thanos-io/thanos · error

validate relabel config

Error message

validate relabel config

What it means

LoadRelabelConfigs strictly unmarshals the relabel_configs YAML into []*relabel.Config and then calls Validate(model.UTF8Validation) on each; any relabel rule failing Prometheus relabel validation (bad regex, unknown action, missing fields) is wrapped with 'validate relabel config'.

Solutions

1. Read the wrapped underlying error to see which relabel config and field failed; fix the regex/action/field in that rule.
2. Validate the relabel YAML locally with a Prometheus relabel.Config strict unmarshal before deploying.
3. Cross-check actions against relabel.Config supported actions for this Prometheus version.

Example fix

// before
- action: regex
  regex: '.*('
// after
- action: drop
  regex: '.*debug.*'

var cfgs []*relabel.Config
if err := yaml.UnmarshalStrict(relabelYaml, &cfgs); err != nil { return err }
for _, c := range cfgs {
    if err := c.Validate(model.UTF8Validation); err != nil {
        return fmt.Errorf("relabel config invalid: %w", err)
    }
}

When it happens

Trigger: runRule loads alerting relabel configs; a rule has an invalid regex (bad RE2 pattern), an unsupported action name, a missing required field (e.g. source_labels/target_label), or duplicate labels in invalid UTF-8.

Common situations: Typo in action: keep/match instead of keep/match; invalid regex like '.*(' for the drop action; copying scrape relabel configs that use actions unsupported in this context.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

• unsupported format for label
• --auto-gomemlimit.ratio must be greater than 0 and less…
• 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/e857dad43b1134a6. Report an issue: GitHub.

Appendix: source

Thrown at pkg/alert/config.go:151

		EndpointsConfig: clientconfig.HTTPEndpointsConfig{
			PathPrefix:      parsed.Path,
			Scheme:          scheme,
			StaticAddresses: []string{host},
		},
		Timeout:    model.Duration(timeout),
		APIVersion: APIv2,
	}, nil
}

// LoadRelabelConfigs loads a list of relabel.Config from YAML data.
func LoadRelabelConfigs(confYaml []byte) ([]*relabel.Config, error) {
	var cfg []*relabel.Config
	if err := yaml.UnmarshalStrict(confYaml, &cfg); err != nil {
		return nil, err
	}
	for _, c := range cfg {
		if err := c.Validate(model.UTF8Validation); err != nil {
			return nil, errors.Wrap(err, "validate relabel config")
		}
	}
	return cfg, nil
}

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