Remove username prompt on buf registry login

CHANGELOG.md

@@ -5,6 +5,8 @@
 - Add `buf generate --clean` flag that will delete the directories, jar files, or zip files that the
   plugins will write to, prior to generation. Allows cleaning of existing assets without having
   to call `rm -rf`.
+- Deprecate `--username` flag on and username prompt on `buf registry login`. A username is no longer
+  required to log in.
 
 ## [v1.34.0] - 2024-06-21
 

private/buf/cmd/buf/command/registry/registrylogin/registrylogin.go

@@ -47,7 +47,7 @@ func NewCommand(
 	return &appcmd.Command{
 		Use:   name + " <domain>",
 		Short: `Log in to the Buf Schema Registry`,
-		Long: fmt.Sprintf(`This prompts for your BSR username and a BSR token and updates your %s file with these credentials.
+		Long: fmt.Sprintf(`This prompts for your BSR token and updates your %s file with these credentials.
 The <domain> argument will default to buf.build if not specified.`, netrc.Filename),
 		Args: appcmd.MaximumNArgs(1),
 		Run: builder.NewRunFunc(
@@ -73,8 +73,10 @@ func (f *flags) Bind(flagSet *pflag.FlagSet) {
 		&f.Username,
 		usernameFlagName,
 		"",
-		"The username to use. This command prompts for a username by default",
+		"The username to use.",
 	)
+	_ = flagSet.MarkDeprecated(usernameFlagName, "This flag is no longer needed as the username is automatically derived from the token")
+	_ = flagSet.MarkHidden(usernameFlagName)
 	flagSet.BoolVar(
 		&f.TokenStdin,
 		tokenStdinFlagName,
@@ -135,26 +137,15 @@ func inner(
 		remote = container.Arg(0)
 	}
 	// Do not print unless we are prompting
-	if flags.Username == "" && !flags.TokenStdin {
+	if !flags.TokenStdin {
 		if _, err := fmt.Fprintf(
 			container.Stdout(),
-			"Log in with your Buf Schema Registry username. If you don't have a username, create one at https://%s.\n\n",
+			"Enter the BSR token created at https://%s/settings/user.\n\n",
 			remote,
 		); err != nil {
 			return err
 		}
 	}
-	username := flags.Username
-	if username == "" {
-		var err error
-		username, err = bufcli.PromptUser(container, "Username: ")
-		if err != nil {
-			if errors.Is(err, bufcli.ErrNotATTY) {
-				return errors.New("cannot perform an interactive login from a non-TTY device")
-			}
-			return err
-		}
-	}
 	var token string
 	if flags.TokenStdin {
 		data, err := io.ReadAll(container.Stdin())
@@ -197,14 +188,11 @@ func inner(
 	if user == nil {
 		return errors.New("no user found for provided token")
 	}
-	if user.Username != username {
-		return errors.New("the username associated with the provided token does not match the provided username")
-	}
 	if err := netrc.PutMachines(
 		container,
 		netrc.NewMachine(
 			remote,
-			username,
+			user.Username,
 			token,
 		),
 	); err != nil {
@@ -217,9 +205,9 @@ func inner(
 	if err != nil {
 		return err
 	}
-	loggedInMessage := fmt.Sprintf("Credentials saved to %s.\n", netrcFilePath)
+	loggedInMessage := fmt.Sprintf("Logged in as %s. Credentials saved to %s.\n", user.Username, netrcFilePath)
 	// Unless we did not prompt at all, print a newline first
-	if flags.Username == "" || !flags.TokenStdin {
+	if !flags.TokenStdin {
 		loggedInMessage = "\n" + loggedInMessage
 	}
 	if _, err := container.Stdout().Write([]byte(loggedInMessage)); err != nil {