Move label filter to snapshots package

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

metadata/snapshot.go

@@ -219,7 +219,7 @@ func (s *snapshotter) Update(ctx context.Context, info snapshots.Info, fieldpath
 
 		inner := snapshots.Info{
 			Name:   bkey,
-			Labels: filterInheritedLabels(local.Labels),
+			Labels: snapshots.FilterInheritedLabels(local.Labels),
 		}
 
 		// NOTE: Perform this inside the transaction to reduce the
@@ -306,7 +306,7 @@ func (s *snapshotter) createSnapshot(ctx context.Context, key, parent string, re
 		bparent string
 		bkey    string
 		bopts   = []snapshots.Opt{
-			snapshots.WithLabels(filterInheritedLabels(base.Labels)),
+			snapshots.WithLabels(snapshots.FilterInheritedLabels(base.Labels)),
 		}
 	)
 
@@ -586,7 +586,7 @@ func (s *snapshotter) Commit(ctx context.Context, name, key string, opts ...snap
 			return err
 		}
 
-		inheritedOpt := snapshots.WithLabels(filterInheritedLabels(base.Labels))
+		inheritedOpt := snapshots.WithLabels(snapshots.FilterInheritedLabels(base.Labels))
 
 		// NOTE: Backend snapshotters should commit fast and reliably to
 		// prevent metadata store locking and minimizing rollbacks.
@@ -939,20 +939,3 @@ func (s *snapshotter) pruneBranch(ctx context.Context, node *treeNode) error {
 func (s *snapshotter) Close() error {
 	return s.Snapshotter.Close()
 }
-
-// filterInheritedLabels filters the provided labels by removing any key which
-// isn't a snapshot label. Snapshot labels have a prefix of "containerd.io/snapshot/"
-// or are the "containerd.io/snapshot.ref" label.
-func filterInheritedLabels(labels map[string]string) map[string]string {
-	if labels == nil {
-		return nil
-	}
-
-	filtered := make(map[string]string)
-	for k, v := range labels {
-		if k == labelSnapshotRef || strings.HasPrefix(k, inheritedLabelsPrefix) {
-			filtered[k] = v
-		}
-	}
-	return filtered
-}

metadata/snapshot_test.go

@@ -227,7 +227,7 @@ func TestFilterInheritedLabels(t *testing.T) {
 	}
 
 	for _, test := range tests {
-		if actual := filterInheritedLabels(test.labels); !reflect.DeepEqual(actual, test.expected) {
+		if actual := snapshots.FilterInheritedLabels(test.labels); !reflect.DeepEqual(actual, test.expected) {
 			t.Fatalf("expected %v but got %v", test.expected, actual)
 		}
 	}

snapshots/snapshotter.go

@@ -25,6 +25,11 @@ import (
 	"github.com/containerd/containerd/mount"
 )
 
+const (
+	inheritedLabelsPrefix = "containerd.io/snapshot/"
+	labelSnapshotRef      = "containerd.io/snapshot.ref"
+)
+
 // Kind identifies the kind of snapshot.
 type Kind uint8
 
@@ -346,3 +351,20 @@ func WithLabels(labels map[string]string) Opt {
 		return nil
 	}
 }
+
+// FilterInheritedLabels filters the provided labels by removing any key which
+// isn't a snapshot label. Snapshot labels have a prefix of "containerd.io/snapshot/"
+// or are the "containerd.io/snapshot.ref" label.
+func FilterInheritedLabels(labels map[string]string) map[string]string {
+	if labels == nil {
+		return nil
+	}
+
+	filtered := make(map[string]string)
+	for k, v := range labels {
+		if k == labelSnapshotRef || strings.HasPrefix(k, inheritedLabelsPrefix) {
+			filtered[k] = v
+		}
+	}
+	return filtered
+}

unpacker.go

@@ -22,7 +22,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"math/rand"
-	"strings"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -43,8 +42,7 @@ import (
 )
 
 const (
-	inheritedLabelsPrefix = "containerd.io/snapshot/"
-	labelSnapshotRef      = "containerd.io/snapshot.ref"
+	labelSnapshotRef = "containerd.io/snapshot.ref"
 )
 
 type unpacker struct {
@@ -119,13 +117,10 @@ EachLayer:
 			return errors.Wrapf(err, "failed to stat snapshot %s", chainID)
 		}
 
-		// filters the provided annotations by removing any key which isn't a snapshot
-		// label. Snapshot labels have a prefix of "containerd.io/snapshot/".
-		labels := make(map[string]string)
-		for k, v := range desc.Annotations {
-			if strings.HasPrefix(k, inheritedLabelsPrefix) {
-				labels[k] = v
-			}
+		// inherits annotations which are provided as snapshot labels.
+		labels := snapshots.FilterInheritedLabels(desc.Annotations)
+		if labels == nil {
+			labels = make(map[string]string)
 		}
 		labels[labelSnapshotRef] = chainID
 		labelOpt := snapshots.WithLabels(labels)