cmd: allow overriding registry client writer; suppress in helm push

Add an optional io.Writer parameter to newRegistryClient (and the
internal newDefaultRegistryClient / newRegistryClientWithTLS helpers)
so callers can control where registry client output goes.

All existing callers are unaffected (default remains os.Stderr).

For helm push, pass io.Discard so that the registry client's built-in
"Pushed:"/"Digest:" lines are suppressed. The --output writer
(WriteTable / WriteJSON / WriteYAML) is the single source of truth for
push result output, preventing duplication on the terminal.

Signed-off-by: Ilya Kiselev <kis-ilya-a@yandex.ru>

pkg/cmd/push.go

@@ -102,8 +102,12 @@ func newPushCmd(cfg *action.Configuration, out io.Writer) *cobra.Command {
 			return noMoreArgsComp()
 		},
 		RunE: func(_ *cobra.Command, args []string) error {
+			// Suppress the registry client's built-in "Pushed:"/"Digest:" lines;
+			// the --output writer (WriteTable/WriteJSON/WriteYAML) is the single
+			// source of structured push output for this command.
 			registryClient, err := newRegistryClient(
 				o.certFile, o.keyFile, o.caFile, o.insecureSkipTLSVerify, o.plainHTTP, o.username, o.password,
+				io.Discard,
 			)
 
 			if err != nil {

pkg/cmd/root.go

@@ -257,7 +257,7 @@ func newRootCmdWithConfig(actionConfig *action.Configuration, out io.Writer, arg
 		log.Fatal(err)
 	}
 
-	registryClient, err := newDefaultRegistryClient(false, "", "")
+	registryClient, err := newDefaultRegistryClient(false, "", "", os.Stderr)
 	if err != nil {
 		return nil, err
 	}
@@ -402,28 +402,36 @@ func checkForExpiredRepos(repofile string) {
 
 }
 
+// newRegistryClient creates a registry client. The optional w parameter
+// overrides where the registry client writes its output (default: os.Stderr).
+// Pass io.Discard to suppress the client's built-in push/pull summary lines.
 func newRegistryClient(
 	certFile, keyFile, caFile string, insecureSkipTLSVerify, plainHTTP bool, username, password string,
+	w ...io.Writer,
 ) (*registry.Client, error) {
+	out := io.Writer(os.Stderr)
+	if len(w) > 0 {
+		out = w[0]
+	}
 	if certFile != "" && keyFile != "" || caFile != "" || insecureSkipTLSVerify {
-		registryClient, err := newRegistryClientWithTLS(certFile, keyFile, caFile, insecureSkipTLSVerify, username, password)
+		registryClient, err := newRegistryClientWithTLS(certFile, keyFile, caFile, insecureSkipTLSVerify, username, password, out)
 		if err != nil {
 			return nil, err
 		}
 		return registryClient, nil
 	}
-	registryClient, err := newDefaultRegistryClient(plainHTTP, username, password)
+	registryClient, err := newDefaultRegistryClient(plainHTTP, username, password, out)
 	if err != nil {
 		return nil, err
 	}
 	return registryClient, nil
 }
 
-func newDefaultRegistryClient(plainHTTP bool, username, password string) (*registry.Client, error) {
+func newDefaultRegistryClient(plainHTTP bool, username, password string, out io.Writer) (*registry.Client, error) {
 	opts := []registry.ClientOption{
 		registry.ClientOptDebug(settings.Debug),
 		registry.ClientOptEnableCache(true),
-		registry.ClientOptWriter(os.Stderr),
+		registry.ClientOptWriter(out),
 		registry.ClientOptCredentialsFile(settings.RegistryConfig),
 		registry.ClientOptBasicAuth(username, password),
 	}
@@ -440,7 +448,7 @@ func newDefaultRegistryClient(plainHTTP bool, username, password string) (*regis
 }
 
 func newRegistryClientWithTLS(
-	certFile, keyFile, caFile string, insecureSkipTLSVerify bool, username, password string,
+	certFile, keyFile, caFile string, insecureSkipTLSVerify bool, username, password string, out io.Writer,
 ) (*registry.Client, error) {
 	tlsConf, err := tlsutil.NewTLSConfig(
 		tlsutil.WithInsecureSkipVerify(insecureSkipTLSVerify),
@@ -456,7 +464,7 @@ func newRegistryClientWithTLS(
 	registryClient, err := registry.NewClient(
 		registry.ClientOptDebug(settings.Debug),
 		registry.ClientOptEnableCache(true),
-		registry.ClientOptWriter(os.Stderr),
+		registry.ClientOptWriter(out),
 		registry.ClientOptCredentialsFile(settings.RegistryConfig),
 		registry.ClientOptHTTPClient(&http.Client{
 			Transport: &http.Transport{