What causes "failed to create the log directory: %v" in owasp-amass/amass?

Pre-create the directory with correct ownership (mkdir -p && chown) or choose a writable location such as /tmp or $HOME

failed to create the log directory: %v

Error message

failed to create the log directory: %v

What it means

NewFileLogger creates the log directory with os.MkdirAll (mode 0640) when dir is non-empty. This error wraps MkdirAll failing, so the log directory could not be created — permissions, a non-directory in the path, or an invalid path.

Source

Thrown at internal/tools/log.go:43

		return err
	}

	ctx := context.Background()
	if l.Handler().Enabled(ctx, record.Level) {
		return l.Handler().Handle(ctx, record)
	}

	return errors.New("logger handler is not enabled")
}

func NewFileLogger(dir, logfile string) (*slog.Logger, error) {
	if logfile == "" {
		return nil, fmt.Errorf("no log file specified")
	}

	if dir != "" {
		if err := os.MkdirAll(dir, 0640); err != nil {
			return nil, fmt.Errorf("failed to create the log directory: %v", err)
		}
	}

	f, err := os.OpenFile(filepath.Join(dir, logfile), os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
	if err != nil {
		return nil, fmt.Errorf("failed to open the log file: %v", err)
	}

	return slog.New(slog.NewJSONHandler(f, nil)), nil
}

func NewSyslogLogger() (*slog.Logger, error) {
	port := os.Getenv("SYSLOG_PORT")
	host := strings.ToLower(os.Getenv("SYSLOG_HOST"))
	transport := strings.ToLower(os.Getenv("SYSLOG_TRANSPORT"))

	if host == "" {
		return nil, fmt.Errorf("no syslog host specified")

View on GitHub (pinned to 79299dce87)

Solutions

Pre-create the directory with correct ownership (mkdir -p <dir> && chown) or choose a writable location such as /tmp or $HOME
Verify each path component is a directory (ls -ld) and remove any blocking file
Check the mount is not read-only (mount output) and disk space is available
Pass an empty dir to write the log file relative to the current directory if a directory is not required

Example fix

// before
logger, err := tools.NewFileLogger("/var/log/amass", "amass.log") // EACCES
// after
logger, err := tools.NewFileLogger("/tmp/amass-logs", "amass.log")

Defensive patterns

Strategy: validation

Validate before calling

if dir != "" {
	if st, err := os.Stat(dir); err == nil && !st.IsDir() {
		return fmt.Errorf("%s is a file, not a directory", dir)
	}
	if err := os.MkdirAll(dir, 0750); err != nil {
		return fmt.Errorf("cannot prepare log dir: %v", err)
	}
}

Try / catch

logger, err := tools.NewFileLogger(dir, logfile)
if err != nil {
	if strings.Contains(err.Error(), "failed to create the log directory") {
		logger, err = tools.NewFileLogger("", logfile) // fall back to cwd
	}
	if err != nil { return err }
}

Prevention

Use user-writable locations ($HOME, /tmp) for log directories in containers
Pre-create log directories in Dockerfile/entrypoint with correct ownership
Avoid mounting log volumes read-only unless an alternative dir is configured
Verify each path component of dir is not an existing regular file

When it happens

Trigger: Calling NewFileLogger with a dir whose parent is unwritable, a path component that is a regular file, a read-only filesystem, or dir containing invalid characters for the platform.

Common situations: LOG_DIR pointing to /var/log/foo without root or membership in the adm group; container volumes mounted read-only; a file named like the intended directory left behind by earlier tooling.

Understand the failure class

Background: mkdir permission denied (EACCES): failed to create directory errors explained — this error's family across 32 libraries.

Related errors

AI-assisted analysis of owasp-amass/amass@79299dce87 (2026-09-06). Data as JSON: /api/errors/316fedf2cf91b728. Report an issue: GitHub.