feat: surpress output when template is set

Signed-off-by: Billy Zha <[email protected]>

cmd/oras/internal/display/print.go

@@ -28,24 +28,33 @@ import (
 	"oras.land/oras-go/v2/registry"
 )
 
-var printLock sync.Mutex
+var (
+	printLock sync.Mutex
+	to        io.Writer
+)
 
-// PrintFunc is the function type returned by StatusPrinter.
-type PrintFunc func(ocispec.Descriptor) error
+func init() {
+	to = os.Stdout
+}
 
-// PrintErr prints into stderr.
-func PrintErr(a ...any) error {
-	printLock.Lock()
-	defer printLock.Unlock()
-	_, err := fmt.Fprintln(os.Stderr, a...)
-	return err
+// Set sets the output writer for printing.
+func Set(template string, tty io.Writer) {
+	if template != "" {
+		to = tty
+	}
 }
 
+// PrintFunc is the function type returned by StatusPrinter.
+type PrintFunc func(ocispec.Descriptor) error
+
 // Print objects to display concurrent-safely.
 func Print(a ...any) error {
+	if to == nil {
+		return nil
+	}
 	printLock.Lock()
 	defer printLock.Unlock()
-	_, err := fmt.Println(a...)
+	_, err := fmt.Fprintln(to, a...)
 	return err
 }
 

cmd/oras/internal/option/format.go

@@ -25,16 +25,18 @@ import (
 )
 
 type Format struct {
-	template string
+	Template string
 }
 
 // ApplyFlag implements FlagProvider.ApplyFlag
 func (opts *Format) ApplyFlags(fs *pflag.FlagSet) {
-	fs.StringVar(&opts.template, "format", "", `Format output with go template syntax`)
+	fs.StringVar(&opts.Template, "format", "", `Format output with go template syntax`)
 }
 
 func (opts *Format) WriteTo(w io.Writer, data interface{}) error {
-	switch opts.template {
+	switch opts.Template {
+	case "":
+		return nil
 	case "json":
 		// output json
 		// write marshalled data
@@ -50,7 +52,7 @@ func (opts *Format) WriteTo(w io.Writer, data interface{}) error {
 		// go templating
 		var err error
 		t := template.New("out").Funcs(sprig.FuncMap())
-		t, err = t.Parse(opts.template)
+		t, err = t.Parse(opts.Template)
 		if err != nil {
 			return err
 		}

cmd/oras/root/attach.go

@@ -87,6 +87,7 @@ Example - Attach file to the manifest tagged 'v1' in an OCI image layout folder
 			return nil
 		},
 		RunE: func(cmd *cobra.Command, args []string) error {
+			display.Set(opts.Template, opts.TTY)
 			return runAttach(cmd.Context(), opts)
 		},
 	}
@@ -181,8 +182,8 @@ func runAttach(ctx context.Context, opts attachOptions) error {
 	if !strings.HasSuffix(opts.RawReference, digest) {
 		opts.RawReference = fmt.Sprintf("%s@%s", opts.Path, subject.Digest)
 	}
-	display.PrintErr("Attached to", opts.AnnotatedReference())
-	display.PrintErr("Digest:", root.Digest)
+	display.Print("Attached to", opts.AnnotatedReference())
+	display.Print("Digest:", root.Digest)
 
 	// Export manifest
 	if err = opts.ExportManifest(ctx, store, root); err != nil {

cmd/oras/root/file.go

@@ -59,7 +59,7 @@ func loadFiles(ctx context.Context, store *file.Store, annotations map[string]ma
 		files = append(files, file)
 	}
 	if len(files) == 0 {
-		display.PrintErr("Uploading empty artifact")
+		display.Print("Uploading empty artifact")
 	}
 	return files, nil
 }

cmd/oras/root/push.go

@@ -124,6 +124,7 @@ Example - Push file "hi.txt" into an OCI image layout folder 'layout-dir' with t
 			return nil
 		},
 		RunE: func(cmd *cobra.Command, args []string) error {
+			display.Set(opts.Template, opts.TTY)
 			return runPush(cmd.Context(), opts)
 		},
 	}
@@ -213,7 +214,7 @@ func runPush(ctx context.Context, opts pushOptions) error {
 	if err != nil {
 		return err
 	}
-	display.PrintErr("Pushed", opts.AnnotatedReference())
+	display.Print("Pushed", opts.AnnotatedReference())
 
 	if len(opts.extraRefs) != 0 {
 		contentBytes, err := content.FetchAll(ctx, memoryStore, root)
@@ -227,7 +228,7 @@ func runPush(ctx context.Context, opts pushOptions) error {
 		}
 	}
 
-	display.PrintErr("Digest:", root.Digest)
+	display.Print("Digest:", root.Digest)
 
 	// Export manifest
 	if err := opts.ExportManifest(ctx, memoryStore, root); err != nil {