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rust.missing_correlation_id

Observability Medium

Detects HTTP handlers or services without correlation ID propagation for request tracing.

Why It Matters

Missing correlation IDs:

Break tracing — Can’t follow requests across services
Hinder debugging — No way to correlate logs
Increase MTTR — Slower incident resolution

Example

// ❌ Before (no correlation ID)
async fn handle_request(req: Request) -> Response {
    let result = service.process(req.body).await?;
    Ok(Response::new(result))
}

// ✅ After (with correlation ID)
use uuid::Uuid;

async fn handle_request(req: Request) -> Response {
    let correlation_id = req
        .headers()
        .get("x-correlation-id")
        .map(|v| v.to_str().unwrap_or_default().to_string())
        .unwrap_or_else(|| Uuid::new_v4().to_string());

    let span = tracing::info_span!("request", correlation_id = %correlation_id);

    async move {
        let result = service.process(req.body).await?;
        Ok(Response::builder()
            .header("x-correlation-id", correlation_id)
            .body(result)?)
    }.instrument(span).await
}

What Unfault Detects

Handlers without correlation ID extraction
Missing correlation ID header forwarding
No tracing span with correlation ID