Fixes and docs for usage as plugin

command.go

@@ -1187,10 +1187,11 @@ func (c *Command) InitDefaultHelpFlag() {
 	c.mergePersistentFlags()
 	if c.Flags().Lookup("help") == nil {
 		usage := "help for "
-		if c.Name() == "" {
+		name := c.displayName()
+		if name == "" {
 			usage += "this command"
 		} else {
-			usage += c.Name()
+			usage += name
 		}
 		c.Flags().BoolP("help", "h", false, usage)
 		_ = c.Flags().SetAnnotation("help", FlagSetByCobraAnnotation, []string{"true"})
@@ -1236,7 +1237,7 @@ func (c *Command) InitDefaultHelpCmd() {
 			Use:   "help [command]",
 			Short: "Help about any command",
 			Long: `Help provides help for any command in the application.
-Simply type ` + c.Name() + ` help [path to command] for full details.`,
+Simply type ` + c.displayName() + ` help [path to command] for full details.`,
 			ValidArgsFunction: func(c *Command, args []string, toComplete string) ([]string, ShellCompDirective) {
 				var completions []string
 				cmd, _, e := c.Root().Find(args)
@@ -1427,6 +1428,10 @@ func (c *Command) CommandPath() string {
 	if c.HasParent() {
 		return c.Parent().CommandPath() + " " + c.Name()
 	}
+	return c.displayName()
+}
+
+func (c *Command) displayName() string {
 	if displayName, ok := c.Annotations[CommandDisplayNameAnnotation]; ok {
 		return displayName
 	}
@@ -1436,10 +1441,11 @@ func (c *Command) CommandPath() string {
 // UseLine puts out the full usage for a given command (including parents).
 func (c *Command) UseLine() string {
 	var useline string
+	use := strings.Replace(c.Use, c.Name(), c.displayName(), 1)
 	if c.HasParent() {
-		useline = c.parent.CommandPath() + " " + c.Use
+		useline = c.parent.CommandPath() + " " + use
 	} else {
-		useline = c.Use
+		useline = use
 	}
 	if c.DisableFlagsInUseLine {
 		return useline
@@ -1642,7 +1648,7 @@ func (c *Command) GlobalNormalizationFunc() func(f *flag.FlagSet, name string) f
 // to this command (local and persistent declared here and by all parents).
 func (c *Command) Flags() *flag.FlagSet {
 	if c.flags == nil {
-		c.flags = flag.NewFlagSet(c.Name(), flag.ContinueOnError)
+		c.flags = flag.NewFlagSet(c.displayName(), flag.ContinueOnError)
 		if c.flagErrorBuf == nil {
 			c.flagErrorBuf = new(bytes.Buffer)
 		}
@@ -1656,7 +1662,7 @@ func (c *Command) Flags() *flag.FlagSet {
 func (c *Command) LocalNonPersistentFlags() *flag.FlagSet {
 	persistentFlags := c.PersistentFlags()
 
-	out := flag.NewFlagSet(c.Name(), flag.ContinueOnError)
+	out := flag.NewFlagSet(c.displayName(), flag.ContinueOnError)
 	c.LocalFlags().VisitAll(func(f *flag.Flag) {
 		if persistentFlags.Lookup(f.Name) == nil {
 			out.AddFlag(f)
@@ -1670,7 +1676,7 @@ func (c *Command) LocalFlags() *flag.FlagSet {
 	c.mergePersistentFlags()
 
 	if c.lflags == nil {
-		c.lflags = flag.NewFlagSet(c.Name(), flag.ContinueOnError)
+		c.lflags = flag.NewFlagSet(c.displayName(), flag.ContinueOnError)
 		if c.flagErrorBuf == nil {
 			c.flagErrorBuf = new(bytes.Buffer)
 		}
@@ -1697,7 +1703,7 @@ func (c *Command) InheritedFlags() *flag.FlagSet {
 	c.mergePersistentFlags()
 
 	if c.iflags == nil {
-		c.iflags = flag.NewFlagSet(c.Name(), flag.ContinueOnError)
+		c.iflags = flag.NewFlagSet(c.displayName(), flag.ContinueOnError)
 		if c.flagErrorBuf == nil {
 			c.flagErrorBuf = new(bytes.Buffer)
 		}
@@ -1725,7 +1731,7 @@ func (c *Command) NonInheritedFlags() *flag.FlagSet {
 // PersistentFlags returns the persistent FlagSet specifically set in the current command.
 func (c *Command) PersistentFlags() *flag.FlagSet {
 	if c.pflags == nil {
-		c.pflags = flag.NewFlagSet(c.Name(), flag.ContinueOnError)
+		c.pflags = flag.NewFlagSet(c.displayName(), flag.ContinueOnError)
 		if c.flagErrorBuf == nil {
 			c.flagErrorBuf = new(bytes.Buffer)
 		}
@@ -1738,9 +1744,9 @@ func (c *Command) PersistentFlags() *flag.FlagSet {
 func (c *Command) ResetFlags() {
 	c.flagErrorBuf = new(bytes.Buffer)
 	c.flagErrorBuf.Reset()
-	c.flags = flag.NewFlagSet(c.Name(), flag.ContinueOnError)
+	c.flags = flag.NewFlagSet(c.displayName(), flag.ContinueOnError)
 	c.flags.SetOutput(c.flagErrorBuf)
-	c.pflags = flag.NewFlagSet(c.Name(), flag.ContinueOnError)
+	c.pflags = flag.NewFlagSet(c.displayName(), flag.ContinueOnError)
 	c.pflags.SetOutput(c.flagErrorBuf)
 
 	c.lflags = nil
@@ -1857,7 +1863,7 @@ func (c *Command) mergePersistentFlags() {
 // If c.parentsPflags == nil, it makes new.
 func (c *Command) updateParentsPflags() {
 	if c.parentsPflags == nil {
-		c.parentsPflags = flag.NewFlagSet(c.Name(), flag.ContinueOnError)
+		c.parentsPflags = flag.NewFlagSet(c.displayName(), flag.ContinueOnError)
 		c.parentsPflags.SetOutput(c.flagErrorBuf)
 		c.parentsPflags.SortFlags = false
 	}

command_test.go

@@ -370,8 +370,28 @@ func TestAliasPrefixMatching(t *testing.T) {
 // executable is `kubectl-plugin`, but we run it as `kubectl plugin`. The help
 // text should reflect the way we run the command.
 func TestPlugin(t *testing.T) {
+	cmd := &Command{
+		Use:  "kubectl-plugin",
+		Args: NoArgs,
+		Annotations: map[string]string{
+			CommandDisplayNameAnnotation: "kubectl plugin",
+		},
+		Run: emptyRun,
+	}
+
+	cmdHelp, err := executeCommand(cmd, "-h")
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+
+	checkStringContains(t, cmdHelp, "kubectl plugin [flags]")
+	checkStringContains(t, cmdHelp, "help for kubectl plugin")
+}
+
+// TestPlugin checks usage as plugin with sub commands.
+func TestPluginWithSubCommands(t *testing.T) {
 	rootCmd := &Command{
-		Use:  "plugin",
+		Use:  "kubectl-plugin",
 		Args: NoArgs,
 		Annotations: map[string]string{
 			CommandDisplayNameAnnotation: "kubectl plugin",
@@ -387,13 +407,24 @@ func TestPlugin(t *testing.T) {
 	}
 
 	checkStringContains(t, rootHelp, "kubectl plugin [command]")
+	checkStringContains(t, rootHelp, "help for kubectl plugin")
+	checkStringContains(t, rootHelp, "kubectl plugin [command] --help")
 
 	childHelp, err := executeCommand(rootCmd, "sub", "-h")
 	if err != nil {
 		t.Errorf("Unexpected error: %v", err)
 	}
 
 	checkStringContains(t, childHelp, "kubectl plugin sub [flags]")
+	checkStringContains(t, childHelp, "help for sub")
+
+	helpHelp, err := executeCommand(rootCmd, "help", "-h")
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+
+	checkStringContains(t, helpHelp, "kubectl plugin help [path to command]")
+	checkStringContains(t, helpHelp, "kubectl plugin help [command]")
 }
 
 // TestChildSameName checks the correct behaviour of cobra in cases,

site/content/user_guide.md

@@ -748,3 +748,57 @@ Read more about it in [Shell Completions](completions/_index.md).
 Cobra makes use of the shell-completion system to define a framework allowing you to provide Active Help to your users.
 Active Help are messages (hints, warnings, etc) printed as the program is being used.
 Read more about it in [Active Help](active_help.md).
+
+## Creating a plugin
+
+When creating a plugin for tools like *kubectl*, the executable is named
+`kubectl-myplugin`, but it is used as `kubectl myplugin`. To fix help
+messages and completions, annotate the root command with the
+`cobra.CommandDisplayNameAnnotation` annotation.
+
+### Example kubectl plugin
+
+```go
+package main
+
+import (
+	"fmt"
+
+	"github.com/spf13/cobra"
+)
+
+func main() {
+	rootCmd := &cobra.Command{
+		Use: "kubectl-myplugin",
+		Annotations: map[string]string{
+			cobra.CommandDisplayNameAnnotation: "kubectl myplugin",
+		},
+	}
+	subCmd := &cobra.Command{
+		Use: "subcmd",
+		Run: func(cmd *cobra.Command, args []string) {
+			fmt.Println("kubectl myplugin subcmd")
+		},
+	}
+	rootCmd.AddCommand(subCmd)
+	rootCmd.Execute()
+}
+```
+
+Example run as a kubectl plugin:
+
+```
+$ kubectl myplugin
+Usage:
+  kubectl myplugin [command]
+
+Available Commands:
+  completion  Generate the autocompletion script for the specified shell
+  help        Help about any command
+  subcmd
+
+Flags:
+  -h, --help   help for kubectl myplugin
+
+Use "kubectl myplugin [command] --help" for more information about a command.
+```