thanos-io/thanos · error

parsing config YAML file

Error message

parsing config YAML file

What it means

NewCacheConfig parses a Thanos query-frontend cache configuration YAML into a Cortex cache config. yaml.UnmarshalStrict rejects unknown or malformed fields, and the error is wrapped with 'parsing config YAML file'. It means the cache YAML supplied (e.g. via --query-range.response-cache-config-file) is not a valid cache provider config.

Solutions

1. Fix the YAML so it strictly matches CacheProviderConfig: only 'type' and 'config' keys with valid types.
2. Validate the YAML against the Thanos documentation example for the chosen cache backend (in-memory, memcached, redis).
3. Remove unknown/renamed fields; check for version drift between Thanos releases.
4. Test the config parsing locally before deploying.

Example fix

# before
cache:
  type: memcached
  memcached:
    addresses: [localhost:11211]
# after
type: MEMCACHED
config:
  addresses: [localhost:11211]

// validate cache YAML before handing to Thanos
var probe struct {
    Type   string                 `yaml:"type"`
    Config map[string]interface{} `yaml:"config"`
}
if err := yaml.UnmarshalStrict(data, &probe); err != nil {
    return fmt.Errorf("invalid cache config: %w", err)
}

cfg, err := queryfrontend.NewCacheConfig(logger, yamlBytes)
if err != nil {
    if strings.Contains(err.Error(), "parsing config YAML file") {
        return fmt.Errorf("cache config YAML invalid, fix fields per docs: %w", err)
    }
    return err
}

When it happens

Trigger: The YAML passed to NewCacheConfig does not strictly unmarshal into CacheProviderConfig: unknown keys (strict mode), wrong types, or invalid YAML syntax.

Common situations: Typos in YAML keys, using Cortex fields unsupported by Thanos's strict schema, copying configs between Thanos versions where fields changed, or malformed YAML indentation.

Related errors

• marshal content of cache backend configuration
• initializing the query range cache config
• initializing the labels cache config
• response cache with type
• invalid ResultsCache config for labels tripperware

AI-assisted analysis of thanos-io/thanos@35b8b99117 (2026-09-07). Data as JSON: /api/errors/c5785f0cee611c9a. Report an issue: GitHub.

Appendix: source

Thrown at pkg/queryfrontend/config.go:92

// RedisResponseCacheConfig holds the configs for the redis cache provider.
type RedisResponseCacheConfig struct {
	Redis cacheutil.RedisClientConfig `yaml:",inline"`
	// Expiration sets a global expiration limit for all cached items.
	Expiration time.Duration `yaml:"expiration"`
}

// CacheProviderConfig is the initial CacheProviderConfig struct holder before parsing it into a specific cache provider.
// Based on the config type the config is then parsed into a specific cache provider.
type CacheProviderConfig struct {
	Type   ResponseCacheProvider `yaml:"type"`
	Config any                   `yaml:"config"`
}

// NewCacheConfig is a parser that converts a Thanos cache config yaml into a cortex cache config struct.
func NewCacheConfig(logger log.Logger, confContentYaml []byte) (*cortexcache.Config, error) {
	cacheConfig := &CacheProviderConfig{}
	if err := yaml.UnmarshalStrict(confContentYaml, cacheConfig); err != nil {
		return nil, errors.Wrap(err, "parsing config YAML file")
	}

	backendConfig, err := yaml.Marshal(cacheConfig.Config)
	if err != nil {
		return nil, errors.Wrap(err, "marshal content of cache backend configuration")
	}

	switch strings.ToUpper(string(cacheConfig.Type)) {
	case string(INMEMORY):
		var config InMemoryResponseCacheConfig
		if err := yaml.Unmarshal(backendConfig, &config); err != nil {
			return nil, err
		}

		return &cortexcache.Config{
			EnableFifoCache: true,
			Fifocache: cortexcache.FifoCacheConfig{
				MaxSizeBytes: config.MaxSize,

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