remotecache: fix missing CheckDescriptor method

tonistiigi · tonistiigi · commit 5a8856de504a · 2024-03-17T21:52:28.000-07:00
This method is needed by GHA cache backend to detect
if Github deletes blobs from the cache because of
storage caps. It got missing when Info() support was
added.

Signed-off-by: Tonis Tiigi &lt;tonistiigi@gmail.com&gt;
diff --git a/cache/remotecache/v1/chains.go b/cache/remotecache/v1/chains.go
@@ -122,6 +122,8 @@ type DescriptorProviderPair struct {
 	Provider   content.Provider
 }
 
+var _ withCheckDescriptor = DescriptorProviderPair{}
+
 func (p DescriptorProviderPair) ReaderAt(ctx context.Context, desc ocispecs.Descriptor) (content.ReaderAt, error) {
 	return p.Provider.ReaderAt(ctx, desc)
 }
@@ -156,6 +158,13 @@ func (p DescriptorProviderPair) SnapshotLabels(descs []ocispecs.Descriptor, inde
 	return nil
 }
 
+func (p DescriptorProviderPair) CheckDescriptor(ctx context.Context, desc ocispecs.Descriptor) error {
+	if cd, ok := p.Provider.(withCheckDescriptor); ok {
+		return cd.CheckDescriptor(ctx, desc)
+	}
+	return nil
+}
+
 // item is an implementation of a record in the cache chain. After validation,
 // normalization and marshalling into the cache config, the item results form
 // into the "layers", while the digests and the links form into the "records".
diff --git a/cache/remotecache/v1/utils.go b/cache/remotecache/v1/utils.go
@@ -12,6 +12,11 @@ import (
 	"github.com/pkg/errors"
 )
 
+type withCheckDescriptor interface {
+	// CheckDescriptor is additional method on Provider to check if the descriptor is available without opening the reader
+	CheckDescriptor(context.Context, ocispecs.Descriptor) error
+}
+
 // sortConfig sorts the config structure to make sure it is deterministic
 func sortConfig(cc *CacheConfig) {
 	type indexedLayer struct {
@@ -279,9 +284,7 @@ func marshalRemote(ctx context.Context, r *solver.Remote, state *marshalState) s
 		return ""
 	}
 
-	if cd, ok := r.Provider.(interface {
-		CheckDescriptor(context.Context, ocispecs.Descriptor) error
-	}); ok && len(r.Descriptors) > 0 {
+	if cd, ok := r.Provider.(withCheckDescriptor); ok && len(r.Descriptors) > 0 {
 		for _, d := range r.Descriptors {
 			if cd.CheckDescriptor(ctx, d) != nil {
 				return ""
