fix(storage): do not open/download blobs when validating manifests (#1566)

when pushing manifests, zot will validate blobs (layers + config blob) are
present in repo, currently it opens(in case of filesystem storage) or download(
in case of cloud storage) each blob.

fixed that by adding a new method ImageStore.CheckBlobPresence() on storage
to check blobs presence without checking the cache like ImageStore.CheckBlob() method does.

Signed-off-by: Petu Eusebiu <peusebiu@cisco.com>

pkg/storage/local/local.go

@@ -1087,7 +1087,11 @@ func (is *ImageStoreLocal) BlobPath(repo string, digest godigest.Digest) string
 	return path.Join(is.rootDir, repo, "blobs", digest.Algorithm().String(), digest.Encoded())
 }
 
-// CheckBlob verifies a blob and returns true if the blob is correct.
+/*
+	CheckBlob verifies a blob and returns true if the blob is correct
+
+If the blob is not found but it's found in cache then it will be copied over.
+*/
 func (is *ImageStoreLocal) CheckBlob(repo string, digest godigest.Digest) (bool, int64, error) {
 	var lockLatency time.Time
 
@@ -1095,8 +1099,6 @@ func (is *ImageStoreLocal) CheckBlob(repo string, digest godigest.Digest) (bool,
 		return false, -1, err
 	}
 
-	blobPath := is.BlobPath(repo, digest)
-
 	if is.dedupe && fmt.Sprintf("%v", is.cache) != fmt.Sprintf("%v", nil) {
 		is.Lock(&lockLatency)
 		defer is.Unlock(&lockLatency)
@@ -1105,14 +1107,13 @@ func (is *ImageStoreLocal) CheckBlob(repo string, digest godigest.Digest) (bool,
 		defer is.RUnlock(&lockLatency)
 	}
 
-	binfo, err := os.Stat(blobPath)
-	if err == nil {
-		is.log.Debug().Str("blob path", blobPath).Msg("blob path found")
-
-		return true, binfo.Size(), nil
+	if ok, size, err := is.StatBlob(repo, digest); err == nil || ok {
+		return true, size, nil
 	}
 
-	is.log.Debug().Err(err).Str("blob", blobPath).Msg("failed to find blob, searching it in cache")
+	blobPath := is.BlobPath(repo, digest)
+
+	is.log.Debug().Str("blob", blobPath).Msg("failed to find blob, searching it in cache")
 
 	// Check blobs in cache
 	dstRecord, err := is.checkCacheBlob(digest)
@@ -1135,6 +1136,24 @@ func (is *ImageStoreLocal) CheckBlob(repo string, digest godigest.Digest) (bool,
 	return true, blobSize, nil
 }
 
+// StatBlob verifies if a blob is present inside a repository. The caller function SHOULD lock from outside.
+func (is *ImageStoreLocal) StatBlob(repo string, digest godigest.Digest) (bool, int64, error) {
+	if err := digest.Validate(); err != nil {
+		return false, -1, err
+	}
+
+	blobPath := is.BlobPath(repo, digest)
+
+	binfo, err := os.Stat(blobPath)
+	if err != nil {
+		is.log.Debug().Str("blob path", blobPath).Msg("failed to find blob")
+
+		return false, -1, zerr.ErrBlobNotFound
+	}
+
+	return true, binfo.Size(), nil
+}
+
 func (is *ImageStoreLocal) checkCacheBlob(digest godigest.Digest) (string, error) {
 	if err := digest.Validate(); err != nil {
 		return "", err

pkg/storage/local/local_test.go

@@ -2191,10 +2191,18 @@ func TestGarbageCollect(t *testing.T) {
 			So(err, ShouldNotBeNil)
 			So(hasBlob, ShouldEqual, false)
 
+			hasBlob, _, err = imgStore.StatBlob(repoName, odigest)
+			So(err, ShouldNotBeNil)
+			So(hasBlob, ShouldEqual, false)
+
 			hasBlob, _, err = imgStore.CheckBlob(repoName, bdigest)
 			So(err, ShouldBeNil)
 			So(hasBlob, ShouldEqual, true)
 
+			hasBlob, _, err = imgStore.StatBlob(repoName, bdigest)
+			So(err, ShouldBeNil)
+			So(hasBlob, ShouldEqual, true)
+
 			// sleep so orphan blob can be GC'ed
 			time.Sleep(5 * time.Second)