add FindManifests

Signed-off-by: Avi Deitcher <[email protected]>

pkg/v1/errors.go

@@ -0,0 +1,43 @@
+// Copyright 2018 Google LLC All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package v1
+
+// NotImageError tried to resolve a non-image manifest into an Image
+type NotImageError struct {
+	err string
+}
+
+func (e NotImageError) Error() string {
+	return e.err
+}
+
+// ErrNotImage create a NotImageError with a given message
+func ErrNotImage(err string) NotImageError {
+	return NotImageError{err}
+}
+
+// NotIndexError tried to resolve a non-index manifest into an Index
+type NotIndexError struct {
+	err string
+}
+
+func (e NotIndexError) Error() string {
+	return e.err
+}
+
+// ErrNotIndex create a NotIndexError with a given message
+func ErrNotIndex(err string) NotIndexError {
+	return NotIndexError{err}
+}

pkg/v1/index.go

@@ -35,9 +35,11 @@ type ImageIndex interface {
 	// RawManifest returns the serialized bytes of IndexManifest().
 	RawManifest() ([]byte, error)
 
-	// Image returns a v1.Image that this ImageIndex references.
+	// Image returns a v1.Image that this ImageIndex references. If it matches the Hash
+	// but the item is not an Image manifest, should return NotImageError.
 	Image(Hash) (Image, error)
 
-	// ImageIndex returns a v1.ImageIndex that this ImageIndex references.
+	// ImageIndex returns a v1.ImageIndex that this ImageIndex references. If it matches the Hash
+	// but the item is not an Index, should return NotIndexError.
 	ImageIndex(Hash) (ImageIndex, error)
 }

pkg/v1/layout/index.go

@@ -89,7 +89,7 @@ func (i *layoutIndex) Image(h v1.Hash) (v1.Image, error) {
 	}
 
 	if !isExpectedMediaType(desc.MediaType, types.OCIManifestSchema1, types.DockerManifestSchema2) {
-		return nil, fmt.Errorf("unexpected media type for %v: %s", h, desc.MediaType)
+		return nil, v1.ErrNotImage(fmt.Sprintf("unexpected media type for %v: %s", h, desc.MediaType))
 	}
 
 	img := &layoutImage{
@@ -107,7 +107,7 @@ func (i *layoutIndex) ImageIndex(h v1.Hash) (v1.ImageIndex, error) {
 	}
 
 	if !isExpectedMediaType(desc.MediaType, types.OCIImageIndex, types.DockerManifestList) {
-		return nil, fmt.Errorf("unexpected media type for %v: %s", h, desc.MediaType)
+		return nil, v1.ErrNotIndex(fmt.Sprintf("unexpected media type for %v: %s", h, desc.MediaType))
 	}
 
 	rawIndex, err := i.path.Bytes(h)

pkg/v1/partial/index.go

@@ -0,0 +1,88 @@
+// Copyright 2018 Google LLC All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package partial
+
+import (
+	"errors"
+	"fmt"
+
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/match"
+)
+
+// FindManifests given a v1.ImageIndex, find the manifests that fit the matcher
+func FindManifests(index v1.ImageIndex, matcher match.Matcher) ([]v1.Descriptor, error) {
+	// get the actual manifest list
+	indexManifest, err := index.IndexManifest()
+	if err != nil {
+		return nil, fmt.Errorf("unable to get raw index: %v", err)
+	}
+	manifests := []v1.Descriptor{}
+	// try to get the root of our image
+	for _, manifest := range indexManifest.Manifests {
+		if matcher(manifest) {
+			manifests = append(manifests, manifest)
+		}
+	}
+	return manifests, nil
+}
+
+// FindImages given a v1.ImageIndex, find the images that fit the matcher. If a Descriptor
+// matches the provider Matcher, but the referenced item is not an Image, ignores it.
+// Only returns those that match the Matcher and are images.
+func FindImages(index v1.ImageIndex, matcher match.Matcher) ([]v1.Image, error) {
+	matches := []v1.Image{}
+	manifests, err := FindManifests(index, matcher)
+	if err != nil {
+		return nil, err
+	}
+	for _, desc := range manifests {
+		img, err := index.Image(desc.Digest)
+		// if it is not an image, ignore it
+		// we probably should differentiate between different error types
+		if err != nil && errors.Is(err, v1.NotImageError{}) {
+			continue
+		}
+		if err != nil {
+			return nil, err
+		}
+		matches = append(matches, img)
+	}
+	return matches, nil
+}
+
+// FindIndexes given a v1.ImageIndex, find the indexes that fit the matcher. If a Descriptor
+// matches the provider Matcher, but the referenced item is not an Index, ignores it.
+// Only returns those that match the Matcher and are indexes.
+func FindIndexes(index v1.ImageIndex, matcher match.Matcher) ([]v1.ImageIndex, error) {
+	matches := []v1.ImageIndex{}
+	manifests, err := FindManifests(index, matcher)
+	if err != nil {
+		return nil, err
+	}
+	for _, desc := range manifests {
+		idx, err := index.ImageIndex(desc.Digest)
+		// if it is not an index, ignore it
+		// we probably should differentiate between different error types
+		if err != nil && errors.Is(err, v1.NotIndexError{}) {
+			continue
+		}
+		if err != nil {
+			return nil, err
+		}
+		matches = append(matches, idx)
+	}
+	return matches, nil
+}

pkg/v1/remote/descriptor.go

@@ -181,7 +181,7 @@ func (d *Descriptor) ImageIndex() (v1.ImageIndex, error) {
 		return nil, newErrSchema1(d.MediaType)
 	case types.OCIManifestSchema1, types.DockerManifestSchema2:
 		// We want an index but the registry has an image, nothing we can do.
-		return nil, fmt.Errorf("unexpected media type for ImageIndex(): %s; call Image() instead", d.MediaType)
+		return nil, v1.ErrNotIndex(fmt.Sprintf("unexpected media type for ImageIndex(): %s; call Image() instead", d.MediaType))
 	case types.OCIImageIndex, types.DockerManifestList:
 		// These are expected.
 	default: