add FindManifests (#828)

Signed-off-by: Avi Deitcher <avi@deitcher.net>
Co-authored-by: jonjohnsonjr <jonjohnson@google.com>
Signed-off-by: Avi Deitcher <avi@deitcher.net>

Co-authored-by: jonjohnsonjr <jonjohnson@google.com>

pkg/v1/partial/index.go

@@ -0,0 +1,85 @@
+// Copyright 2020 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 (
+	"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 {
+		// if it is not an image, ignore it
+		if !desc.MediaType.IsImage() {
+			continue
+		}
+		img, err := index.Image(desc.Digest)
+		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 {
+		if !desc.MediaType.IsIndex() {
+			continue
+		}
+		// if it is not an index, ignore it
+		idx, err := index.ImageIndex(desc.Digest)
+		if err != nil {
+			return nil, err
+		}
+		matches = append(matches, idx)
+	}
+	return matches, nil
+}

pkg/v1/partial/index_test.go

@@ -0,0 +1,122 @@
+// Copyright 2020 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_test
+
+import (
+	"testing"
+
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/mutate"
+	"github.com/google/go-containerregistry/pkg/v1/partial"
+	"github.com/google/go-containerregistry/pkg/v1/random"
+	"github.com/google/go-containerregistry/pkg/v1/types"
+)
+
+func TestFindManifests(t *testing.T) {
+
+	ii, err := random.Index(100, 5, 6) // random image of 6 manifests, each having 5 layers of size 100
+	if err != nil {
+		t.Fatal("could not create random index:", err)
+	}
+	m, _ := ii.IndexManifest()
+	digest := m.Manifests[0].Digest
+
+	matcher := func(desc v1.Descriptor) bool {
+		return desc.Digest != digest
+	}
+
+	descriptors, err := partial.FindManifests(ii, matcher)
+	expected := len(m.Manifests) - 1
+	switch {
+	case err != nil:
+		t.Error("unexpected error:", err)
+	case len(descriptors) != expected:
+		t.Errorf("failed on manifests, actual %d, expected %d", len(descriptors), expected)
+	}
+}
+
+func TestFindImages(t *testing.T) {
+	// create our imageindex with which to work
+	ii, err := random.Index(100, 5, 6) // random image of 6 manifests, each having 5 layers of size 100
+	if err != nil {
+		t.Fatal("could not create random index:", err)
+	}
+	m, _ := ii.IndexManifest()
+	digest := m.Manifests[0].Digest
+
+	matcher := func(desc v1.Descriptor) bool {
+		return desc.Digest != digest
+	}
+	images, err := partial.FindImages(ii, matcher)
+	expected := len(m.Manifests) - 1
+	switch {
+	case err != nil:
+		t.Error("unexpected error:", err)
+	case len(images) != expected:
+		t.Errorf("failed on images, actual %d, expected %d", len(images), expected)
+	}
+}
+
+func TestFindIndexes(t *testing.T) {
+	// there is no utility to generate an index of indexes, so we need to create one
+	// base index
+	var (
+		indexCount = 5
+		imageCount = 7
+	)
+	base, err := random.Index(0, 0, 0)
+	if err != nil {
+		t.Fatal("error creating random index:", err)
+	}
+	// we now have 5 indexes and 5 images, so wrap them into a single index
+	adds := []mutate.IndexAddendum{}
+	for i := 0; i < indexCount; i++ {
+		ii, err := random.Index(100, 5, 6)
+		if err != nil {
+			t.Fatalf("%d: unable to create random index: %v", i, err)
+		}
+		adds = append(adds, mutate.IndexAddendum{
+			Add: ii,
+			Descriptor: v1.Descriptor{
+				MediaType: types.OCIImageIndex,
+			},
+		})
+	}
+	for i := 0; i < imageCount; i++ {
+		img, err := random.Image(100, 5)
+		if err != nil {
+			t.Fatalf("%d: unable to create random image: %v", i, err)
+		}
+		adds = append(adds, mutate.IndexAddendum{
+			Add: img,
+			Descriptor: v1.Descriptor{
+				MediaType: types.OCIManifestSchema1,
+			},
+		})
+	}
+
+	// just see if it finds all of the indexes
+	matcher := func(desc v1.Descriptor) bool {
+		return true
+	}
+	index := mutate.AppendManifests(base, adds...)
+	idxes, err := partial.FindIndexes(index, matcher)
+	switch {
+	case err != nil:
+		t.Error("unexpected error:", err)
+	case len(idxes) != indexCount:
+		t.Errorf("failed on index, actual %d, expected %d", len(idxes), indexCount)
+	}
+}

pkg/v1/types/types.go

@@ -51,3 +51,21 @@ func (m MediaType) IsDistributable() bool {
 	}
 	return true
 }
+
+// IsImage returns true if the mediaType represents an image manifest, as opposed to something else, like an index.
+func (m MediaType) IsImage() bool {
+	switch m {
+	case OCIManifestSchema1, DockerManifestSchema2:
+		return true
+	}
+	return false
+}
+
+// IsIndex returns true if the mediaType represents an index, as opposed to something else, like an image.
+func (m MediaType) IsIndex() bool {
+	switch m {
+	case OCIImageIndex, DockerManifestList:
+		return true
+	}
+	return false
+}

pkg/v1/types/types_test.go

@@ -34,3 +34,65 @@ func TestIsDistributable(t *testing.T) {
 		}
 	}
 }
+
+func TestIsImage(t *testing.T) {
+	for _, mt := range []MediaType{
+		OCIManifestSchema1, DockerManifestSchema2,
+	} {
+		if !mt.IsImage() {
+			t.Errorf("%s: should be image", mt)
+		}
+	}
+
+	for _, mt := range []MediaType{
+		OCIContentDescriptor,
+		OCIImageIndex,
+		OCIConfigJSON,
+		OCILayer,
+		OCIRestrictedLayer,
+		OCIUncompressedLayer,
+		OCIUncompressedRestrictedLayer,
+
+		DockerManifestList,
+		DockerLayer,
+		DockerConfigJSON,
+		DockerPluginConfig,
+		DockerForeignLayer,
+		DockerUncompressedLayer,
+	} {
+		if mt.IsImage() {
+			t.Errorf("%s: should not be image", mt)
+		}
+	}
+}
+
+func TestIsIndex(t *testing.T) {
+	for _, mt := range []MediaType{
+		OCIImageIndex, DockerManifestList,
+	} {
+		if !mt.IsIndex() {
+			t.Errorf("%s: should be index", mt)
+		}
+	}
+
+	for _, mt := range []MediaType{
+		OCIContentDescriptor,
+		OCIConfigJSON,
+		OCILayer,
+		OCIRestrictedLayer,
+		OCIUncompressedLayer,
+		OCIUncompressedRestrictedLayer,
+		OCIManifestSchema1,
+
+		DockerManifestSchema2,
+		DockerLayer,
+		DockerConfigJSON,
+		DockerPluginConfig,
+		DockerForeignLayer,
+		DockerUncompressedLayer,
+	} {
+		if mt.IsIndex() {
+			t.Errorf("%s: should not be index", mt)
+		}
+	}
+}