cachebench: trace request %q has invalid identity, body, or

Error message

cachebench: trace request %q has invalid identity, body, or digest

What it means

A trace record failed one of the identity/body checks: Provider or Epoch blank, Body not a valid unique JSON object, BodySHA256 empty, or BodySHA256 not equal to bodyDigest(Body). The digest check guarantees the recorded body is byte-faithful, which the evidence chain in the report relies on.

Source

Thrown at cacheengine/cachebench/observed.go:49

// EvaluateObservedAgainstTrace requires exact request population and body joins.
func EvaluateObservedAgainstTrace(records []ObservationRecord, trace []TraceRecord, target Target) (Report, error) {
	if err := validateObservationRecords(records); err != nil {
		return Report{}, err
	}
	if len(records) != len(trace) {
		return Report{}, fmt.Errorf("cachebench: observation population %d does not match trace population %d", len(records), len(trace))
	}
	byID := make(map[string]TraceRecord, len(trace))
	for index, request := range trace {
		if request.Schema != TraceSchema && request.Schema != TraceSchemaV2 || strings.TrimSpace(request.RequestID) == "" {
			return Report{}, fmt.Errorf("cachebench: trace request %d has invalid schema or request_id", index)
		}
		if _, exists := byID[request.RequestID]; exists {
			return Report{}, fmt.Errorf("cachebench: duplicate trace request %q", request.RequestID)
		}
		if strings.TrimSpace(request.Provider) == "" || strings.TrimSpace(request.Epoch) == "" || !validUniqueJSONObject(request.Body) || request.BodySHA256 == "" || request.BodySHA256 != bodyDigest(request.Body) {
			return Report{}, fmt.Errorf("cachebench: trace request %q has invalid identity, body, or digest", request.RequestID)
		}
		if request.StableSegmentCount < 0 || request.StableSegmentCount > len(request.Prefix) || !validPrefix(request.Prefix) {
			return Report{}, fmt.Errorf("cachebench: trace request %q has invalid prefix", request.RequestID)
		}
		byID[request.RequestID] = request
	}
	for _, record := range records {
		request, exists := byID[record.RequestID]
		if !exists {
			return Report{}, fmt.Errorf("cachebench: observation request %q absent from trace", record.RequestID)
		}
		if record.Provider != request.Provider || record.Epoch != request.Epoch {
			return Report{}, fmt.Errorf("cachebench: observation request %q provider/epoch mismatch", record.RequestID)
		}
		if record.RequestBodySHA256 == "" || record.RequestBodySHA256 != request.BodySHA256 {
			return Report{}, fmt.Errorf("cachebench: observation request %q body digest mismatch", record.RequestID)
		}
	}

View on GitHub (pinned to 27d5a3981a)

Solutions

Recompute and store bodyDigest(body) whenever the body field is written or modified.
Keep body as a compact, canonical JSON object; avoid pretty-printing or key reordering after generation.
Fill in provider and epoch on every trace record.
Regenerate the trace from the replay rather than transforming it externally.

Defensive patterns

Strategy: validation

Validate before calling

func validTraceRecord(r TraceRecord) error {
	if strings.TrimSpace(r.Provider) == "" || strings.TrimSpace(r.Epoch) == "" {
		return fmt.Errorf("request %q missing provider/epoch", r.RequestID)
	}
	if !validUniqueJSONObject(r.Body) {
		return fmt.Errorf("request %q body not a unique JSON object", r.RequestID)
	}
	if r.BodySHA256 != bodyDigest(r.Body) {
		return fmt.Errorf("request %q digest stale; recompute", r.RequestID)
	}
	return nil
}

Prevention

Compute BodySHA256 with bodyDigest at write time and never reformat the body afterwards.
Treat body bytes as opaque; pass them through unchanged between stages.
Add a CI check that recomputes digests over fixture traces.

When it happens

Trigger: EvaluateObservedAgainstTrace validating a trace record whose provider/epoch fields are whitespace, whose body is an array or contains duplicate JSON keys, or whose recorded BodySHA256 does not match a fresh SHA-256 of the body bytes.

Common situations: Re-serializing trace JSON through a tool that reformats the body field (breaking the digest); editing body content by hand after generation; body stored as a JSON array instead of an object.

Related errors

AI-assisted analysis of JuliusBrussee/caveman@27d5a3981a (2026-08-15). Data as JSON: /api/errors/0a6e530755a19f0d. Report an issue: GitHub.