Support usage as plugin for tools like kubectl

command.go

@@ -30,7 +30,10 @@ import (
 	flag "github.com/spf13/pflag"
 )
 
-const FlagSetByCobraAnnotation = "cobra_annotation_flag_set_by_cobra"
+const (
+	FlagSetByCobraAnnotation     = "cobra_annotation_flag_set_by_cobra"
+	CommandDisplayNameAnnotation = "cobra_annotation_command_display_name"
+)
 
 // FParseErrWhitelist configures Flag parse errors to be ignored
 type FParseErrWhitelist flag.ParseErrorsWhitelist
@@ -99,7 +102,7 @@ type Command struct {
 	Deprecated string
 
 	// Annotations are key/value pairs that can be used by applications to identify or
-	// group commands.
+	// group commands or set special options.
 	Annotations map[string]string
 
 	// Version defines the version for this command. If this value is non-empty and the command does not
@@ -1402,6 +1405,9 @@ func (c *Command) CommandPath() string {
 	if c.HasParent() {
 		return c.Parent().CommandPath() + " " + c.Name()
 	}
+	if displayName, ok := c.Annotations[CommandDisplayNameAnnotation]; ok {
+		return displayName
+	}
 	return c.Name()
 }
 

command_test.go

@@ -366,6 +366,36 @@ func TestAliasPrefixMatching(t *testing.T) {
 	EnablePrefixMatching = defaultPrefixMatching
 }
 
+// TestPlugin checks usage as plugin for another command such as kubectl.  The
+// 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) {
+	rootCmd := &Command{
+		Use:  "plugin",
+		Args: NoArgs,
+		Annotations: map[string]string{
+			CommandDisplayNameAnnotation: "kubectl plugin",
+		},
+	}
+
+	subCmd := &Command{Use: "sub [flags]", Args: NoArgs, Run: emptyRun}
+	rootCmd.AddCommand(subCmd)
+
+	rootHelp, err := executeCommand(rootCmd, "-h")
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+
+	checkStringContains(t, rootHelp, "kubectl plugin [command]")
+
+	childHelp, err := executeCommand(rootCmd, "sub", "-h")
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+
+	checkStringContains(t, childHelp, "kubectl plugin sub [flags]")
+}
+
 // TestChildSameName checks the correct behaviour of cobra in cases,
 // when an application with name "foo" and with subcommand "foo"
 // is executed with args "foo foo".