Filter dangling images using image filters.

Signed-off-by: Manu Gupta <manugupt1@gmail.com>

cmd/nerdctl/images.go

@@ -119,6 +119,8 @@ func imagesAction(cmd *cobra.Command, args []string) error {
 			return err
 		}
 
+		imageList = filterDangling(imageList, f.Dangling)
+
 		imageList, err = filterByLabel(ctx, client, imageList, f.Labels)
 		if err != nil {
 			return err
@@ -182,6 +184,25 @@ func filterByReference(imageList []images.Image, filters []string) ([]images.Ima
 	return filteredImageList, nil
 }
 
+func filterDangling(imageList []images.Image, dangling imgutil.Dangling) []images.Image {
+	if dangling == imgutil.DanglingUnset {
+		return imageList
+	}
+
+	var filtered []images.Image
+	for _, image := range imageList {
+		_, tag := imgutil.ParseRepoTag(image.Name)
+
+		if dangling == imgutil.DanglingTrue && tag == "" {
+			filtered = append(filtered, image)
+		}
+		if dangling == imgutil.DanglingFalse && tag != "" {
+			filtered = append(filtered, image)
+		}
+	}
+	return filtered
+}
+
 func filterByLabel(ctx context.Context, client *containerd.Client, imageList []images.Image, filters map[string]string) ([]images.Image, error) {
 	for lk, lv := range filters {
 		var imageLabels []images.Image

cmd/nerdctl/images_test.go

@@ -116,3 +116,22 @@ LABEL version=0.1`, testutil.CommonImage)
 	base.Cmd("images", "--filter", "reference=busy*:*libc*").AssertOutContains("glibc")
 	base.Cmd("images", "--filter", "reference=busy*:*libc*").AssertOutContains("uclibc")
 }
+
+func TestDanglingImagesFilter(t *testing.T) {
+	testutil.RequiresBuild(t)
+	base := testutil.NewBase(t)
+	base.Cmd("images", "prune", "--all").AssertOK()
+
+	dockerfile := fmt.Sprintf(`FROM %s
+CMD ["echo", "nerdctl-build-notag-string"]
+	`, testutil.CommonImage)
+	buildCtx, err := createBuildContext(dockerfile)
+	assert.NilError(t, err)
+
+	defer os.RemoveAll(buildCtx)
+	base.Cmd("build", "-f", buildCtx+"/Dockerfile", buildCtx).AssertOK()
+
+	// dangling image test
+	base.Cmd("images", "--filter", "dangling=true").AssertOutContains("<none>")
+	base.Cmd("images", "--filter", "dangling=false").AssertOutNotContains("<none>")
+}

pkg/imgutil/imgutil.go

@@ -56,6 +56,7 @@ var (
 	FilterSinceType     = "since"
 	FilterLabelType     = "label"
 	FilterReferenceType = "reference"
+	FilterDanglingType  = "dangling"
 )
 
 // PullMode is either one of "always", "missing", "never"
@@ -369,7 +370,7 @@ func ParseRepoTag(imgName string) (string, string) {
 
 	ref, err := refdocker.ParseDockerRef(imgName)
 	if err != nil {
-		logrus.WithError(err).Warnf("unparsable image name %q", imgName)
+		logrus.WithError(err).Debugf("unparsable image name %q", imgName)
 		return "", ""
 	}
 
@@ -383,11 +384,20 @@ func ParseRepoTag(imgName string) (string, string) {
 	return repository, tag
 }
 
+type Dangling int
+
+const (
+	DanglingUnset Dangling = iota
+	DanglingTrue
+	DanglingFalse
+)
+
 type Filters struct {
 	Before    []string
 	Since     []string
 	Labels    map[string]string
 	Reference []string
+	Dangling  Dangling
 }
 
 func ParseFilters(filters []string) (*Filters, error) {
@@ -398,7 +408,15 @@ func ParseFilters(filters []string) (*Filters, error) {
 		case 1:
 			return nil, fmt.Errorf("invalid filter %q", filter)
 		case 2:
-			if tempFilterToken[0] == FilterBeforeType {
+			if tempFilterToken[0] == FilterDanglingType {
+				if strings.EqualFold(tempFilterToken[1], "true") {
+					f.Dangling = DanglingTrue
+				} else if strings.EqualFold(tempFilterToken[1], "false") {
+					f.Dangling = DanglingFalse
+				} else {
+					return nil, fmt.Errorf("invalid filter %q", filter)
+				}
+			} else if tempFilterToken[0] == FilterBeforeType {
 				canonicalRef, err := referenceutil.ParseAny(tempFilterToken[1])
 				if err != nil {
 					return nil, err