fix: Allow to delete images when names of images are short digest ids of another images.

"nerdctl rmi <REPOSITORY>" can be run to delete the target images.

However, at the current implementation, the deletion fails when images
names are the short digest ids of another images.

The specific behavior is described below, which is how it works in the
current implementation.

First, suppose there are alpine and busybox images.

    ```
    > nerdctl images
    REPOSITORY    TAG       IMAGE ID        CREATED           PLATFORM       SIZE       BLOB SIZE
    busybox       latest    768e5c6f5cb6    3 seconds ago     linux/arm64    4.092MB    1.845MB
    alpine        latest    beefdbd8a1da    11 seconds ago    linux/arm64    10.46MB    4.09MB
    ```

Then, we tag the alpine image using digest id of the busybox image.

    ```
    > nerdctl tag alpine $(dn inspect busybox | jq -rc .[0].RepoDigests[0] | awk -F':' '{print substr($2, 1, 8)}')

    > nerdctl images
    REPOSITORY    TAG       IMAGE ID        CREATED          PLATFORM       SIZE       BLOB SIZE
    768e5c6f      latest    beefdbd8a1da    4 seconds ago    linux/arm64    10.46MB    4.09MB
    busybox       latest    768e5c6f5cb6    22 hours ago     linux/arm64    4.092MB    1.845MB
    alpine        latest    beefdbd8a1da    22 hours ago     linux/arm64    10.46MB    4.09MB
    ```

In this situation, running 'nerdctl rmi "$(dn inspect busybox | jq -rc .[0].RepoDigests[0] | awk -F':' '{print substr($2, 1, 8)}')"'
will fail to remove the image.

The details of the error are as follows.

    ```
    > nerdctl rmi "$(dn inspect busybox | jq -rc .[0].RepoDigests[0] | awk -F':' '{print substr($2, 1, 8)}')"
    FATA[0000] 1 errors:
    multiple IDs found with provided prefix: 768e5c6f
    ```

This issue is reported in the following issue.

    - #3016

Therefore, this pull request modifies this so that images can be deleted
with "nerdctl rmi <short digest id of another image>" when images names are
the short digest ids of another images.

Signed-off-by: Hayato Kiwata <[email protected]>

Author: haytok

cmd/nerdctl/image/image_remove_test.go

@@ -18,8 +18,11 @@ package image
 
 import (
 	"errors"
+	"strings"
 	"testing"
 
+	"gotest.tools/v3/assert"
+
 	"github.com/containerd/nerdctl/v2/pkg/imgutil"
 	"github.com/containerd/nerdctl/v2/pkg/testutil"
 	"github.com/containerd/nerdctl/v2/pkg/testutil/nerdtest"
@@ -302,3 +305,49 @@ func TestRemove(t *testing.T) {
 
 	testCase.Run(t)
 }
+
+// TestIssue3016 tests https://github.com/containerd/nerdctl/issues/3016
+func TestIssue3016(t *testing.T) {
+	testCase := nerdtest.Setup()
+
+	const (
+		tagIDKey = "tagID"
+	)
+
+	testCase.SubTests = []*test.Case{
+		{
+			Description: "Issue #3016 - Tags created using the short digest ids of container images cannot be deleted using the nerdctl rmi command.",
+			Setup: func(data test.Data, helpers test.Helpers) {
+				helpers.Ensure("pull", testutil.CommonImage)
+				helpers.Ensure("pull", testutil.NginxAlpineImage)
+
+				img := nerdtest.InspectImage(helpers, testutil.NginxAlpineImage)
+				repoName, _ := imgutil.ParseRepoTag(testutil.NginxAlpineImage)
+				tagID := strings.TrimPrefix(img.RepoDigests[0], repoName+"@sha256:")[0:8]
+
+				helpers.Ensure("tag", testutil.CommonImage, tagID)
+
+				data.Set(tagIDKey, tagID)
+			},
+			Command: func(data test.Data, helpers test.Helpers) test.TestableCommand {
+				return helpers.Command("rmi", data.Get(tagIDKey))
+			},
+			Expected: func(data test.Data, helpers test.Helpers) *test.Expected {
+				return &test.Expected{
+					ExitCode: 0,
+					Errors:   []error{},
+					Output: func(stdout string, info string, t *testing.T) {
+						helpers.Command("images", data.Get(tagIDKey)).Run(&test.Expected{
+							ExitCode: 0,
+							Output: func(stdout string, info string, t *testing.T) {
+								assert.Equal(t, len(strings.Split(stdout, "\n")), 2)
+							},
+						})
+					},
+				}
+			},
+		},
+	}
+
+	testCase.Run(t)
+}

pkg/cmd/image/remove.go

@@ -65,11 +65,18 @@ func Remove(ctx context.Context, client *containerd.Client, args []string, optio
 	walker := &imagewalker.ImageWalker{
 		Client: client,
 		OnFound: func(ctx context.Context, found imagewalker.Found) error {
-			// if found multiple images, return error unless in force-mode and
-			// there is only 1 unique image.
-			if found.MatchCount > 1 && !(options.Force && found.UniqueImages == 1) {
-				return fmt.Errorf("multiple IDs found with provided prefix: %s", found.Req)
+			if found.NameMatchIndex == -1 {
+				// if found multiple images, return error unless in force-mode and
+				// there is only 1 unique image.
+				if found.MatchCount > 1 && !(options.Force && found.UniqueImages == 1) {
+					return fmt.Errorf("multiple IDs found with provided prefix: %s", found.Req)
+				}
+			} else if found.NameMatchIndex != found.MatchIndex {
+				// when there is an image with a name matching the argument but the argument is a digest short id,
+				// the deletion process is not performed.
+				return nil
 			}
+
 			if cid, ok := runningImages[found.Image.Name]; ok {
 				return fmt.Errorf("conflict: unable to delete %s (cannot be forced) - image is being used by running container %s", found.Req, cid)
 			}

pkg/idutil/imagewalker/imagewalker.go

@@ -31,11 +31,12 @@ import (
 )
 
 type Found struct {
-	Image        images.Image
-	Req          string // The raw request string. name, short ID, or long ID.
-	MatchIndex   int    // Begins with 0, up to MatchCount - 1.
-	MatchCount   int    // 1 on exact match. > 1 on ambiguous match. Never be <= 0.
-	UniqueImages int    // Number of unique images in all found images.
+	Image          images.Image
+	Req            string // The raw request string. name, short ID, or long ID.
+	MatchIndex     int    // Begins with 0, up to MatchCount - 1.
+	MatchCount     int    // 1 on exact match. > 1 on ambiguous match. Never be <= 0.
+	UniqueImages   int    // Number of unique images in all found images.
+	NameMatchIndex int    // Image index with a name matching the argument for `nerdctl rmi`.
 }
 
 type OnFound func(ctx context.Context, found Found) error
@@ -50,8 +51,12 @@ type ImageWalker struct {
 // Returns the number of the found entries.
 func (w *ImageWalker) Walk(ctx context.Context, req string) (int, error) {
 	var filters []string
-	if parsedReference, err := referenceutil.Parse(req); err == nil {
-		filters = append(filters, fmt.Sprintf("name==%s", parsedReference.String()))
+	var parsedReferenceStr string
+
+	parsedReference, err := referenceutil.Parse(req)
+	if err == nil {
+		parsedReferenceStr = parsedReference.String()
+		filters = append(filters, fmt.Sprintf("name==%s", parsedReferenceStr))
 	}
 	filters = append(filters,
 		fmt.Sprintf("name==%s", req),
@@ -68,17 +73,23 @@ func (w *ImageWalker) Walk(ctx context.Context, req string) (int, error) {
 	// to handle the `rmi -f` case where returned images are different but
 	// have the same short prefix.
 	uniqueImages := make(map[digest.Digest]bool)
-	for _, image := range images {
+	nameMatchIndex := -1
+	for i, image := range images {
 		uniqueImages[image.Target.Digest] = true
+		// to get target image index for `nerdctl rmi <short digest ids of another images>`.
+		if (parsedReferenceStr != "" && image.Name == parsedReferenceStr) || image.Name == req {
+			nameMatchIndex = i
+		}
 	}
 
 	for i, img := range images {
 		f := Found{
-			Image:        img,
-			Req:          req,
-			MatchIndex:   i,
-			MatchCount:   matchCount,
-			UniqueImages: len(uniqueImages),
+			Image:          img,
+			Req:            req,
+			MatchIndex:     i,
+			MatchCount:     matchCount,
+			UniqueImages:   len(uniqueImages),
+			NameMatchIndex: nameMatchIndex,
 		}
 		if e := w.OnFound(ctx, f); e != nil {
 			return -1, e