cmd/root: Use string template instead of function for usage

In version 1.1.2 of Cobra has been included a change[0] that changes the
behaviour of how custom usage functions are printed. The change prepends
"Error: " to the text. This is not desired since the usage text is not
an error text.

A workaround is to define a template string for the usage instead. The
template uses the templating language of Go[1]. See the default template
string in version 1.2.1[2].

This change has the positive benefit of getting more helpful usage
messages. E.g., for command 'toolbox enter' the usage text is no longer
"Run 'toolbox --help' for usage." but "Run 'toolbox enter --help' for usage.".

Upstream issue: spf13/cobra#1532

[0] spf13/cobra#1044
[1] https://pkg.go.dev/text/template
[2] https://github.com/spf13/cobra/blob/v1.2.1/command.go#L491

src/cmd/root.go

@@ -96,12 +96,12 @@ func init() {
 	persistentFlags.CountVarP(&rootFlags.verbose, "verbose", "v", "Set log-level to 'debug'")
 
 	rootCmd.SetHelpFunc(rootHelp)
-	rootCmd.SetUsageFunc(rootUsage)
+
+	var usageTemplate = `Run '{{.CommandPath}} --help' for usage.`
+	rootCmd.SetUsageTemplate(usageTemplate)
 }
 
 func preRun(cmd *cobra.Command, args []string) error {
-	cmd.Root().SilenceUsage = true
-
 	if err := setUpLoggers(); err != nil {
 		return err
 	}
@@ -244,12 +244,6 @@ func rootRun(cmd *cobra.Command, args []string) error {
 	return nil
 }
 
-func rootUsage(cmd *cobra.Command) error {
-	err := fmt.Errorf("Run '%s --help' for usage.", executableBase)
-	fmt.Fprintf(os.Stderr, "%s", err)
-	return err
-}
-
 func migrate() error {
 	logrus.Debug("Migrating to newer Podman")
 

test/system/002-help.bats

@@ -63,61 +63,61 @@ setup() {
 
   assert_failure
   assert_line --index 0 "Error: unknown flag: --foo"
-  assert_line --index 1 "Run 'toolbox --help' for usage."
+  assert_line --index 1 "Run 'toolbox create --help' for usage."
 }
 
 @test "help: Try to run 'toolbox enter' with non-existent flag (shows usage screen)" {
   run $TOOLBOX enter --foo
 
   assert_failure
   assert_line --index 0 "Error: unknown flag: --foo"
-  assert_line --index 1 "Run 'toolbox --help' for usage."
+  assert_line --index 1 "Run 'toolbox enter --help' for usage."
 }
 
 @test "help: Try to run 'toolbox help' with non-existent flag (shows usage screen)" {
   run $TOOLBOX help --foo
 
   assert_failure
   assert_line --index 0 "Error: unknown flag: --foo"
-  assert_line --index 1 "Run 'toolbox --help' for usage."
+  assert_line --index 1 "Run 'toolbox help --help' for usage."
 }
 
 @test "help: Try to run 'toolbox init-container' with non-existent flag (shows usage screen)" {
   run $TOOLBOX init-container --foo
 
   assert_failure
   assert_line --index 0 "Error: unknown flag: --foo"
-  assert_line --index 1 "Run 'toolbox --help' for usage."
+  assert_line --index 1 "Run 'toolbox init-container --help' for usage."
 }
 
 @test "help: Try to run 'toolbox list' with non-existent flag (shows usage screen)" {
   run $TOOLBOX list --foo
 
   assert_failure
   assert_line --index 0 "Error: unknown flag: --foo"
-  assert_line --index 1 "Run 'toolbox --help' for usage."
+  assert_line --index 1 "Run 'toolbox list --help' for usage."
 }
 
 @test "help: Try to run 'toolbox rm' with non-existent flag (shows usage screen)" {
   run $TOOLBOX rm --foo
 
   assert_failure
   assert_line --index 0 "Error: unknown flag: --foo"
-  assert_line --index 1 "Run 'toolbox --help' for usage."
+  assert_line --index 1 "Run 'toolbox rm --help' for usage."
 }
 
 @test "help: Try to run 'toolbox rmi' with non-existent flag (shows usage screen)" {
   run $TOOLBOX rmi --foo
 
   assert_failure
   assert_line --index 0 "Error: unknown flag: --foo"
-  assert_line --index 1 "Run 'toolbox --help' for usage."
+  assert_line --index 1 "Run 'toolbox rmi --help' for usage."
 }
 
 @test "help: Try to run 'toolbox run' with non-existent flag (shows usage screen)" {
   run $TOOLBOX run --foo
 
   assert_failure
   assert_line --index 0 "Error: unknown flag: --foo"
-  assert_line --index 1 "Run 'toolbox --help' for usage."
+  assert_line --index 1 "Run 'toolbox run --help' for usage."
 }