thanos-io/thanos · error

unquote label value

Error message

unquote label value

What it means

The label value (text after the first '=') must be a valid Go quoted string; parseFlagLabels runs strconv.Unquote on it. If Unquote fails (missing surrounding quotes with escapes, or unterminated quotes), the error is wrapped as "unquote label value" and returned. This lets values contain UTF-8 escapes and quoted characters.

Solutions

1. Quote the whole argument so quotes reach Thanos: --label 'key="value"' (single-quote outside, double-quote inside).
2. If the value needs no escapes, pass it unquoted: --label key=value.
3. Ensure escape sequences are balanced and inside quotes, e.g. --label 'key="a\nb"'.

Example fix

// before (shell strips quotes; \n then fails Unquote)
thanos sidecar --label note=a\nb
// after
thanos sidecar --label 'note="a\nb"'

func unquotableLabelValue(l string) bool {
    parts := strings.SplitN(l, "=", 2)
    if len(parts) != 2 { return false }
    _, err := strconv.Unquote(parts[1])
    return err == nil
}

// Go
if _, err := parseFlagLabels(args); err != nil {
    var unwrap interface{ Unwrap() error }
    _ = unwrap // errors.Wrap adds "unquote label value" context; log full chain
}

When it happens

Trigger: Passing --label key="value" where the shell strips the quotes so Unquote sees a bare string containing an escape sequence (e.g. key=a\nb), or a value with an unbalanced quote like key="value.

Common situations: Double-quoting confusion in shells (quotes consumed before Thanos sees them); documenting --label cluster="eu-1" literally; Windows cmd quoting differences; copy-pasted examples where quotes were part of shell syntax.

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

Related errors

• unrecognized label
• unsupported format for label
• parse labels
• level is bigger then default set of
• unknown sync strategy

AI-assisted analysis of thanos-io/thanos@35b8b99117 (2026-09-07). Data as JSON: /api/errors/0d9a944bbc0e20d0. Report an issue: GitHub.

Appendix: source

Thrown at cmd/thanos/config.go:339

	ac.alertRelabelConfigPath = extflag.RegisterPathOrContent(cmd, "alert.relabel-config", "YAML file that contains alert relabelling configuration.", extflag.WithEnvSubstitution())
	ac.alertSourceTemplate = cmd.Flag("alert.query-template", "Template to use in alerts source field. Need only include {{.Expr}} parameter").Default("/graph?g0.expr={{.Expr}}&g0.tab=1").String()

	return ac
}

func parseFlagLabels(s []string) (labels.Labels, error) {
	var lset labels.ScratchBuilder
	for _, l := range s {
		parts := strings.SplitN(l, "=", 2)
		if len(parts) != 2 {
			return labels.EmptyLabels(), errors.Errorf("unrecognized label %q", l)
		}
		if !model.UTF8Validation.IsValidLabelName(parts[0]) {
			return labels.EmptyLabels(), errors.Errorf("unsupported format for label %s", l)
		}
		val, err := strconv.Unquote(parts[1])
		if err != nil {
			return labels.EmptyLabels(), errors.Wrap(err, "unquote label value")
		}
		lset.Add(parts[0], val)
	}
	lset.Sort()
	return lset.Labels(), nil
}

type goMemLimitConfig struct {
	enableAutoGoMemlimit bool
	memlimitRatio        float64
}

func (gml *goMemLimitConfig) registerFlag(cmd extkingpin.FlagClause) *goMemLimitConfig {
	cmd.Flag("enable-auto-gomemlimit",
		"Enable go runtime to automatically limit memory consumption.").
		Default("false").BoolVar(&gml.enableAutoGoMemlimit)

	cmd.Flag("auto-gomemlimit.ratio",

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