support int exemplar value type

When the exemplar type is an int, it incorrectly gets converted to a 0
when DoubleValue() is called on the exemplar. This adds a check to
ensure that the value is converted properly based on the type.

Signed-off-by: Charlie Le <charlie_le@apple.com>

storage/remote/otlptranslator/prometheusremotewrite/helper.go

@@ -351,9 +351,17 @@ func getPromExemplars[T exemplarType](ctx context.Context, everyN *everyNTimes,
 		exemplarRunes := 0
 
 		promExemplar := prompb.Exemplar{
-			Value:     exemplar.DoubleValue(),
 			Timestamp: timestamp.FromTime(exemplar.Timestamp().AsTime()),
 		}
+		switch exemplar.ValueType() {
+		case pmetric.ExemplarValueTypeInt:
+			promExemplar.Value = float64(exemplar.IntValue())
+		case pmetric.ExemplarValueTypeDouble:
+			promExemplar.Value = exemplar.DoubleValue()
+		default:
+			return nil, fmt.Errorf("unsupported exemplar value type: %v", exemplar.ValueType())
+		}
+
 		if traceID := exemplar.TraceID(); !traceID.IsEmpty() {
 			val := hex.EncodeToString(traceID[:])
 			exemplarRunes += utf8.RuneCountInString(traceIDKey) + utf8.RuneCountInString(val)

storage/remote/otlptranslator/prometheusremotewrite/helper_test.go

@@ -406,3 +406,38 @@ func TestPrometheusConverter_AddHistogramDataPoints(t *testing.T) {
 		})
 	}
 }
+
+func TestGetPromExemplars(t *testing.T) {
+	ctx := context.Background()
+	everyN := &everyNTimes{n: 1}
+
+	t.Run("Exemplars with int value", func(t *testing.T) {
+		pt := pmetric.NewNumberDataPoint()
+		exemplar := pt.Exemplars().AppendEmpty()
+		exemplar.SetTimestamp(pcommon.Timestamp(time.Now().UnixNano()))
+		exemplar.SetIntValue(42)
+		exemplars, err := getPromExemplars(ctx, everyN, pt)
+		assert.NoError(t, err)
+		assert.Len(t, exemplars, 1)
+		assert.Equal(t, float64(42), exemplars[0].Value)
+	})
+
+	t.Run("Exemplars with double value", func(t *testing.T) {
+		pt := pmetric.NewNumberDataPoint()
+		exemplar := pt.Exemplars().AppendEmpty()
+		exemplar.SetTimestamp(pcommon.Timestamp(time.Now().UnixNano()))
+		exemplar.SetDoubleValue(69.420)
+		exemplars, err := getPromExemplars(ctx, everyN, pt)
+		assert.NoError(t, err)
+		assert.Len(t, exemplars, 1)
+		assert.Equal(t, 69.420, exemplars[0].Value)
+	})
+
+	t.Run("Exemplars with unsupported value type", func(t *testing.T) {
+		pt := pmetric.NewNumberDataPoint()
+		exemplar := pt.Exemplars().AppendEmpty()
+		exemplar.SetTimestamp(pcommon.Timestamp(time.Now().UnixNano()))
+		_, err := getPromExemplars(ctx, everyN, pt)
+		assert.Error(t, err)
+	})
+}