glanceapp/glance · error

validating config file: %w

Error message

validating config file: %w

What it means

Startup error raised in the fallback path when the config file watcher could not be started: main.go re-validates by calling newConfigFromYAML(configContents) and that validation failed. Despite the 'validating' label, it covers strict YAML decoding into the typed config struct — unknown fields, bad types, failed custom unmarshalers (e.g. orderedYAMLMap errors) all surface here.

Source

Thrown at internal/glance/main.go:165

	onErr := func(err error) {
		log.Printf("Error watching config files: %v", err)
	}

	configContents, configIncludes, err := parseYAMLIncludes(configPath)
	if err != nil {
		return fmt.Errorf("parsing config: %w", err)
	}

	stopWatching, err := configFilesWatcher(configPath, configContents, configIncludes, onChange, onErr)
	if err == nil {
		defer stopWatching()
	} else {
		log.Printf("Error starting file watcher, config file changes will require a manual restart. (%v)", err)

		config, err := newConfigFromYAML(configContents)
		if err != nil {
			return fmt.Errorf("validating config file: %w", err)
		}

		app, err := newApplication(config)
		if err != nil {
			return fmt.Errorf("creating application: %w", err)
		}

		startServer, _ := app.server()
		if err := startServer(); err != nil {
			return fmt.Errorf("starting server: %w", err)
		}
	}

	<-exitChannel
	return nil
}

func serveUpdateNoticeIfConfigLocationNotMigrated(configPath string) bool {

View on GitHub (pinned to 91324e8de7)

Solutions

1. Read the wrapped error for the offending key/line and fix or remove it
2. Cross-check the config against the current glance config reference for renamed fields after upgrades
3. Fix the watcher environment (raise fs.inotify.max_user_watches, ensure /proc and inotify available) so the normal hot-reload path is used

Example fix

# before
server:
  portt: 8080   # typo'd/unknown key
# after
server:
  port: 8080

// Strict-decode a probe struct mirroring top-level keys to catch unknowns
var probe map[string]yaml.Node
if err := yaml.Unmarshal(cfg, &probe); err != nil { return err }
for k := range probe {
    if !knownTopLevelKeys[k] { return fmt.Errorf("unknown top-level key %q", k) }
}

Catch the %w chain; the strict decoder names the unknown/invalid key — fail the deploy with that message.

When it happens

Trigger: The filesystem watcher init failed (e.g. inotify limits, unsupported FS) AND the config, while syntactically parseable, violates the typed schema: unknown top-level keys, wrong field types, invalid widget/struct fields caught by KnownFields-strict decoding.

Common situations: Upgrading glance and keeping old config keys that were renamed/removed; watcher unavailable in restricted containers forcing this path; typos in top-level config sections.

Related errors

• secret-key must be exactly %d bytes
• initializing preset theme %s: %v
• initializing default theme: %v
• URL is required
• nested groups are not supported

AI-assisted analysis of glanceapp/glance@91324e8de7 (2026-08-15). Data as JSON: /api/errors/3bb36f2897aa4e06. Report an issue: GitHub.