nydusify: support --with-referrer option

With this option, we can track all nydus images associated with
an OCI image. For example, in Harbor we can cascade to show nydus
images linked to an OCI image, deleting the OCI image can also delete
the corresponding nydus images. At runtime, nydus snapshotter can also
automatically upgrade an OCI image run to nydus image.

Prior to this PR, we had enabled this feature by default. However,
it is now known that Docker Hub does not yet support Referrer.

Therefore, adding this option to disable this feature by default,
to ensure broad compatibility with various image registries.

Fix dragonflyoss#1363.

Signed-off-by: Yan Song <imeoer@linux.alibaba.com>

contrib/nydusify/cmd/nydusify.go

@@ -338,6 +338,12 @@ func main() {
 					Usage:   "Convert to OCI-referenced nydus zran image",
 					EnvVars: []string{"OCI_REF"},
 				},
+				&cli.BoolFlag{
+					Name:    "with-referrer",
+					Value:   false,
+					Usage:   "Associate a reference to the source image, see https://github.com/opencontainers/distribution-spec/blob/main/spec.md#listing-referrers",
+					EnvVars: []string{"WITH_REFERRER"},
+				},
 				&cli.BoolFlag{
 					Name:    "oci",
 					Value:   false,
@@ -510,6 +516,7 @@ func main() {
 					BatchSize:        c.String("batch-size"),
 
 					OCIRef:       c.Bool("oci-ref"),
+					WithReferrer: c.Bool("with-referrer"),
 					AllPlatforms: c.Bool("all-platforms"),
 					Platforms:    c.String("platform"),
 

contrib/nydusify/pkg/converter/config.go

@@ -22,6 +22,7 @@ func getConfig(opt Opt) map[string]string {
 	cfg["docker2oci"] = strconv.FormatBool(opt.Docker2OCI)
 	cfg["merge_manifest"] = strconv.FormatBool(opt.MergePlatform)
 	cfg["oci_ref"] = strconv.FormatBool(opt.OCIRef)
+	cfg["with_referrer"] = strconv.FormatBool(opt.WithReferrer)
 
 	cfg["prefetch_patterns"] = opt.PrefetchPatterns
 	cfg["compressor"] = opt.Compressor

contrib/nydusify/pkg/converter/converter.go

@@ -45,6 +45,7 @@ type Opt struct {
 	BatchSize        string
 	PrefetchPatterns string
 	OCIRef           bool
+	WithReferrer     bool
 
 	AllPlatforms bool
 	Platforms    string