Merge pull request #634 from tonistiigi/schema1-config-fix

imageutil: fix getting schema1 configs

frontend/dockerfile/dockerfile2llb/convert.go

@@ -251,6 +251,13 @@ func Dockerfile2LLB(ctx context.Context, dt []byte, opt ConvertOpt) (*llb.State,
 							_ = ref
 							if len(img.RootFS.DiffIDs) == 0 {
 								isScratch = true
+								// schema1 images can't return diffIDs so double check :(
+								for _, h := range img.History {
+									if !h.EmptyLayer {
+										isScratch = false
+										break
+									}
+								}
 							}
 						}
 					}

util/imageutil/config.go

@@ -14,12 +14,12 @@ import (
 	"github.com/pkg/errors"
 )
 
-type IngesterProvider interface {
+type ContentCache interface {
 	content.Ingester
 	content.Provider
 }
 
-func Config(ctx context.Context, str string, resolver remotes.Resolver, ingester IngesterProvider, p *specs.Platform) (digest.Digest, []byte, error) {
+func Config(ctx context.Context, str string, resolver remotes.Resolver, cache ContentCache, p *specs.Platform) (digest.Digest, []byte, error) {
 	// TODO: fix buildkit to take interface instead of struct
 	var platform platforms.MatchComparer
 	if p != nil {
@@ -36,7 +36,7 @@ func Config(ctx context.Context, str string, resolver remotes.Resolver, ingester
 		Digest: ref.Digest(),
 	}
 	if desc.Digest != "" {
-		ra, err := ingester.ReaderAt(ctx, desc)
+		ra, err := cache.ReaderAt(ctx, desc)
 		if err == nil {
 			desc.Size = ra.Size()
 			mt, err := DetectManifestMediaType(ra)
@@ -58,19 +58,23 @@ func Config(ctx context.Context, str string, resolver remotes.Resolver, ingester
 		return "", nil, err
 	}
 
+	if desc.MediaType == images.MediaTypeDockerSchema1Manifest {
+		return readSchema1Config(ctx, ref.String(), desc, fetcher, cache)
+	}
+
 	handlers := []images.Handler{
-		remotes.FetchHandler(ingester, fetcher),
+		remotes.FetchHandler(cache, fetcher),
-		childrenConfigHandler(ingester, platform),
+		childrenConfigHandler(cache, platform),
 	}
 	if err := images.Dispatch(ctx, images.Handlers(handlers...), desc); err != nil {
 		return "", nil, err
 	}
-	config, err := images.Config(ctx, ingester, desc, platform)
+	config, err := images.Config(ctx, cache, desc, platform)
 	if err != nil {
 		return "", nil, err
 	}
 
-	dt, err := content.ReadBlob(ctx, ingester, config)
+	dt, err := content.ReadBlob(ctx, cache, config)
 	if err != nil {
 		return "", nil, err
 	}

util/imageutil/schema1.go

@@ -0,0 +1,87 @@
+package imageutil
+
+import (
+	"context"
+	"encoding/json"
+	"io/ioutil"
+	"strings"
+	"time"
+
+	"github.com/containerd/containerd/remotes"
+	digest "github.com/opencontainers/go-digest"
+	specs "github.com/opencontainers/image-spec/specs-go/v1"
+	"github.com/pkg/errors"
+)
+
+func readSchema1Config(ctx context.Context, ref string, desc specs.Descriptor, fetcher remotes.Fetcher, cache ContentCache) (digest.Digest, []byte, error) {
+	rc, err := fetcher.Fetch(ctx, desc)
+	if err != nil {
+		return "", nil, err
+	}
+	defer rc.Close()
+	dt, err := ioutil.ReadAll(rc)
+	if err != nil {
+		return "", nil, errors.Wrap(err, "failed to fetch schema1 manifest")
+	}
+	dt, err = convertSchema1ConfigMeta(dt)
+	if err != nil {
+		return "", nil, err
+	}
+	return desc.Digest, dt, nil
+}
+
+func convertSchema1ConfigMeta(in []byte) ([]byte, error) {
+	type history struct {
+		V1Compatibility string `json:"v1Compatibility"`
+	}
+	var m struct {
+		History []history `json:"history"`
+	}
+	if err := json.Unmarshal(in, &m); err != nil {
+		return nil, errors.Wrap(err, "failed to unmarshal schema1 manifest")
+	}
+	if len(m.History) == 0 {
+		return nil, errors.Errorf("invalid schema1 manifest")
+	}
+
+	var img specs.Image
+	if err := json.Unmarshal([]byte(m.History[0].V1Compatibility), &img); err != nil {
+		return nil, errors.Wrap(err, "failed to unmarshal image from schema 1 history")
+	}
+
+	img.RootFS = specs.RootFS{
+		Type: "layers", // filled in by exporter
+	}
+	img.History = make([]specs.History, len(m.History))
+
+	for i := range m.History {
+		var h v1History
+		if err := json.Unmarshal([]byte(m.History[i].V1Compatibility), &h); err != nil {
+			return nil, errors.Wrap(err, "failed to unmarshal history")
+		}
+		img.History[len(m.History)-i-1] = specs.History{
+			Author:     h.Author,
+			Comment:    h.Comment,
+			Created:    &h.Created,
+			CreatedBy:  strings.Join(h.ContainerConfig.Cmd, " "),
+			EmptyLayer: (h.ThrowAway != nil && *h.ThrowAway) || (h.Size != nil && *h.Size == 0),
+		}
+	}
+
+	dt, err := json.MarshalIndent(img, "", "   ")
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to marshal schema1 config")
+	}
+	return dt, nil
+}
+
+type v1History struct {
+	Author          string    `json:"author,omitempty"`
+	Created         time.Time `json:"created"`
+	Comment         string    `json:"comment,omitempty"`
+	ThrowAway       *bool     `json:"throwaway,omitempty"`
+	Size            *int      `json:"Size,omitempty"` // used before ThrowAway field
+	ContainerConfig struct {
+		Cmd []string `json:"Cmd,omitempty"`
+	} `json:"container_config,omitempty"`
+}