Allow pruning of target directory's contents

README.md

@@ -103,6 +103,7 @@ Flags:
       --include-triple-dash    if enabled, the typical "---" YAML separator is included at the beginning of resources sliced
   -f, --input-file string      the input file used to read the initial macro YAML file; if empty or "-", stdin is used
   -o, --output-dir string      the output directory used to output the splitted files
+      --prune                  if enabled, the output directory will be pruned before writing the files
   -q, --quiet                  if true, no output is written to stdout/err
   -s, --skip-non-k8s           if enabled, any YAMLs that don't contain at least an "apiVersion", "kind" and "metadata.name" will be excluded from the split
       --sort-by-kind           if enabled, resources are sorted by Kind, a la Helm, before saving them to disk

app.go

@@ -113,6 +113,7 @@ func root() *cobra.Command {
 	rootCommand.Flags().BoolVar(&opts.AllowEmptyKinds, "allow-empty-kinds", false, "if enabled, resources with empty kinds don't produce an error when filtering")
 	rootCommand.Flags().BoolVar(&opts.AllowEmptyNames, "allow-empty-names", false, "if enabled, resources with empty names don't produce an error when filtering")
 	rootCommand.Flags().BoolVar(&opts.IncludeTripleDash, "include-triple-dash", false, "if enabled, the typical \"---\" YAML separator is included at the beginning of resources sliced")
+	rootCommand.Flags().BoolVar(&opts.PruneOutputDir, "prune", false, "if enabled, the output directory will be pruned before writing the files")
 
 	_ = rootCommand.Flags().MarkHidden("debug")
 	return rootCommand

slice/execute.go

@@ -155,6 +155,18 @@ func (s *Split) store() error {
 		s.opts.OutputDirectory = "."
 	}
 
+	// If the user wants to prune the output directory, do it
+	if s.opts.PruneOutputDir && !s.opts.OutputToStdout && !s.opts.DryRun {
+		// Check if the directory exists and if it does, prune it
+		if _, err := os.Stat(s.opts.OutputDirectory); !os.IsNotExist(err) {
+			s.log.Printf("Pruning output directory %q", s.opts.OutputDirectory)
+			if err := deleteFolderContents(s.opts.OutputDirectory); err != nil {
+				return fmt.Errorf("unable to prune output directory %q: %w", s.opts.OutputDirectory, err)
+			}
+			s.log.Printf("Output directory %q pruned", s.opts.OutputDirectory)
+		}
+	}
+
 	// Now save those files to disk (or if dry-run is on, print what it would
 	// save). Files will be overwritten.
 	s.fileCount = 0

slice/split.go

@@ -65,6 +65,7 @@ type Options struct {
 
 	InputFile         string // the name of the input file to be read
 	OutputDirectory   string // the path to the directory where the files will be stored
+	PruneOutputDir    bool   // if true, the output directory will be pruned before writing the files
 	OutputToStdout    bool   // if true, the output will be written to stdout instead of a file
 	GoTemplate        string // the go template code to render the file names
 	DryRun            bool   // if true, no files are created

slice/utils.go

@@ -38,3 +38,24 @@ func openFile(fp string) (*os.File, error) {
 
 	return f, nil
 }
+
+func deleteFolderContents(location string) error {
+	f, err := os.Open(location)
+	if err != nil {
+		return fmt.Errorf("unable to open folder %q: %s", location, err.Error())
+	}
+	defer f.Close()
+
+	names, err := f.Readdirnames(-1)
+	if err != nil {
+		return fmt.Errorf("unable to read folder %q: %s", location, err.Error())
+	}
+
+	for _, name := range names {
+		if err := os.RemoveAll(location + "/" + name); err != nil {
+			return fmt.Errorf("unable to remove %q: %s", name, err.Error())
+		}
+	}
+
+	return nil
+}