retrieving rule files failed. Ignoring file. pattern

Error message

retrieving rule files failed. Ignoring file. pattern %s

What it means

reloadRules expands each configured rule-file pattern with filepath.Glob. The only possible error is a syntactically bad pattern (e.g. unmatched '['); when that happens the pattern is skipped and a wrapped error "retrieving rule files failed. Ignoring file. pattern %s" is added to the error group, so the reload continues with remaining patterns but ultimately fails.

Solutions

Fix the offending --rule-file glob pattern (close brackets, escape metacharacters).
Quote the pattern in the shell so it isn't expanded or mangled before reaching Thanos.
Test the pattern with a quick Go/Python glob or ls to confirm it matches the intended files.
Check logs for the exact pattern reported in the message and correct it in the deployment manifest.

Example fix

// before
--rule-file=/etc/thanos/rules/[abc     # unclosed bracket
// after
--rule-file=/etc/thanos/rules/*.yaml

Defensive patterns

Strategy: validation

Validate before calling

// validate patterns before handing them to thanos
for pat in "$@"; do python3 -c "import glob,sys; glob.glob(sys.argv[1])" "$pat" || echo "bad pattern: $pat"; done

Prevention

Prefer simple *.yaml globs over hand-written character classes
Quote globs in shell to prevent mangling
Smoke-test patterns with ls before deploying

When it happens

Trigger: Passing --rule-file with a malformed glob such as '/etc/rules/[abc' (unclosed bracket) or an invalid character class; ErrBadPattern from filepath.Glob.

Common situations: Shell quoting stripping or mangling brackets in the flag; templating tool emitting a partially-expanded pattern; hand-edited config with a typo in a glob.

Related errors

AI-assisted analysis of thanos-io/thanos@35b8b99117 (2026-09-07). Data as JSON: /api/errors/46b6f42644084914. Report an issue: GitHub.

Appendix: source

Thrown at cmd/thanos/rule.go:1092

	})
}

func reloadRules(logger log.Logger,
	ruleFiles []string,
	ruleMgr *thanosrules.Manager,
	evalInterval time.Duration,
	metrics *RuleMetrics) error {
	level.Debug(logger).Log("msg", "configured rule files", "files", strings.Join(ruleFiles, ","))
	var (
		errs      errutil.MultiError
		files     []string
		seenFiles = make(map[string]struct{})
	)
	for _, pat := range ruleFiles {
		fs, err := filepath.Glob(pat)
		if err != nil {
			// The only error can be a bad pattern.
			errs.Add(errors.Wrapf(err, "retrieving rule files failed. Ignoring file. pattern %s", pat))
			continue
		}

		for _, fp := range fs {
			if _, ok := seenFiles[fp]; ok {
				continue
			}
			files = append(files, fp)
			seenFiles[fp] = struct{}{}
		}
	}

	level.Info(logger).Log("msg", "reload rule files", "numFiles", len(files))

	if err := ruleMgr.Update(evalInterval, files); err != nil {
		metrics.configSuccess.Set(0)
		errs.Add(errors.Wrap(err, "reloading rules failed"))
		return errs.Err()

View on GitHub (pinned to 35b8b99117)