remotecache: support createdat and fix order

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

cache/remotecache/import.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"io"
 	"sync"
+	"time"
 
 	"github.com/containerd/containerd/content"
 	"github.com/containerd/containerd/images"
@@ -131,12 +132,7 @@ func (ci *contentCacheImporter) importInlineCache(ctx context.Context, dt []byte
 					return err
 				}
 
-				var img struct {
-					Rootfs struct {
-						DiffIDs []digest.Digest `json:"diff_ids"`
-					} `json:"rootfs"`
-					Cache json.RawMessage `json:"moby.buildkit.cache.v0"`
-				}
+				var img image
 
 				if err := json.Unmarshal(p, &img); err != nil {
 					return err
@@ -156,11 +152,19 @@ func (ci *contentCacheImporter) importInlineCache(ctx context.Context, dt []byte
 					return err
 				}
 
+				createdDates, err := parseCreatedLayerDates(img)
+				if err != nil {
+					return err
+				}
+
 				layers := v1.DescriptorProvider{}
 				for i, m := range m.Layers {
 					if m.Annotations == nil {
 						m.Annotations = map[string]string{}
 					}
+					if createdAt := createdDates[i]; createdAt != "" {
+						m.Annotations["buildkit/createdat"] = createdAt
+					}
 					m.Annotations["containerd.io/uncompressed"] = img.Rootfs.DiffIDs[i].String()
 					layers[m.Digest] = v1.DescriptorProviderPair{
 						Descriptor: m,
@@ -172,6 +176,11 @@ func (ci *contentCacheImporter) importInlineCache(ctx context.Context, dt []byte
 					})
 				}
 
+				dt, err := json.Marshal(config)
+				if err != nil {
+					return err
+				}
+
 				mu.Lock()
 				if err := v1.ParseConfig(config, layers, cc); err != nil {
 					return err
@@ -224,3 +233,32 @@ func (ci *contentCacheImporter) allDistributionManifests(ctx context.Context, dt
 
 	return nil
 }
+
+type image struct {
+	Rootfs struct {
+		DiffIDs []digest.Digest `json:"diff_ids"`
+	} `json:"rootfs"`
+	Cache   []byte `json:"moby.buildkit.cache.v0"`
+	History []struct {
+		Created    *time.Time `json:"created,omitempty"`
+		EmptyLayer bool       `json:"empty_layer,omitempty"`
+	} `json:"history,omitempty"`
+}
+
+func parseCreatedLayerDates(img image) ([]string, error) {
+	dates := make([]string, 0, len(img.Rootfs.DiffIDs))
+	for _, h := range img.History {
+		if !h.EmptyLayer {
+			str := ""
+			if h.Created != nil {
+				dt, err := h.Created.MarshalText()
+				if err != nil {
+					return nil, err
+				}
+				str = string(dt)
+			}
+			dates = append(dates, str)
+		}
+	}
+	return dates, nil
+}

cache/remotecache/inline/inline.go

@@ -45,7 +45,7 @@ func (ce *exporter) ExportForLayers(layers []digest.Digest) ([]byte, error) {
 	}
 
 	cc := v1.NewCacheChains()
-	if err := v1.ParseConfig(*config, descs, cc); err != nil {
+	if err := v1.ParseConfig(*config, descs2, cc); err != nil {
 		return nil, err
 	}
 
@@ -59,7 +59,17 @@ func (ce *exporter) ExportForLayers(layers []digest.Digest) ([]byte, error) {
 		return nil, nil
 	}
 
-	// TODO: are the layers always ordered already or should we check?
+	cache := map[digest.Digest]int{}
+
+	// reorder layers based on the order in the image
+	for i, r := range cfg.Records {
+		for j, rr := range r.Results {
+			n := getSortedLayerIndex(rr.LayerIndex, cfg.Layers, cache)
+			rr.LayerIndex = n
+			r.Results[j] = rr
+			cfg.Records[i] = r
+		}
+	}
 
 	dt, err := json.Marshal(cfg.Records)
 	if err != nil {
@@ -68,3 +78,15 @@ func (ce *exporter) ExportForLayers(layers []digest.Digest) ([]byte, error) {
 
 	return dt, nil
 }
+
+func getSortedLayerIndex(idx int, layers []v1.CacheLayer, cache map[digest.Digest]int) int {
+	if idx == -1 {
+		return -1
+	}
+	l := layers[idx]
+	if i, ok := cache[l.Blob]; ok {
+		return i
+	}
+	cache[l.Blob] = getSortedLayerIndex(l.ParentIndex, layers, cache) + 1
+	return cache[l.Blob]
+}

exporter/containerimage/writer.go

@@ -350,7 +350,11 @@ func patchImageConfig(dt []byte, dps []blobs.DiffPair, history []ocispec.History
 	}
 
 	if cache != nil {
-		m["moby.buildkit.cache.v0"] = cache
+		dt, err := json.Marshal(cache)
+		if err != nil {
+			return nil, err
+		}
+		m["moby.buildkit.cache.v0"] = dt
 	}
 
 	dt, err = json.Marshal(m)