util/estargz: export labels and use consts

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

Author: thaJeztah

cache/refs.go

@@ -7,6 +7,7 @@ import (
 	"os"
 	"path/filepath"
 	"slices"
+	"strconv"
 	"strings"
 	"sync"
 	"time"
@@ -26,6 +27,7 @@ import (
 	"github.com/moby/buildkit/solver"
 	"github.com/moby/buildkit/util/bklog"
 	"github.com/moby/buildkit/util/compression"
+	"github.com/moby/buildkit/util/estargz"
 	"github.com/moby/buildkit/util/flightcontrol"
 	"github.com/moby/buildkit/util/leaseutil"
 	"github.com/moby/buildkit/util/overlay"
@@ -1155,7 +1157,7 @@ func makeTmpLabelsStargzMode(labels map[string]string, s session.Group) (fields
 		res[tmpKey] = v
 	}
 	for i, sid := range session.AllSessionIDs(s) {
-		sidKey := "containerd.io/snapshot/remote/stargz.session." + fmt.Sprintf("%d", i) + "." + id
+		sidKey := estargz.TargetSessionLabel + "." + strconv.Itoa(i) + "." + id
 		fields = append(fields, "labels."+sidKey)
 		res[sidKey] = sid
 	}

cmd/buildkitd/main_oci_worker.go

@@ -34,6 +34,7 @@ import (
 	"github.com/moby/buildkit/session"
 	"github.com/moby/buildkit/util/bklog"
 	"github.com/moby/buildkit/util/disk"
+	"github.com/moby/buildkit/util/estargz"
 	"github.com/moby/buildkit/util/network/cniprovider"
 	"github.com/moby/buildkit/util/network/netproviders"
 	"github.com/moby/buildkit/util/resolver"
@@ -461,22 +462,6 @@ func validOCIBinary() bool {
 	return true
 }
 
-const (
-	// targetRefLabel is a label which contains image reference.
-	targetRefLabel = "containerd.io/snapshot/remote/stargz.reference"
-
-	// targetDigestLabel is a label which contains layer digest.
-	targetDigestLabel = "containerd.io/snapshot/remote/stargz.digest"
-
-	// targetImageLayersLabel is a label which contains layer digests contained in
-	// the target image.
-	targetImageLayersLabel = "containerd.io/snapshot/remote/stargz.layers"
-
-	// targetSessionLabel is a labeld which contains session IDs usable for
-	// authenticating the target snapshot.
-	targetSessionLabel = "containerd.io/snapshot/remote/stargz.session"
-)
-
 // sourceWithSession returns a callback which implements a converter from labels to the
 // typed snapshot source info. This callback is called everytime the snapshotter resolves a
 // snapshot. This callback returns configuration that is based on buildkitd's registry config
@@ -487,15 +472,15 @@ func sourceWithSession(hosts docker.RegistryHosts, sm *session.Manager) sgzsourc
 		// to the snapshotter API. So, first, get all these IDs
 		var ids []string
 		for k := range labels {
-			if strings.HasPrefix(k, targetRefLabel+".") {
-				ids = append(ids, strings.TrimPrefix(k, targetRefLabel+"."))
+			if strings.HasPrefix(k, estargz.TargetRefLabel+".") {
+				ids = append(ids, strings.TrimPrefix(k, estargz.TargetRefLabel+"."))
 			}
 		}
 
 		// Parse all labels
 		for _, id := range ids {
 			// Parse session labels
-			ref, ok := labels[targetRefLabel+"."+id]
+			ref, ok := labels[estargz.TargetRefLabel+"."+id]
 			if !ok {
 				continue
 			}
@@ -505,7 +490,7 @@ func sourceWithSession(hosts docker.RegistryHosts, sm *session.Manager) sgzsourc
 			}
 			var sids []string
 			for i := 0; ; i++ {
-				sidKey := targetSessionLabel + "." + fmt.Sprintf("%d", i) + "." + id
+				sidKey := estargz.TargetSessionLabel + "." + fmt.Sprintf("%d", i) + "." + id
 				sid, ok := labels[sidKey]
 				if !ok {
 					break
@@ -520,9 +505,9 @@ func sourceWithSession(hosts docker.RegistryHosts, sm *session.Manager) sgzsourc
 					HostsFunc(ref.Hostname())
 			})
 			if s, err := parse(map[string]string{
-				targetRefLabel:         ref,
-				targetDigestLabel:      labels[targetDigestLabel+"."+id],
-				targetImageLayersLabel: labels[targetImageLayersLabel+"."+id],
+				estargz.TargetRefLabel:         ref,
+				estargz.TargetDigestLabel:      labels[estargz.TargetDigestLabel+"."+id],
+				estargz.TargetImageLayersLabel: labels[estargz.TargetImageLayersLabel+"."+id],
 			}); err == nil {
 				src = append(src, s...)
 			}

util/estargz/labels.go

@@ -8,27 +8,33 @@ import (
 )
 
 const (
-	// targetRefLabel is a label which contains image reference.
+	// TargetRefLabel is a label which contains image reference.
 	//
 	// It is a copy of [stargz-snapshotter/fs/source.targetRefLabel].
 	//
 	// [stargz-snapshotter/fs/source.targetRefLabel]: https://github.com/containerd/stargz-snapshotter/blob/v0.16.3/fs/source/source.go#L64-L65
-	targetRefLabel = "containerd.io/snapshot/remote/stargz.reference"
+	TargetRefLabel = "containerd.io/snapshot/remote/stargz.reference"
 
-	// targetDigestLabel is a label which contains layer digest.
+	// TargetDigestLabel is a label which contains layer digest.
 	//
 	// It is a copy of [stargz-snapshotter/fs/source.targetDigestLabel].
 	//
 	// [stargz-snapshotter/fs/source.targetDigestLabel]: https://github.com/containerd/stargz-snapshotter/blob/v0.16.3/fs/source/source.go#L67-L68
-	targetDigestLabel = "containerd.io/snapshot/remote/stargz.digest"
+	TargetDigestLabel = "containerd.io/snapshot/remote/stargz.digest"
 
-	// targetImageLayersLabel is a label which contains layer digests contained in
+	// TargetImageLayersLabel is a label which contains layer digests contained in
 	// the target image.
 	//
 	// It is a copy of [stargz-snapshotter/fs/source.targetImageLayersLabel].
 	//
 	// [stargz-snapshotter/fs/source.targetImageLayersLabel]: https://github.com/containerd/stargz-snapshotter/blob/v0.16.3/fs/source/source.go#L70-L72
-	targetImageLayersLabel = "containerd.io/snapshot/remote/stargz.layers"
+	TargetImageLayersLabel = "containerd.io/snapshot/remote/stargz.layers"
+
+	// TargetSessionLabel is a label which contains session IDs usable for
+	// authenticating the target snapshot.
+	//
+	// It has no equivalent in github.com/containerd/stargz-snapshotter.
+	TargetSessionLabel = "containerd.io/snapshot/remote/stargz.session"
 )
 
 const (
@@ -63,16 +69,16 @@ func SnapshotLabels(ref string, descs []ocispecs.Descriptor, targetIndex int) ma
 	for _, l := range descs[targetIndex:] {
 		// This avoids the label hits the size limitation.
 		// Skipping layers is allowed here and only affects performance.
-		if err := labels.Validate(targetImageLayersLabel, layers+l.Digest.String()); err != nil {
+		if err := labels.Validate(TargetImageLayersLabel, layers+l.Digest.String()); err != nil {
 			break
 		}
 		layers += l.Digest.String() + ","
 	}
 	return map[string]string{
 		TOCJSONDigestAnnotation:         desc.Annotations[TOCJSONDigestAnnotation],
 		StoreUncompressedSizeAnnotation: desc.Annotations[StoreUncompressedSizeAnnotation],
-		targetRefLabel:                  ref,
-		targetDigestLabel:               desc.Digest.String(),
-		targetImageLayersLabel:          strings.TrimSuffix(layers, ","),
+		TargetRefLabel:                  ref,
+		TargetDigestLabel:               desc.Digest.String(),
+		TargetImageLayersLabel:          strings.TrimSuffix(layers, ","),
 	}
 }