Merge pull request #3135 from dmcgowan/archive-importer-docker-types

Compress import blobs in Docker compatibility code

images/archive/importer.go

@@ -22,12 +22,14 @@ import (
 	"bytes"
 	"context"
 	"encoding/json"
+	"fmt"
 	"io"
 	"io/ioutil"
 	"path"
 
 	"github.com/containerd/containerd/archive/compression"
 	"github.com/containerd/containerd/content"
+	"github.com/containerd/containerd/errdefs"
 	"github.com/containerd/containerd/images"
 	"github.com/containerd/containerd/log"
 	digest "github.com/opencontainers/go-digest"
@@ -137,17 +139,21 @@ func ImportIndex(ctx context.Context, store content.Store, reader io.Reader) (oc
 		if !ok {
 			return ocispec.Descriptor{}, errors.Errorf("image config %q not found", mfst.Config)
 		}
-		config.MediaType = ocispec.MediaTypeImageConfig
+		config.MediaType = images.MediaTypeDockerSchema2Config
 
 		layers, err := resolveLayers(ctx, store, mfst.Layers, blobs)
 		if err != nil {
 			return ocispec.Descriptor{}, errors.Wrap(err, "failed to resolve layers")
 		}
 
-		manifest := ocispec.Manifest{
-			Versioned: specs.Versioned{
+		manifest := struct {
+			SchemaVersion int                  `json:"schemaVersion"`
+			MediaType     string               `json:"mediaType"`
+			Config        ocispec.Descriptor   `json:"config"`
+			Layers        []ocispec.Descriptor `json:"layers"`
+		}{
 			SchemaVersion: 2,
-			},
+			MediaType:     images.MediaTypeDockerSchema2Manifest,
 			Config:        config,
 			Layers:        layers,
 		}
@@ -212,35 +218,111 @@ func onUntarBlob(ctx context.Context, r io.Reader, store content.Ingester, size
 }
 
 func resolveLayers(ctx context.Context, store content.Store, layerFiles []string, blobs map[string]ocispec.Descriptor) ([]ocispec.Descriptor, error) {
-	var layers []ocispec.Descriptor
-	for _, f := range layerFiles {
+	layers := make([]ocispec.Descriptor, len(layerFiles))
+	descs := map[digest.Digest]*ocispec.Descriptor{}
+	filters := []string{}
+	for i, f := range layerFiles {
 		desc, ok := blobs[f]
 		if !ok {
 			return nil, errors.Errorf("layer %q not found", f)
 		}
+		layers[i] = desc
+		descs[desc.Digest] = &layers[i]
+		filters = append(filters, "labels.\"containerd.io/uncompressed\"=="+desc.Digest.String())
+	}
 
+	err := store.Walk(ctx, func(info content.Info) error {
+		dgst, ok := info.Labels["containerd.io/uncompressed"]
+		if ok {
+			desc := descs[digest.Digest(dgst)]
+			if desc != nil {
+				desc.MediaType = images.MediaTypeDockerSchema2LayerGzip
+				desc.Digest = info.Digest
+				desc.Size = info.Size
+			}
+		}
+		return nil
+	}, filters...)
+	if err != nil {
+		return nil, errors.Wrap(err, "failure checking for compressed blobs")
+	}
+
+	for i, desc := range layers {
+		if desc.MediaType != "" {
+			continue
+		}
 		// Open blob, resolve media type
 		ra, err := store.ReaderAt(ctx, desc)
 		if err != nil {
-			return nil, errors.Wrapf(err, "failed to open %q (%s)", f, desc.Digest)
+			return nil, errors.Wrapf(err, "failed to open %q (%s)", layerFiles[i], desc.Digest)
 		}
 		s, err := compression.DecompressStream(content.NewReader(ra))
 		if err != nil {
-			return nil, errors.Wrapf(err, "failed to detect compression for %q", f)
+			return nil, errors.Wrapf(err, "failed to detect compression for %q", layerFiles[i])
 		}
 		if s.GetCompression() == compression.Uncompressed {
-			// TODO: Support compressing and writing back to content store
-			desc.MediaType = ocispec.MediaTypeImageLayer
-		} else {
-			desc.MediaType = ocispec.MediaTypeImageLayerGzip
+			ref := fmt.Sprintf("compress-blob-%s-%s", desc.Digest.Algorithm().String(), desc.Digest.Encoded())
+			labels := map[string]string{
+				"containerd.io/uncompressed": desc.Digest.String(),
 			}
+			layers[i], err = compressBlob(ctx, store, s, ref, content.WithLabels(labels))
+			if err != nil {
+				s.Close()
+				return nil, err
+			}
+		}
+		layers[i].MediaType = images.MediaTypeDockerSchema2LayerGzip
 		s.Close()
 
-		layers = append(layers, desc)
 	}
 	return layers, nil
 }
 
+func compressBlob(ctx context.Context, cs content.Store, r io.Reader, ref string, opts ...content.Opt) (desc ocispec.Descriptor, err error) {
+	w, err := content.OpenWriter(ctx, cs, content.WithRef(ref))
+	if err != nil {
+		return ocispec.Descriptor{}, errors.Wrap(err, "failed to open writer")
+	}
+
+	defer func() {
+		w.Close()
+		if err != nil {
+			cs.Abort(ctx, ref)
+		}
+	}()
+	if err := w.Truncate(0); err != nil {
+		return ocispec.Descriptor{}, errors.Wrap(err, "failed to truncate writer")
+	}
+
+	cw, err := compression.CompressStream(w, compression.Gzip)
+	if err != nil {
+		return ocispec.Descriptor{}, err
+	}
+
+	if _, err := io.Copy(cw, r); err != nil {
+		return ocispec.Descriptor{}, err
+	}
+	if err := cw.Close(); err != nil {
+		return ocispec.Descriptor{}, err
+	}
+
+	cst, err := w.Status()
+	if err != nil {
+		return ocispec.Descriptor{}, errors.Wrap(err, "failed to get writer status")
+	}
+
+	desc.Digest = w.Digest()
+	desc.Size = cst.Offset
+
+	if err := w.Commit(ctx, desc.Size, desc.Digest, opts...); err != nil {
+		if !errdefs.IsAlreadyExists(err) {
+			return ocispec.Descriptor{}, errors.Wrap(err, "failed to commit")
+		}
+	}
+
+	return desc, nil
+}
+
 func writeManifest(ctx context.Context, cs content.Ingester, manifest interface{}, mediaType string) (ocispec.Descriptor, error) {
 	manifestBytes, err := json.Marshal(manifest)
 	if err != nil {

import_test.go

@@ -28,6 +28,7 @@ import (
 	"runtime"
 	"testing"
 
+	"github.com/containerd/containerd/archive/compression"
 	"github.com/containerd/containerd/archive/tartest"
 	"github.com/containerd/containerd/images"
 	"github.com/containerd/containerd/images/archive"
@@ -289,6 +290,16 @@ func createContent(size int64, seed int64) ([]byte, digest.Digest) {
 	if err != nil {
 		panic(err)
 	}
+	wb := bytes.NewBuffer(nil)
+	cw, err := compression.CompressStream(wb, compression.Gzip)
+	if err != nil {
+		panic(err)
+	}
+
+	if _, err := cw.Write(b); err != nil {
+		panic(err)
+	}
+	b = wb.Bytes()
 	return b, digest.FromBytes(b)
 }