeRecorder, fakeRuntime, backOff)
 
-		fakeRuntime.ImageList = []Image{{"present_image", nil, 0}}
+		fakeRuntime.ImageList = []Image{{"present_image", nil, nil, 1}}
 		fakeRuntime.Err = c.pullerErr
 		fakeRuntime.InspectErr = c.inspectErr
 

pkg/kubelet/container/runtime.go

@@ -319,6 +319,8 @@ type Image struct {
 	ID string
 	// Other names by which this image is known.
 	RepoTags []string
+	// Digests by which this image is known.
+	RepoDigests []string
 	// The size of the image in bytes.
 	Size int64
 }

pkg/kubelet/container/serialized_image_puller_test.go

@@ -108,7 +108,7 @@ func TestSerializedPuller(t *testing.T) {
 		fakeRecorder := &record.FakeRecorder{}
 		puller := NewSerializedImagePuller(fakeRecorder, fakeRuntime, backOff)
 
-		fakeRuntime.ImageList = []Image{{"present_image", nil, 0}}
+		fakeRuntime.ImageList = []Image{{"present_image", nil, nil, 0}}
 		fakeRuntime.Err = c.pullerErr
 		fakeRuntime.InspectErr = c.inspectErr
 

pkg/kubelet/dockertools/convert.go

@@ -76,8 +76,9 @@ func toRuntimeImage(image *dockertypes.Image) (*kubecontainer.Image, error) {
 	}
 
 	return &kubecontainer.Image{
-		ID:       image.ID,
-		RepoTags: image.RepoTags,
-		Size:     image.VirtualSize,
+		ID:          image.ID,
+		RepoTags:    image.RepoTags,
+		RepoDigests: image.RepoDigests,
+		Size:        image.VirtualSize,
 	}, nil
 }

pkg/kubelet/dockertools/convert_test.go

@@ -72,12 +72,14 @@ func TestToRuntimeImage(t *testing.T) {
 	original := &dockertypes.Image{
 		ID:          "aeeea",
 		RepoTags:    []string{"abc", "def"},
+		RepoDigests: []string{"123", "456"},
 		VirtualSize: 1234,
 	}
 	expected := &kubecontainer.Image{
-		ID:       "aeeea",
-		RepoTags: []string{"abc", "def"},
-		Size:     1234,
+		ID:          "aeeea",
+		RepoTags:    []string{"abc", "def"},
+		RepoDigests: []string{"123", "456"},
+		Size:        1234,
 	}
 
 	actual, err := toRuntimeImage(original)

pkg/kubelet/image_manager.go

@@ -164,6 +164,7 @@ func (im *realImageManager) detectImages(detectTime time.Time) error {
 	imagesInUse := sets.NewString()
 	for _, pod := range pods {
 		for _, container := range pod.Containers {
+			glog.V(5).Infof("Pod %s/%s, container %s uses image %s", pod.Namespace, pod.Name, container.Name, container.Image)
 			imagesInUse.Insert(container.Image)
 		}
 	}
@@ -174,10 +175,12 @@ func (im *realImageManager) detectImages(detectTime time.Time) error {
 	im.imageRecordsLock.Lock()
 	defer im.imageRecordsLock.Unlock()
 	for _, image := range images {
+		glog.V(5).Infof("Adding image ID %s to currentImages", image.ID)
 		currentImages.Insert(image.ID)
 
 		// New image, set it as detected now.
 		if _, ok := im.imageRecords[image.ID]; !ok {
+			glog.V(5).Infof("Image ID %s is new", image.ID)
 			im.imageRecords[image.ID] = &imageRecord{
 				firstDetected: detectTime,
 			}
@@ -185,15 +188,18 @@ func (im *realImageManager) detectImages(detectTime time.Time) error {
 
 		// Set last used time to now if the image is being used.
 		if isImageUsed(image, imagesInUse) {
+			glog.V(5).Infof("Setting Image ID %s lastUsed to %v", image.ID, now)
 			im.imageRecords[image.ID].lastUsed = now
 		}
 
+		glog.V(5).Infof("Image ID %s has size %d", image.ID, image.Size)
 		im.imageRecords[image.ID].size = image.Size
 	}
 
 	// Remove old images from our records.
 	for image := range im.imageRecords {
 		if !currentImages.Has(image) {
+			glog.V(5).Infof("Image ID %s is no longer present; removing from imageRecords", image)
 			delete(im.imageRecords, image)
 		}
 	}
@@ -266,8 +272,10 @@ func (im *realImageManager) freeSpace(bytesToFree int64, freeTime time.Time) (in
 	var lastErr error
 	spaceFreed := int64(0)
 	for _, image := range images {
+		glog.V(5).Infof("Evaluating image ID %s for possible garbage collection", image.id)
 		// Images that are currently in used were given a newer lastUsed.
 		if image.lastUsed.Equal(freeTime) || image.lastUsed.After(freeTime) {
+			glog.V(5).Infof("Image ID %s has lastUsed=%v which is >= freeTime=%v, not eligible for garbage collection", image.id, image.lastUsed, freeTime)
 			break
 		}
 
@@ -275,6 +283,7 @@ func (im *realImageManager) freeSpace(bytesToFree int64, freeTime time.Time) (in
 		// In such a case, the image may have just been pulled down, and will be used by a container right away.
 
 		if freeTime.Sub(image.firstDetected) < im.policy.MinAge {
+			glog.V(5).Infof("Image ID %s has age %v which is less than the policy's minAge of %v, not eligible for garbage collection", image.id, freeTime.Sub(image.firstDetected), im.policy.MinAge)
 			continue
 		}
 
@@ -315,11 +324,11 @@ func (ev byLastUsedAndDetected) Less(i, j int) bool {
 }
 
 func isImageUsed(image container.Image, imagesInUse sets.String) bool {
-	// Check the image ID and all the RepoTags.
+	// Check the image ID and all the RepoTags and RepoDigests.
 	if _, ok := imagesInUse[image.ID]; ok {
 		return true
 	}
-	for _, tag := range image.RepoTags {
+	for _, tag := range append(image.RepoTags, image.RepoDigests...) {
 		if _, ok := imagesInUse[tag]; ok {
 			return true
 		}

pkg/kubelet/image_manager_test.go

@@ -337,6 +337,34 @@ func TestFreeSpaceImagesAlsoDoesLookupByRepoTags(t *testing.T) {
 	assert.Len(fakeRuntime.ImageList, 1)
 }
 
+func TestFreeSpaceImagesAlsoDoesLookupByRepoDigests(t *testing.T) {
+	manager, fakeRuntime, _ := newRealImageManager(ImageGCPolicy{})
+	fakeRuntime.ImageList = []container.Image{
+		makeImage(0, 1024),
+		{
+			ID:          "5678",
+			RepoDigests: []string{"potato", "salad"},
+			Size:        2048,
+		},
+	}
+	fakeRuntime.AllPodList = []*container.Pod{
+		{
+			Containers: []*container.Container{
+				{
+					ID:    container.ContainerID{Type: "test", ID: "c5678"},
+					Image: "salad",
+				},
+			},
+		},
+	}
+
+	spaceFreed, err := manager.freeSpace(1024, time.Now())
+	assert := assert.New(t)
+	require.NoError(t, err)
+	assert.EqualValues(1024, spaceFreed)
+	assert.Len(fakeRuntime.ImageList, 1)
+}
+
 func TestGarbageCollectBelowLowThreshold(t *testing.T) {
 	policy := ImageGCPolicy{
 		HighThresholdPercent: 90,

pkg/kubelet/kubelet.go

@@ -3009,7 +3009,7 @@ func (kl *Kubelet) setNodeStatusImages(node *api.Node) {
 	} else {
 		for _, image := range containerImages {
 			imagesOnNode = append(imagesOnNode, api.ContainerImage{
-				Names:     image.RepoTags,
+				Names:     append(image.RepoTags, image.RepoDigests...),
 				SizeBytes: image.Size,
 			})
 		}