Export remote snapshotter label handler

Signed-off-by: Kohei Tokunaga <ktokunaga.mail@gmail.com>

pkg/cri/server/image_pull.go

@@ -42,10 +42,10 @@ import (
 	"github.com/containerd/containerd"
 	"github.com/containerd/containerd/errdefs"
 	containerdimages "github.com/containerd/containerd/images"
-	"github.com/containerd/containerd/labels"
 	"github.com/containerd/containerd/log"
 	"github.com/containerd/containerd/pkg/cri/annotations"
 	criconfig "github.com/containerd/containerd/pkg/cri/config"
+	snpkg "github.com/containerd/containerd/pkg/snapshotters"
 	distribution "github.com/containerd/containerd/reference/docker"
 	"github.com/containerd/containerd/remotes/docker"
 	"github.com/containerd/containerd/remotes/docker/config"
@@ -170,7 +170,7 @@ func (c *criService) PullImage(ctx context.Context, r *runtime.PullImageRequest)
 	pullOpts = append(pullOpts, c.encryptedImagesPullOpts()...)
 	if !c.config.ContainerdConfig.DisableSnapshotAnnotations {
 		pullOpts = append(pullOpts,
-			containerd.WithImageHandlerWrapper(appendInfoHandlerWrapper(ref)))
+			containerd.WithImageHandlerWrapper(snpkg.AppendInfoHandlerWrapper(ref)))
 	}
 
 	if c.config.ContainerdConfig.DiscardUnpackedLayers {
@@ -552,76 +552,6 @@ func (c *criService) encryptedImagesPullOpts() []containerd.RemoteOpt {
 	return nil
 }
 
-const (
-	// targetRefLabel is a label which contains image reference and will be passed
-	// to snapshotters.
-	targetRefLabel = "containerd.io/snapshot/cri.image-ref"
-	// targetManifestDigestLabel is a label which contains manifest digest and will be passed
-	// to snapshotters.
-	targetManifestDigestLabel = "containerd.io/snapshot/cri.manifest-digest"
-	// targetLayerDigestLabel is a label which contains layer digest and will be passed
-	// to snapshotters.
-	targetLayerDigestLabel = "containerd.io/snapshot/cri.layer-digest"
-	// targetImageLayersLabel is a label which contains layer digests contained in
-	// the target image and will be passed to snapshotters for preparing layers in
-	// parallel. Skipping some layers is allowed and only affects performance.
-	targetImageLayersLabel = "containerd.io/snapshot/cri.image-layers"
-)
-
-// appendInfoHandlerWrapper makes a handler which appends some basic information
-// of images like digests for manifest and their child layers as annotations during unpack.
-// These annotations will be passed to snapshotters as labels. These labels will be
-// used mainly by stargz-based snapshotters for querying image contents from the
-// registry.
-func appendInfoHandlerWrapper(ref string) func(f containerdimages.Handler) containerdimages.Handler {
-	return func(f containerdimages.Handler) containerdimages.Handler {
-		return containerdimages.HandlerFunc(func(ctx context.Context, desc imagespec.Descriptor) ([]imagespec.Descriptor, error) {
-			children, err := f.Handle(ctx, desc)
-			if err != nil {
-				return nil, err
-			}
-			switch desc.MediaType {
-			case imagespec.MediaTypeImageManifest, containerdimages.MediaTypeDockerSchema2Manifest:
-				for i := range children {
-					c := &children[i]
-					if containerdimages.IsLayerType(c.MediaType) {
-						if c.Annotations == nil {
-							c.Annotations = make(map[string]string)
-						}
-						c.Annotations[targetRefLabel] = ref
-						c.Annotations[targetLayerDigestLabel] = c.Digest.String()
-						c.Annotations[targetImageLayersLabel] = getLayers(ctx, targetImageLayersLabel, children[i:], labels.Validate)
-						c.Annotations[targetManifestDigestLabel] = desc.Digest.String()
-					}
-				}
-			}
-			return children, nil
-		})
-	}
-}
-
-// getLayers returns comma-separated digests based on the passed list of
-// descriptors. The returned list contains as many digests as possible as well
-// as meets the label validation.
-func getLayers(ctx context.Context, key string, descs []imagespec.Descriptor, validate func(k, v string) error) (layers string) {
-	var item string
-	for _, l := range descs {
-		if containerdimages.IsLayerType(l.MediaType) {
-			item = l.Digest.String()
-			if layers != "" {
-				item = "," + item
-			}
-			// This avoids the label hits the size limitation.
-			if err := validate(key, layers+item); err != nil {
-				log.G(ctx).WithError(err).WithField("label", key).Debugf("%q is omitted in the layers list", l.Digest.String())
-				break
-			}
-			layers += item
-		}
-	}
-	return
-}
-
 const (
 	// minPullProgressReportInternal is used to prevent the reporter from
 	// eating more CPU resources

pkg/cri/server/image_pull_test.go

@@ -20,11 +20,8 @@ import (
 	"context"
 	"encoding/base64"
 	"fmt"
-	"strings"
 	"testing"
 
-	digest "github.com/opencontainers/go-digest"
-	imagespec "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/stretchr/testify/assert"
 	runtime "k8s.io/cri-api/pkg/apis/runtime/v1"
 
@@ -338,51 +335,6 @@ func TestEncryptedImagePullOpts(t *testing.T) {
 	}
 }
 
-func TestImageLayersLabel(t *testing.T) {
-	sampleKey := "sampleKey"
-	sampleDigest, err := digest.Parse("sha256:aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa")
-	assert.NoError(t, err)
-	sampleMaxSize := 300
-	sampleValidate := func(k, v string) error {
-		if (len(k) + len(v)) > sampleMaxSize {
-			return fmt.Errorf("invalid: %q: %q", k, v)
-		}
-		return nil
-	}
-
-	tests := []struct {
-		name      string
-		layersNum int
-		wantNum   int
-	}{
-		{
-			name:      "valid number of layers",
-			layersNum: 2,
-			wantNum:   2,
-		},
-		{
-			name:      "many layers",
-			layersNum: 5, // hits sampleMaxSize (300 chars).
-			wantNum:   4, // layers should be omitted for avoiding invalid label.
-		},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			var sampleLayers []imagespec.Descriptor
-			for i := 0; i < tt.layersNum; i++ {
-				sampleLayers = append(sampleLayers, imagespec.Descriptor{
-					MediaType: imagespec.MediaTypeImageLayerGzip,
-					Digest:    sampleDigest,
-				})
-			}
-			gotS := getLayers(context.Background(), sampleKey, sampleLayers, sampleValidate)
-			got := len(strings.Split(gotS, ","))
-			assert.Equal(t, tt.wantNum, got)
-		})
-	}
-}
-
 func TestSnapshotterFromPodSandboxConfig(t *testing.T) {
 	defaultSnashotter := "native"
 	runtimeSnapshotter := "devmapper"

pkg/snapshotters/annotations.go

@@ -0,0 +1,97 @@
+/*
+   Copyright The containerd Authors.
+
+   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 snapshotters
+
+import (
+	"context"
+
+	"github.com/containerd/containerd/images"
+	"github.com/containerd/containerd/labels"
+	"github.com/containerd/containerd/log"
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+)
+
+// NOTE: The following labels contain "cri" prefix but they are not specific to CRI and
+// can be used by non-CRI clients as well for enabling remote snapshotters. We need to
+// retain that string for keeping compatibility with snapshotter implementations.
+const (
+	// TargetRefLabel is a label which contains image reference and will be passed
+	// to snapshotters.
+	TargetRefLabel = "containerd.io/snapshot/cri.image-ref"
+	// TargetManifestDigestLabel is a label which contains manifest digest and will be passed
+	// to snapshotters.
+	TargetManifestDigestLabel = "containerd.io/snapshot/cri.manifest-digest"
+	// TargetLayerDigestLabel is a label which contains layer digest and will be passed
+	// to snapshotters.
+	TargetLayerDigestLabel = "containerd.io/snapshot/cri.layer-digest"
+	// TargetImageLayersLabel is a label which contains layer digests contained in
+	// the target image and will be passed to snapshotters for preparing layers in
+	// parallel. Skipping some layers is allowed and only affects performance.
+	TargetImageLayersLabel = "containerd.io/snapshot/cri.image-layers"
+)
+
+// AppendInfoHandlerWrapper makes a handler which appends some basic information
+// of images like digests for manifest and their child layers as annotations during unpack.
+// These annotations will be passed to snapshotters as labels. These labels will be
+// used mainly by remote snapshotters for querying image contents from the remote location.
+func AppendInfoHandlerWrapper(ref string) func(f images.Handler) images.Handler {
+	return func(f images.Handler) images.Handler {
+		return images.HandlerFunc(func(ctx context.Context, desc ocispec.Descriptor) ([]ocispec.Descriptor, error) {
+			children, err := f.Handle(ctx, desc)
+			if err != nil {
+				return nil, err
+			}
+			switch desc.MediaType {
+			case ocispec.MediaTypeImageManifest, images.MediaTypeDockerSchema2Manifest:
+				for i := range children {
+					c := &children[i]
+					if images.IsLayerType(c.MediaType) {
+						if c.Annotations == nil {
+							c.Annotations = make(map[string]string)
+						}
+						c.Annotations[TargetRefLabel] = ref
+						c.Annotations[TargetLayerDigestLabel] = c.Digest.String()
+						c.Annotations[TargetImageLayersLabel] = getLayers(ctx, TargetImageLayersLabel, children[i:], labels.Validate)
+						c.Annotations[TargetManifestDigestLabel] = desc.Digest.String()
+					}
+				}
+			}
+			return children, nil
+		})
+	}
+}
+
+// getLayers returns comma-separated digests based on the passed list of
+// descriptors. The returned list contains as many digests as possible as well
+// as meets the label validation.
+func getLayers(ctx context.Context, key string, descs []ocispec.Descriptor, validate func(k, v string) error) (layers string) {
+	for _, l := range descs {
+		if images.IsLayerType(l.MediaType) {
+			item := l.Digest.String()
+			if layers != "" {
+				item = "," + item
+			}
+			// This avoids the label hits the size limitation.
+			if err := validate(key, layers+item); err != nil {
+				log.G(ctx).WithError(err).WithField("label", key).WithField("digest", l.Digest.String()).Debug("omitting digest in the layers list")
+				break
+			}
+			layers += item
+		}
+	}
+	return
+}

pkg/snapshotters/annotations_test.go

@@ -0,0 +1,74 @@
+/*
+   Copyright The containerd Authors.
+
+   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 snapshotters
+
+import (
+	"context"
+	"fmt"
+	"strings"
+	"testing"
+
+	digest "github.com/opencontainers/go-digest"
+	imagespec "github.com/opencontainers/image-spec/specs-go/v1"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestImageLayersLabel(t *testing.T) {
+	sampleKey := "sampleKey"
+	sampleDigest, err := digest.Parse("sha256:aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa")
+	assert.NoError(t, err)
+	sampleMaxSize := 300
+	sampleValidate := func(k, v string) error {
+		if (len(k) + len(v)) > sampleMaxSize {
+			return fmt.Errorf("invalid: %q: %q", k, v)
+		}
+		return nil
+	}
+
+	tests := []struct {
+		name      string
+		layersNum int
+		wantNum   int
+	}{
+		{
+			name:      "valid number of layers",
+			layersNum: 2,
+			wantNum:   2,
+		},
+		{
+			name:      "many layers",
+			layersNum: 5, // hits sampleMaxSize (300 chars).
+			wantNum:   4, // layers should be omitted for avoiding invalid label.
+		},
+	}
+
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			sampleLayers := make([]imagespec.Descriptor, 0, tt.layersNum)
+			for i := 0; i < tt.layersNum; i++ {
+				sampleLayers = append(sampleLayers, imagespec.Descriptor{
+					MediaType: imagespec.MediaTypeImageLayerGzip,
+					Digest:    sampleDigest,
+				})
+			}
+			gotS := getLayers(context.Background(), sampleKey, sampleLayers, sampleValidate)
+			got := len(strings.Split(gotS, ","))
+			assert.Equal(t, tt.wantNum, got)
+		})
+	}
+}