main: fix --verbose logging

rootCmd.PersistentFlags().GetBool("verbose") always returned false prior
this commit because flags are not parse yet. This happens only when
rootCmd.Execute() is called.

Fix this by using one of the cobra hooks that runs after flags are
parsed. Note that the hook is needed because we want to enable verbose
logging for all subcommands. Otherwise, we would have to enable it in
every single subcommand.

I also added a small log message that actually informs users that
verbose logging is enabled.

Author: ondrejbudai

cmd/image-builder/main.go

@@ -646,14 +646,19 @@ operating systems like Fedora, CentOS and RHEL with easy customizations support.
 
 	rootCmd.AddCommand(describeImgCmd)
 
-	verbose, err := rootCmd.PersistentFlags().GetBool("verbose")
-	if err != nil {
-		return err
-	}
-	if verbose {
-		olog.SetDefault(log.New(os.Stderr, "", 0))
-		// XXX: add once images has olog support
-		//images_log.SetDefault(log.New(os.Stderr, "", 0))
+	// Flags are not parsed yet, so we need to use this hook for enabling verbose logging for all commands
+	rootCmd.PersistentPreRunE = func(cmd *cobra.Command, args []string) error {
+		verbose, err := cmd.Flags().GetBool("verbose")
+		if err != nil {
+			return err
+		}
+		if verbose {
+			olog.SetDefault(log.New(os.Stderr, "", 0))
+			olog.Print("verbose logging enabled")
+			// XXX: add once images has olog support
+			//images_log.SetDefault(log.New(os.Stderr, "", 0))
+		}
+		return nil
 	}
 
 	return rootCmd.Execute()