[exporter/logging] log min and max for histograms (#5520)

* fix(exporter/logging): log min and max for histograms.

* fix(changelog): update changelog.

* fix(otlptext): check if sum/min/max are present before adding them to the buffer.

* fix(otlptext): make test data include a variation of histogram min/max presence.

* fix(otlptext): check if sum exists on exponential histogram before adding it to the buffer.

* fix(otlptext): use min=0 for ExponentialHistogram test data as zero_count=1.

CHANGELOG.md

@@ -19,6 +19,7 @@
 
 - Use OpenCensus `metric` package for process metrics instead of `stats` package (#5486)
 - Update OTLP to v0.18.0 (#5530)
+- Log histogram min/max fields with `logging` exporter (#5520)
 
 ### 🧰 Bug fixes 🧰
 

internal/otlptext/databuffer.go

@@ -117,7 +117,18 @@ func (b *dataBuffer) logDoubleHistogramDataPoints(ps pmetric.HistogramDataPointS
 		b.logEntry("StartTimestamp: %s", p.StartTimestamp())
 		b.logEntry("Timestamp: %s", p.Timestamp())
 		b.logEntry("Count: %d", p.Count())
-		b.logEntry("Sum: %f", p.Sum())
+
+		if p.HasSum() {
+			b.logEntry("Sum: %f", p.Sum())
+		}
+
+		if p.HasMin() {
+			b.logEntry("Min: %f", p.Min())
+		}
+
+		if p.HasMax() {
+			b.logEntry("Max: %f", p.Max())
+		}
 
 		bounds := p.MExplicitBounds()
 		if len(bounds) != 0 {
@@ -144,7 +155,18 @@ func (b *dataBuffer) logExponentialHistogramDataPoints(ps pmetric.ExponentialHis
 		b.logEntry("StartTimestamp: %s", p.StartTimestamp())
 		b.logEntry("Timestamp: %s", p.Timestamp())
 		b.logEntry("Count: %d", p.Count())
-		b.logEntry("Sum: %f", p.Sum())
+
+		if p.HasSum() {
+			b.logEntry("Sum: %f", p.Sum())
+		}
+
+		if p.HasMin() {
+			b.logEntry("Min: %f", p.Min())
+		}
+
+		if p.HasMax() {
+			b.logEntry("Max: %f", p.Max())
+		}
 
 		scale := int(p.Scale())
 		factor := math.Ldexp(math.Ln2, -scale)

internal/testdata/metric.go

@@ -206,6 +206,8 @@ func initHistogramMetric(hm pmetric.Metric) {
 	hdp1.SetTimestamp(TestMetricTimestamp)
 	hdp1.SetCount(1)
 	hdp1.SetSum(15)
+	hdp1.SetMin(15)
+	hdp1.SetMax(15)
 	hdp1.SetMBucketCounts([]uint64{0, 1})
 	exemplar := hdp1.Exemplars().AppendEmpty()
 	exemplar.SetTimestamp(TestMetricExemplarTimestamp)
@@ -247,6 +249,8 @@ func initExponentialHistogramMetric(hm pmetric.Metric) {
 	hdp1.SetTimestamp(TestMetricTimestamp)
 	hdp1.SetCount(3)
 	hdp1.SetSum(1.25)
+	hdp1.SetMin(0)
+	hdp1.SetMax(1)
 	hdp1.SetZeroCount(1)
 	hdp1.SetScale(-1)