quickwit-oss/quickwit · error

{} contains an empty label value: {}

Error message

{} contains an empty label value: {}

What it means

parse_metrics_labels rejects any 'name=value' label in QW_METRICS_LABELS_ENV_VAR whose value (after '=') is empty or whitespace-only after trimming, since an empty label value is meaningless for metrics.

Source

Thrown at quickwit/quickwit-metrics/src/lib.rs:445

    for label in labels.split(LABELS_SEPARATOR) {
        let (name, value) = label.split_once(KEY_VALUE_SEPARATOR).ok_or_else(|| {
            anyhow::anyhow!(
                "{} contains invalid label format: {}",
                QW_METRICS_LABELS_ENV_VAR,
                label
            )
        })?;
        let name = name.trim();
        if name.is_empty() {
            anyhow::bail!(
                "{} contains an empty label name: {}",
                QW_METRICS_LABELS_ENV_VAR,
                label
            );
        }
        let value = value.trim();
        if value.is_empty() {
            anyhow::bail!(
                "{} contains an empty label value: {}",
                QW_METRICS_LABELS_ENV_VAR,
                label
            );
        }
        let label = Label::new(name.to_string(), value.to_string());
        parsed_labels.push(label);
    }

    Ok(parsed_labels)
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_parse_metrics_labels() {

View on GitHub (pinned to a39730c5cd)

Solutions

1. Provide a non-empty value for each label: "cluster=prod" instead of "cluster="
2. Ensure interpolated shell variables are set before export, or hardcode the value
3. Drop labels you don't intend to set instead of leaving them empty

Example fix

// before
export QW_METRICS_LABELS_ENV_VAR="cluster="
// after
export QW_METRICS_LABELS_ENV_VAR="cluster=prod"

fn all_values_present(s: &str) -> bool {
    s.split(',').filter(|l| !l.is_empty()).all(|l| {
        l.split_once('=').map(|(_, v)| !v.trim().is_empty()).unwrap_or(false)
    })
}

match parse_metrics_labels(&raw) {
    Err(e) if e.to_string().contains("empty label value") => {
        eprintln!("missing value in QW_METRICS_LABELS_ENV_VAR: {e}");
    }
    other => other?,
}

When it happens

Trigger: Setting QW_METRICS_LABELS_ENV_VAR to entries like "cluster=" or "team= ,a=b" where a value is missing after the '='.

Common situations: Variable interpolation producing an empty value, e.g. QW_METRICS_LABELS_ENV_VAR="cluster=${CLUSTER}" with CLUSTER unset; partial manual edits.

Understand the failure class

Background: "Invalid value" and "allowed values are" config errors: what your library rejected and how to fix it — this error's family across 41 libraries.

Related errors

• {} contains an empty label name: {}
• {QW_METRICS_LABELS_ENV_VAR} must contain valid Unicode
• index ID pattern `{pattern}` is invalid: patterns must not c
• index ID pattern `{pattern}` is invalid: an index ID must ha
• index config merge policy `max_merge_factor` must be superio

AI-assisted analysis of quickwit-oss/quickwit@a39730c5cd (2026-09-08). Data as JSON: /api/errors/d07bc7294fd4e698. Report an issue: GitHub.