fix: allow non-existent output directories with --output flag

When using the --output flag, PerfSpect now accepts and creates
directories that don't exist yet, rather than requiring them to exist
beforehand. The directory is created once, early during initialization,
to validate write permissions before data collection begins.

Changes:
- Removed existence check in initializeApplication()
- Added createOutputDir() function in root.go (single use, kept local)
- Create output directory early (after logging, before data collection)
- Only log creation when directory is actually created
- Removed redundant directory creation calls from commands
- Detects if output path exists as a file and fails with clear error

Benefits:
- Improved usability - no manual directory creation needed
- Fail-fast validation - catches permission/disk issues immediately
- No wasted data collection - validates write access before work begins
- Single point of directory creation - simpler, more maintainable
- Cleaner logs - only logs when directory is actually created
- Creates nested directories automatically (e.g., /path/to/new/dir)

Directory creation timing:
- After logging is configured (errors can be logged)
- Before app context is set and data collection starts
- Early enough to fail fast and save time

Error handling:
- Permission denied - clear error before any work
- Disk full - detected immediately
- Read-only filesystem - fails at start
- Path exists as file - caught with clear error
- Path already exists as directory - succeeds silently

Fixes #556

Signed-off-by: Jason Harper <[email protected]>
Signed-off-by: Harper, Jason M <[email protected]>

Author: harp-intel

cmd/metrics/metrics.go

@@ -842,16 +842,8 @@ func runCmd(cmd *cobra.Command, args []string) error {
 	signalMgr := newSignalManager()
 	// short circuit when --input flag is set
 	if flagInput != "" {
-		// create output directory
-		err := common.CreateOutputDir(localOutputDir)
-		if err != nil {
-			err = fmt.Errorf("failed to create output directory: %w", err)
-			fmt.Fprintf(os.Stderr, "Error: %+v\n", err)
-			cmd.SilenceUsage = true
-			return err
-		}
 		// skip data collection and use raw data for reports
-		err = processRawData(localOutputDir)
+		err := processRawData(localOutputDir)
 		if err != nil {
 			fmt.Fprintf(os.Stderr, "Error: %v\n", err)
 			slog.Error(err.Error())
@@ -1057,16 +1049,6 @@ func runCmd(cmd *cobra.Command, args []string) error {
 			createPrometheusMetrics(targetContext.metricDefinitions)
 		}
 	}
-	// create the local output directory
-	if !flagLive && !flagPrometheusServer {
-		err = common.CreateOutputDir(localOutputDir)
-		if err != nil {
-			err = fmt.Errorf("failed to create output directory: %w", err)
-			fmt.Fprintf(os.Stderr, "Error: %+v\n", err)
-			cmd.SilenceUsage = true
-			return err
-		}
-	}
 	// start the metric production for each target
 	collectOnTargetWG := sync.WaitGroup{}
 	for i := range targetContexts {

cmd/root.go

@@ -146,6 +146,30 @@ func Execute() {
 	}
 }
 
+// createOutputDir creates the output directory if it does not exist.
+// Returns true if the directory was created, false if it already existed.
+func createOutputDir(outputDir string) (bool, error) {
+	// Check if directory already exists
+	info, err := os.Stat(outputDir)
+	if err == nil {
+		// Path exists, verify it's a directory
+		if !info.IsDir() {
+			return false, fmt.Errorf("output path exists but is not a directory: %s", outputDir)
+		}
+		return false, nil // Already exists
+	}
+	// If error is not "not exists", something else is wrong
+	if !os.IsNotExist(err) {
+		return false, fmt.Errorf("failed to check output directory: %w", err)
+	}
+	// Directory doesn't exist, create it
+	err = os.MkdirAll(outputDir, 0755) // #nosec G301
+	if err != nil {
+		return false, fmt.Errorf("failed to create output directory: %w", err)
+	}
+	return true, nil // Created successfully
+}
+
 func initializeApplication(cmd *cobra.Command, args []string) error {
 	timestamp := time.Now().Local().Format("2006-01-02_15-04-05") // app startup time
 	// set output directory path (directory will be created later when needed)
@@ -213,13 +237,15 @@ func initializeApplication(cmd *cobra.Command, args []string) error {
 	}
 	// create the output directory now to fail fast if there are permission or disk space issues
 	// this validates write access before any data collection begins
-	err = common.CreateOutputDir(outputDir)
+	created, err := createOutputDir(outputDir)
 	if err != nil {
 		slog.Error("failed to create output directory", slog.String("path", outputDir), slog.String("error", err.Error()))
 		fmt.Printf("Error: failed to create output directory: %v\n", err)
 		os.Exit(1)
 	}
-	slog.Debug("output directory created", slog.String("path", outputDir))
+	if created {
+		slog.Debug("output directory created", slog.String("path", outputDir))
+	}
 	// set app context
 	cmd.Parent().SetContext(
 		context.WithValue(

internal/common/common.go

@@ -204,17 +204,9 @@ func (rc *ReportingCommand) Run() error {
 			return err
 		}
 	}
-	// we have output data so create the output directory
-	err := CreateOutputDir(outputDir)
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "Error: %v\n", err)
-		slog.Error(err.Error())
-		rc.Cmd.SilenceUsage = true
-		return err
-	}
 	// create the raw report before processing the data, so that we can save the raw data even if there is an error while processing
 	var rawReports []string
-	rawReports, err = rc.createRawReports(appContext, orderedTargetScriptOutputs)
+	rawReports, err := rc.createRawReports(appContext, orderedTargetScriptOutputs)
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "Error: %v\n", err)
 		slog.Error(err.Error())
@@ -289,15 +281,6 @@ func (rc *ReportingCommand) Run() error {
 	return nil
 }
 
-// CreateOutputDir creates the output directory if it does not exist
-func CreateOutputDir(outputDir string) error {
-	err := os.MkdirAll(outputDir, 0755) // #nosec G301
-	if err != nil {
-		return fmt.Errorf("failed to create output directory: %w", err)
-	}
-	return nil
-}
-
 // DefaultInsightsFunc returns the insights table values from the table values
 func DefaultInsightsFunc(allTableValues []report.TableValues, scriptOutputs map[string]script.ScriptOutput) report.TableValues {
 	insightsTableValues := report.TableValues{