thanos-io/thanos · error

unable to load config content

Error message

unable to load config content: %s

What it means

This error is raised when the endpoint config file's content cannot be read from disk (configFile.Content() fails) while parsing endpointset configuration. Thanos wraps the underlying I/O error with the config file path so operators know which file failed. It aborts building the endpoint config provider.

Solutions

1. Verify the file exists at the exact path reported in the error (ls -l) and is readable by the Thanos process user.
2. Fix mount/secret setup so the config file is present at startup (e.g., correct ConfigMap volume mount path).
3. If using the nop/static endpoints mode, ensure no endpoint-config flag is passed so a NopConfig is used instead.
4. Check fsnotify/watcher support on the filesystem (NFS, tmpfs) — fall back to static --endpoint flags if watching is unreliable.

Example fix

// before: file may not exist
content, err := configFile.Content()
if err != nil { return EndpointConfig{}, errors.Wrapf(err, "unable to load config content: %s", configFile.Path()) }
// after: guard with an existence check before parse
if _, statErr := os.Stat(configFile.Path()); os.IsNotExist(statErr) {
    return EndpointConfig{}, errors.Errorf("endpoint config file does not exist: %s", configFile.Path())
}
content, err := configFile.Content()

func canReadConfig(p string) error { fi, err := os.Stat(p); if err != nil { return err }; if fi.IsDir() { return fmt.Errorf("%s is a directory", p) }; f, err := os.Open(p); if err != nil { return err }; return f.Close() }

func fileReadable(p string) bool { f, err := os.Open(p); if err != nil { return false }; _ = f.Close(); return true }

cfg, err := provider.parse(configFile)
if err != nil {
    var pathErr *os.PathError
    if errors.As(err, &pathErr) { log.Fatalf("endpoint config unreadable: %s: %v", pathErr.Path, pathErr.Err) }
    return err
}

When it happens

Trigger: Calling endpointConfigProvider.parse when configFile.Content() errors: the file was deleted/moved after discovery, permissions deny read, it's a directory not a file, or the underlying watch/reader returns an I/O error.

Common situations: Operator points --endpoint-config or --endpoint-config-ndjson at a missing or renamed file; k8s ConfigMap mount not yet present or removed; file unreadable by the Thanos process user (permissions/SELinux).

Understand the failure class

Background: "failed to read file", EACCES, ENOENT and "could not read <path>" errors: when a program can't read a file from disk — this error's family across 49 libraries.

Related errors

• unable to load config file
• unable to load config initially
• unable to unmarshal config content
• endpoint
• unable to validate endpoints

AI-assisted analysis of thanos-io/thanos@35b8b99117 (2026-09-07). Data as JSON: /api/errors/3b359685186add95. Report an issue: GitHub.

Appendix: source

Thrown at cmd/thanos/endpointset.go:175

	if cfg.Compression != "none" && cfg.Compression != "snappy" {
		return errors.Newf("invalid compression: %s, must be 'none' or 'snappy'", cfg.Compression)
	}
	return nil
}

func (er *endpointConfigProvider) config() EndpointConfig {
	er.mu.Lock()
	defer er.mu.Unlock()

	res := EndpointConfig{Endpoints: make([]endpointSettings, len(er.cfg.Endpoints)), DefaultClientConfig: er.cfg.DefaultClientConfig}
	copy(res.Endpoints, er.cfg.Endpoints)
	return res
}

func (er *endpointConfigProvider) parse(configFile fileContent) (EndpointConfig, error) {
	content, err := configFile.Content()
	if err != nil {
		return EndpointConfig{}, errors.Wrapf(err, "unable to load config content: %s", configFile.Path())
	}
	var cfg EndpointConfig
	if err := yaml.Unmarshal(content, &cfg); err != nil {
		return EndpointConfig{}, errors.Wrapf(err, "unable to unmarshal config content: %s", configFile.Path())
	}
	return cfg, nil
}

func (er *endpointConfigProvider) addStaticEndpoints(cfg *EndpointConfig) {
	for _, e := range er.endpoints {
		cfg.Endpoints = append(cfg.Endpoints, endpointSettings{
			Address: e,
		})
	}
	for _, e := range er.endpointGroups {
		cfg.Endpoints = append(cfg.Endpoints, endpointSettings{
			Address: e,
			Group:   true,

View on GitHub (pinned to 35b8b99117)