Counter Exemplars with Context

Build a protobuf payload for a single counter metric that carries exemplar context (labels, value, timestamp) without leaking exemplar labels into the metric's base label set.

Capabilities

Counter exemplar payload

• Serializes a counter metric named "request_duration_seconds_total" with base labels method=GET and status=200, attaches an exemplar containing trace_id=abc-123, exemplar value 0.42, and timestamp 2023-11-20T10:00:00Z, and returns bytes that decode back to those exact values. @test
• If the provided exemplar timestamp is the zero value, returns an error instead of emitting a payload. @test
• Ensures metric labels remain service=checkout and region=us-east-1, while exemplar labels remain trace_id=xyz-789 and span_id=def-456, with no cross-contamination between the two label sets. @test

Implementation

@generates

API

package exemplar

import "time"

// MarshalCounterWithExemplar builds a single-sample counter metric payload with an exemplar and returns the protobuf bytes.
func MarshalCounterWithExemplar(
    metricName string,
    metricLabels map[string]string,
    exemplarLabels map[string]string,
    counterValue float64,
    exemplarValue float64,
    exemplarTime time.Time,
) ([]byte, error)

Dependencies { .dependencies }

Prometheus client model { .dependency }

Provides protobuf data model types for metrics and exemplars.

@satisfied-by