What causes "while reading %s: %w" in crowdsecurity/crowdsec?

Check permissions on the reported parser.assert path (ls -l) and chmod/chown so the running user can read it

while reading %s: %w

Error message

while reading %s: %w

What it means

After globbing parser.assert files, GetParsersCoverage opens each one with os.Open. If opening a specific assert file fails, the function stops and returns 'while reading <path>: <err>'. The wrapped os error (e.g. permission denied) identifies the actual cause.

Source

Thrown at pkg/hubtest/coverage.go:116

	for i, name := range pkeys {
		coverage[i] = Coverage{
			Name:       name,
			TestsCount: 0,
			PresentIn:  make(map[string]bool),
		}
	}

	// parser the expressions a-la-oneagain
	passerts, err := filepath.Glob(filepath.Join(hubDir, ".tests", "*", "parser.assert"))
	if err != nil {
		return nil, fmt.Errorf("while find parser asserts: %w", err)
	}

	for _, assert := range passerts {
		file, err := os.Open(assert)
		if err != nil {
			return nil, fmt.Errorf("while reading %s: %w", assert, err)
		}

		scanner := bufio.NewScanner(file)
		for scanner.Scan() {
			line := scanner.Text()
			log.Debugf("assert line : %s", line)

			match := parserResultRE.FindStringSubmatch(line)
			if len(match) == 0 {
				log.Debugf("%s doesn't match", line)
				continue
			}

			sidx := parserResultRE.SubexpIndex("parser")
			capturedParser := match[sidx]

			for idx, pcover := range coverage {
				if pcover.Name == capturedParser {

View on GitHub (pinned to 909b515798)

Solutions

Check permissions on the reported parser.assert path (ls -l) and chmod/chown so the running user can read it
Verify the path is a regular file, not a directory; remove/recreate it if wrong
Re-run hub update / re-checkout to replace a truncated or missing assert file
Run hubtest with the same user that owns the hub directory

Example fix

// before
-rw------- parser.assert  (owned by root, hubtest runs as ci)
// after
chmod 644 parser.assert && chown ci:ci parser.assert

Defensive patterns

Strategy: try-catch

Validate before calling

info, err := os.Stat(assertPath)
if err != nil || info.IsDir() { return fmt.Errorf("unreadable assert %s", assertPath) }
if f, err := os.Open(assertPath); err == nil { f.Close() }

Try / catch

cov, err := hubtest.GetParsersCoverage(hubDir, ...)
if err != nil {
    var pe *fs.PathError
    if errors.As(err, &pe) { log.Fatalf("cannot read %s: %v — check permissions", pe.Path, pe.Err) }
}

Prevention

Ensure the CI user owns or can read the hub tests directory
Avoid concurrent hub cache updates during coverage runs
Verify assert files are regular files after cloning

When it happens

Trigger: os.Open fails on a parser.assert path: the file was deleted between glob and open, the file is a directory named parser.assert, or the process lacks read permission on it.

Common situations: Tests directory mounted read-only or owned by another user (CI running as non-root); a stale glob result after the hub cache was concurrently updated; someone created a directory named parser.assert.

Understand the failure class

Background: "open() failed", "failed to open file", "cannot create file" — what a file open error means and how to fix it — this error's family across 42 libraries.

Related errors

AI-assisted analysis of crowdsecurity/crowdsec@909b515798 (2026-09-06). Data as JSON: /api/errors/ec420fa62b0a0b59. Report an issue: GitHub.