manifest removed unexpectly from the OCI layout index.json file

[qweeah]

In an oci.Store, if a manifest m has its entry in the index.json file. Using Store.Tag with the digest as the reference will remove m from index.json file.

Run below go file to reproduce the issue. oras-go version: v2.0.1.

package main

import (
	"context"
	_ "crypto/sha256"
	"fmt"
	"os"
	"path/filepath"
	"strings"

	"github.com/opencontainers/go-digest"
	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
	"oras.land/oras-go/v2/content/oci"
)

func main() {
	// prepare
	root := os.TempDir()
	defer os.RemoveAll(root)
	oci, err := oci.New(root)
	if err != nil {
		panic(err)
	}
	ctx := context.Background()
	manifestContent := `{"schemaVersion":2,"mediaType":"application/vnd.oci.image.manifest.v1+json","config":{"mediaType":"application/vnd.oci.image.config.v1+json","digest":"sha256:44136fa355b3678a1146ad16f7e8649e94fb4fc21fe77e8310c060f61caaff8a","size":2},"layers":[]}`
	desc := ocispec.Descriptor{
		Digest:    digest.FromString(manifestContent),
		Size:      int64(len(manifestContent)),
		MediaType: "application/vnd.oci.image.manifest.v1+json",
	}

	// push a manifest
	oci.Push(ctx, desc, strings.NewReader(manifestContent))
	index, err := os.ReadFile(filepath.Join(root, "index.json"))
	if err != nil {
		panic(err)
	}
	fmt.Println(">>>>>>>>>>> after pushing >>>>>>>>>>>>>>")
	fmt.Println(string(index))

	// tag the manifest with its digest
	oci.Tag(ctx, desc, desc.Digest.String())
	index, err = os.ReadFile(filepath.Join(root, "index.json"))
	if err != nil {
		panic(err)
	}
	fmt.Println(">>>>>>>>>>> after tagging >>>>>>>>>>>>>>")
	fmt.Println(string(index))
}

[FeynmanZhou]

Do we plan to fix it and cut a release of v2.0.2 in ORAS-go? Then ORAS CLI v1.0.0 could bump up the ORAS-go dep to this version.