images: Extract ImageInspect from GetImage

Remove a special `Details` parameter from the `GetImage` options and
extract its behavior to a `ImageInspect` method as it was only used by
the `/images/{name}/json` endpoint (`docker image inspect`).

This makes it easier for the containerd image service to output an image
inspect output without having to use the same data structures as the
graphdrivers.

Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>

api/server/router/image/backend.go

@@ -26,6 +26,7 @@ type imageBackend interface {
 	ImageHistory(ctx context.Context, imageName string) ([]*image.HistoryResponseItem, error)
 	Images(ctx context.Context, opts image.ListOptions) ([]*image.Summary, error)
 	GetImage(ctx context.Context, refOrID string, options backend.GetImageOpts) (*dockerimage.Image, error)
+	ImageInspect(ctx context.Context, refOrID string, options backend.ImageInspectOpts) (*image.InspectResponse, error)
 	TagImage(ctx context.Context, id dockerimage.ID, newRef reference.Named) error
 	ImagesPrune(ctx context.Context, pruneFilters filters.Args) (*image.PruneReport, error)
 }

api/server/router/image/image_routes.go

@@ -18,7 +18,6 @@ import (
 	"github.com/docker/docker/api/types/filters"
 	imagetypes "github.com/docker/docker/api/types/image"
 	"github.com/docker/docker/api/types/registry"
-	"github.com/docker/docker/api/types/storage"
 	"github.com/docker/docker/api/types/versions"
 	"github.com/docker/docker/builder/remotecontext"
 	"github.com/docker/docker/dockerversion"
@@ -303,14 +302,18 @@ func (ir *imageRouter) deleteImages(ctx context.Context, w http.ResponseWriter,
 }
 
 func (ir *imageRouter) getImagesByName(ctx context.Context, w http.ResponseWriter, r *http.Request, vars map[string]string) error {
-	img, err := ir.backend.GetImage(ctx, vars["name"], backend.GetImageOpts{Details: true})
+	imageInspect, err := ir.backend.ImageInspect(ctx, vars["name"], backend.ImageInspectOpts{})
 	if err != nil {
 		return err
 	}
 
-	imageInspect, err := ir.toImageInspect(img)
-	if err != nil {
-		return err
+	// Make sure we output empty arrays instead of nil. While Go nil slice is functionally equivalent to an empty slice,
+	// it matters for the JSON representation.
+	if imageInspect.RepoTags == nil {
+		imageInspect.RepoTags = []string{}
+	}
+	if imageInspect.RepoDigests == nil {
+		imageInspect.RepoDigests = []string{}
 	}
 
 	version := httputils.VersionFromContext(ctx)
@@ -330,74 +333,6 @@ func (ir *imageRouter) getImagesByName(ctx context.Context, w http.ResponseWrite
 	return httputils.WriteJSON(w, http.StatusOK, imageInspect)
 }
 
-func (ir *imageRouter) toImageInspect(img *image.Image) (*imagetypes.InspectResponse, error) {
-	var repoTags, repoDigests []string
-	for _, ref := range img.Details.References {
-		switch ref.(type) {
-		case reference.NamedTagged:
-			repoTags = append(repoTags, reference.FamiliarString(ref))
-		case reference.Canonical:
-			repoDigests = append(repoDigests, reference.FamiliarString(ref))
-		}
-	}
-
-	comment := img.Comment
-	if len(comment) == 0 && len(img.History) > 0 {
-		comment = img.History[len(img.History)-1].Comment
-	}
-
-	// Make sure we output empty arrays instead of nil.
-	if repoTags == nil {
-		repoTags = []string{}
-	}
-	if repoDigests == nil {
-		repoDigests = []string{}
-	}
-
-	var created string
-	if img.Created != nil {
-		created = img.Created.Format(time.RFC3339Nano)
-	}
-
-	return &imagetypes.InspectResponse{
-		ID:              img.ID().String(),
-		RepoTags:        repoTags,
-		RepoDigests:     repoDigests,
-		Parent:          img.Parent.String(),
-		Comment:         comment,
-		Created:         created,
-		Container:       img.Container,        //nolint:staticcheck // ignore SA1019: field is deprecated, but still set on API < v1.45.
-		ContainerConfig: &img.ContainerConfig, //nolint:staticcheck // ignore SA1019: field is deprecated, but still set on API < v1.45.
-		DockerVersion:   img.DockerVersion,
-		Author:          img.Author,
-		Config:          img.Config,
-		Architecture:    img.Architecture,
-		Variant:         img.Variant,
-		Os:              img.OperatingSystem(),
-		OsVersion:       img.OSVersion,
-		Size:            img.Details.Size,
-		GraphDriver: storage.DriverData{
-			Name: img.Details.Driver,
-			Data: img.Details.Metadata,
-		},
-		RootFS: rootFSToAPIType(img.RootFS),
-		Metadata: imagetypes.Metadata{
-			LastTagTime: img.Details.LastUpdated,
-		},
-	}, nil
-}
-
-func rootFSToAPIType(rootfs *image.RootFS) imagetypes.RootFS {
-	var layers []string
-	for _, l := range rootfs.DiffIDs {
-		layers = append(layers, l.String())
-	}
-	return imagetypes.RootFS{
-		Type:   rootfs.Type,
-		Layers: layers,
-	}
-}
-
 func (ir *imageRouter) getImagesJSON(ctx context.Context, w http.ResponseWriter, r *http.Request, vars map[string]string) error {
 	if err := httputils.ParseForm(r); err != nil {
 		return err

api/types/backend/backend.go

@@ -141,9 +141,11 @@ type CreateImageConfig struct {
 // from the backend.
 type GetImageOpts struct {
 	Platform *ocispec.Platform
-	Details  bool
 }
 
+// ImageInspectOpts holds parameters to inspect an image.
+type ImageInspectOpts struct{}
+
 // CommitConfig is the configuration for creating an image as part of a build.
 type CommitConfig struct {
 	Author              string

daemon/containerd/image.go

@@ -7,8 +7,6 @@ import (
 	"sort"
 	"strconv"
 	"strings"
-	"sync/atomic"
-	"time"
 
 	containerdimages "github.com/containerd/containerd/images"
 	cerrdefs "github.com/containerd/errdefs"
@@ -23,7 +21,6 @@ import (
 	"github.com/opencontainers/go-digest"
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/pkg/errors"
-	"golang.org/x/sync/semaphore"
 )
 
 var errInconsistentData error = errors.New("consistency error: data changed during operation, retry")
@@ -44,8 +41,8 @@ func (i *ImageService) GetImage(ctx context.Context, refOrID string, options bac
 	if err != nil {
 		return nil, err
 	}
-	ociImage := presentImages[0]
 
+	ociImage := presentImages[0]
 	img := dockerOciImageToDockerImagePartial(image.ID(desc.Target.Digest), ociImage)
 
 	parent, err := i.getImageLabelByDigest(ctx, desc.Target.Digest, imageLabelClassicBuilderParent)
@@ -55,68 +52,6 @@ func (i *ImageService) GetImage(ctx context.Context, refOrID string, options bac
 		img.Parent = image.ID(parent)
 	}
 
-	if options.Details {
-		lastUpdated := time.Unix(0, 0)
-		size, err := i.size(ctx, desc.Target, platform)
-		if err != nil {
-			return nil, err
-		}
-
-		tagged, err := i.images.List(ctx, "target.digest=="+desc.Target.Digest.String())
-		if err != nil {
-			return nil, err
-		}
-
-		// Usually each image will result in 2 references (named and digested).
-		refs := make([]reference.Named, 0, len(tagged)*2)
-		for _, i := range tagged {
-			if i.UpdatedAt.After(lastUpdated) {
-				lastUpdated = i.UpdatedAt
-			}
-			if isDanglingImage(i) {
-				if len(tagged) > 1 {
-					// This is unexpected - dangling image should be deleted
-					// as soon as another image with the same target is created.
-					// Log a warning, but don't error out the whole operation.
-					log.G(ctx).WithField("refs", tagged).Warn("multiple images have the same target, but one of them is still dangling")
-				}
-				continue
-			}
-
-			name, err := reference.ParseNamed(i.Name)
-			if err != nil {
-				// This is inconsistent with `docker image ls` which will
-				// still include the malformed name in RepoTags.
-				log.G(ctx).WithField("name", name).WithError(err).Error("failed to parse image name as reference")
-				continue
-			}
-			refs = append(refs, name)
-
-			if _, ok := name.(reference.Digested); ok {
-				// Image name already contains a digest, so no need to create a digested reference.
-				continue
-			}
-
-			digested, err := reference.WithDigest(reference.TrimNamed(name), desc.Target.Digest)
-			if err != nil {
-				// This could only happen if digest is invalid, but considering that
-				// we get it from the Descriptor it's highly unlikely.
-				// Log error just in case.
-				log.G(ctx).WithError(err).Error("failed to create digested reference")
-				continue
-			}
-			refs = append(refs, digested)
-		}
-
-		img.Details = &image.Details{
-			References:  refs,
-			Size:        size,
-			Metadata:    nil,
-			Driver:      i.snapshotter,
-			LastUpdated: lastUpdated,
-		}
-	}
-
 	return img, nil
 }
 
@@ -231,34 +166,6 @@ func (i *ImageService) GetImageManifest(ctx context.Context, refOrID string, opt
 	return nil, errdefs.NotFound(errors.New("failed to find manifest"))
 }
 
-// size returns the total size of the image's packed resources.
-func (i *ImageService) size(ctx context.Context, desc ocispec.Descriptor, platform platforms.MatchComparer) (int64, error) {
-	var size atomic.Int64
-
-	cs := i.content
-	handler := containerdimages.LimitManifests(containerdimages.ChildrenHandler(cs), platform, 1)
-
-	var wh containerdimages.HandlerFunc = func(ctx context.Context, desc ocispec.Descriptor) ([]ocispec.Descriptor, error) {
-		children, err := handler(ctx, desc)
-		if err != nil {
-			if !cerrdefs.IsNotFound(err) {
-				return nil, err
-			}
-		}
-
-		size.Add(desc.Size)
-
-		return children, nil
-	}
-
-	l := semaphore.NewWeighted(3)
-	if err := containerdimages.Dispatch(ctx, wh, l, desc); err != nil {
-		return 0, err
-	}
-
-	return size.Load(), nil
-}
-
 // resolveDescriptor searches for a descriptor based on the given
 // reference or identifier. Returns the descriptor of
 // the image, which could be a manifest list, manifest, or config.

daemon/containerd/image_inspect.go

@@ -0,0 +1,158 @@
+package containerd
+
+import (
+	"context"
+	"sync/atomic"
+	"time"
+
+	containerdimages "github.com/containerd/containerd/images"
+	cerrdefs "github.com/containerd/errdefs"
+	"github.com/containerd/log"
+	"github.com/containerd/platforms"
+	"github.com/distribution/reference"
+	"github.com/docker/docker/api/types/backend"
+	imagetypes "github.com/docker/docker/api/types/image"
+	"github.com/docker/docker/api/types/storage"
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+	"golang.org/x/sync/semaphore"
+)
+
+func (i *ImageService) ImageInspect(ctx context.Context, refOrID string, _ backend.ImageInspectOpts) (*imagetypes.InspectResponse, error) {
+	img, err := i.GetImage(ctx, refOrID, backend.GetImageOpts{})
+	if err != nil {
+		return nil, err
+	}
+
+	lastUpdated := time.Unix(0, 0)
+
+	tagged, err := i.images.List(ctx, "target.digest=="+img.ImageID())
+	if err != nil {
+		return nil, err
+	}
+
+	// This could happen only if the image was deleted after the GetImage call above.
+	if len(tagged) == 0 {
+		return nil, errInconsistentData
+	}
+
+	platform := matchAllWithPreference(platforms.Default())
+
+	size, err := i.size(ctx, tagged[0].Target, platform)
+	if err != nil {
+		return nil, err
+	}
+	imgDgst := tagged[0].Target.Digest
+
+	repoTags := make([]string, 0, len(tagged))
+	repoDigests := make([]string, 0, len(tagged))
+	for _, i := range tagged {
+		if i.UpdatedAt.After(lastUpdated) {
+			lastUpdated = i.UpdatedAt
+		}
+		if isDanglingImage(i) {
+			if len(tagged) > 1 {
+				// This is unexpected - dangling image should be deleted
+				// as soon as another image with the same target is created.
+				// Log a warning, but don't error out the whole operation.
+				log.G(ctx).WithField("refs", tagged).Warn("multiple images have the same target, but one of them is still dangling")
+			}
+			continue
+		}
+
+		name, err := reference.ParseNamed(i.Name)
+		if err != nil {
+			log.G(ctx).WithField("name", name).WithError(err).Error("failed to parse image name as reference")
+			// Include the malformed name in RepoTags to be consistent with `docker image ls`.
+			repoTags = append(repoTags, i.Name)
+			continue
+		}
+
+		repoTags = append(repoTags, reference.FamiliarString(name))
+		if _, ok := name.(reference.Digested); ok {
+			repoDigests = append(repoDigests, reference.FamiliarString(name))
+			// Image name is a digested reference already, so no need to create a digested reference.
+			continue
+		}
+
+		digested, err := reference.WithDigest(reference.TrimNamed(name), imgDgst)
+		if err != nil {
+			// This could only happen if digest is invalid, but considering that
+			// we get it from the Descriptor it's highly unlikely.
+			// Log error just in case.
+			log.G(ctx).WithError(err).Error("failed to create digested reference")
+			continue
+		}
+		repoDigests = append(repoDigests, reference.FamiliarString(digested))
+	}
+
+	var comment string
+	if len(comment) == 0 && len(img.History) > 0 {
+		comment = img.History[len(img.History)-1].Comment
+	}
+
+	var created string
+	if img.Created != nil {
+		created = img.Created.Format(time.RFC3339Nano)
+	}
+
+	var layers []string
+	for _, layer := range img.RootFS.DiffIDs {
+		layers = append(layers, layer.String())
+	}
+
+	return &imagetypes.InspectResponse{
+		ID:            img.ImageID(),
+		RepoTags:      repoTags,
+		RepoDigests:   repoDigests,
+		Parent:        img.Parent.String(),
+		Comment:       comment,
+		Created:       created,
+		DockerVersion: "",
+		Author:        img.Author,
+		Config:        img.Config,
+		Architecture:  img.Architecture,
+		Variant:       img.Variant,
+		Os:            img.OS,
+		OsVersion:     img.OSVersion,
+		Size:          size,
+		GraphDriver: storage.DriverData{
+			Name: i.snapshotter,
+			Data: nil,
+		},
+		RootFS: imagetypes.RootFS{
+			Type:   img.RootFS.Type,
+			Layers: layers,
+		},
+		Metadata: imagetypes.Metadata{
+			LastTagTime: lastUpdated,
+		},
+	}, nil
+}
+
+// size returns the total size of the image's packed resources.
+func (i *ImageService) size(ctx context.Context, desc ocispec.Descriptor, platform platforms.MatchComparer) (int64, error) {
+	var size atomic.Int64
+
+	cs := i.content
+	handler := containerdimages.LimitManifests(containerdimages.ChildrenHandler(cs), platform, 1)
+
+	var wh containerdimages.HandlerFunc = func(ctx context.Context, desc ocispec.Descriptor) ([]ocispec.Descriptor, error) {
+		children, err := handler(ctx, desc)
+		if err != nil {
+			if !cerrdefs.IsNotFound(err) {
+				return nil, err
+			}
+		}
+
+		size.Add(desc.Size)
+
+		return children, nil
+	}
+
+	l := semaphore.NewWeighted(3)
+	if err := containerdimages.Dispatch(ctx, wh, l, desc); err != nil {
+		return 0, err
+	}
+
+	return size.Load(), nil
+}

daemon/image_service.go

@@ -43,6 +43,7 @@ type ImageService interface {
 	ImageHistory(ctx context.Context, name string) ([]*imagetype.HistoryResponseItem, error)
 	CommitImage(ctx context.Context, c backend.CommitConfig) (image.ID, error)
 	SquashImage(id, parent string) (string, error)
+	ImageInspect(ctx context.Context, refOrID string, opts backend.ImageInspectOpts) (*imagetype.InspectResponse, error)
 
 	// Containerd related methods
 

daemon/images/image.go

@@ -16,7 +16,6 @@ import (
 	"github.com/docker/docker/api/types/backend"
 	"github.com/docker/docker/errdefs"
 	"github.com/docker/docker/image"
-	"github.com/docker/docker/layer"
 	"github.com/opencontainers/go-digest"
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/pkg/errors"
@@ -163,49 +162,12 @@ func (i *ImageService) manifestMatchesPlatform(ctx context.Context, img *image.I
 	return false, nil
 }
 
-// GetImage returns an image corresponding to the image referred to by refOrID.
-func (i *ImageService) GetImage(ctx context.Context, refOrID string, options backend.GetImageOpts) (*image.Image, error) {
-	img, err := i.getImage(ctx, refOrID, options)
-	if err != nil {
-		return nil, err
-	}
-	if options.Details {
-		var size int64
-		var layerMetadata map[string]string
-		layerID := img.RootFS.ChainID()
-		if layerID != "" {
-			l, err := i.layerStore.Get(layerID)
-			if err != nil {
-				return nil, err
-			}
-			defer layer.ReleaseAndLog(i.layerStore, l)
-			size = l.Size()
-			layerMetadata, err = l.Metadata()
-			if err != nil {
-				return nil, err
-			}
-		}
-
-		lastUpdated, err := i.imageStore.GetLastUpdated(img.ID())
-		if err != nil {
-			return nil, err
-		}
-		img.Details = &image.Details{
-			References:  i.referenceStore.References(img.ID().Digest()),
-			Size:        size,
-			Metadata:    layerMetadata,
-			Driver:      i.layerStore.DriverName(),
-			LastUpdated: lastUpdated,
-		}
-	}
-	return img, nil
-}
-
 func (i *ImageService) GetImageManifest(ctx context.Context, refOrID string, options backend.GetImageOpts) (*ocispec.Descriptor, error) {
 	panic("not implemented")
 }
 
-func (i *ImageService) getImage(ctx context.Context, refOrID string, options backend.GetImageOpts) (retImg *image.Image, retErr error) {
+// GetImage returns an image corresponding to the image referred to by refOrID.
+func (i *ImageService) GetImage(ctx context.Context, refOrID string, options backend.GetImageOpts) (retImg *image.Image, retErr error) {
 	defer func() {
 		if retErr != nil || retImg == nil || options.Platform == nil {
 			return

daemon/images/image_inspect.go

@@ -0,0 +1,104 @@
+package images
+
+import (
+	"context"
+	"time"
+
+	"github.com/distribution/reference"
+	"github.com/docker/docker/api/types/backend"
+	imagetypes "github.com/docker/docker/api/types/image"
+	"github.com/docker/docker/api/types/storage"
+	"github.com/docker/docker/image"
+	"github.com/docker/docker/layer"
+)
+
+func (i *ImageService) ImageInspect(ctx context.Context, refOrID string, _ backend.ImageInspectOpts) (*imagetypes.InspectResponse, error) {
+	img, err := i.GetImage(ctx, refOrID, backend.GetImageOpts{})
+	if err != nil {
+		return nil, err
+	}
+
+	size, layerMetadata, err := i.getLayerSizeAndMetadata(img)
+	if err != nil {
+		return nil, err
+	}
+
+	lastUpdated, err := i.imageStore.GetLastUpdated(img.ID())
+	if err != nil {
+		return nil, err
+	}
+
+	var repoTags, repoDigests []string
+	for _, ref := range i.referenceStore.References(img.ID().Digest()) {
+		switch ref.(type) {
+		case reference.NamedTagged:
+			repoTags = append(repoTags, reference.FamiliarString(ref))
+		case reference.Canonical:
+			repoDigests = append(repoDigests, reference.FamiliarString(ref))
+		}
+	}
+
+	comment := img.Comment
+	if len(comment) == 0 && len(img.History) > 0 {
+		comment = img.History[len(img.History)-1].Comment
+	}
+
+	var created string
+	if img.Created != nil {
+		created = img.Created.Format(time.RFC3339Nano)
+	}
+
+	var layers []string
+	for _, l := range img.RootFS.DiffIDs {
+		layers = append(layers, l.String())
+	}
+
+	return &imagetypes.InspectResponse{
+		ID:              img.ID().String(),
+		RepoTags:        repoTags,
+		RepoDigests:     repoDigests,
+		Parent:          img.Parent.String(),
+		Comment:         comment,
+		Created:         created,
+		Container:       img.Container,        //nolint:staticcheck // ignore SA1019: field is deprecated, but still set on API < v1.45.
+		ContainerConfig: &img.ContainerConfig, //nolint:staticcheck // ignore SA1019: field is deprecated, but still set on API < v1.45.
+		DockerVersion:   img.DockerVersion,
+		Author:          img.Author,
+		Config:          img.Config,
+		Architecture:    img.Architecture,
+		Variant:         img.Variant,
+		Os:              img.OperatingSystem(),
+		OsVersion:       img.OSVersion,
+		Size:            size,
+		GraphDriver: storage.DriverData{
+			Name: i.layerStore.DriverName(),
+			Data: layerMetadata,
+		},
+		RootFS: imagetypes.RootFS{
+			Type:   img.RootFS.Type,
+			Layers: layers,
+		},
+		Metadata: imagetypes.Metadata{
+			LastTagTime: lastUpdated,
+		},
+	}, nil
+}
+
+func (i *ImageService) getLayerSizeAndMetadata(img *image.Image) (int64, map[string]string, error) {
+	var size int64
+	var layerMetadata map[string]string
+	layerID := img.RootFS.ChainID()
+	if layerID != "" {
+		l, err := i.layerStore.Get(layerID)
+		if err != nil {
+			return 0, nil, err
+		}
+		defer layer.ReleaseAndLog(i.layerStore, l)
+		size = l.Size()
+		layerMetadata, err = l.Metadata()
+		if err != nil {
+			return 0, nil, err
+		}
+	}
+	return size, layerMetadata, nil
+}